An overall pseudo-static loading device for ancient building wood structure and a loading method thereof

Abstract

The application discloses a kind of whole pseudo-static force loading devices of ancient building wood structure, comprising: core force transmission unit, it includes first H-shaped steel beam, first load-bearing beam and force transmission beam device, first H-shaped steel beam includes first girder and first short beam, two first short beams are fixed in the two sides of first girder respectively, and force transmission beam device is fixed at the outside of first girder;Opposite side force transmission unit, it is arranged at the opposite side of core force transmission unit, and opposite side force transmission unit includes second H-shaped steel beam, and second H-shaped steel beam includes second girder and two second short beams;Side force transmission unit, two side force transmission units are symmetrically arranged, and respectively with core force transmission unit and opposite side force transmission unit connection, and side force transmission unit includes third H-shaped steel beam and second load-bearing beam, and third H-shaped steel beam includes third girder and two third short beams;First H-shaped steel beam, second H-shaped steel beam and third H-shaped steel beam are respectively provided with multiple loading assemblies, and each loading assembly includes loading pad and two loading hoops.

Description

Technical Field

[0001] This invention relates to the field of ancient wooden structure protection technology, specifically to an overall quasi-static loading device and loading method for ancient wooden structures. Background Technology

[0002] Unlike concrete or steel structures, the beams and columns of ancient wooden buildings (such as pagodas, palaces, and corridors) are primarily connected by mortise and tenon joints. This connection method has semi-rigid characteristics and cannot achieve the completely rigid connection of concrete or steel structures. The strong discreteness of mortise and tenon joints leads to significant differences in relative slippage and deformation between components (such as beams and columns) under load, resulting in asynchronous load loading during the overall structural mechanical performance test.

[0003] The existing loading device has the following defects:

[0004] (1) Non-uniform load transfer: Existing devices cannot synchronously and controllably transfer horizontal forces to the entire wooden structure. That is, during the loading process, the load is often concentrated in local areas (such as certain column joints), causing premature failure, while other areas do not fully participate in the stress, resulting in distorted test data. This not only affects the accuracy of test results and limits the scientific assessment of the overall stress performance of ancient wooden structures, but also limits the systematic evaluation of key indicators such as the seismic performance and stability of ancient wooden structures, hindering the development of protective restoration technology.

[0005] (2) Limitations caused by local loading: Since the existing device design does not take into account the integrity of the wooden structure, the test is mostly limited to the study of local components, which makes it difficult to reflect the overall response mechanism of ancient wooden structures under real stress conditions (such as earthquakes and wind loads). Summary of the Invention

[0006] The purpose of this invention is to provide a quasi-static loading device and loading method for the overall wooden structure of ancient buildings, so as to solve the problem that the existing devices mentioned in the background art cannot transmit horizontal forces synchronously, uniformly and controllably to the entire wooden structure, and are difficult to reflect the overall response mechanism of the wooden structure of ancient buildings under real stress conditions.

[0007] To achieve the above objectives, the present invention provides an integral quasi-static loading device for ancient wooden structures, comprising:

[0008] The core force transmission unit includes a first H-shaped steel beam, a first load-bearing beam, and a force transmission beam device. The first H-shaped steel beam includes a first main beam and two first short beams. The two first short beams are fixed on both sides of the first main beam, and the angle between them and the first main beam is 135°. The two first load-bearing beams are fixed parallel to and symmetrically on the first short beams along the direction of the first main beam. The force transmission beam device is fixed on the outside of the first main beam.

[0009] The opposite side force transmission unit is located on the opposite side of the core force transmission unit. The opposite side force transmission unit includes a second H-shaped steel beam. The second H-shaped steel beam includes a second main beam and two second short beams. The two second short beams are fixed to both sides of the second main beam, and the included angle with the second main beam is 135°.

[0010] The side force transmission unit consists of two symmetrically arranged side force transmission units, which are respectively connected to the core force transmission unit and the opposite side force transmission unit. The side force transmission unit includes a third H-shaped steel beam and a second load-bearing beam. The third H-shaped steel beam includes a third main beam and two third short beams. The two third short beams are respectively fixed on both sides of the third main beam, and the included angle with the third main beam is 135°. The two second load-bearing beams are parallel and symmetrically fixed on the outside of the third short beams in a direction perpendicular to the third main beam.

[0011] The first H-beam, the second H-beam, and the third H-beam are each equipped with multiple loading components, each of which includes a loading pad and two loading rings.

[0012] In a preferred embodiment, the ends of the first short beam and the third short beam, and the second short beam and the third short beam are detachably connected by connecting plates and bolts, so that the first H-shaped steel beam, the second H-shaped steel beam and the third H-shaped steel beam form an octagonal structure as a whole.

