Earthquake detection system and method

Abstract

1. A method for detecting earthquake events, the method comprising the steps of: a) collecting acceleration data over a given period of time from one or more accelerometers located on a grid framework structure, the grid framework structure comprising: i) a first set of horizontal grid members extending in a first direction; ii) a second set of horizontal grid members extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members at an intersection; the first set of horizontal grid members and the second set of horizontal grid members arranged in a horizontal plane to form a grid comprising a plurality of substantially rectangular frames, the plurality of substantially rectangular frames being spaced apart from one another; iii) a plurality of upright columns supporting a first set of horizontal grid members and a second set of horizontal grid members, the plurality of upright columns forming a plurality of vertical storage locations for containers to be stacked between the upright columns; b) comparing the collected acceleration data with ground acceleration data from one or more accelerometers located on the ground; c) determining a differential acceleration between the acceleration data and the ground acceleration data; d) determining displacement data from the differential acceleration; and e) determining whether a seismic event has occurred over a given period of time based on the displacement data.

Description

[Technical Field]

[0001] The present invention relates to the field of seismic detection systems and methods for grid framework structures that support remotely operated load handling devices on trucks located on the grid framework structure for handling storage containers or bins stacked in the grid framework structure. [Background technology]

[0002] Storage systems comprising a three-dimensional storage grid structure in which storage containers / bins are stacked on top of each other are well known. PCT Publication No. WO2015 / 185628A (Ocado) describes a known storage and fulfillment system in which stacks of bins or containers are arranged within a grid framework structure. The bins or containers are accessed by remotely operable load handling devices on trucks positioned on top of the grid framework structure. A system of this type is shown schematically in Figures 1 to 3 of the accompanying drawings.

[0003] As shown in Figures 1 and 2, stackable containers, known as bins or containers 10, are stacked on top of each other to form a stack 12. The stacks 12 are arranged in a grid framework structure 14 in a warehousing or manufacturing environment. The grid framework structure consists of a plurality of storage columns or grid columns. Each grid in the grid framework structure has at least one grid column for storing a stack of containers. Figure 1 is a schematic perspective view of the grid framework structure 14, and Figure 2 is a top-down view showing the stack 12 of bins 10 arranged within the grid framework structure 14. Each bin 10 typically holds multiple product items (not shown), which may be of the same or different product types, depending on the application.

[0004] The grid framework structure 14 includes a plurality of upright members or columns 16 supporting horizontal members 18, 20. A first set of parallel horizontal grid members 18 are positioned perpendicular to a second set of parallel horizontal grid members 20 to form a plurality of horizontal grid structures supported by the upright members 16. The members 16, 18, 20 are typically fabricated from metal and are typically welded or bolted to one another, or a combination of both. The bins 10 are stacked between the members 16, 18, 20 of the grid framework structure 14 such that the grid framework structure 14 guards against horizontal movement of the stack 12 of bins 10 and guides vertical movement of the bins 10.

[0005] The top level of the grid framework structure 14 includes rails 22 arranged in a grid pattern across the top of the stacks 12. With further reference to FIG. 3 , the rails 22 support a plurality of load handling devices 30. A first set 22a of parallel rails 22 guides movement of the robotic load handling devices 30 in a first direction (e.g., the X direction) across the top of the grid framework structure 14, and a second set 22b of parallel rails 22, arranged perpendicular to the first set 22a, guides movement of the load handling devices 30 in a second direction (e.g., the Y direction) perpendicular to the first direction. In this manner, the rails 22 enable movement of the robotic load handling devices 30 laterally in two dimensions in the horizontal XY plane so that the load handling devices 30 can be moved to positions above any of the stacks 12.

[0006] A known load handling device 30 shown in Figures 4 and 5 is described in PCT Patent Publication No. WO2015 / 019055 (Ocado), which is incorporated herein by reference, comprising a vehicle body 32, with each load handling device 30 covering only one grid space of a grid framework structure 14. Here, the load handling device 30 comprises a wheel assembly comprising a first set of wheels 34 consisting of a pair of wheels on the front of the vehicle body 32 and a pair of wheels 34 on the rear of the vehicle body 32 for engaging a first set of rails or tracks to guide movement of the device in a first direction, and a second set of wheels 36 consisting of a pair of wheels 36 on each side of the vehicle body 32 for engaging a second set of rails or tracks to guide movement of the device in a second direction. Each of the sets of wheels is driven to enable movement of the vehicle in the X and Y directions, respectively, along the rails. One or both sets of wheels can be moved vertically to lift each set of wheels off its respective rail, thereby allowing the vehicle to move in a desired direction.

[0007] The load handling device 30 is equipped with a lifting device or crane mechanism for lifting the storage container from above. The crane mechanism includes a winch tether or cable 38 wound on a spool or reel (not shown) and a grabber device 39. The lifting device includes a set of lifting tethers 38 (one tether near each of the four corners of the grabber device) extending vertically and connected near or at the four corners of a lifting frame 39, sometimes known as the grabber device, for releasable connection to the storage container 10. The grabber device 39 is configured to releasably grasp the top of the storage container 10 to lift it from a stack of containers in a storage system of the type shown in FIGS. 1 and 2.

[0008] The wheels 34, 36 are positioned around the periphery of a cavity or recess in the lower portion known as the container receiving recess or container receiving space 40. The recess is sized to accommodate the container 10 when it is lifted by the crane mechanism, as shown in Figures 5(a and b). While in the recess, the container is lifted off the lower rail to allow the vehicle to move laterally to a different location. Upon reaching the target location, e.g., another stack, an access point in a storage system, or a conveyor belt, the bin or container can be lowered from the container receiving portion and released from the grabber device.

[0009] In other examples, the container receiving space 40 of the load handling device 30 may not be located within the body 32 of the load handling device 30. For example, in some examples, the container receiving space 40 may be adjacent to the body 32 of the load handling device 30, e.g., in a cantilever arrangement where the weight of the body 32 of the load handling device 30 balances the weight of the container to be lifted. In such embodiments, a frame or arm of the lifting device may project horizontally from the body 32 of the load handling device 30, and the lifting tethers 38 may be disposed at respective locations on the projecting frame / arms and configured to be raised and lowered from those locations to lift and lower the container 10 into the container receiving space 40 adjacent the body 32.

[0010] Grid framework structures are subject to a variety of external and internal forces, including, but not limited to, ground movement that may be due to the composition of the ground or soil type, forces caused by movement of load handling devices on the grid framework structure that may weigh in excess of 100 kg, movement as a result of nearby structures or moving vehicles such as trains, and even during earthquakes or storms. It is of utmost importance that the individual elements within the grid framework structure remain intact as a result of such external forces experienced by the grid framework structure.

[0011] To ensure the stability of the grid framework structure, prior art storage systems rely heavily on various supports and bracings located within or at least partially along the perimeter of the grid. However, the use of various supports and bracings (anti-shift braces) to stabilize the grid framework structure from internal and external forces is disadvantageous for several reasons. The grid framework structure occupies space or area that could be utilized by the grid to store containers, thereby preventing optimal use of the available space or area for container storage. The need for support structures can limit available options for positioning the grid framework structure, as any auxiliary grid support structure often requires connection to surrounding structures, such as the interior walls of a building, and the requirement for support structures that are not cost-effective.

[0012] WO2019 / 101367 (Autostore Technology AS) teaches a grid support structure for integration into a storage grid structure of an automated storage system. The grid support structure consists of four storage columns interconnected by a plurality of vertically inclined support struts. The storage column profile has a cross section with a hollow central section and four corner sections, each with two right-angled bin guide plates for accommodating the corners of a storage bin. The support struts have a width that allows them to fit midway between two parallel guide plates without impairing the storage column's ability to accommodate a stack of containers or storage bins.

[0013] Therefore, there is a need for an alternative grid framework structure that minimizes the impact on the available space or area for storage of containers to provide a free-standing storage grid, or at least requires less extensive auxiliary grid support structures.

[0014] A large portion of the world's population is located along earthquake fault lines or in the path of powerful storms, such as hurricanes and tornadoes. Locating grid frame structures in such areas risks structural damage from earthquakes and storm events because current grid framework structures may not hold the grid structure together. Powerful earthquakes and storm events can result in the failure of their structural integrity, for example, as a result of structural fasteners not being able to keep the grid rigidly attached to the upright members. Earthquakes can be labeled into four categories, labeled as Type A, B, C, or D, depending on the severity of the earthquake, with Type A being considered the least powerful and Type D being the most powerful. Types A-D can be graded by their spectral acceleration, which is the maximum acceleration, measured in g, that objects above ground level will experience during an earthquake. Type D, considered to represent the most powerful seismic events, generally has measured spectral accelerations (Short-Term Spectral Response Accelerations SDS, see https: / / www.fegstructural.com / seismic-design-category-101 / ) in the range of 0.5g to 1.83g and results in the failure of a large portion of the building. When a powerful seismic event acts on a structure, three-dimensional dynamic forces can compromise the structural fasteners that hold the grid framework structure together, causing the structural fasteners to gradually loosen or disengage from the members in which they are embedded, or, if the structural fasteners remain in place, they can be disrupted through the structural fasteners.

[0015] Many jurisdictions, such as U.S. states, have passed laws mandating that all new residential or commercial buildings be constructed with some seismic bracing features incorporated therein. A grid framework structure is incorporated within the grid framework structure, whereby one or more of the upright members are braced together by one or more bracing members or towers, as shown in FIG. 6. Generally, the bracing members are distributed internally throughout the grid framework structure. The distribution of the internal bracing is highly dependent on the size of the grid framework structure, ground conditions, and environmental conditions such as temperature. However, while grid framework structures can withstand extremely low-level seismic events with spectral accelerations of less than 0.3 g, there are currently no seismic suppression systems for grid framework structures capable of withstanding more powerful Type C and Type C earthquake events, categorized by spectral accelerations in the range of 0.5 g to 1.83 g.

[0016] After a seismic event, the condition of the grid framework structure needs to be assessed. Manual inspection after a seismic event is possible, but of course it is preferable to understand the condition of the grid framework structure before bringing in personnel.

[0017] Before damage in a grid framework structure can be remedied, the first step is to understand the extent of the damage, particularly to measure the degree of yielding in the grid framework structure. Doing this manually would require measuring the positions of structural members at the edges and inside the grid framework structure, which is a labor-intensive and time-consuming process. Another method of measuring displacement that does not require manual intervention is needed.

[0018] Therefore, there is a need for an earthquake detection system that can determine whether a seismic event has occurred and assess the degree of deflection of the grid framework structure without the need for a human to enter the grid and take manual measurements. Summary of the Invention

[0019] One aspect of the present invention is a method for detecting an earthquake event, the method comprising: a) collecting acceleration data over a given period of time from one or more accelerometers located on a grid framework structure, said grid framework structure comprising: i) a first set of horizontal grid members extending in a first direction; ii) a second set of horizontal grid members extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members at intersections, the first set of horizontal grid members and the second set of horizontal grid members being arranged to form a grid comprising a plurality of substantially rectangular frames in a horizontal plane, each substantially rectangular frame defining a grid cell; iii) a plurality of upright columns supporting a first set of horizontal grid members and a second set of horizontal grid members, the plurality of upright columns forming a plurality of vertical storage locations for containers to be stacked between the upright columns; Equipped with b) comparing the collected acceleration data with ground acceleration data from one or more accelerometers located on the ground; c) determining a differential acceleration between the acceleration data and the ground acceleration data; d) determining displacement data from the differential acceleration; e) determining whether a seismic event occurred over a given time period based on the displacement data; The present invention provides a method comprising:

[0020] The acceleration data is collected from one or more accelerometers as a signal of acceleration as a function of time. The differential acceleration is calculated by subtracting the ground acceleration data from the acceleration data, and is the difference between the acceleration data and the ground acceleration data. The differential acceleration represents the acceleration of the grid framework structure relative to the ground.

[0021] The given time period represents the time between the start of the earthquake event and the end of the earthquake event. For example, the given time period may be the time during which the acceleration measured by the accelerometer is significantly higher than the background acceleration, or the time period during which the differential acceleration exceeds a minimum acceleration threshold.

[0022] The step of determining the displacement data may comprise performing a double integration on the differential acceleration data. Integrating the differential acceleration once with respect to time provides the differential velocity (the velocity of the grid framework structure relative to the ground). Integrating the differential acceleration a second time, i.e., integrating the differential velocity with respect to time, provides the displacement data. The displacement data represents the differential displacement (the displacement of the grid framework structure relative to the ground as a result of movement of the grid framework structure) and is a signal of displacement as a function of time. The acceleration data and displacement data represent the acceleration and displacement of points on the grid structure at which each of the one or more accelerometers is located, relative to the ground. The ground acceleration data represents the acceleration of the ground, as the ground acceleration data is collected from one or more accelerometers located on the ground and provides a reference point for calculating the differential acceleration data.

[0023] The one or more accelerometers located on the ground may be attached to a substructure (e.g., a concrete foundation or slab) on which the grid framework structure is built, or alternatively, the one or more accelerometers located on the ground may be placed directly on top of the soil (e.g., located inside a hole in the substructure).

[0024] The step of determining whether an earthquake event has occurred comprises: a) detecting a non-proportional response from displacement data; b) detecting period elongation in the displacement data; c) calculating static displacement from the displacement data; may comprise one or more of:

[0025] In each of these three cases a), b) and c), the step of determining whether a seismic event has occurred may comprise identifying the presence of one or more characteristic vibration regimes in the displacement data, wherein the one or more characteristic vibration regimes are: a) a non-proportional response region; b) a periodic extension region; c) residual drift region and Equipped with.

[0026] In each of these three cases a), b), and c), determining whether a seismic event has occurred may comprise comparing the displacement data, or a parameter derived from the displacement data, to a predetermined threshold. In case a) non-proportional response, the predetermined threshold may comprise a displacement threshold; in case b) period stretching, the predetermined threshold may comprise a predetermined frequency and / or a predetermined period of vibration; and in case c) residual drift, the predetermined threshold may comprise a predetermined static displacement threshold. Each of these three characteristic vibration regions is described in more detail below.

[0027] Case a), the non-proportional response region, can occur when the structural members of the grid framework structure extend beyond their elastic limits and exhibit inelastic behavior.

[0028] Determining whether a seismic event has occurred over a given period of time may comprise determining whether the displacement data exceeds a predetermined displacement threshold corresponding to an elastic limit of a member of the grid structure. Determining whether a seismic event has occurred may comprise identifying a non-proportional response region by determining whether the displacement is proportional to the acceleration.

[0029] Case b), the periodic elongation region, can occur when structural members deflect, resulting in a change in the dynamic properties of the grid framework structure.