[0013] In a preferred embodiment, the loading ring is a U-shaped structure, with two loading rings spaced apart and symmetrically arranged in the vertical direction. The arc-shaped closed end of the loading ring is located inside the main beam, and the ends of the two U-shaped arms pass through the flanges of the H-shaped steel beam and extend to the outside of the main beam. The model column is set in the loading ring near the arc-shaped closed end, and the distance between the two U-shaped arms matches the diameter of the model column so that the loading ring fits snugly against the column body. A loading pad is provided between the model column and the H-shaped steel beam to tightly connect the H-shaped steel beam and the model column and form a two-way constraint on the model column.

[0014] In a preferred embodiment, the height of the loading pad is consistent with the distance between the upper and lower loading rings, the width of the loading pad is consistent with the distance between the two U-shaped arms, the side of the loading pad closer to the main beam is a plane, and the side of the loading pad away from the main beam is an arc surface.

[0015] In a preferred embodiment, the length of the first main beam is determined by scaling the side length of the test model plane proportionally, so that the planar outline of the loading device is proportionally enlarged to the plane of the test model. The lengths of the first main beam, the second main beam, and the third main beam are equal, and the lengths of the first short beam, the second short beam, and the third short beam are each 1 / 2 of the lengths of the first main beam, the second main beam, and the third main beam.

[0016] In a preferred embodiment, the force transmission beam device includes a force transmission beam, which is made of H-beam of the same type as the H-beam. The force transmission beam is connected to the first main beam by three steel pads. The steel pads are respectively arranged at both ends and the middle of the force transmission beam and are welded and fixed to the force transmission beam and the first main beam respectively. Stiffening ribs are welded to the upper and lower sides of the web of the force transmission beam corresponding to the position of the steel pads.

[0017] In a preferred embodiment, a connecting plate is welded to the other side of the force transmission beam for connecting the actuator. The size of the connecting plate is the same as that of the actuator end plate. Four stiffening ribs are welded at equal intervals above and below the connecting plate on the web of the first main beam.

[0018] In a preferred embodiment, the outer ends of the first and second load-bearing beams are mounted on the two support frame beams of the support frame. The cross-sectional heights of the first and second load-bearing beams are the same as the flange widths of the first and third short beams, respectively, for transferring the weight of the device to the support frame. Horizontal pulleys are provided at the bottom of the outer ends of the two first and two second load-bearing beams. Lateral limiting devices are correspondingly provided at the bottom of the outer ends of the two first and two second load-bearing beams. The lateral limiting devices are located inside the horizontal pulleys, and lateral limiting pulleys are provided on the outer end faces of the lateral limiting devices.

[0019] The present invention also provides a loading test method using the above-mentioned quasi-static loading device for the overall wooden structure of ancient buildings, comprising the following steps:

[0020] S1. Model Making and Scaling: Create a scaled-down model of the ancient wooden structure.

[0021] S2. Selection of loading components: Determine the quantity and location of loading rings and loading pads based on whether the test target involves overall or partial loading.

[0022] S3. Installation of loading device: Assemble the core force transmission unit, the opposite side force transmission unit and the side force transmission unit;

[0023] S4. Install the support frame, place the loading device, and use the first and second load-bearing beams to transfer the weight of the loading device to the support frame.

[0024] S5, Actuator connected to core force transmission unit;

[0025] S6. Conduct a full loading test or a partial loading test;

[0026] S7. Experimental data acquisition and processing.

[0027] In a preferred embodiment, the overall loading test includes the following steps:

[0028] S611. Loading rings and loading pads are installed at the top of all model columns in the floors corresponding to the severely damaged parts of the wooden structure, and displacement sensors are installed at the top and bottom of the model columns.

[0029] S612. The actuator applies a low-cycle reciprocating load and controls the loading rate to maintain a quasi-static state.

[0030] S613. Real-time acquisition of displacement sensor data at the top and bottom of each model column, and recording of load-displacement curves;

[0031] The local loading test includes the following steps:

[0032] S621. Remove the loading ring and loading pad of the non-target model column, and only retain the loading ring and loading pad of the target model column;

[0033] S622, The actuator applies a low-cycle reciprocating load and controls the loading rate to maintain a quasi-static state;

[0034] S623. Real-time acquisition of displacement sensor data at the top and bottom of the target model column at the loading end and the non-target model column symmetrical to the target model column at the non-loading end, and recording of load-displacement curves.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. Existing loading devices, due to differences in slippage and deformation of mortise and tenon connections, cannot synchronously transmit horizontal forces to all wooden columns, resulting in large deviations in test results. This invention employs an H-beam steel main structure, and through the setting of core force transmission units, opposite-side force transmission units, lateral force transmission units, and loading components, a U-shaped loading ring and loading pads work together to form a bidirectional constraint mechanism, ensuring synchronous displacement of each column and achieving overall synchronous loading. Furthermore, this invention allows for selective placement of the U-shaped loading ring, enabling both overall synchronous loading of all model columns and zoned loading only on the target column, meeting diverse research needs.

[0037] 2. Existing loading devices add their own weight to the test model, causing distortion of the stress state and affecting the scientific validity. This invention, while achieving the loading function, uses an independent load-bearing beam to completely transfer the device's own weight to the external support frame via horizontal pulleys, avoiding additional loads on the test model. The rolling support further isolates the coupling between the loading device and the model, ensuring the scientific validity and accuracy of the test results.

[0038] 3. Wooden structures are prone to torsion under load, causing the load direction to deviate and the test to become uncontrollable. The lateral limiting device, lateral limiting pulley, and horizontal pulley of this invention are arranged at the ends of the load-bearing beam, precisely positioned according to the cross-sectional dimensions of the supporting frame, and connected by bolts to suppress torsion. Simultaneously, the lateral limiting pulley contacts the supporting frame beam, forming a physical constraint to ensure that the load is transmitted along the preset direction. Attached Figure Description

[0039] Figure 1 This is a schematic plan view of the overall structure of the loading device of the present invention;

[0040] Figure 2 This is a three-dimensional schematic diagram of the overall structure of the loading device of the present invention;

[0041] Figure 3 This is a schematic diagram of the core force transmission unit structure of the present invention;

[0042] Figure 4 This is a schematic diagram of the force transmission unit structure on opposite sides of the present invention;

[0043] Figure 5 This is a schematic diagram of the side force transmission unit structure of the present invention;

[0044] Figure 6 Assumption model for design calculation of the loading device of the present invention;

[0045] Figure 7 This is a two-story plan view of the wooden pagoda according to an embodiment of the present invention;

[0046] Figure 8 The above diagram shows the loading device and experimental model according to an embodiment of the present invention.

[0047] Figure 9 The load-column top-to-column bottom relative displacement curve of column W11 under the overall loading test of this invention;

[0048] Figure 10 The load-column top-to-column bottom relative displacement curve of column W23 under the overall loading test of this invention;

[0049] Figure 11 This is the load-column top-to-column bottom relative displacement curve of column W11 under the local loading test of the present invention;

[0050] Figure 12 This is the load-column top-to-column bottom relative displacement curve of column W23 under the local loading test of the present invention. Detailed Implementation

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0052] Example 1:

[0053] like Figures 1 to 7As shown, the preferred embodiment of the quasi-static loading device for the overall wooden structure of ancient buildings of the present invention includes: a core force transmission unit 1, a side force transmission unit 2, a lateral force transmission unit 3, and multiple loading components. The core force transmission unit 1, the side force transmission unit 2, and the lateral force transmission unit 3 are detachably connected by connecting plates 7 and bolts, which greatly improves the installation and disassembly efficiency while ensuring connection strength. The core force transmission unit 1 includes a first H-shaped steel beam 11, a first load-bearing beam 12, a force transmission beam device 13, a lateral limiting device 8, and a lateral limiting pulley 92. The first H-shaped steel beam 11 includes a first main beam 111 and two first short beams 112. The two first short beams 112 are fixed to both sides of the first main beam 111, and the included angle with the first main beam 111 is 135°. The two first load-bearing beams 12 are fixed parallel and symmetrically to the first short beams 112 along the direction of the first main beam 111. The force transmission beam device is fixed to the outside of the first main beam 111. The opposite side force transmission unit 2 is located on the opposite side of the core force transmission unit 1. The opposite side force transmission unit 2 includes a second H-shaped steel beam 21, which includes a second main beam 211 and two second short beams 212. The two second short beams 212 are fixed to both sides of the second main beam 211, and the included angle between them and the second main beam 211 is 135°. Two side force transmission units 3 are symmetrically arranged and connected to the core force transmission unit 1 and the opposite side force transmission unit 2, respectively. The side force transmission unit 3 includes a third H-shaped steel beam 31 and a second load-bearing beam 32. The third H-shaped steel beam 31 includes a third main beam 311 and two third short beams 312. The two third short beams 312 are fixed to both sides of the third main beam 311, and the included angle between them and the third main beam 311 is 135°. Two second load-bearing beams 32 are fixed parallel and symmetrically to the outside of the third short beam 312 in a direction perpendicular to the third main beam 311, and the second load-bearing beams 32 are parallel to the first load-bearing beam 12.