[0030] Determining whether a seismic event has occurred may comprise determining a change in frequency and / or period of vibration of the displacement data over a given period of time. Determining the change in frequency and / or period of vibration of the displacement data may comprise determining whether the frequency and / or period of vibration differs from a predetermined frequency and / or predetermined period of vibration. Determining the change in frequency and / or period of vibration of the displacement data may comprise calculating a Fourier transform of the displacement data to obtain a frequency spectrum of the grid framework structure. The method may further comprise providing reference displacement data representative of the behavior of the grid framework structure in the absence of a seismic event and calculating a Fourier transform of the reference displacement data to obtain a reference frequency spectrum of the grid framework structure. The method may further comprise comparing the frequency spectrum of the grid framework structure to the reference frequency spectrum of the grid framework structure. A natural frequency of vibration of the grid structure may be obtained from the frequency spectrum of the grid framework structure. If the natural frequencies obtained from the reference frequency spectrum of the grid framework structure (i.e., the natural frequencies in the absence of a seismic event) differ from the natural frequencies obtained from the frequency spectrum of the grid framework structure, the change in natural frequency may be an indication of deflection in the grid framework structure.

[0031] Case c), residual drift region, can occur when there is static displacement of the grid framework structure that remains after the vibration has subsided, i.e., when the static displacement indicates that the accelerometer has moved from its initial position.

[0032] The displacement data can be divided into two parts: vibration or dynamic displacement, which represents the vibration of the accelerometer around its central position, and static displacement, which represents the movement of the central position of the vibration displacement relative to its origin or initial position. The dynamic displacement indicates that the position of the accelerometer is vibrating around its central position, and the static displacement indicates that the accelerometer has moved or been displaced from its origin or initial position. The displacement data is a superposition of the vibration displacement and the static displacement.

[0033] The step of determining whether a seismic event has occurred over a given period of time may comprise determining a static displacement from the displacement data and determining whether the static displacement exceeds a predetermined static displacement threshold.

[0034] If the center position of the vibration displacement remains at the origin, the static displacement is 0. However, if the structural member to which the accelerometer is attached deflects, the accelerometer will move, and therefore, the center position of its vibration displacement will no longer be at the origin or initial position of the accelerometer. This movement of the center position can also be described as residual drift, which means that the accelerometer has been displaced (i.e., drifted) from its initial position after the vibration displacement has subsided or damped.

[0035] Rather than determining whether a seismic event has occurred from the presence of a non-zero static displacement or residual drift, it is advantageous to define a predetermined static displacement threshold greater than 0. When the static displacement exceeds this predetermined static displacement threshold, a seismic event is deemed to have occurred. A predetermined static displacement of 0 will pick up small displacements and cause false alarms (e.g., measurement errors) due to small displacements that are not caused by a seismic event.

[0036] Any or all of the three cases a), b), and c) may be used to determine whether a seismic event has occurred. In some cases, it may be advantageous to use two or more of these methods to ensure that the event is in fact a seismic event rather than a false positive (e.g., residual drift / static displacement may be detected if the accelerometer moves relative to the grid framework structure rather than indicating a failure of the structural member to which the accelerometer is attached).

[0037] The method may further comprise filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events. Non-seismic events that may cause seismic signals may include the normal operation of storage and retrieval systems or other machinery in the same building or in the surrounding area. For example, seismic motion may be generated by load handling devices moving on a grid framework structure, or conveyor systems, pick stations, moving vehicles (e.g., forklift trucks), or other machinery in the same building. Outside the building, seismic motion may be generated by passing traffic, road construction, or ground movement. Filtering out these non-seismic signals is advantageous because the filtered data is cleaner and less likely to result in false positives (i.e., the method detects a seismic event when one did not occur).

[0038] Filtering the acceleration data may comprise using a high-pass filter, a low-pass filter, and / or a band-pass filter. A high-pass filter removes or attenuates signals at frequencies below a threshold frequency and allows signals at frequencies above the threshold frequency to pass. A low-pass filter removes or attenuates signals at frequencies above the threshold frequency and allows signals at frequencies below the threshold frequency to pass. A band-pass filter removes or attenuates signals at frequencies below a lower threshold frequency or above an upper threshold frequency and allows signals at frequencies between the lower and upper threshold frequencies to pass. Filtering is advantageous because it can remove noise at frequencies other than the frequency range of interest, e.g., the frequency range in which a seismic event occurs or in which signals may change as a result of a seismic event.

[0039] The step of filtering the acceleration data to remove or attenuate one or more signals associated with a non-seismic event may comprise determining frequency ranges in which vibrations occurred in the absence of a seismic event and attenuating or filtering out these frequency ranges from the acceleration data.

[0040] The step of filtering the acceleration data to remove or attenuate one or more signals associated with a non-seismic event may comprise providing reference acceleration data representative of the behavior of the grid framework structure in the absence of a seismic event, determining frequency ranges in the reference acceleration data in which vibrations occurred in the absence of a seismic event, and attenuating or filtering out these frequency ranges from the acceleration data.

[0041] Determining which frequency ranges to filter out may be done by performing a Fourier transform of the acceleration and / or reference acceleration data to obtain a frequency spectrum.

[0042] The one or more accelerometers located on the grid framework structure may comprise a plurality of accelerometers, and determining whether a seismic event has occurred may be based on displacement data from the plurality of accelerometers.

[0043] An advantage of using multiple accelerometers located on the grid framework structure is that there is redundancy added to the method. If a first accelerometer is unable to detect an earthquake event, a second accelerometer is performing the same task and can detect the earthquake event if the first accelerometer does not. If the method relied only on a single accelerometer located on the grid framework structure, the problems with the single accelerometer would mean that the earthquake event would not be detected.

[0044] In some examples with multiple accelerometers located on a grid framework structure, a voting system may be used to determine whether an earthquake event has occurred. Each accelerometer will vote "yes" or "no" depending on whether the data collected by that accelerometer positively identifies an earthquake event. For example, if a majority of the multiple accelerometers vote "yes" (i.e., data from a majority of the multiple accelerometers positively identifies that an earthquake event has occurred), an earthquake event may be deemed to have occurred. A threshold for determining whether an earthquake event has occurred may be based on a percentage of the multiple accelerometers voting "yes," which may be the number of accelerometers (e.g., at least 10 accelerometers) or a percentage of the total number of accelerometers (e.g., a majority or 50%, 2 out of 3, 75%).

[0045] The step of determining whether an earthquake event has occurred may comprise at least two of three of the plurality of accelerometers detecting an earthquake event, where if there are three accelerometers located on a grid framework structure, an earthquake event will be deemed to have occurred if the first accelerometer and the second accelerometer vote "yes" but the third votes "no."

[0046] The method may further comprise sending a signal to one or more output devices in response to determining that an earthquake event has occurred over a given period of time, which is important to alert personnel to the earthquake event so that they can be evacuated from the building.

[0047] The method comprises: a) Whether the grid framework structure has been permanently deformed; and / or b) Whether the grid framework structure is sufficiently intact to continue to operate; and / or c) Whether the grid framework structure is safe for personnel to enter; and / or d) Whether the grid framework structure has the structural capacity to withstand aftershocks. The method may further comprise using differential acceleration and / or displacement data to determine:

[0048] These different states of the grid framework structure are explained in more detail below.

[0049] In examples where the one or more accelerometers comprise multiple accelerometers distributed across the grid framework structure, the method may further comprise using differential acceleration and / or displacement data to determine the extent of damage to different parts of the grid framework structure.

[0050] The method may further comprise preparing the grid framework structure for further seismic activity if the method detects an early stage of a seismic event.

[0051] The step of preparing the grid framework structure for a seismic event includes: cutting off power to components of the grid framework structure; deactivating a load handling device operable on the grid framework structure; activating a brake on the load handling device; cutting off power to a load handling device operable on the grid framework structure; may comprise one or more of:

[0052] Alternatively or additionally, preparatory actions may be taken as a result of an alert from an earthquake early warning system, sometimes known as an Earthquake Early Warning (EEW) or Early Warning System (EWS). Such systems operate on the principle that electronic alerts from the region of the earthquake event's epicenter can travel more quickly than seismic waves. During an earthquake event, P waves (pressure waves or first waves) are followed by S waves (shear waves or second waves). P waves are longitudinal compressional waves that travel faster than S waves and can propagate through liquid layers in the Earth's interior. S waves are transverse shear waves that are more destructive than P waves but travel more slowly. When an earthquake event occurs, the initial P waves trigger sensors that detect their presence. The location and magnitude of the earthquake event are estimated from the P waves, and the system sends an alert to the affected area. Locations farther from the earthquake event's epicenter can have seconds or minutes to prepare before the more destructive S waves arrive. The combination of early warning systems and automated responses can help prevent some of the injuries and damage commonly associated with large earthquake events.

[0053] As a result of an alert from the earthquake early warning system, appropriate actions may be taken. For example, personnel may be evacuated from buildings housing the grid framework structure, vehicles may be parked, power sources (e.g., engines or motors) may be switched off, and other machinery may be turned off or shut down. Additionally, the steps described above for preparing the grid framework structure are applicable.

[0054] In another aspect, the present invention provides a method for condition monitoring a grid framework structure following a seismic event, the grid framework structure comprising: i) a first set of horizontal grid members extending in a first direction; ii) a second set of horizontal grid members extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members at intersections, the first set of horizontal grid members and the second set of horizontal grid members being arranged to form a grid comprising a plurality of substantially rectangular frames in a horizontal plane, each substantially rectangular frame defining a grid cell; iii) a plurality of upright columns supporting a first set of horizontal grid members and a second set of horizontal grid members, the plurality of upright columns forming a plurality of vertical storage locations for containers to be stacked between the upright columns; iv) one or more accelerometers located on the grid framework structure; and Equipped with The method comprises: a) collecting acceleration data from one or more accelerometers over a given period of time; b) comparing the collected acceleration data with ground acceleration data over a given period of time from one or more accelerometers located on the ground; c) determining a differential acceleration between the acceleration data and the ground acceleration data; d) determining the extent of damage to different portions of the grid framework structure that occurred during a given time period by determining whether the differential acceleration data exceeds a predetermined acceleration threshold during the given time period; The present invention provides a method comprising:

[0055] The purpose of condition monitoring is to determine the condition of the grid framework structure after a seismic event, for example, the extent of damage to different portions of the grid framework structure. Condition monitoring after a seismic event is important to assess the extent of damage to different portions of the grid framework structure, allowing the grid framework structure to be repaired faster and reducing downtime. Without condition monitoring, the entire grid framework structure would need to be assessed for damage, and more importantly, there would be no indication of whether the grid framework structure is safe for personnel to enter. The predetermined acceleration threshold is an acceleration value used to define the status of a portion of the grid framework structure; i.e., different actions (e.g., inspection, repair) may be required depending on whether the differential acceleration exceeds the predetermined acceleration threshold.

[0056] The predetermined acceleration threshold may comprise a plurality of predetermined acceleration thresholds, each of the plurality of predetermined acceleration thresholds indicating a different level of damage to one or more of the portions of the grid framework structure, which allows different portions of the grid framework structure to be classified or categorized according to the level of damage so that appropriate action (e.g., inspection and / or repair) can be efficiently undertaken.

[0057] The plurality of predetermined acceleration thresholds may comprise a first acceleration threshold indicative of an elastic limit of a portion of the grid framework structure, such that a differential acceleration of the portion of the grid framework structure that exceeds the first acceleration threshold provides an indication that the portion of the grid framework structure has been permanently deformed. If permanently deformed, the portion of the grid framework structure may not be in a suitable condition to continue operating; for example, a load handling device may not be able to move over a deformed or misaligned track, or the load handling device may not be able to lift a storage container from a stack if the vertical uprights are deformed or misaligned. If not permanently deformed, the portion of the grid framework structure may be in a suitable condition to continue operating; for example, the track has returned to its original shape and position, and thus the load handling device can still operate over the track, and the vertical uprights have returned to their original shape and position, and thus the load handling device can continue to lift a storage container from a stack to retrieve products for customer orders.

[0058] The first acceleration threshold may be substantially 0.6 g.

[0059] The plurality of predetermined acceleration thresholds may comprise a second acceleration threshold that indicates a safety limit, such that a differential acceleration of a portion of the grid framework structure that exceeds the second acceleration threshold provides an indication that the portion of the grid framework structure is unsafe for personnel to enter. Understanding which portions of the grid framework structure are safe for personnel to enter is advantageous for both reducing risk to personnel and allowing personnel to confidently and safely inspect portions of the grid framework structure that are safe for personnel to enter.

[0060] The second acceleration threshold may be substantially 1.0 g.

[0061] The plurality of predetermined acceleration thresholds may comprise a third acceleration threshold indicative of a structural limit, such that a differential acceleration of a portion of the grid framework structure that exceeds the third acceleration threshold provides an indication that the portion of the grid framework structure does not have sufficient structural capacity to withstand the aftershock. The structural limit is a measure of whether the portion of the grid framework structure has sufficient structural capacity to withstand the aftershock, i.e., if the differential acceleration remains below the structural limit, the portion of the grid framework structure is able to withstand the aftershock, and if the differential acceleration exceeds the structural limit, the portion of the grid framework structure is not able to withstand the aftershock and is therefore at risk of collapse as a result of the aftershock. If the third acceleration threshold is exceeded, no personnel should enter the grid framework structure.

[0062] The third acceleration threshold may be substantially 1.83 g.

[0063] The method comprises: f) determining displacement data from the differential acceleration; g) determining the extent of damage to different parts of the grid framework structure by determining whether the displacement data exceeds a predetermined displacement threshold; The sensor may further include:

[0064] A predetermined displacement threshold may indicate an elastic limit, such that a displacement of a portion of the grid framework structure that exceeds the predetermined displacement threshold provides an indication that the portion of the grid framework structure has been permanently deformed. If the displacement of the portion of the grid framework structure is below the predetermined displacement threshold, the elastic limit has not been exceeded and the portion of the grid framework structure has elastically deformed and returned to its original position. This may indicate that the portion of the grid framework structure can continue to operate normally, i.e., that the truck supporting the load handling device is not misaligned and therefore can continue to be used. Knowing which portions of the grid framework structure have not exceeded their elastic limit is advantageous because some portions may be able to continue to operate normally, while other portions are assessed for damage and repaired as necessary. Ensuring business continuity, i.e., being able to continue fulfilling customer orders, is a major benefit.

[0065] In another aspect, the present invention provides an earthquake detection system for a grid framework structure configured to perform the method of any preceding aspect, the earthquake detection system comprising: a) one or more accelerometers mounted on a grid framework structure; b) an input module configured to collect acceleration data from one or more accelerometers; c) a controller in communication with the input module, the controller comprising one or more processors and a memory storing instructions, the instructions, when executed by the one or more processors, causing the one or more processors to: i) determining whether a seismic event has occurred based on the collected acceleration data from the one or more accelerometers; ii) sending a signal to one or more output devices in response to determining that a seismic event has occurred; and to carry out An earthquake detection system is provided, comprising:

[0066] In some cases, the input module may also provide power to the accelerometer.

[0067] The earthquake detection system may further include an output module configured to enable the controller to send signals to one or more output devices.

[0068] The earthquake detection system may further include one or more accelerometers located on the ground near the grid framework structure, which may be used to collect ground acceleration data to be used as a reference in calculating the differential acceleration data, as described above.

[0069] The one or more output devices may comprise a beacon, an alarm, and / or a siren.