[0054] The first H-beam 11, the second H-beam 21, and the third H-beam 31 are each equipped with multiple loading components, each including a loading pad 4 and two loading rings 5. Preferably, in this embodiment, two loading components are spaced apart on the first main beam 111 of the first H-beam 11, one loading component is on the first short beam 112, and one loading component is located at the joint between the first main beam 111 and the first short beam 112. The multiple loading components of the first H-beam 11, the second H-beam 21, and the third H-beam 31 are centrally symmetrically arranged and detachable.

[0055] Furthermore, the ends of the first short beam 112 and the third short beam 312, and the second short beam 212 and the third short beam 312, are detachably connected by connecting plates 7 and bolts, respectively. The connecting plates 7 form an octagonal structure for the first H-beam 11, the second H-beam 21, and the third H-beam 31, consistent with the shape of an octagonal wooden structure. The connecting plates include upper flange connecting plates, lower flange connecting plates, and web connecting plates. Each connecting plate is connected using M20 high-strength bolts and is arranged in corresponding positions according to structural and stress requirements.

[0056] The specific design is as follows:

[0057] The width of the upper flange connecting plate is the same as the flange width of the H-beam. Its length must be determined according to the relevant requirements of the current "Code for Design of Steel Structures," taking into account the bolt arrangement, end distance, and edge distance, among other structural specifications. Its thickness can be the same as the flange thickness. The width of the lower flange connecting plate is the flange width minus half the web thickness to ensure matching with the lower flange of the H-beam. Its length and thickness are consistent with the upper connecting plate. The width of the web connecting plate is the same as the web height of the H-beam. Its length is also determined based on the bolt arrangement in the web area and the end distance requirements specified in the code. Its thickness can be the same as the web thickness. The web connecting plates are symmetrically arranged on both sides of the beam web.

[0058] Furthermore, the loading ring 5 has a U-shaped structure, with two loading rings 5 ​​spaced vertically and symmetrically arranged. The arc-shaped closed end of the loading ring 5 is located inside the main beam. The ends of the two U-shaped arms pass through the flanges of the H-shaped steel beam and extend to the outside of the main beam. The model column 6 is placed in the loading ring 5 near the arc-shaped closed end. The distance between the two U-shaped arms matches the diameter of the model column 6, so that the loading ring 5 fits snugly against the column body of the model column 6. A loading pad 4 is placed between the model column and the H-shaped steel beam, so that the H-shaped steel beam and the model column 6 are tightly connected, forming a two-way constraint on the model column 6. The height of the loading pad 4 is consistent with the distance between the upper and lower loading rings 5, and the width of the loading pad 4 is consistent with the distance between the two U-shaped arms. The side of the loading pad 4 near the main beam is flat, and the side of the loading pad 4 away from the main beam is an arc surface that matches the curvature of the model column, which can accurately fill the physical gap between the H-shaped steel beam and the model column. The loading pad 4 is made of wood, and the type of wood selected is consistent with the material used in the test model to ensure the uniformity of material properties.

[0059] To ensure that the loading pads always fill gaps tightly and reliably, and to avoid affecting the accuracy of load transfer due to loosening or poor contact, the following systematic measures can be taken:

[0060] Precision machining and pre-control: During the machining stage, high-precision control is performed on the arc surface and thickness dimensions of the loading pad, and a small amount of trimming allowance is reserved to reduce errors from the source;

[0061] Graded Adaptation and Fine-tuning: Before formal installation, conduct trial assembly. If gaps are found, use wooden wedges to fill them first. The wooden wedges should be made of the same material as the model to ensure that their mechanical properties are coordinated and that they can share the load with the pads and model pillars after being driven in.

[0062] Fine shaping and verification: For interference fit, use an angle grinder to perform fine grinding in "small amounts and multiple times" and repeatedly verify its fit with the cylindrical surface until uniform contact is achieved over the entire circumference.

[0063] Integrated locking and coordination: Ultimately, the loading pad and loading ring work together. The strong preload provided by tightening the loading ring bolts firmly presses the positioned loading pad, wooden wedge, and model column together, forming a rigid composite force transmission unit that completely eliminates the gaps between components.

[0064] Through the above measures, the loading pads not only fill the gaps between the beams and columns, but also work together with the U-shaped loading rings to tightly connect the H-shaped steel beams with the model columns, thereby forming a two-way constraint mechanism on the model columns and realizing the reciprocating push-pull loading of the structural model.

[0065] This invention allows for the simultaneous loading or regional, batch loading of model columns by selectively arranging loading rings. For example, if loading rings are applied to all model columns, static or quasi-static loading can be applied to the entire structure; if loading rings are applied only to the target column while the remaining rings are removed, independent loading can be achieved only for the target column. This invention also supports an actuator-side loading mode, where only the loading rings on the opposite side of the actuator are tightened while the other loading rings are removed, thus enabling load transfer only through the actuator's opposite side.

[0066] Furthermore, the U-shaped arm is manufactured according to the standard of 12.9 grade high-strength bolts, with threads at the end. The U-shaped arm is installed in a pre-drilled circular hole in the flange of the H-beam and secured with double nuts. To control slippage of the U-shaped loading ring during loading, a disc spring washer is added between the nut and the inner side of the H-beam flange. A preload torque is applied to control the slippage to within 0.05mm. In addition, to enhance the flange's cooperative load-bearing performance, transverse stiffening ribs are provided in the U-shaped section of the loading ring, the H-beam connection area, and the pressure-bearing parts of the loading pad.

[0067] Furthermore, the length of the first main beam 111 is determined by scaling the side length of the test model plane proportionally. The scaling ratio depends on the gap between the test model and the loading device, so that the planar profile of the loading device is proportionally enlarged to the plane of the test model. The lengths of the first main beam 111, the second main beam 211, and the third main beam 311 are all equal, and the lengths of the first short beam 112, the second short beam 212, and the third short beam 312 are each half the lengths of the first main beam 111, the second main beam 211, and the third main beam 311, respectively.

[0068] Furthermore, the force transmission beam device 13 includes a force transmission beam 131. The function of the force transmission beam is to ensure that the load of the actuator is evenly transmitted to the loading device. The force transmission beam 131 is made of H-beam of the same type as the H-beam, and its length is determined according to the spacing between the model columns. For example, in this device, the end of the force transmission beam is positioned in the middle between the corner column and the horizontal column. The force transmission beam 131 is connected to the first main beam 111 by three steel pads 132. The steel pads 132 are respectively arranged at both ends and the middle of the force transmission beam 131, and are welded and fixed to the force transmission beam 131 and the first main beam 111 respectively. Stiffening ribs are welded to the upper and lower sides of the web of the force transmission beam 131 corresponding to the positions of the steel pads. A connecting plate 133 is welded to the other side of the force transmission beam 131 for connecting the actuator. The size of the connecting plate is the same as that of the actuator end plate. Four stiffening ribs are welded at equal intervals on the upper and lower sides of the web of the first main beam corresponding to the positions of the connecting plate 133.

[0069] Furthermore, the first load-bearing beam 12 and the second load-bearing beam 32 are made of HW-shaped steel. The outer ends of the first load-bearing beam 12 and the second load-bearing beam 32 are set on the two support frame beams 10 of the support frame. The cross-sectional height of the first load-bearing beam 12 and the second load-bearing beam 32 is the same as the flange width of the first short beam 112 and the third main beam 311, respectively, to transfer the weight of the device to the support frame. Horizontal pulleys 91 are provided at the bottom of the outer ends of the two sections of the first load-bearing beam 12 and the two sections of the second load-bearing beam 32. Lateral limiting devices 8 are correspondingly provided at the bottom of the outer ends of the two sections of the first load-bearing beam 12 and the two sections of the second load-bearing beam 32. The lateral limiting devices 8 are located inside the horizontal pulleys 91, and lateral limiting pulleys 92 are provided on the outer end face of the lateral limiting devices 8. The horizontal pulley 91 and the lateral limiting pulley 92 constitute a roller support system with double rolling bearings. The horizontal pulley 91 serves as the end vertical force transmission bearing, and the lateral limiting pulley 92 serves as the end inner force transmission bearing. The H-beam load is transferred to the independent load-bearing frame through the rolling support system.

[0070] To ensure that the octagonal loading device can transfer horizontal forces to each column of the ancient building model, the stiffness of the wooden columns and the loading device must be matched during the design of the loading device. When selecting the H-beam for the loading device, a suitable H-beam size can be selected based on the model dimensions, loading location, and loading force range. Then, a finite element simulation analysis can be performed on the assumed model of the loading device to obtain deformation and stress cloud diagrams of the device under different loads, thereby determining whether the selected steel profile meets the test requirements.

[0071] Taking an octagonal wooden tower as an example, the second floor of the tower structure has suffered severe damage. A stability assessment and protective study are needed. A scaled-down model will be constructed for a quasi-static test, in which the aforementioned loading device will be applied.

[0072] The stiffness of the second floor of the wooden tower is calculated and equivalent to a spring support 61. The column top and lintel of the wooden tower model are considered hinged, and the column bottom and the ground floor paving or foundation are considered rigid. For a column with a hinged top and a rigid bottom, the formula for its lateral stiffness k is:

[0073]

[0074] Where E is the elastic modulus of the wood, I is the moment of inertia of the column section, and h is the story height.