[0070] In another aspect, the present invention provides a method for producing a pharmaceutical composition comprising: a first set of horizontal grid members extending in a first direction; a second set of horizontal grid members extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members at intersections, the first set of horizontal grid members and the second set of horizontal grid members arranged to form a grid comprising a plurality of substantially rectangular frames in a substantially horizontal plane, each substantially rectangular frame defining a grid cell; a plurality of upright columns supporting a first set of horizontal grid members and a second set of horizontal grid members, the plurality of upright columns forming a plurality of vertical storage locations for containers to be stacked between the upright columns; A grid framework structure comprising: There is provided a grid framework structure, wherein the grid framework structure further comprises an earthquake detection system of the present invention.

[0071] The one or more accelerometers mounted on the grid framework structure may comprise a plurality of accelerometers arranged along a first direction and / or a second direction of the grid. For example, the first direction may represent the X direction, and the second direction may represent the Y direction, which is perpendicular to the X direction. The accelerometers may be arranged in one or more lines along the X direction and / or the Y direction, or may be arranged in a grid pattern. The plurality of accelerometers may be arranged along at least a portion of the periphery of the grid. For example, the plurality of accelerometers may be arranged in lines along one edge of the grid, or two edges of the grid, or three edges of the grid, or all four edges of the grid. In some examples, a portion of the plurality of accelerometers may be arranged on the periphery of the grid, and the remainder of the accelerometers may be arranged within the grid. At least a portion of the plurality of accelerometers may be arranged diagonally with respect to the first and second directions of the grid. For example, a portion of the plurality of accelerometers may be arranged diagonally across the grid. Combinations of these and other arrangements are also possible.

[0072] The accelerometers may be in a substantially horizontal plane. They may be in the same plane as the grid itself (e.g., mounted on a track or on a horizontal grid member) or in a parallel horizontal plane. They may be located at or near the top of the grid framework structure to measure differential acceleration between the top of the grid framework structure and the ground.

[0073] The advantage of having multiple accelerometers distributed horizontally on the grid framework structure is that the accuracy of the data is improved: a larger number of accelerometers allows the displacement of the grid framework structure to be determined with greater accuracy and more detail.

[0074] An additional benefit of having multiple accelerometers distributed horizontally on the grid framework structure is that data from the accelerometers can be used to determine which part(s) of the grid framework structure sustained damage in a seismic event. If one part of the grid framework structure is damaged but another part remains intact, it may be possible for a load handling device to continue operating on the undamaged part of the grid while the damaged part is repaired. Accelerometer data can also be used to determine the extent of deflection / damage to the grid framework structure, for example, to determine whether a part of the grid framework structure has not exceeded its elastic limit and can continue to operate normally, or whether it is damaged but safe for personnel to enter and assess the situation and take corrective action, or whether it is so damaged that it is unsafe for personnel to enter that area of ​​the grid framework structure.

[0075] The plurality of accelerometers may consist of between 15 and 28 accelerometers.

[0076] One or more accelerometers mounted on a grid framework structure may be mounted on horizontal grid members, hi some examples, the accelerometers may be mounted on tracks, on track supports, or on vertical uprights.

[0077] The grid framework structure may further comprise an exoskeleton comprising a plurality of vertical frame columns braced by one or more bracing members, the grid further being supported by the exoskeleton to form a seismic force restraint system (SFRS). As described in more detail below, the exoskeleton provides additional support to the grid framework structure and protects it from damage in the event of a seismic event.

[0078] One or more accelerometers mounted on the grid framework structure may be mounted on the SFRS. In particular, one or more accelerometers mounted on the grid framework structure may be attached to one or more brace members. The brace members act as sacrificial members in the event of a seismic event (i.e., the brace members will deflect first, protecting the grid framework structure from damage). Therefore, by placing accelerometers on the brace members, the earthquake detection system can detect whether the brace members are deflecting. If the brace members are not deflecting, the grid and supporting framework structure remain intact and can continue to operate. Being able to determine that part of the grid is undamaged and can continue to operate is advantageous because in that case, at least a portion of the storage system can continue to fulfill customer orders without significant downtime, thus reducing costs and enabling business continuity.

[0079] The grid framework structure may be subdivided into multiple modular frames, such that the grid extends across the multiple modular frames. In instances where the grid framework structure is modular, some or all of the modular frames may be supported by an exoskeleton. Each of the multiple modular frames may include an exoskeleton with multiple vertical frame columns braced by one or more bracing members, and the grid is supported by the exoskeleton to form a seismic force restraint system (SFRS), where adjacent modular frames are arranged such that at least a portion of the SFRS is shared between adjacent modular frames.

[0080] Another way to describe the modular grid framework structure is as an assembly comprising a plurality of modular frames, wherein each of the plurality of modular frames comprises the grid framework structure, a grid extends across the plurality of modular frames, and at least one of the plurality of modular frames comprises the earthquake detection system described above.

[0081] An advantage of subdividing a grid framework structure into multiple modular frames is that if one of the modular frames is deflected by a seismic event, the other modular frames may be unaffected and able to continue operating.

[0082] The grid framework structure may further comprise a seismic isolation system for reducing seismic forces acting on the grid framework structure, wherein the grid framework structure is supported by the seismic isolation system, the seismic isolation system comprising a superstructure, a substructure, and at least one base isolation device disposed between the superstructure and the substructure, wherein the at least one base isolation device thus inhibits movement of the superstructure relative to the substructure in a seismic event.

[0083] An earthquake isolation system has the advantage of partially isolating or decoupled the grid framework structure from its foundations, thus attenuating the horizontal component of ground movement during a seismic event. At least one isolation device allows relative movement between the superstructure and substructure, so that not all of the horizontal movement of the ground is translated into horizontal movement of the grid framework structure.

[0084] In another aspect, the present invention provides a method for producing a pharmaceutical composition comprising: i) a first grid framework structure at a first level; ii) a second grid framework structure at a second level, the second level being above the first level; A multi-storey grid framework structure comprising: There is provided herein a multi-storey grid framework structure, wherein a first grid framework structure and a second grid framework structure each comprise a grid framework structure as defined herein.

[0085] An advantage of multi-storey grid framework construction is that it provides more storage space for the same footprint, which is particularly useful in territories where usable land is at a premium and therefore there is an advantage to building upwards rather than outwards, which makes the most efficient use of available space.

[0086] In another aspect, the present invention provides a method for producing a pharmaceutical composition comprising: a grid framework structure as defined herein; one or more load handling devices remotely operable to move one or more containers stored in the grid framework structure; and each of the one or more load handling devices: i) a wheel assembly for guiding a load handling device on the grid framework structure; ii) a container receiving space located on top of the grid framework structure; iii) a lifting device arranged to lift a single container from the stack and place it in the container receiving space; Equipped with A storage and retrieval system is provided, comprising:

[0087] Further features and aspects of the present invention will become apparent from the following detailed description of illustrative embodiments which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0088] [Figure 1]1 is a schematic diagram of a grid framework structure according to known systems; [Figure 2] Schematic of a top-down view showing a stack of bins arranged within the framework structure of FIG. 1. [Figure 3] 1 is a schematic diagram of a known system of load handling devices operating on a grid framework structure. [Figure 4] 1 is a schematic perspective view of a load handling device showing a lifting device gripping a container from above; [Figure 5(a)] 5(a) is a schematic perspective cutaway view of the load handling device of FIG. 4 showing a container accommodated within the container receiving space of the load handling device; FIG. [Figure 5(b)] 5(b) is a schematic perspective cutaway view of the load handling device of FIG. 4, showing the container receiving space of the load handling device; [Figure 6] 1 is a perspective view of a grid framework structure according to one embodiment of the present invention; [Figure 7] FIG. 10 is a perspective view of a cap plate for joining adjacent grid elements at intersections, according to one embodiment of the present invention. [Figure 8] FIG. 10 is a perspective view of a cap plate linking adjacent grid elements by connecting the ends of the grid elements at intersections, according to one embodiment of the present invention. [Figure 9] 1 is a perspective view of a cap plate linking adjacent grid elements at intersections by connecting a central section of a grid element with an end of an adjacent grid element, according to an embodiment of the present invention; FIG. [Figure 10] 1 is a perspective view of a cap plate fitted to an upright column for connecting adjacent grid elements to each other at their crossover points, according to one embodiment of the present invention. FIG. [Figure 11] FIG. 10 is a perspective view illustrating a pattern of grid elements at an intersection, according to one embodiment of the present invention. [Figure 12(a)] 1 is a schematic diagram of a braced tower according to one embodiment of the present invention. [Figure 12(b)] 1 is a schematic diagram of a brace tower according to one embodiment of the present invention. [Figure 13] FIG. 1 is a perspective view of an adjustable foot, according to one embodiment of the present invention. [Figure 14] 1A and 1B are (a) a side view and (b) a plan view of an anchor foot according to a second embodiment of the present invention; [Figure 15] 1 is a perspective view of a seismic grid framework structure according to a first embodiment of the present invention; [Figure 16] Schematic diagram of the main hardware components of the earthquake detection system. [Figure 17] FIG. 1 illustrates a possible arrangement of an earthquake detection system architecture where post-event data processing occurs in the cloud. [Figure 18(a)] 1 is a schematic plan view of a grid structure showing different options for the location of accelerometers on the grid structure. [Figure 18(b)] 1 is a schematic plan view of a grid structure showing different options for the location of accelerometers on the grid structure. [Figure 19] 1 is a flowchart illustrating steps in a method for detecting earthquake events, according to one embodiment of the present invention. [Figure 20] Graph of exemplary displacement data showing non-proportional response, periodic elongation, and residual drift regions. [Figure 21] 2 is a schematic diagram of a controller and other components of an earthquake detection system, according to one embodiment of the present invention. [Figure 22] A floor plan showing the modularity of the grid framework construction. [Figure 23] Schematic plan view of a modular grid structure with pick aisles and mezzanines. [Figure 24] 24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on the diagonals of the grid structure. [Figure 25] 24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on the diagonals of the grid structure. [Figure 26]24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on two sides of the grid structure. [Figure 27] 24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on two sides of the grid structure. [Figure 28] 24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on four sides of the grid structure. [Figure 29] 27 is a schematic plan view of the grid structure with the accelerometer placement shown in FIG. 26 showing the approximate location of the damage on the grid structure. [Figure 30] Schematic diagram of (a) a single-storey storage system and (b) a multi-storey storage system. [Figure 31] 1 is a cross-sectional view of a portion of an earthquake isolation system showing the isolation devices. DETAILED DESCRIPTION OF THE INVENTION

[0089] [Grid framework structure] FIG. 6 shows a perspective view of a grid framework structure 114 according to one embodiment of the present invention. The basic component of the grid framework structure 114 according to the present invention comprises a grid or grid structure 50 in a horizontal plane attached to a plurality of upright columns or members 116. The terms “upright member(s)” and “upright column(s)” are used interchangeably herein to mean the same thing. As shown in FIG. 6 , the grid 50 comprises a series of horizontal cross beams or grid members 118, 120 arranged to form a plurality of rectangular frames 54; more specifically, a first set of grid members 118 extends in a first direction x, and a second set of grid members 120 extends in a second direction y, the second set of grid members 120 extending transversely relative to the first set of grid members 118 in a substantially horizontal plane. Each of the grid members extending in the first direction and / or the grid members extending in the second direction may be subdivided or segmented into individual grid elements that are coupled or linked to one another.

[0090] As an alternative to a grid framework structure 114 that directly supports a two-dimensional grid 50 on a plurality of upright columns 116 as described with reference to FIG. 6 , in another example, the grid framework structure 114 supports the grid 50 on top of a plurality of prefabricated modular panels arranged in a grid pattern, the details of which are described briefly below and fully in PCT application WO2022034195A1 in the name of Ocado Innovation Ltd, which is incorporated herein by reference. The grid framework structure described in WO2022034195A1 addresses the issues of time and cost to assemble by supporting a 2D grid on a supporting framework structure comprising a plurality of prefabricated modular panels arranged in a three-dimensional grid pattern to define a plurality of grid cells. Each of the grid cells of the supporting framework structure is sized to support two or more grid cells of the grid upon which load handling devices operate. The grid framework structure is formed from fewer structural components, yet still maintains the same structural integrity as the typical "stick-built" grid framework structure 114 described above, and is much faster and cheaper to construct.

[0091] The prefabricated modular panels of the grid framework structure described above include upright columns 116. For example, subgroups of the upright columns may be braced by one or more bracing members to form a prefabricated panel or frame. For purposes of the present invention, a plurality of upright columns 116 may also include upright columns 116 in a prefabricated panel. The grid framework structure 114 may include any suitable supporting framework structure for supporting the grid, including upright columns 116 that directly support the grid and / or prefabricated panels and / or frames that incorporate the upright columns 116.

[0092] The connecting plate or cap plate 150 shown in FIG. 7 can be used to link or join individual grid elements to one another in both the first and second directions at the junctions where the grid elements crisscross or intersect in each of the upright columns; i.e., the cap plate 150 is used to connect the grid elements together in the upright columns 116. As a result, the upright columns are interconnected at the upper ends of the multiple grid elements at the junctions where the grid elements crisscross in a grid structure by the cap plate 150. As shown in FIG. 7, the cap plate 150 is cross-shaped and has four connecting portions 152 for connecting to the grid elements at their intersections, at their ends, or anywhere along their lengths (see FIGS. 8 and 9). The cap plate 150 includes a spigot or protrusion 154 sized to fit snugly into the hollow central section 70 of the upright column 116 (at the second end of the upright column) to interconnect multiple upright columns to the grid member, as shown in Figure 10. Figure 13 illustrates the joint at the intersection between adjacent grid elements at the upper ends of the upright columns with one or more cap plates. For purposes of illustration, the lower end of the upright column attached to the floor constitutes the first end of the upright column, and the upper end of the upright column adjacent the grid 50 constitutes the second end of the upright column.

[0093] The first set of grid members and the second set of grid members support a first set of tracks or rails 22a and a second set of tracks or rails 22b, respectively, along which a load handling device moves one or more containers on the grid framework structure. In some examples, the tracks 22a, 22b may be integral with the grid members. In other examples, the tracks may be attached to the top of the grid members (also known as track supports). For purposes of this description, the intersections 56 form nodes of the grid structure. Each of the rectangular frames 54 forms a grid cell and is sized for a remotely operated load handling device or bot to travel on the grid framework structure to retrieve and lower one or more containers stacked between the upright columns 116. The grid 50 is elevated above ground level by grid members 118, 120 attached to a plurality of upright columns 116 at crisscrossing intersections or nodes 56 so as to form a plurality of vertical storage locations 58 for containers to be stacked between and guided by the upright columns 116 vertically through a plurality of substantially rectangular frames 54. For purposes of the present invention, a stack of containers can encompass a plurality of containers or one or more containers.

[0094] The grid framework structure 114 can be considered a free-standing (or self-supporting) linear assembly of upright columns 116, i.e., a four-walled framework, that supports the grid 50 formed from intersecting horizontal grid members 118, 120. Two or more of the upright columns are braced by at least one diagonal brace member to provide one or more brace towers 80 within the grid framework structure 114. The structural rigidity and moment resistance of the grid framework structure are provided in large part by incorporating one or more truss assemblies, or brace towers 80, at least partially around the periphery of the grid framework structure and / or within its body (see FIG. 6). The truss assemblies can have triangular or other non-trapezoidal shapes. For example, the truss assemblies can be any type of truss that provides structural rigidity to the grid framework structure against lateral forces, including, but not limited to, a Warren truss, a K truss, a Fink truss, a Pratt truss, a Gambrel truss, or a Howe truss. Bolts or other suitable attachment means can be used to secure the diagonal braces to the upright columns. The brace tower 80 shown in FIG. 12 according to one embodiment of the present invention may be formed by rigidly connecting a subset or subgroup of multiple upright columns 116 with one or more angled or diagonal braces or diagonal brace members 82. For purposes of the present invention, the diagonal braces 82 cooperate with the upright columns 116 in the brace tower 80 to form one or more triangles. The subset of multiple upright columns braced together to form the brace tower 80 of the present invention may be two or more adjacent upright columns 116 that lie in the same or a single vertical plane and are joined to each other by one or more diagonal braces 82. Stated another way, two or more adjacent upright columns 116 connected by one or more diagonal braces 82 lie in the same or a single vertical plane, i.e., they are coplanar.In the specific embodiment of the present invention shown in FIG. 12, each brace tower 80 includes three parallel upright columns that lie in a single vertical plane (coplanar) and are rigidly connected to one another by a plurality of diagonal braces 82. Two of the three upright columns 116a, 116b are disposed laterally on either side of a middle upright column 116c, and the two laterally disposed upright columns 116a, 116b are rigidly connected to the middle upright column 116c by a plurality of diagonal braces 82. In the brace tower 80 of the present invention, one end of the diagonal brace member 82 is connected to the middle upright column by a joining plate 121. The joining plate 121 is inserted into a slot through the hollow central section of the middle upright column 116c, perpendicular to the longitudinal direction of the upright columns. The structural rigidity of the grid framework structure is improved by bracing one or more subgroups of upright columns 116 internally within the grid framework structure with one or more diagonal braces 82. For purposes of this invention, the terms "vertical upright column," "upright column," and "upright member" are used interchangeably throughout the description.

[0095] The grid framework structure is anchored to the ground, in this case, to the superstructure, by one or more anchor bolts. In one embodiment of the present invention, one or more of the upright columns are attached at their lower ends to the superstructure by adjustable feet (see FIG. 13). The adjustable feet allow the height of one or more of the upright columns, and therefore the height of the grid framework structure as a whole, to be adjusted. This allows the level of the grid in the horizontal plane to be substantially flat for load handling devices, mostly remotely operated, to advance on the grid structure, thereby preventing any tracks or rails from being subjected to strain due to variations in the height of one or more of the upright members 116 in the grid framework structure. The adjustable foot 90 shown in FIG. 13 comprises a base plate 92 and a threaded spindle or rod 94 that is threadably engageable with a separate push-fit cap or plug 96 placed at the lower end of the upright column, as shown in FIG. 8. As shown in FIG. 6, one or more of the upright columns 116 are attached to the floor or superstructure by the base plate 92. The base plate 92 has one or more mounting holes for attaching the base plate 92 to the floor with one or more bolts.

[0096] In addition to attaching the upright columns that make up the grid framework structure with the adjustable feet described above, one or more of the upright columns that make up the brast tower 80 are anchored to the superstructure with one or more anchor feet 132a, 132b (see FIG. 12). In the specific embodiment shown in FIG. 12, the outer upright columns 116a, 116b or the laterally disposed upright columns 116a, 116b are anchored to the concrete foundation with one or more anchor feet 132, and the middle upright column 116c is supported on the adjustable foot 90 described above. The lower end (first end) of the brast tower is anchored to the concrete foundation with one or more anchor bolts. Various types of anchor feet 132a, 132b for rigidly anchoring the brast tower to the concrete foundation are applicable to the present invention. The anchor foot functions to bear the upright column load and the bracing load of the brace assembly 82 of the brace tower 80.

[0097] 12 and 14 show two examples of anchor feet used to anchor a brace tower to a concrete foundation according to the present invention. The anchor foot shown in FIG. 12 is more substantial in terms of size and weight compared to the anchor foot shown in FIG. 14. The anchor foot 132a shown in FIG. 12 is fabricated as a T-joint with a base plate 133 in a horizontal plane for anchoring to the floor with one or more anchor bolts and an anchor plate 134 perpendicular to the base plate 133 for attaching to the lower end of the upright column and the end of the brace member 82. The anchor plate 134 is oriented so that the surface of the anchor plate 134 with the largest surface area is in the same vertical plane as the three upright columns 116a, 116b, and 116c of the brace tower 80, e.g., so that the surface of the anchor plate 134 with the largest surface area is coplanar with the upright members 116a, 116b, and 116c of the brace tower 80. A problem with the anchor foot 132a shown in Figure 12 is the substantial weight and therefore cost to make the anchor foot.

[0098] 14 illustrates an alternative anchor foot 132b for anchoring a brace tower 80 to a concrete foundation according to a second embodiment of the present invention. Instead of a solid rectangular base plate 133, the anchor foot is a topology optimized design that optimizes the material layout within a given design space for a given set of loads. Two loads considered in the topology optimization of the anchor foot are the load from the upright columns 116a, 116b, 116c and the load from the brace member 82. Based on the constraints imposed by the applied loads, the anchor foot 132b of the present invention includes a stabilizer 136 with multiple individual fingers or digits 138 extending from an upright portion 140, such that the load is distributed among the multiple fingers 138, e.g., the separate fingers. In the specific embodiment of the invention shown in Figure 14, upright portion 140 comprises an anchor plate arranged to rigidly connect upright columns 116a, 116b and diagonal brace 82 by one or more bolts so as to support the load of upright columns 116a, 116b and the applied load of diagonal brace 82. Like anchor plate 134 of the first embodiment of the invention shown in Figure 12, anchor plate 140 is oriented so that the surface of anchor plate 140 with the largest surface area lies in the same vertical plane as the three upright columns 116a, 116b, 116c that make up brace tower 80 of the invention (see Figure 7). Using the terminology of the invention, the surfaces of upright columns 116a, 116b, 116c, diagonal brace 82, and anchor plates 134, 140 all lie in the same plane, i.e., they are coplanar.

[0099] One or more of the individual fingers 138 of the anchor foot 132b extend or splay in two or more different directions from the upright portion 140 to provide improved stability of the anchor foot 132b. One or more of the fingers 138 are of different lengths to aid in the stability of the anchor foot 132b of the present invention. The lengths of the fingers 138 can vary, thus providing different levels of stability for the brace tower 80. One or more connecting webs 142 are used to support one or more of the fingers 138 from axial movement. The anchor foot 132b is anchored to a concrete foundation by one or more bolts through holes in the fingers 138 of the anchor foot 132b.

[0100] In a particular embodiment of the invention, five fingers 138 of varying lengths are shown extending from an upright portion 140 with holes at the distal ends of the fingers 138 for anchoring the anchor foot in the ground via an anchor bolt (see FIG. 14b). The anchor foot 132b, according to a second embodiment of the invention, may be formed as a single body, e.g., a casting, or as separate parts joined together, e.g., a weldment. [Earthquake Framework Suppression System] While the current grid framework structure 114 is sufficient when the ground is relatively stable, i.e., has spectral accelerations of less than 0.33 g, categorized as Type A and Type B events, it is not sufficient when the grid framework structure is subjected to a powerful seismic event generating strong lateral forces exceeding 0.55 g spectral accelerations, categorized as Type C or D seismic events. Such a powerful seismic event can damage the structural fasteners connecting grid elements (e.g., track support elements) at their intersections, causing the structural fasteners to gradually loosen or disengage from the cap plates to which they are bolted. The result is a weakening or complete loss of structural integrity of the grid framework structure, as lateral forces can no longer be safely transmitted to the structural foundation. Failure can occur at the intersections of the grid members or track support elements that make up the grid. The braced towers 80 described above, used to maintain the structural integrity of the grid framework structure, may not be able to withstand the lateral forces resulting from a powerful Type D seismic event significantly exceeding 0.55 g.

[0101] One way to alleviate the above problems is to support the grid framework structure with an exoskeleton, as described in WO2021175873 (Ocado), the contents of which are incorporated herein by reference. The exoskeleton provides an additional level of support to the grid framework structure from earthquake events. More specifically, the exoskeleton comprises a plurality of vertical frame columns 218 braced by at least one bracing member, and the grid is further supported by the exoskeleton to form a seismic force suppression system (SFRS).

[0102] The present invention provides a seismically restrained grid framework structure 214, sometimes known as a seismic force restraint system (SFRS), as shown in FIG. 15 to maintain the structural integrity of the grid framework structure during strong earthquake and storm events. That is, the SFRS supports the grid framework structure against strong lateral forces resulting from Type C and / or D earthquake events. The restraint system reduces or eliminates failure of structural fasteners, such as joints securing grid elements to upright columns via cap plates at intersections, due to breakage, loosening, detachment, or fracture across the structural components. The SFRS of the present invention includes a perimeter bracing structure 215 supported by multiple vertical frame columns 218 to support the grid against lateral forces. The perimeter bracing structure 215 includes at least one brace member 220, 222 extending from the multiple vertical frame columns 218. For purposes of the present invention, the term "support" is interpreted to cover any form of mechanical connection between the SFRS and the grid. For example, lateral forces generated at the grid level are transferred to the SFRS of the present invention at the perimeter of the grid 250. Additionally, for purposes of the present invention, at least one brace member 220, 222 may be at least one horizontal frame beam between vertical frame columns 218 and / or at least one diagonal brace member 222 between vertical frame columns 218. For purposes of the present invention, the terms "vertical frame column" and "vertical support frame column" are used interchangeably herein to refer to the columns 218 supporting the brace members 220, 222. The vertical frame columns 218 differ from the vertical upright columns 116 supporting the grid, described above, in that they are spaced apart by one or more spacers 74. The vertical frame columns 218, along with the perimeter brace structure of the present invention, form part of the SFRS. The SFRS may be envisioned as forming an exoskeleton around the grid framework structure.

[0103] The SFRS can be envisioned as forming an exoskeleton around the grid framework structure of the present invention. In a specific embodiment of the present invention, the perimeter bracing structure 215 is supported by at least one vertical frame column 218a at the corners of the grid framework structure and braced by at least one horizontal frame beam 220 extending from the corners of the grid framework structure. In a specific embodiment of the present invention shown in FIG. 15, four vertical frame support columns 218a are arranged at the four corners of the grid framework structure to form a three-dimensional exoskeleton, e.g., a rectangular parallelepiped structure, having a top surface and four sides. Because the SFRS forms an exoskeleton around the perimeter of the grid framework structure of the present invention, the vertical frame support columns 218a at the corners of the grid framework structure may be referred to as perimeter frame columns to simplify the description of the SFRS of the present invention. In a specific embodiment of the present invention, four horizontal frame beams 220 are attached to the top of each of the four perimeter frame columns 218a to extend from each corner of the SFRS frame. The horizontal frame beam 220 may be assumed to represent an upper chord that connects the two vertical frame columns 218a at their upper ends of the perimeter bracing structure 215, and may be referred to as the perimeter frame beam.

[0104] At least two of the vertical frame columns 218 a, 218 b are connected to each other by at least one diagonal brace member 222 to form a brace frame for providing lateral support for the grid framework structure in the forward and / or rearward directions. A brace frame is a structural system designed to withstand seismic forces. The diagonal brace members 222, like trusses, are designed to work in tension and compression and are designed to withstand lateral loads in the form of axial stresses, either in tension or compression. The brace frame may be positioned around the perimeter of the grid framework structure or around at least one face of the grid framework structure and designed to absorb most of the lateral forces experienced by the grid framework structure.

[0105] Any type of braced frame commonly known in the art for providing lateral support to grid and / or grid framework structures is applicable to the present invention. In FIG. 15, the braced frame is a cross-braced frame, in which two diagonal braces 222 cross each other to form an X. The braced frame may also be a K-braced frame, in which two diagonal braces meet at an apex on a horizontal frame beam. Bracing at least two of the vertical frame columns 218a, 218b with at least one horizontal frame beam 220 at the top of the vertical frame columns 218a, 218b forms at least one drag strut or collector, commonly known in the art. A drag strut or collector is where at least two vertical frame columns 218a, 218b are braced by the horizontal frame beam 220 at the top of the two vertical frame columns 218a, 218b, and functions to collect and transmit diaphragm shear forces to the vertical frame columns.

[0106] Each of the vertical frame columns 218a, 218b may be a solid support with a C-shaped or U-shaped cross section, a double C, or a double U. Preferably, each of the vertical frame columns 218a, 218b is an I-shaped solid support with an upper beam flange and a lower beam flange. At least two of the vertical frame columns 218a, 218b are rigidly connected to each other by at least one bracing member 220, such as a diagonal bracing member 222 and / or a horizontal frame beam. Each of the vertical frame columns 218a, 218b has an upper end and a lower end, and the lower end is anchored to a concrete foundation using one or more anchor bolts. Various methods commonly known in the art for anchoring the lower end of a vertical frame column to a concrete foundation to provide lateral support to a braced frame against strong seismic events are applicable to the present invention.

[0107] Multiple brace frames of SFRS can be arranged around the perimeter of the grid framework structure (i.e., around each face of the grid framework structure) to form a single frame body, as shown in FIG. 15 , i.e., the SFRS form an exoskeleton that supports the grid framework structure against strong lateral forces resulting from a Type C or Type D earthquake event. Alternatively, at least one brace frame can be arranged on at least one face of the grid framework structure. Brace frames of the present invention can be arranged on at least one of the four sides of a rectangular parallelepiped. In the specific embodiment shown in FIG. 15 , a brace frame is arranged on each of the four sides of the rectangular parallelepiped. Perimeter frame columns 218 a at the corners of the grid framework structure are braced by at least one horizontal frame beam 220, 320 extending longitudinally from the top of each of the four perimeter frame columns 218 a to form a substantially rectangular or square perimeter frame in the horizontal plane that surrounds the perimeter of the grid.

[0108] At least one 218b of the plurality of vertical frame columns 218a, 218b may be disposed midway or between two vertical frame columns 218a at the corners of the grid framework structure to divide the exoskeleton into a braced frame in which at least two vertical frame columns 218a, 218b are braced by at least one diagonal brace 222 and a drag strut or collector 232. The drag strut or collector 232 is where the at least two vertical frame columns 218a, 218b are braced by a horizontal frame beam 220 at the top of those two vertical frame columns 218a, 218b and functions to collect and transfer diaphragm shear forces to the vertical frame columns 218a, 218b. In a specific embodiment of the present invention, shown in FIG. 15, the SFRS comprises a braced frame in which at least two of the vertical frame columns 218a, 218b are braced with at least one diagonal brace 222 and a horizontal frame beam 220 to form a drag strut. Also shown in FIG. 15, at least one diagonal brace member 222 is disposed on one side of the intermediate vertical support column 218b to form a braced frame 230, and a drag strut 232 is disposed on the other side of the braced frame. The bracing of the vertical frame columns at the corners of the SFRS and the intermediate vertical support column with at least one diagonal brace member on each side of the SFRS around the grid framework structure depends on the nature of the earthquake event, i.e., whether the earthquake event is a Type C or Type D earthquake event. For a more robust suppression system to respond to a Type D earthquake event, a braced frame with at least one diagonal brace according to the present invention is disposed around the perimeter of the grid framework structure. [Modular grid framework structure] In some examples, the seismic grid framework structure 214 may be modularized, such that adjacent modules 514 of a grid framework structure in an assembly of two or more modules or modular frames share at least a portion of the SFRS of one or more neighboring modular frames. Each of the modules 514 comprises the seismic grid framework structure described above with reference to FIG. 15 , and thus each module 514 comprises a predetermined number of grid cells and a perimeter bracing structure 215 supported by a plurality of vertical frame columns 218 a, b of the present invention, which further support the grid. Two or more module assemblies may be assembled together to increase the storage capacity of the overall seismic grid framework structure, where adjacent modules in the assembly share at least a portion of the perimeter bracing structure of the present invention, i.e., a first modular frame shares at least a portion of the perimeter bracing structure of a second modular frame, whereby the first modular frame is adjacent to the second modular frame. In other words, adjacent modules share common brace members 220, 222 that are supported by at least two vertical frame columns 218a. Brace members include, but are not limited to, horizontal frame beams 220 and / or diagonal brace members 222.