[0075] If all model columns in each floor have the same EI and height h, then the stiffness of the first floor and the stiffness of the second floor are respectively:

[0076]

[0077] The wooden tower structure is dominated by inter-story shear deformation, and the stiffness of each story is in series. The relationship between the stiffness K at the loading position and the stiffness of the first and second stories is as follows:

[0078]

[0079] The wooden tower has 24 columns on its second floor. Therefore, the equivalent spring stiffness at each connection between the loading device and the tower is:

[0080]

[0081] Example 2:

[0082] The present invention also provides a loading test method using the above-mentioned quasi-static loading device for the overall wooden structure of ancient buildings, comprising the following steps:

[0083] Step S1, Model Making and Scaling: Make a scaled-down model (e.g., 1:8) of the ancient wooden structure (such as an octagonal wooden tower) to ensure geometric similarity.

[0084] Step S2, Selection of loading components: Determine the quantity and location of the loading ring 5 and loading pad 4 according to whether the test target is overall or partial loading.

[0085] Step S3, Installation of loading device: The core force transmission unit 1, the opposite side force transmission unit 2 and the side force transmission unit 3 are quickly assembled by connecting plates and bolts. The length of the main beam of the H-shaped steel beam is calculated according to the side length ratio of the model. The length of the short beam is 1 / 2 of the main beam, with an included angle of 135°, forming a multi-octagonal profile.

[0086] Step S4: Install the support frame, place the loading device, and use the first load-bearing beam 12 and the second load-bearing beam 32 to transfer the weight of the loading device to the support frame.

[0087] Step S5: Connect the actuator to the core force transmission unit;

[0088] Step S6: Conduct an overall loading test or a partial loading test;

[0089] Step S7: Data Acquisition and Processing.

[0090] In step S6, the overall loading test includes the following steps: Step S611: Install loading rings 5 ​​and loading pads 4 at the top of all model columns 6 in the floors corresponding to the severely damaged parts of the wooden structure. The U-shaped loading rings 5 ​​encircle the model columns 6. The U-shaped arms are connected to the flanges of the H-beams with high-strength bolts (grade 12.9) and secured with double nuts. The wooden loading pads 4 fill the gaps between the beams and columns. The size of the pads is determined according to the actual gaps. Steel wedge-shaped pads are added at the corner columns to ensure the torque of the nuts is applied. Displacement sensors are installed at the top and bottom of the model columns 6. Step S612: Apply low-cycle reciprocating loads with the actuators and control the loading rate to maintain a quasi-static state. Step S613: Collect the displacement sensor data at the top and bottom of each model column 6 in real time, record the load-displacement curves, and compare the load-displacement curves of two symmetrically arranged model columns. If the deformation of each model column is consistent, it indicates that the synchronous loading is successful.

[0091] In step S6, the local loading test includes the following steps: Step S621, disassemble the loading ring 5 and loading pad 4 of the non-target model column, leaving only the loading ring 5 and loading pad 4 of the target model column; Step S622, apply a low-cycle reciprocating load to the actuator, control the loading rate to maintain a quasi-static state, and directly transmit the load to the target model column through the core force transmission unit; Step S623, collect displacement sensor data of the top and bottom of the target model column at the loading end and the non-target model column symmetrical to the target model column at the non-loading end in real time, record the load-displacement curve, and under the same load, if the relative displacement value of the non-loading end model column is significantly lower than the relative displacement value of the loading end model column, it indicates that the local loading is effective.

[0092] Example 3:

[0093] This embodiment takes an octagonal wooden tower as an example. The second floor of the tower structure has suffered severe damage, and a stability assessment and protective study are needed. A scaled-down model is made for a quasi-static loading test. The loading device from Embodiment 1 is used in this loading test. The specific process is as follows:

[0094] (1) This experiment mainly explores the failure mode of the second floor of the wooden pagoda and the impact of the deformation of the second floor on the overall stability of the pagoda. Therefore, the second floor of the wooden pagoda is used as the loading layer, and local or overall loading is applied to it to achieve the experimental purpose. The wooden pagoda structural model is made at a scale of 1:8 based on the prototype structure. According to the model size, suitable H-beams are selected and processed into loading devices, and corresponding loading rings and loading pads are designed and made according to the cross-sectional dimensions of the model columns. Repeated loading tests cause the outer groove columns of the second floor of the wooden pagoda ( Figure 7 The columns (W1-W24) showed obvious residual deformation. To ensure the smooth application of the loading ring and loading pad, loading rings and loading pads of different lengths were prepared.