[0109] The sharing of at least a portion of the SFRS by adjacent modules can be envisioned in the plan view shown in FIG. 22 . Four modular grids are shown in FIG. 22 , sharing portions of the SFRS of adjacent modular grids. In FIG. 22 , a common brace frame 230 of the SFRS, shown as a triangular drawing, is shared between adjacent modular grids 514(a-d). Also, a drag strut 232, shown as a dashed line in FIG. 22 , is shared between adjacent modules 514(a-d) such that adjacent modules share the common drag strut 232. Because adjacent modules share at least a portion of the SFRS, the grids from adjacent modules are connected to a common horizontal frame beam 220, and thus, lateral forces generated within the grids of adjacent modules are transferred to the common horizontal frame beam 220. Because the grids are supported at the boundaries of the grids such that portions of the grid overhang the SFRS, the grids from adjacent modules can be coupled to each other by connecting the overhangs from adjacent modules.

[0110] Also shared between adjacent modules are vertical frame columns 218a, 218b, which support at least one brace member 220, 222. By sharing portions of the SFRS between adjacent modules, the external bracing structures of adjacent modules 514 cooperate together as a single body to deflect lateral forces. In other words, by connecting grids 50 from adjacent modules with common bracing members 220, 222, e.g., horizontal frame beams, multiple adjacent grids 50 can function together to form at least one Vierendeel truss, thereby transmitting lateral forces across multiple grids to vertical frame columns 218a, 218b at the perimeter of the module. The perimeter bracing structure 215 shared between adjacent modules 514 also provides internal bracing within the assembly of modules 514. Internal bracing includes adjacent modules that share a common brace frame 230 and / or a common drag strut 232.

[0111] The seismic grid framework structure of the present invention allows a mezzanine structure 700 to be integrated with the perimeter bracing structure 215 and vertical frame columns 218 of the present invention. The ability to modularize the seismic grid framework structure, as described above, allows a mezzanine 702 to share at least a portion of the SFRS of an adjacent module, i.e., share a common brace frame 230 and / or drag struts 232, with an adjacent or neighboring module. A cross-sectional view of an assembly of modules 514 incorporating an integrated mezzanine 702 within the assembly is shown in FIG. 23. As seen in FIG. 23, the mezzanine structure 700 shares the perimeter bracing structure 215 and vertical frame columns 218 of the adjacent module 514, and thus the mezzanine structure 700 is supported by the vertical frame columns 218a, b that support the adjacent module 514. The adjacent module 514 may be a grid framework structure that stores one or more containers or storage bins in a stack. In comparison to the stand-alone mezzanines used in prior art storage systems, the mezzanine of the seismic grid framework structure is integrated within the SFRS such that a separate vertical support column is not required to support the mezzanine.

[0112] To create a mezzanine, vertical frame columns 218a, b supporting the grid frame structure of adjacent or laterally disposed modules 514 are connected to one another by one or more bracing members, e.g., horizontal frame beams to create a mezzanine floor, and one or more diagonal bracing members 222. The vertical support (frame) columns supporting the mezzanine floor can be braced to provide more support to the mezzanine structure, as shown in FIG. 23. The combination of the SFRS, incorporating the grid framework structure and mezzanine, provides a single framework that surrounds the assembly. The SFRS is versatile in that the perimeter frame structure 215 is flexible to integrate various other structures into the SFRS, and thus integrate additional perimeter frame structures to support the grid and / or integrated mezzanines, simply by linking the perimeter frame structure and vertical frame columns of adjacent modules together using one or more bracing members, e.g., horizontal frame beams. A plan view of an assembly of modules, each with a seismic grid framework structure on either side of a mezzanine structure 700 to house a station, is shown in Figure 23. As seen in Figure 23, the mezzanine structure 700 is integrated with SFRS on either side of the mezzanine structure 700, such that the SFRS of the individual modules or modular frames 514 are shared to provide an integrated SFRS that encompasses those modules and the mezzanine.

[0113] In the particular arrangement shown in Figure 23, twelve modules 514 are arranged in a 3x4 grid. The bold lines indicate the edges of the modules, where bracing members (e.g., horizontal frame beams or diagonal bracing members) support the grid 50. The bold lines around the outside of the structure indicate the perimeter frame structure 215. The grid structure 50 extends continuously across the top of all of the modules 514, so that the load handling device 30 can move across the grid 50 from one module 514 to another.

[0114] The grid framework structure is divided into two parts, and a mezzanine structure 700 extends across a pick aisle 702 between the two parts. The pick aisle 702 can house a pick station or other service area below the grid 50. A perimeter brace structure 215 extends around the modules 514, the pick aisle 702, and the mezzanine 700. An additional mezzanine 704 extends to the side to provide a maintenance area where load handling devices can be de-inducted from the grid to perform routine maintenance activities or repairs. The mezzanine 704 also provides additional space below the grid 50 for storage or service areas. [Earthquake Detection System Hardware] 16, an earthquake detection system 300 comprises one or more accelerometers 302 mounted on the grid framework structure 114. The one or more accelerometers 302 may be located at or near the top of the grid framework structure 114. An additional one or more accelerometers 302a may be located on the ground to provide a reference point and allow differential acceleration to be measured at the top of the grid framework structure 114 with respect to the ground. The accelerometers 302 may be located around the periphery of the grid framework structure and / or within the grid framework structure.

[0115] In examples where the grid framework structure 114 comprises an SFRS or perimeter brace structure 215, as in the example shown in Figure 15, the accelerometers 302 may be mounted either on the horizontal grid members 118, 120 or on components of the SFRS, for example, on the horizontal brace members 220 or diagonal brace members 222. The accelerometers 302, 302a may be specially designed for the purpose or may be off-the-shelf components.

[0116] 22 and 23 , in examples where the grid framework structure is modular and comprises an assembly of modular frames 514, the accelerometers 302 may be mounted either on the horizontal grid members 118, 120 or on components of the SFRS, such as on horizontal brace members 220 or diagonal brace members 222. The accelerometers 302 may be mounted on parts of the SFRS shared between adjacent modules 514, such as at the intersections of horizontal brace members or horizontal frame beams 220 at the corners of the modules 514, or at the center of the horizontal frame beams. The earthquake detection system 300 further comprises an input module 304 configured to receive input from the one or more accelerometers 302. In some examples, the input module 304 may also be configured to supply / provide power to the one or more accelerometers 302.

[0117] The earthquake detection system 300 further comprises a controller 306 communicatively coupled to the input module for processing data collected from the one or more accelerometers 302. The controller 306 may be described as a cDAQ (compact data acquisition), and may also be either specially designed for the purpose or an off-the-shelf component. The controller 306 may be provided with a mains power supply.

[0118] The earthquake detection system 300 further comprises an output module 308 coupled to one or more output devices 310. The output module is communicatively coupled to the controller 306 and configured to receive signals from the controller 306 indicative of an earthquake event. The output module 308 may be a relay output module. In some examples, multiple relays may be triggered based on different criteria. The output device 310 may include an alarm, a beacon, a siren, a graphical user interface display, or any other suitable output device. The controller 306 may be located in a maintenance area adjacent to or near the grid framework structure. The accelerometer 302 may be connected to the controller 306 wirelessly or via a cable (in which case a junction box may be used). Signal processing and data analysis are performed by the controller 306.

[0119] 16 is a simplified schematic diagram of the major hardware components of earthquake detection system 300. As shown, data from accelerometer 302 and ground accelerometer 302a is collected by input module 304 and sent to controller 306. Controller 306 then processes the data and sends signals via output module 308 to output device 310.

[0120] In some examples, data from the accelerometers (raw data and / or post-processed data from the controller) may be stored in a database, stored either locally at the maintenance area or in the cloud. In some examples, further processing of the data may occur after the event to confirm that a seismic event occurred and / or to perform further calculations.

[0121] FIG. 21 shows an exemplary embodiment of the controller 306 with its input modules 304 and output modules 308. In this embodiment, the controller is an N9133 cDAQ (Miniature Data Acquisition). A cDAQ chassis 312 houses the controller 306 and provides eight slots into which input or output modules can be inserted. In this example, six of the slots are occupied by input modules 304 (NI-9231) for receiving data from the accelerometer 302, one slot is occupied by output module 308 (NI-9482 relay output module), and one slot is occupied by a digital input / output module 314 (NI-9401). In this system, the digital input / output module 314 can be used as a digital output to drive an output device 310 and also receive fault alarms from auxiliary equipment. The cDAQ is enclosed within an outer casing 316, which also houses other components, as described below.

[0122] The input module 304 is connected to an input terminal 318, which is connected to a connection point 320 on the outside of the outer casing 316. The connection point 320 connects cables from the accelerometers 302 on the grid framework structure and also connects cables from the ground accelerometer 302a located on the ground.

[0123] The output module 308 is connected to a relay output terminal 322, which is connected to an output device 310 (in this case, a beacon and a buzzer with three different colors). When an earthquake event is detected, the beacon can light up to provide a visual indication and the buzzer can sound to provide an audible warning. Different colors can be used to represent the severity of the earthquake event (e.g., red for the most severe event, yellow for a less severe event, and green if no event was detected). After an earthquake event, the output device 310 can be reset using an alarm reset key switch 324.

[0124] A UPS (uninterruptible power supply) 326 and a UPS battery 330 are provided which connect to the controller 306 via a power input terminal 328. The UPS ensures that the earthquake detection system can still operate if the main power is interrupted. A UPS is generally used to provide emergency power to a load when there is a failure in the input power or main power, providing near instantaneous protection from input power interruptions.

[0125] A wireless router 332 is provided for transmitting data from the controller. A wireless antenna 334 is provided on the outside of the external casing 316. Data from the controller may be transmitted to a computer and stored locally (e.g., in a maintenance area) or in the cloud, as described above.

[0126] The outer casing 316 is provided with attachment points 336 for attaching the outer casing to a wall or other structure.

[0127] FIG. 17 shows one possible arrangement of the system architecture in which post-event data processing occurs in the cloud. In this example, accelerometer 302 is located on the SFRS beam or brace members 220, 222 of the grid framework structure or on the horizontal members 118, 120. An additional accelerometer 302b is located on the ground. Input from all of these accelerometers is directed to controller 306 by junction box 312. The controller processes the data from the accelerometers, and a visual indicator (an example of an output device 310) indicates whether an earthquake event has been detected. Data from the controller (which may be raw or processed data from the accelerometers) is directed to wifi router 314 and then sent to cloud database 316. Further processing of the data can occur in the cloud via cloud processor 318, and a graphic user interface 320 can display visual indicators of failure and / or more detailed data using data from the cloud processor obtained via a web app. An advantage of processing data on the cloud is that the data can be viewed from anywhere, on-site or off-site, to monitor the status of the grid framework structure and to further understand the impact of seismic events.

[0128] In some examples, the controller 306 of the earthquake detection system may be integrated into other control systems for the grid framework structure 114 .

[0129] One or more output devices 310 may be used by personnel to check the status of the grid framework structure and determine whether it is structurally safe to access after an event. Visual and audible indicators may be used to communicate the status and inform personnel whether it is safe to access the grid. For example, a visual indicator may show a red, amber, or green status. A red status means that the grid framework structure is unsafe and the building needs to be evacuated; an amber status means that the grid framework structure is safe for personnel to enter but needs to be inspected and repaired or realigned before load handling devices can operate on the grid; and a green status means that the grid framework structure is safe to continue operating.

[0130] In some cases, a spectral acceleration threshold may be used to determine whether the status is red, amber, or green. For example, if the measured acceleration exceeds a predetermined spectral acceleration threshold, the status of the grid framework structure may be classified as "red." In some cases, there may be more than one predetermined spectral acceleration threshold; for example, if a lower spectral acceleration threshold is exceeded, the status may be defined as "amber," and if an upper spectral acceleration threshold is exceeded, the status may be defined as "red."

[0131] One or more output devices 310 may be remote, i.e., not located inside the building in which the grid framework structure is housed, so that personnel can check the status remotely if they do not have access to the building.

[0132] After an earthquake event, one or more output devices may be reset (e.g., alarms may be turned off) so that they do not continue to operate after investigation and / or corrective action. Positioning the accelerometer on the grid FIG. 18 shows two possible arrangements of accelerometer locations on the grid structure 50. In FIG. 18(a), the majority of the accelerometers 302 are arranged in a diagonal across the center of the grid structure 50. In FIG. 18(b), the accelerometers 302 are arranged along the periphery of the grid structure 50, along two of the four edges. In both cases, an additional accelerometer 302a is positioned on the ground to measure the differential acceleration of the accelerometers on the grid structure relative to the ground. Of course, these are only illustrative examples, and any suitable arrangement of accelerometers 302 on the periphery of and / or within the grid structure may be used.

[0133] In instances where the grid framework structure includes SFRS or external braced structures, it may be advantageous to place accelerometers on structural members of the braced structures, as these members are expected to be the first to buckle in a seismic event. In the grid framework structure shown in Figure 15, for example, accelerometers may be placed on the horizontal frame beams 220 or diagonal brace members 222 of the perimeter braced framework.

[0134] Accelerometers 302 may be located at or near the top of the grid framework structure, allowing displacement of the grid to be measured relative to displacement on the ground, giving an indication of deflection at the top of the structure.

[0135] The accelerometer 302a located on the ground may be attached to a concrete foundation or slab on which the grid framework structure is built, or alternatively, the accelerometer 302a may be placed directly on top of the soil (e.g., located inside a hole in the concrete foundation slab).

[0136] A recent study (see https: / / www.nature.com / articles / s41598-018-37716-y) found that the asymmetric vertical acceleration records observed during a magnitude 6.3 earthquake can be explained by the "flapping effect," i.e., the local elastic bounce of the foundation slab on which the sensor was installed. The results suggest that the extremely large accelerations recorded did not reflect actual ground shaking, but were caused by the local system response around the sensor. This finding has important implications for both seismic hazard assessment and accelerometer installation methodology in all earthquake-prone countries. A simulation model consisting of a foundation slab and an irregular contact surface between the slab and the underlying soil successfully explained both the mainshock and aftershock records. The elastic bounce ("flapping effect") of a slab, for example, resting on an irregular surface, is induced by vertical movement through the system, accompanied by variations in the horizontal direction. Rather than representing the actual shaking of the ground, the measurements are, at least in part, the local system response around the sensor.