[0095] (2) Before loading, connect the loading ring, loading pad, and model column to be loaded according to the loading conditions. Double nuts are used to connect the loading ring to the H-beam, and wedge-shaped steel pads are added between the loading ring and the H-beam at the corner columns to ensure smooth application of the nut torque. One side of the loading pad is in close contact with the model column, and the other side is in contact with the H-beam; if there is a gap, wooden wedges need to be embedded. The effect of assembling the wooden tower loading device with the test model is as follows: Figure 8 As shown.

[0096] (3) Before the overall loading test begins, the loading ring and loading pad are connected to the 24 columns of the outer groove. During the test, the displacement of the column head and column foot of each wooden column is collected and the load-displacement curve is plotted. Figure 9 and Figure 10 The load-displacement curves are shown for column W23, which is the most severely damaged column in the current state of the wooden pagoda, and column W11, which is symmetrical to W11 about the central axis perpendicular to the loading direction on the second floor plane of the wooden pagoda. The load-displacement curves of columns W11 and W23 are basically the same under the overall loading, indicating that the loading device successfully achieved simultaneous loading on each ancient pagoda column.

[0097] (4) In order to investigate the impact of the most severely damaged columns W23 and W24 on the stability of the overall structure of the wooden tower, it is necessary to apply local loading only to columns W23 and W24. During the experiment, the loading rings and loading pads of the other model columns were removed, and only the loading rings and loading pads of columns W23 and W24 were retained.

[0098] (5) During the local loading test, the displacement of the top of the column head and the bottom of the column foot of each model column was collected, and the load-displacement curve was plotted. The load-displacement curves of the loaded end W23 column and the unloaded end W11 column are shown below. Figure 11 and 12 As shown, under the same load, the relative displacement value of the load-displacement curve of column W11 at the unloaded end is significantly smaller than that of column W23 at the loaded end, indicating that the device successfully achieved local loading of the ancient pagoda.

[0099] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A quasi-static loading device for an integral wooden structure of an ancient building, characterized in that: include: The core force transmission unit (1) includes a first H-shaped steel beam (11), a first load-bearing beam (12), and a force transmission beam device (13). The first H-shaped steel beam (11) includes a first main beam (111) and two first short beams (112). The two first short beams (112) are respectively fixed on both sides of the first main beam (111), and the included angle with the first main beam (111) is 135°. The two first load-bearing beams (12) are parallel and symmetrically fixed on the first short beams (112) along the direction of the first main beam (111). The force transmission beam device is fixed on the outside of the first main beam (111). The opposite side force transmission unit (2) is set on the opposite side of the core force transmission unit (1). The opposite side force transmission unit (2) includes a second H-shaped steel beam (21). The second H-shaped steel beam (21) includes a second main beam (211) and two second short beams (212). The two second short beams (212) are fixed on both sides of the second main beam (211) and the included angle with the second main beam (211) is 135°. Side force transmission unit (3), two side force transmission units (3) are symmetrically arranged and connected to the core force transmission unit (1) and the opposite side force transmission unit (2) respectively. The side force transmission unit (3) includes a third H-shaped steel beam (31) and a second load-bearing beam (32). The third H-shaped steel beam (31) includes a third main beam (311) and two third short beams (312). The two third short beams (312) are fixed on both sides of the third main beam (311) and the included angle with the third main beam (311) is 135°. The two second load-bearing beams (32) are parallel and symmetrically fixed on the outside of the third short beams (312) in a direction perpendicular to the third main beam (311). Among them, the first H-shaped steel beam (11), the second H-shaped steel beam (21) and the third H-shaped steel beam (31) are respectively provided with multiple loading components, each of the loading components including a loading pad (4) and two loading rings (5).

2. The overall pseudo-static loading device for ancient wooden structures according to claim 1, characterized in that: The ends of the first short beam (112) and the third short beam (312), and the second short beam (212) and the third short beam (312) are detachably connected by connecting plates (7) and bolts, so that the first H-shaped steel beam (11), the second H-shaped steel beam (21) and the third H-shaped steel beam (31) form an octagonal structure.

3. The overall pseudo-static loading device for ancient wooden structures according to claim 2, characterized in that: The loading ring (5) is a U-shaped structure. The two loading rings (5) are spaced apart and symmetrically arranged in the vertical direction. The arc-shaped closed end of the loading ring (5) is located inside the main beam. The ends of the two U-shaped arms pass through the flange of the H-shaped steel beam and extend to the outside of the main beam. The model column (6) is set in the loading ring (5) near the arc-shaped closed end. The distance between the two U-shaped arms matches the column diameter of the model column (6) so that the loading ring (5) fits the column body of the model column (6). A loading pad (4) is set between the model column and the H-shaped steel beam so that the H-shaped steel beam and the model column (6) are tightly connected and form a two-way constraint on the model column (6).

4. The overall pseudo-static loading device for ancient wooden structures according to claim 3, characterized in that: The height of the loading pad (4) is consistent with the distance between the upper and lower loading rings (5), the width of the loading pad (4) is consistent with the distance between the two U-shaped arms, the side of the loading pad (4) near the main beam is a plane, and the side of the loading pad (4) away from the main beam is an arc surface.

5. The overall pseudo-static loading device for ancient wooden structures according to claim 1, characterized in that: The length of the first main beam (111) is determined by scaling the side length of the test model plane proportionally, so that the plane outline of the loading device is proportionally enlarged to the plane of the test model. The lengths of the first main beam (111), the second main beam (211), and the third main beam (311) are equal, and the lengths of the first short beam (112), the second short beam (212), and the third short beam (312) are 1 / 2 of the lengths of the first main beam (111), the second main beam (211), and the third main beam (311), respectively.

6. The overall pseudo-static loading device for ancient wooden structures according to claim 1, characterized in that: The force transmission beam device (13) includes a force transmission beam (131), which is made of H-beam of the same type as the H-beam. The force transmission beam (131) is connected to the first main beam (111) by three steel pads (132). The steel pads (132) are respectively arranged at both ends and the middle of the force transmission beam (131) and are welded and fixed to the force transmission beam (131) and the first main beam (111) respectively. Stiffening ribs are welded on both the upper and lower sides of the web of the force transmission beam (131) corresponding to the position of the steel pads.

7. The overall pseudo-static loading device for ancient wooden structures according to claim 6, characterized in that: The connecting plate (133) is welded to the other side of the force transmission beam (131) for connecting the actuator. The size of the connecting plate is the same as that of the actuator end plate. Four stiffening ribs are welded at equal intervals above and below the connecting plate (133) on the web of the first main beam.

8. The overall pseudo-static loading device for ancient wooden structures according to claim 1, characterized in that: The outer ends of the first load-bearing beam (12) and the second load-bearing beam (32) are set on the two support frame beams (10) of the support frame. The cross-sectional height of the first load-bearing beam (12) and the second load-bearing beam (32) is the same as the flange width of the first short beam (112) and the third short beam (312), respectively, to transfer the weight of the device to the support frame. The bottom of the outer ends of the two first load-bearing beams (12) and the two second load-bearing beams (32) are provided with horizontal pulleys (91). The bottom of the outer ends of the two first load-bearing beams (12) and the two second load-bearing beams (32) are respectively provided with lateral limiting devices (8). The lateral limiting devices (8) are located inside the horizontal pulleys (91), and the outer end face of the lateral limiting devices (8) is provided with lateral limiting pulleys (92).

9. A loading test method using the quasi-static loading device for an integral wooden structure of an ancient building as described in any one of claims 3-8, characterized in that: Includes the following steps: S1. Model Making and Scaling: Create a scaled-down model of the ancient wooden structure. S2. Selection of loading components: Determine the quantity and location of loading ring (5) and loading pad (4) according to the test target of overall loading or partial loading; S3. Installation of loading device: Assemble the core force transmission unit (1), the opposite side force transmission unit (2) and the side force transmission unit (3). S4. Install the support frame, place the loading device, and use the first load-bearing beam (12) and the second load-bearing beam (32) to transfer the weight of the loading device to the support frame. S5, Actuator connected to core force transmission unit; S6. Conduct a full loading test or a partial loading test; S7. Experimental data acquisition and processing.

10. The loading test method according to claim 9, characterized in that: The overall loading test includes the following steps: S611. Loading rings (5) and loading pads (4) are installed at the top of all model columns (6) in the floors corresponding to the severely damaged parts of the wooden structure, and displacement sensors are installed at the top and bottom of the model columns (6). S612. The actuator applies a low-cycle reciprocating load and controls the loading rate to maintain a quasi-static state. S613. Real-time acquisition of displacement sensor data at the top and bottom of each model column (6), and recording of load-displacement curves; The local loading test includes the following steps: S621. Remove the loading ring (5) and loading pad (4) of the non-target model column, and keep only the loading ring (5) and loading pad (4) of the target model column. S622, The actuator applies a low-cycle reciprocating load and controls the loading rate to maintain a quasi-static state; S623. Real-time acquisition of displacement sensor data at the top and bottom of the target model column at the loading end and the non-target model column symmetrical to the target model column at the non-loading end, and recording of load-displacement curves.

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