[0137] The irregular contact surface allows for localized elastic rebound of the concrete slab during earthquake ground shaking. Such irregular contact surfaces, which may have been created by differential settlement of the soil or soil erosion over time, were confirmed by field investigations, which found several small gaps (<1 cm) between the concrete slab and the soil ground.

[0138] To prevent similar soil-slab interactions in grid framework structures, the foundation slab may be rigidly attached to the soil ground, for example, using piles or anchors. Alternatively or additionally, the slab properties (thickness, stiffness) may be designed to minimize the effect of elastic bounce. Alternatively or additionally, the ground accelerometer 302a may be placed directly on the soil ground, for example, through a hole or gap in the foundation slab. The term "located on the ground" in this specification should be interpreted to cover both the situation where the accelerometer 302a is fixed to the foundation slab and the situation where the accelerometer is located directly on the soil ground.

[0139] Further examples of possible arrangements of accelerometer locations, as applied to the modular seismic grid framework structure previously described and shown in FIG. 23, are shown in FIGS. 24-28.

[0140] In the arrangement shown in FIG. 24, five accelerometers 302 are located on the grid framework structure. As in FIG. 18, an additional accelerometer 302a is positioned on the ground to measure the differential acceleration of the accelerometers on the grid structure relative to the ground. The accelerometers 302 are located at the intersection points of the modules 514. In the example shown, the accelerometers are mounted on bracing structures, which may be on vertical frame columns, horizontal frame beams, or diagonal bracing members. Four of the accelerometers are positioned diagonally, with the fifth accelerometer collinear with the fourth accelerometer.

[0141] In the arrangement shown in Figure 25, in addition to the ground accelerometer 302a, nine accelerometers 302 are located on the grid framework structure. Five of the accelerometers are in the same locations as in the example shown in Figure 24. Four additional accelerometers are placed intermediate the five accelerometers of Figure 24, positioned at the center of the module 514 rather than at the intersections. The accelerometers may be mounted on horizontal grid members (track supports). Again, the majority of the accelerometers extend diagonally across the grid.

[0142] In the arrangement shown in Figure 26, in addition to the ground accelerometer 302a, eight accelerometers 302 are located on the grid framework structure. The accelerometers are arranged along two edges of the grid framework structure. One line of the accelerometers extends in a first direction (X direction) and a second line of the accelerometers extends in a second direction (Y direction). As in the example shown in Figure 24, the accelerometers 302 are located at the intersection points of the modules 514 and mounted on the brace structure.

[0143] In the arrangement shown in Figure 27, in addition to the ground accelerometer 302a, fifteen accelerometers 302 are located on the grid framework structure. Eight of the accelerometers 302 are in the same locations as in Figure 26. Seven additional accelerometers are positioned intermediate the eight accelerometers of Figure 26, positioned midway along the edges of the module 514 rather than at the intersections. Again, one line of accelerometers extends in a first direction (X-direction) and a second line of accelerometers extends in a second direction (Y-direction). As in Figure 26, the accelerometers are positioned along two sides of the grid framework structure.

[0144] 28, in addition to the ground accelerometer 302a, 28 accelerometers 302 are located on the grid framework structure. The accelerometers are positioned around the perimeter of the perimeter brace structure 215, along all four edges of the brace structure. In this case, two lines of the accelerometers extend in a first direction (X direction) and two lines of the accelerometers extend in a second direction (Y direction), meeting at the four corners of the grid to form a substantially rectangular shape around the perimeter of the grid.

[0145] These placements of accelerometers are examples only, and other placements are possible. While the illustrated examples apply to a modular seismic grid framework structure, these placements of accelerometers may also be used on standard non-seismic grid framework structures, either modular or non-modular. The number of accelerometers may scale with the size of the grid. In examples where the grid is modular, the number of accelerometers may scale with the number of modules 514.

[0146] In some instances, increasing the number of accelerometers beyond a given number will yield diminishing returns, i.e., further increases in the number of accelerometers will not provide substantial further improvement in the accuracy of the acceleration data. The marginal improvement in accuracy from adding more accelerometers to an earthquake detection system may not justify the increased cost and increased complexity of a system with a greater number of accelerometers.

[0147] The distribution of accelerometers on a grid framework structure differs from that required for other structures, such as a building. While a building may have one or two accelerometers on each floor, a grid framework structure has a greater number of accelerometers at or toward the top of the grid framework structure. This difference in distribution is necessary because an earthquake detection system on a grid framework structure can detect which parts of the grid are damaged, and a typical grid framework structure for a storage and retrieval system extends over a wide area. On the other hand, an earthquake detection system in a building must determine which floors of the building are safe for human entry; therefore, accelerometers may be distributed vertically (one on each floor) rather than horizontally (many accelerometers on upper floors). In a building, the purpose of the earthquake detection system is to assess the structural integrity of each floor or level of the building, whereas in a grid framework structure, the purpose of the earthquake detection system is to assess the structural integrity of the entire grid framework structure, which is located above the ground in the building.

[0148] A typical building in an earthquake zone is a tower block or other tall, multi-story building with many floors, but does not extend over a wide area compared to the height of the building. This is especially true in locations like Japan, where available land is at a premium and there is therefore a tendency to build upward rather than outward. For this reason, the distribution of accelerometers differs from what would be common in tall buildings, with the accelerometers distributed horizontally rather than vertically, at or near the top of a grid framework structure. The accelerometers may be distributed in a substantially horizontal plane.

[0149] For example, FIG. 29 shows a grid framework structure with an accelerometer arrangement similar to that of FIG. 26, with accelerometers positioned along two edges of the grid framework structure and mounted on horizontal frame beam 220. In particular, accelerometer 302b is mounted on horizontal frame beam 220b, and accelerometer 302c is mounted on horizontal frame beam 220c. In the illustrated example, only accelerometer 302b and accelerometer 302c measured significant accelerations sufficient to determine that horizontal frame beams 220b and 220c to which these two accelerometers were attached had deflected and moved away from their initial positions. The other accelerometers 302b measured accelerations that did not indicate deflection. The locations of the two accelerometers 302b and 302c allow the most damaged part of the grid to be identified. The damaged part of the grid, along with the deflected horizontal frame beams 220b and 220c, is highlighted on Figure 26 with an asterisk. This information is useful because it indicates that other parts of the grid (e.g., the upper left corner) are intact and may be able to continue to operate and are safe for human entry.

[0150] The use of several accelerometers at different locations distributed over the grid framework structure, rather than a single accelerometer, is advantageous because it allows damaged section(s) of the grid to be identified after a seismic event. The placement of accelerometers around the grid on two or more edges is particularly useful because it allows identification of which parts of the grid are sufficiently intact to continue operating normally, which parts are too damaged to immediately resume operation but are safe enough to bring in personnel to repair the damage, and which parts are dangerous to personnel.

[0151] In examples where the grid framework structure is a seismic grid framework structure (either a modular structure or a unitary structure), the accelerometers may be mounted directly on the brace structure. In particular, the accelerometers may be mounted on the horizontal frame beams 220, which extend horizontally along the edges of the grid. If the accelerometers mounted on the horizontal frame beams indicate residual drift, the horizontal frame beams are deflecting. Positioning the accelerometers on the perimeter brace structure 215 allows the earthquake detection system to determine whether members of the perimeter brace structure are deflecting. In examples where the grid framework structure is an assembly of modular frames (as in FIG. 23 ), determining which members of the perimeter brace structure are deflecting can allow individual modules 514 to be categorized into different states or failure modes depending on the amount of residual drift. [Failure Mode] A seismic event may result in a variety of different failure modes or conditions of the grid framework structure, which have different consequences and require different actions. Elastic limit - the moment before deflection of the bracing members. If the bracing members are still within their elastic limits, there is no permanent deformation of the grid framework structure and normal operation can continue after a seismic event. The elastic limit state occurs below an acceleration of approximately 0.6g. Immediate occupancy - The level of acceptable plastic or elastic deformation that allows personnel to safely re-enter a building after a seismic event to assess and repair damage. The immediate occupancy state occurs for accelerations between about 0.6g and about 1g. Life Safety - The grid framework structure may have significant structural damage but has reserve structural capacity to withstand aftershocks. The building may not be able to be used until after repairs have been made. Life safety conditions occur for accelerations between about 1g and about 1.83g. Collapse Prevention - The grid framework structure is pushed to the limits of its strength and stiffness and is on the verge of collapse. Aftershocks can cause the grid framework structure or building to collapse. The collapse prevention state occurs for accelerations above approximately 1.83g.

[0152] The condition of the grid framework structure can also be determined based on the spectral acceleration measured by the accelerometers on top of the grid framework structure. The grid framework structure has a natural period and a natural frequency that will depend on the size, shape, and material from which the grid framework structure is constructed. After a seismic event occurs, the data can be analyzed to determine whether the frequency spectrum during the seismic event contained components that were close to the natural frequency of the grid framework structure; if so, further damage would be expected because applied vibrations close to the natural frequency or natural period would result in resonance and therefore higher amplitudes of vibration.

[0153] Many building codes impose limits on the maximum allowable movement during a seismic event before a structure is classified as "deficient." For example, in the United States, the maximum allowable lateral displacement measured during a seismic event is 2% of the structure's height, and in Japan, the maximum allowable lateral displacement measured during a seismic event is 0.5% of the structure's height. If a structure is classified as "deficient" according to a building code, the structure may need to be recertified by an appropriately qualified person before it can be considered in compliance with the building code.

[0154] Grid framework structures can be extremely large structures with thousands of components that can potentially fail. Without a means of identifying where damage occurred, every significant part of the grid framework structure would have to be inspected individually. While visual inspection of parts on the outside of the grid framework structure is relatively straightforward, inspecting parts inside the grid framework structure is extremely time consuming, especially given the presence of stacks of storage containers, which would need to be moved to allow for visual inspection of the components within the grid framework structure.

[0155] When a storage and retrieval system is taken offline for inspection after a seismic event, this is extremely costly because the system cannot fulfill customer orders while it is offline. Therefore, it is advantageous to minimize downtime and get the storage and retrieval system up and running as quickly as possible.

[0156] On the other hand, if the storage and retrieval system continues to operate when it is damaged, this may affect or jeopardize other systems, and therefore it is important to ensure that the system is safe and capable of normal operation before bringing it back online.

[0157] There is a large difference in cost between a "ready to use" failure mode and a "life-safe" failure mode. If there is no way to distinguish between the states of the grid framework structure, a more cautious approach must be taken to avoid endangering life.

[0158] In some instances, particularly where the grid framework structure is modular, different parts of the grid framework structure may be in different states, for example, some parts may be safe to continue operating normally, some parts may be safe to enter by personnel to replace damaged parts, and some parts may be unsafe. Understanding the state or failure modes of different parts of the grid framework structure allows downtime to be minimized while ensuring personnel safety and compliance with building codes. [Method for generating displacement data] A method for generating displacement data to determine if a seismic event has occurred is shown in FIG. 19 and described below.

[0159] In step 101, raw data is captured by an accelerometer in the form of a signal of acceleration versus time.

[0160] The data is filtered in step 102. The controller's first task upon receiving the signal from the accelerometer is to filter the signal to remove excessive noise. This may be done, for example, by using a bandpass filter to band-limit the waveform (i.e., to attenuate or remove vibrations above or below a specified frequency band), or by using a high-pass filter to attenuate low-frequency vibrations, or by using a low-pass filter to attenuate high-frequency noise.

[0161] Additionally, the controller may filter out frequencies associated with other known sources of noise, such as vibrations caused by load handling devices moving on the grid framework structure, or other components or peripheral equipment on the grid framework structure, or even in the same building. To do this, known sources of noise may be characterized by recording a background acceleration signal in the absence of seismic activity and then analyzing this background acceleration signal to determine characteristic background frequencies, for example, by calculating a Fourier transform of the collected signal in the frequency domain. These characteristic background frequencies may then be filtered out or attenuated from the acceleration signal received by the controller from the accelerometer. Alternatively, the Fourier transform of the background acceleration signal may be subtracted from the Fourier transform of the acceleration signal from the accelerometer, thus removing events with characteristic background frequencies from that signal. In this way, detecting seismic events becomes easier, as anomalous events can be more easily distinguished from background noise.

[0162] Filtering out known sources of noise is important for earthquake detection systems for grid framework structures, especially those that do not have an exoskeleton to provide additional support during a seismic event. Acceleration and deceleration of load handling devices as they move on top of the grid is an additional movement that must be taken into account. This movement will affect accelerometer readings significantly more than, for example, people moving within a building because people in a building may be vertically dispersed on different floors rather than all at the top of the structure, may be moving more slowly, and may not be moving continuously. People in a building may move vertically at least as much as horizontally (e.g., riding elevators and going up and down between different floors), and a building may be empty at certain times rather than filled with people moving continuously. For this reason, filtering out known sources of noise is advantageous.

[0163] A ground accelerometer 302a is provided, located on the ground, beside or below the grid framework structure. The ground accelerometer measures acceleration at ground level. In step 103, the acceleration at ground level is then used to calculate a differential acceleration of the accelerometer at the top of the grid framework structure relative to the ground. The controller subtracts the acceleration signal measured by the ground accelerometer from the acceleration signal measured by the accelerometer at the top of the grid framework structure to calculate the differential acceleration.

[0164] In step 104, the controller determines the displacement of the grid framework structure relative to the ground from the calculated differential acceleration. This can be achieved mathematically by performing a double integration on the differential acceleration signal (i.e., integrating once over time to obtain a velocity signal, and then integrating again over time to obtain a displacement signal). Thus, a displacement signal is obtained from each of the accelerometers.

[0165] In step 105, the displacement data may be analyzed to determine whether a seismic event has occurred. [Detecting earthquake events from displacement data] Figure 20 shows an example of displacement data calculated from accelerometers on a grid framework structure during a seismic event. Displacement is plotted as a function of time. There are three distinct regions of displacement response that can be seen on the graph: non-proportional response, period extension, and residual drift.

[0166] The first region is a non-proportional response, characterized by high amplitude spikes. In this region, the amplitude (displacement response) is not proportional to the applied force. This indicates that the flexural strength of the structural member has been exceeded and the material no longer exhibits linear elastic behavior. In the absence of a seismic event, the material of a structural component behaves linearly and follows Hooke's law, where displacement is proportional to the applied force.

[0167] F=kx where F is the applied force, k is the stiffness or spring constant of the material, and x is the displacement. The stiffness k depends on the cross-sectional area, length, and Young's modulus of the material. The above equation applies when the material of a structural component is below its flexural strength. When the flexural strength is exceeded, the material begins to behave nonlinearly and the value of k is no longer a constant. In the non-proportional response region, displacement can be higher than would be expected if the material were behaving elastically.

[0168] A non-proportional response may be detected by determining whether the amplitude of the displacement signal exceeds a predetermined displacement threshold corresponding to the elastic limit of the structural members of the grid framework structure. Alternatively, a non-proportional response may be detected by comparing the acceleration signal (after filtering) with the displacement signal and determining whether the amplitudes of the two signals are proportional.

[0169] The second region is period elongation, where the time period of vibration is increased from its normal value. This occurs because the deflection changes the dynamic properties of the grid framework structure. To determine the period of vibration, a Fourier transform of the signal in the frequency domain can be calculated. The largest spike in the frequency domain will be the vibration frequency of the grid framework structure during the period elongation region of the seismic event. To determine if the period has changed, the vibration period can be compared to a reference period, which corresponds to the natural frequency of the vibration of the grid framework structure. The natural frequency can be determined by taking a Fourier transform of the displacement signal in the absence of a seismic event.

[0170] The third region is residual drift, where there is a static non-zero displacement that remains after the displacement vibrations have stopped or returned to their normal level. This can be seen as the dashed line on Figure 20, where the displacement has shifted away from zero after the amplitude of the vibrations has reduced. This residual drift or residual displacement is an indication of how far the accelerometer has moved from its original position, i.e., how far the structural member to which the accelerometer is attached has moved.

[0171] These three areas (nonlinear response, period elongation, and residual drift) provide three different methods for identifying faults from displacement-time signals. In practice, any one of these three methods can be used, or a combination of two or all three can be used. The simplest method is residual drift, because it simply means that the structure has moved after a seismic event, which indicates a fault. It has the advantage that it is easy to estimate the degree of structural deflection from the magnitude of static displacement. However, the residual drift method alone may not be accurate enough and is prone to the risk of false positives (for example, if the accelerometer moves rather than the grid structure itself). Using a combination of methods will yield more accurate results.

[0172] The non-proportional response method and the cyclic extension method are more complex and require more analysis. However, these two methods are more indicative of a flexure failure in the grid framework structure because the only time the non-proportional response and cyclic extension phenomena occur is when the grid framework structure is deflected. If a non-proportional response and / or cyclic extension is detected, there may be a flexure failure. Determining the degree of flexure failure is more difficult with these methods, but the residual drift allows for an easy estimation of the degree of deflection. Therefore, it is preferable to use a combination of all three methods. [Adaptive gain control and offset compensation] In some cases, adaptive gain control may be used to compensate for the difference between the predicted and measured peak-to-peak displacement as a function of frequency, as described below. For a range of frequencies, the peak-to-peak displacement of the accelerometer is calculated according to the method described above and shown in FIG. 19. The calculated peak-to-peak displacement is compared to the measured peak-to-peak displacement. At low frequencies, the calculated peak-to-peak displacement tends to underestimate the displacement. Filtering out low frequencies from the acceleration signal by using a high-pass or band-pass filter makes the calculated displacement more accurate (closer to the measured displacement).

[0173] If the error in the displacement calculation is a fixed percentage of the displacement, the error can be corrected by multiplying the calculated displacement by a gain or scale factor. This procedure is repeated over a range of frequencies, which produces a reference curve of gain or scale factor versus frequency. This reference curve can be applied to the calculated peak-to-peak displacement to correct for the error and more accurately estimate the peak-to-peak displacement of the accelerometer.

[0174] To simulate residual drift (see residual drift region shown in Figure 20), an acceleration signal is created by superimposing peak-to-peak vibration and static displacement to simulate deflection of structural elements within the grid framework structure. The acceleration signal is filtered and integrated twice to calculate a displacement signal. The calculated displacement signal exhibits an initial transient response that may be expected as a result of double integration, after which the signal settles to its expected position (i.e., static displacement).

[0175] Accelerometers do not measure exactly zero when stationary due to background noise and due to an instrument input offset voltage in the acceleration measurement. This offset voltage is small, but increases when double integrated over a long period of time. To compensate for this effect, offset compensation (e.g., by an averaging algorithm) is applied to the signal to cancel out the offset voltage. As with dynamic displacement, the calculated static displacement tends to be underestimated at low frequencies, so adaptive gain control can be applied, as described above for peak-to-peak displacement calculation. [Multi-storey storage system] The earthquake detection system and method of the present invention can be equally applied to multi-story storage systems located in multi-story buildings. In some instances, as well as having a grid framework structure on the ground floor of a building, additional grid framework structures can be located on one or more upper floors of the building. For example, a perimeter grid framework structure for warm goods can be located on the ground floor, and a (usually smaller) cooling grid framework structure for cold goods can be located on an upper floor. This can be the second floor of the building, i.e., the floor immediately above the ground floor, or a higher floor, such as the third, fourth, or fifth floor. In other instances, there can be three or more grid framework structures located on different floors in the same building. In some instances, a single grid framework structure can be located on a higher floor of a multi-story building rather than on the ground floor.

[0176] Figure 30(a) shows an example with a single storey building 100 having a single grid framework structure 101 located on the ground floor 102 of the building 100. As in the previous example, one or more ground accelerometers 105 are located on the ground (either on the substructure supporting the lower grid framework structure 101, or just above the soil ground, as previously described). One or more accelerometers 106 are mounted on the grid framework structure 101, i.e., either on the grid or on the supporting framework structure.

[0177] FIG. 30(b) shows an example of a multi-story building 100 having a lower grid framework structure 101 located on the ground floor 102 of the building 100 and an upper grid framework structure 103 located on an upper floor 104 of the building 100. The upper floor 104 can be the second floor of the building 100, as in the illustrated example, or another upper floor. As in the previous example, one or more ground accelerometers 105 are located on the ground (either on the substructure supporting the lower grid framework structure 101, as previously described, or just above the soil ground). One or more accelerometers (which will be referred to as lower grid accelerometers 106) are mounted on the lower grid framework structure, i.e., either on the grid or on the supporting framework structure. On the upper floor 104, one or more accelerometers 107 (which will be referred to as upper floor accelerometers 107) are located on the floor at the bottom of the upper grid framework structure 103. One or more accelerometers 108 (which will be referred to as upper grid accelerometers 108) are mounted on the upper grid framework structure 103, either on the grid or on the supporting framework structure.

[0178] Seismic demand is the acceleration or force that ground movement (represented by the signal shown in Figure 30) imparts to a building or structure. The seismic demand at the ground will be measured by ground accelerometers 105. The seismic demand on the upper floors will depend on both ground acceleration and building movement. Generally, the seismic demand will be higher on higher floors of the building. The seismic demand in Figure 30 is represented by right-pointing arrows. In Figure 30(b), the right-pointing arrow on the upper floor 104 is longer than that on the ground floor 102, representing a higher seismic demand (and higher acceleration / displacement) of the upper floor 104 and, therefore, the upper grid framework structure 103.

[0179] Seismic capacity is the acceleration or force that a building or structure can withstand, and is a function of the structure's materials and design. Engineering design requires that the seismic capacity be greater than or equal to the earthquake demand. The seismic capacity of the upper and lower grid framework structures, indicated by the left-pointing arrows in Figure 30, is the same regardless of which floor the grid framework structure is located on.

[0180] When calculating the differential acceleration for the grid framework structure on the upper floor, the same method can be used as described previously in this application. The differential acceleration can be calculated by taking the difference between the acceleration measured by the upper grid accelerometer 108 and the acceleration measured by the upper floor accelerometer 107, as well as by taking the difference between the acceleration measured by the upper grid accelerometer 108 and the acceleration measured by the ground accelerometer 105. This allows the movement of the upper grid structure 103 to be characterized both relative to the floor it rests on within the building 100, and relative to the ground. [Seismic isolation] In some examples, the grid framework structure includes an earthquake isolation system for reducing seismic forces acting on the grid framework structure. A cross-sectional view of an example earthquake isolation system 208 is shown in FIG. 31. The earthquake isolation system 208 includes a superstructure or diaphragm 202 and a substructure or foundation 200. The superstructure 202 includes at least a portion, and in some cases, all, of the load-bearing structure of the grid framework structure 114. The superstructure 202 may be a concrete load-bearing structure. The grid framework structure 114, and more specifically, the footings of the upright columns 116, are attached to the superstructure 202 by one or more anchor bolts. The upright columns 116, and therefore the grid framework structure 114, are attached to the superstructure 202 by one or more adjustable feet 90 and / or anchor feet 132. Further details of the adjustable feet and anchor feet are described above. The requirement for a superstructure 202 at the base of the grid framework structure has the benefit of redistributing concentrated forces from one or more individual brace frame locations to a relatively larger number of support points. The substructure 200 comprises at least the foundation of the grid framework structure, which may be earth or a concrete foundation.

[0181] Disposed intermediate the superstructure 202 and the substructure 200 are one or more isolation devices 204. The distribution of the isolation devices 204 can be adjusted to eliminate irregularities or possible torsional issues in the superstructure 202. The one or more isolation devices 204 isolate the superstructure 202, and thus the grid framework structure 114 mounted thereon, from substructure or ground movement during an earthquake. In this way, large deflections and high accelerations are prevented from being transmitted to the grid framework structure 114. The number and distribution of the one or more isolation devices 204 depend on the weight of the grid framework structure, the height of the grid framework structure, and the composition of the ground. For example, the energy of seismic waves with higher frequencies tends to be absorbed by hard rock soil, while seismic waves with lower frequencies pass through hard rock soil without being absorbed but are ultimately amplified by soft sediments. The isolation devices may be distributed in an array having a grid-like pattern, with each isolation device 204 attached between the substructure 200 and the superstructure 202 by a lower mounting plate and an upper mounting plate, respectively. The isolation devices provide lateral flexibility for the seismic isolation system to damp ground movements transmitted to the grid framework structure. Various known isolation devices that attempt to obtain maximum energy dissipation through seismic control are acceptable in the present invention. Options include (but are not limited to) elastomeric bearings, sliding bearings, or a combination thereof.

[0182] In instances where a grid framework structure is located in a multi-story building, the grid framework structure may be located on an upper floor rather than on the ground floor. Alternatively, in addition to the grid framework structure located on the ground floor, a second grid framework structure may be located on the upper floor. Typically, seismic demands in multi-story buildings are higher for upper floors, but in instances where the entire building utilizes an earthquake isolation system (i.e., the building is supported by a superstructure 202 that can move relative to the substructure 200), in some cases the seismic demands may be lower on the higher floors than on the ground floor. [Definition] As used herein, the phrase "movement in the n-direction," where n is one of x, y, and z (and related expressions), is intended to mean movement in either direction substantially along or parallel to the n-axis (i.e., toward the positive end of the n-axis or toward the negative end of the n-axis). As used herein, the word "connect" and its derivatives are intended to encompass the possibilities of direct and indirect connections. For example, "x is connected to y" is intended to encompass the possibilities of x being directly connected to y, with no intervening components, and the possibilities of x being indirectly connected to y, with one or more intervening components. Where a direct connection is intended, the words "directly connected," "direct connection," or the like will be used. Similarly, the word "support," and its derivatives are intended to encompass the possibilities of direct and indirect contact.

[0183] For example, "x supports y" is intended to include the possibility that x directly supports and directly contacts y without any intervening components, as well as the possibility that x indirectly supports y with one or more intervening components contacting x and / or y. The word "mount" and its derivatives are intended to include the possibilities of direct and indirect mounting. For example, "x is mounted on y" is intended to include the possibility that x is directly mounted on y without any intervening components, as well as the possibility that x is indirectly mounted on y with one or more intervening components.

[0184] As used herein, the word "comprises," and its derivatives, are intended to have an inclusive rather than exclusive meaning. For example, "x comprises y" is intended to include the possibilities that x contains one and only y, contains multiple y's, or contains one or more y's, and one or more other elements. When an exclusive meaning is intended, the phrase "x consists of y" is used, meaning that x contains only y and nothing else. The following is a summary of the claims as originally filed: [C1] 1. A method for detecting a seismic event, the method comprising: a) collecting acceleration data over a given period of time from one or more accelerometers 302 located on a grid framework structure 114, wherein said grid framework structure 114: i) a first set of horizontal grid members 118 extending in a first direction; ii) a second set of horizontal grid members 120 extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members 118 at intersections 56, wherein the first set of horizontal grid members 118 and the second set of horizontal grid members 120 are arranged to form a grid 50 comprising a plurality of substantially rectangular frames 54 in a horizontal plane, each of the substantially rectangular frames defining a grid cell; iii) a plurality of upright columns 116 supporting the first set of horizontal grid members 118 and the second set of horizontal grid members 120, wherein the plurality of upright columns 116 form a plurality of vertical storage locations for containers 10 to be stacked between the upright columns 116; Equipped with b) comparing the collected acceleration data with ground acceleration data from one or more accelerometers 302a located on the ground; c) determining a differential acceleration between the acceleration data and the ground acceleration data; d) determining displacement data from said differential acceleration; e) determining whether a seismic event occurred over the given time period based on the displacement data; A method comprising: [C2] The method of claim C1, wherein the step of determining whether a seismic event has occurred over the given time period comprises determining whether the displacement data exceeds a predetermined displacement threshold corresponding to an elastic limit of a member of the grid framework structure 114. [C3] The method of any one of C1 and C2, wherein the step of determining whether a seismic event has occurred comprises determining a change in frequency and / or period of oscillation of the displacement data over the given time period. [C4] The method of claim 3, wherein determining a change in the frequency and / or period of vibration of the displacement data comprises determining whether the frequency and / or period of vibration differs from a predetermined frequency threshold and / or a predetermined period of vibration. [C5] 5. The method of any one of claims 1 to 4, wherein the step of determining whether a seismic event has occurred over the given time period comprises determining a static displacement from the displacement data and determining whether the static displacement exceeds a predetermined static displacement threshold. [C6] 6. The method of any one of C1 to C5, further comprising filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events. [C7] The method of C6, wherein the step of filtering the acceleration data comprises using a high-pass filter, a low-pass filter, and / or a band-pass filter. [C8] 8. The method of claim 6 or 7, wherein the step of filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events comprises determining frequency ranges in which vibrations occur in the absence of a seismic event, and attenuating or filtering out these frequency ranges from the acceleration data. [C9] 9. The method of any one of C1 to 8, wherein the one or more accelerometers 302 located on the grid framework structure 114 comprise a plurality of accelerometers 302, and wherein the step of determining whether a seismic event has occurred is based on displacement data from each of the plurality of accelerometers 302. [C10] The method of any one of C1 to C9, further comprising sending a signal to one or more output devices 310 in response to determining that an earthquake event has occurred over the given period of time. [C11] 1. A method for condition monitoring a grid framework structure 114 following a seismic event, said grid framework structure 114 comprising: i) a first set of horizontal grid members 118 extending in a first direction; ii) a second set of horizontal grid members 120 extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members 118 at intersections 56, wherein the first set of horizontal grid members 118 and the second set of horizontal grid members 120 are arranged to form a grid 50 comprising a plurality of substantially rectangular frames 54 in a horizontal plane, each of the substantially rectangular frames defining a grid cell; iii) a plurality of upright columns 116 supporting the first set of horizontal grid members 118 and the second set of horizontal grid members 120, wherein the plurality of upright columns 116 form a plurality of vertical storage locations for containers 10 to be stacked between the upright columns 116; iv) one or more accelerometers 302 located on said grid framework structure 114; Equipped with The method comprises: a) collecting acceleration data from the one or more accelerometers 302 over a given period of time; b) comparing the collected acceleration data with ground acceleration data over the given time period from one or more accelerometers 302a located on the ground; c) determining a differential acceleration between the acceleration data and the ground acceleration data; d) determining the extent of damage to different portions of the grid framework structure that occurred during the given time period by determining whether the differential acceleration data exceeds a predetermined acceleration threshold during the given time period; A method comprising: [C12] 12. The method of claim 11, wherein the predetermined acceleration threshold comprises a plurality of predetermined acceleration thresholds, each of the plurality of predetermined acceleration thresholds indicating a different level of damage to one or more of the different portions of the grid framework structure. [C13] 13. The method of claim 12, wherein the plurality of predetermined acceleration thresholds includes a first acceleration threshold indicative of an elastic limit of a portion of the grid framework structure, such that the differential acceleration of the portion of the grid framework structure exceeding the first acceleration threshold provides an indication that the portion of the grid framework structure has been permanently deformed. [C14] The method of C13, wherein the first acceleration threshold is substantially 0.6 g. [C15] 15. The method of claim 13 or 14, wherein the plurality of predetermined acceleration thresholds includes a second acceleration threshold indicative of a safety limit, such that the differential acceleration of the portion of the grid framework structure exceeding the second acceleration threshold provides an indication that it is unsafe for personnel to enter the portion of the grid framework structure. [C16] The method of C15, wherein the second acceleration threshold is substantially 1.0 g. [C17] 17. The method of any one of claims 13 to 16, wherein the plurality of predetermined acceleration thresholds includes a third acceleration threshold indicative of a structural limit, such that the differential acceleration of a portion of the grid framework structure that exceeds the third acceleration threshold provides an indication that the portion of the grid framework structure does not have sufficient structural capacity to withstand an aftershock. [C18] The method of C17, wherein the third acceleration threshold is about 1.83 g. [C19] e) determining displacement data from said differential acceleration; f) determining the extent of damage to different parts of the grid framework structure by determining whether the displacement data exceeds a predetermined displacement threshold; The method of any one of C11 to 18, further comprising: [C20] 20. The method of claim 19, wherein the predetermined displacement threshold indicates an elastic limit, such that a displacement of a portion of the grid framework structure that exceeds the predetermined displacement threshold provides an indication that the portion of the grid framework structure has been permanently deformed. [C21] 21. An earthquake detection system 300 for a grid framework structure 114 configured to perform the method according to any one of C1 to C20, said earthquake detection system 300 comprising: a) one or more accelerometers 302 mounted on the grid framework structure 114; b) an input module 304 configured to collect acceleration data from the one or more accelerometers 302; and c) a controller 306 in communication with said input module 304, said controller 306 comprising one or more processors and a memory storing instructions that, when executed by said one or more processors, cause said one or more processors to: i) determining whether a seismic event has occurred based on the collected acceleration data from the one or more accelerometers 302; ii) in response to determining that a seismic event has occurred, sending a signal to one or more output devices 310; and to carry out An earthquake detection system 300 comprising: [C22] The earthquake detection system of C21, further comprising one or more accelerometers 302a located on the ground near the grid framework structure 114. [C23] The earthquake detection system of claim 21 or 22, wherein the one or more output devices 310 comprise a beacon, an alarm, and / or a siren. [C24] i) a first set of horizontal grid members 118 extending in a first direction; ii) a second set of horizontal grid members 120 extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members 118 at intersections 56, the first set of horizontal grid members 118 and the second set of horizontal grid members 120 arranged to form a grid 50 comprising a plurality of substantially rectangular frames 56 in a substantially horizontal plane, each substantially rectangular frame defining a grid cell 56; iii) a plurality of upright columns 116 supporting the first set of horizontal grid members 118 and the second set of horizontal grid members 120, wherein the plurality of upright columns 116 form a plurality of vertical storage locations for containers 10 to be stacked between the upright columns 116; A grid framework structure 114 comprising: A grid framework structure (114), wherein the grid framework structure (114) further comprises an earthquake detection system (300) according to any one of claims C21 to C23. [C25] The grid framework structure 114 of C24, wherein the one or more accelerometers 302 mounted on the grid framework structure 114 comprise a plurality of accelerometers 302, the plurality of accelerometers 302 being arranged along the first direction and / or the second direction of the grid 50. [C26] The grid framework structure 114 of C25, wherein the plurality of accelerometers 302 are disposed along at least a portion of a periphery of the grid 50. [C27] A grid framework structure 114 as described in C24, wherein the one or more accelerometers mounted on the grid framework structure 114 comprise a plurality of accelerometers 302, at least a portion of which are arranged diagonally relative to the first direction and the second direction of the grid 50. [C28] The grid framework structure 114 of any one of C25 to C27, wherein the plurality of accelerometers 302 lie in a substantially horizontal plane. [C29] The grid framework structure 114 of any one of C25 to C28, wherein the plurality of accelerometers 302 consists of between 15 and 28 accelerometers 302. [C30] The grid framework structure 114 of C24, wherein the one or more accelerometers mounted on the grid framework structure 114 are mounted on the horizontal grid members 118, 120. [C31] 10. The grid framework structure 114 of any one of claims C24 to C30, further comprising an exoskeleton comprising a plurality of vertical frame columns 218 braced by one or more bracing members 220, 222, the grid 50 being further supported by the exoskeleton to form a seismic force suppression system (SFRS). [C32] The grid framework structure 114 of C31, wherein the one or more accelerometers 302 mounted on the grid framework structure 114 are mounted on the SFRS. [C33] The grid framework structure 114 of C32, wherein the one or more accelerometers 302 mounted on the grid framework structure 114 are attached to the one or more brace members 220, 222. [C34] A grid framework structure 114 according to any one of claims C24 to C33, wherein the grid framework structure 114 is subdivided into a plurality of modular frames 514, such that the grid 50 extends across the plurality of modular frames 514. [C35] 35. The grid framework structure 114 of any one of claims C24 to C34, further comprising an earthquake isolation system 208 for reducing seismic forces acting on the grid framework structure 114, the grid framework structure 114 being supported by the earthquake isolation system 208, the earthquake isolation system 208 comprising an upper structure 202, a lower structure 200, and at least one seismic isolation device 204 disposed between the upper structure 202 and the lower structure 200, such that the at least one seismic isolation device 204 inhibits movement of the upper structure 202 relative to the lower structure 200 in an earthquake event. [C36] i) a first grid framework structure at a first level; ii) a second grid framework structure at a second level, wherein said second level is above said first level; A multi-storey grid framework structure comprising: A multi-storey grid framework structure, wherein the first grid framework structure and the second grid framework structure each comprise a grid framework structure as defined in any of C24 to 35. [C37] a) a grid framework structure 114 as defined in any of C24 to C36; b) one or more load handling devices 30 remotely operable to move one or more containers 10 stored in said grid framework structure 114, wherein each of said one or more load handling devices 30: i) a wheel assembly for guiding the load handling device 30 on the grid framework structure 114; ii) a container receiving space 40 located above said grid framework structure 114; iii) a lifting device arranged to lift a single container 10 from the stack 12 and place it into said container receiving space 40; A storage and retrieval system comprising:

Claims

Claim 1: A method for detecting a seismic event in a storage and retrieval system, the storage and retrieval system comprising: a) a grid framework structure (114); and b) one or more load handling devices (30); a) the grid framework structure (114) comprises: i) a first set of horizontal grid members (118) extending in a first direction; ii) a second set of horizontal grid members (120) extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members (118) at intersections (56), wherein the first set of horizontal grid members (118) and the second set of horizontal grid members (120) are arranged to form a grid (50) comprising a plurality of substantially rectangular frames (54) in a horizontal plane, each of the substantially rectangular frames defining a grid cell (54); iii) a plurality of upright columns (116) supporting said first set of horizontal grid members (118) and said second set of horizontal grid members (120), wherein said plurality of upright columns (116) form a plurality of vertical storage locations for containers (10) to be stacked between said upright columns (116); b) one or more of said cargo handling devices (30) are remotely operable to move one or more of said containers (10) stored in said grid framework structure (114), and each of said one or more cargo handling devices (30) comprises: i) a wheel assembly for guiding said load handling device (30) on said grid framework structure (114); ii) a container receiving space (40) located above said grid framework structure (114); iii) a lifting device arranged to lift a single container (10) from the stack (12) and into said container receiving space (40); The method comprises: a) collecting acceleration data over a given period of time from one or more accelerometers (302) located on said grid framework structure (114); b) comparing the collected acceleration data with ground acceleration data from one or more accelerometers (302a) located on the ground; c) determining a differential acceleration between said acceleration data and said ground acceleration data; d) determining displacement data from said differential acceleration; e) determining whether a seismic event has occurred over the given time period based on whether the displacement data exceeds a predetermined displacement threshold corresponding to an elastic limit of members of the grid framework structure (114); A method comprising:

2. The method of claim 1 , wherein the step of determining whether a seismic event has occurred comprises determining a change in frequency and / or period of oscillation of the displacement data over the given time period.

3. 3. The method of claim 2, wherein determining a change in the frequency and / or period of vibration of the displacement data comprises determining whether the frequency and / or period of vibration differs from a predetermined frequency threshold and / or a predetermined period of vibration.

4. 3. The method of claim 1 or 2, wherein the step of determining whether a seismic event has occurred over the given time period comprises determining a static displacement from the displacement data and determining whether the static displacement exceeds a predetermined static displacement threshold.

5. The method of claim 1 or 2, further comprising filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events.

6. 6. The method of claim 5, wherein filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events comprises determining frequency ranges in which vibrations occur in the absence of a seismic event and attenuating or filtering out these frequency ranges from the acceleration data.

7. A method of condition monitoring a grid framework structure (114) in a storage and retrieval system following a seismic event, the storage and retrieval system comprising: a) a grid framework structure (114); and b) one or more load handling devices (30); a) the grid framework structure (114) comprises: i) a first set of horizontal grid members (118) extending in a first direction; ii) a second set of horizontal grid members (120) extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members (118) at intersections (56), wherein the first set of horizontal grid members (118) and the second set of horizontal grid members (120) are arranged to form a grid (50) comprising a plurality of substantially rectangular frames (54) in a horizontal plane, each of the substantially rectangular frames defining a grid cell (54); iii) a plurality of upright columns (116) supporting the first set of horizontal grid members (118) and the second set of horizontal grid members (120), wherein the plurality of upright columns (116) form a plurality of vertical storage locations for containers (10) to be stacked between the upright columns (116); iv) one or more accelerometers (302) located on said grid framework structure (114); b) one or more of said cargo handling devices (30) are remotely operable to move one or more of said containers (10) stored in said grid framework structure (114), and each of said one or more cargo handling devices (30) comprises: i) a wheel assembly for guiding said load handling device (30) on said grid framework structure (114); ii) a container receiving space (40) located above said grid framework structure (114); iii) a lifting device arranged to lift a single container (10) from the stack (12) and into said container receiving space (40); The method comprises: a) collecting acceleration data from one or more of said accelerometers (302) over a given period of time; b) comparing the collected acceleration data with ground acceleration data over the given time period from one or more accelerometers (302a) located on the ground; c) determining a differential acceleration between said acceleration data and said ground acceleration data; d) determining the extent of damage to different portions of the grid framework structure that occurred during said given time period by determining whether said differential acceleration data exceeds a predetermined acceleration threshold during said given time period; wherein the predetermined acceleration threshold comprises a plurality of predetermined acceleration thresholds, each of the plurality of predetermined acceleration thresholds indicative of a different level of damage to one or more of the different portions of the grid framework structure.

8. e) determining displacement data from said differential acceleration; f) determining the extent of damage to different parts of the grid framework structure by determining whether the displacement data exceeds a predetermined displacement threshold.

9. 9. The method of claim 8, wherein the predetermined displacement threshold indicates an elastic limit, such that a displacement of a portion of the grid framework structure beyond the predetermined displacement threshold provides an indication that the portion of the grid framework structure has been permanently deformed.

10. 10. An earthquake detection system (300) for a grid framework structure (114) configured to perform the method of claim 1 or 7, the earthquake detection system (300) comprising: a) one or more accelerometers (302) mounted on said grid framework structure (114); b) an input module (304) configured to collect acceleration data from one or more of said accelerometers (302); c) a controller (306) in communication with said input module (304), said controller (306) comprising one or more processors and a memory storing instructions, said instructions, when executed by said one or more processors, causing said one or more processors to: i) determining whether a seismic event has occurred based on the collected acceleration data from one or more of the accelerometers (302); ii) sending a signal to one or more output devices (310) in response to determining that a seismic event has occurred; to carry out An earthquake detection system (300) comprising:

11. The earthquake detection system (300) of claim 10, further comprising one or more accelerometers (302a) located on the ground near the grid framework structure (114).

12. i) a first set of horizontal grid members (118) extending in a first direction; ii) a second set of horizontal grid members (120) extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members (118) at intersections (56), wherein the first set of horizontal grid members (118) and the second set of horizontal grid members (120) are arranged to form a grid (50) comprising a plurality of substantially rectangular frames (54) in a substantially horizontal plane, each of the substantially rectangular frames defining a grid cell (54); iii) a plurality of upright columns (116) supporting said first set of horizontal grid members (118) and said second set of horizontal grid members (120), wherein said plurality of upright columns (116) form a plurality of vertical storage locations for containers (10) to be stacked between said upright columns (116); A grid framework structure (114) comprising: A grid framework structure (114), wherein the grid framework structure (114) further comprises an earthquake detection system (300) according to claim 10.

13. 13. The grid framework structure (114) of claim 12, wherein the one or more accelerometers (302) mounted on the grid framework structure (114) comprise a plurality of accelerometers (302), the plurality of accelerometers (302) being arranged along the first direction and / or the second direction of the grid (50).

14. The grid framework structure (114) of claim 13, wherein the plurality of accelerometers (302) are disposed along at least a portion of a perimeter of the grid (50).

15. 13. The grid framework structure (114) of claim 12, wherein the one or more accelerometers mounted on the grid framework structure (114) comprise a plurality of accelerometers (302), at least a portion of the plurality of accelerometers (302) disposed diagonally relative to the first direction and the second direction of the grid (50).

16. 13. The grid framework structure (114) of claim 12, wherein the grid framework structure (114) is subdivided into a plurality of modular frames (514), such that the grid (50) extends across the plurality of modular frames (514).

17. i) a first grid framework structure at a first level; ii) a second grid framework structure at a second level, wherein said second level is above said first level; A multi-storey grid framework structure comprising:

13. A multi-storey grid framework structure, wherein the first grid framework structure and the second grid framework structure each comprise a grid framework structure as defined in claim 12.

18. a) a grid framework structure (114) as defined in claim 12; b) one or more load handling devices (30) remotely operable to move one or more of said containers (10) stored in said grid framework structure (114), wherein each of said one or more load handling devices (30) comprises: i) a wheel assembly for guiding said load handling device (30) on said grid framework structure (114); ii) a container receiving space (40) located above said grid framework structure (114); iii) a lifting device arranged to lift a single container (10) from the stack (12) and into said container receiving space (40); A storage and retrieval system comprising:

Images