Concrete structure strain monitoring device

Abstract

The invention discloses a concrete structure strain monitoring device which comprises a shell, a partition plate, a strain sensor and a sensor connecting piece. The partition plate is arranged in the shell and divides the shell into a first cavity and a second cavity; the sensor connecting piece and the strain sensor are arranged in the first cavity, and the second cavity is used for pouring concrete. When concrete is poured, the monitoring device is buried in the concrete, and the concrete in the second cavity pushes the partition plate to move when strain occurs, so that the strain sensor is compressed and strain data is measured. The monitoring device can ensure that concrete inside and outside the shell has the same physical characteristics and maintenance conditions, and the concrete in the shell can freely stretch out and draw back. And moreover, the data processor is used for acquiring concrete strains epsilon inside and outside inside and outside the detection device, so that the stress-related strain epsilon stress correlation of the concrete structure can be calculated, the interference of non-stress strain is reduced, and the concrete quality and safety evaluation is more accurate.

Description

Technical Field

[0001] The invention relates to a concrete structure strain monitoring device, belonging to the technical field of concrete strain monitoring. Background Art

[0002] Concrete is widely used in construction projects and can be used to build various infrastructure such as houses, bridges, high-rise buildings, roads, airport runways, port terminals, etc. The hardening process of concrete is accompanied by plastic shrinkage, temperature strain, autogenous shrinkage, drying shrinkage, creep strain and load strain. However, the stress and strain of concrete do not always correspond one to one. Some strains do not produce stress, and some stresses do not necessarily correspond to strains. Only the strain that produces structural stress affects the stress state of concrete, so it is necessary to distinguish the strain related to structural stress.

[0003] The conventional method for monitoring stress and strain of concrete components is to bury sensors in concrete to directly read strain data. However, the monitoring data of strain sensors directly buried in concrete include all strains of concrete plastic shrinkage, temperature strain, autogenous shrinkage, drying shrinkage, creep strain and load strain. These strains do not correspond to stress and cannot reflect the true stress state of the structure, thus affecting the evaluation results of structural quality and safety.

[0004] In order to monitor the stress and strain of concrete components, some methods also cast concrete component models of the same cross-sectional dimensions at the construction site and perform the same curing conditions. The concrete component model is a free component, and the ends are not subject to load constraints. Then, the concrete structure strain value is subtracted from the concrete free component strain value, and the result is the strain related to the concrete structure stress. For example, the patent document with the publication number CN106524989A and the name "Automatic Analysis System and Data Analysis Method for Deformation of Large Foundation Pit Support Body" adopts this method. However, this method requires the casting of a concrete component model separately, and the temperature and humidity of the curing directly affect the calculation results, increasing the difficulty of curing. Moreover, this method is suitable for slender rod structures, but for large-volume concrete components, such as dam bodies, large bottom plates, etc., it is difficult to establish an effective concrete component model. Summary of the invention

[0005] In the existing concrete component stress and strain monitoring, it is necessary to cast a concrete structure model that can freely expand and contract outside the construction area. The concrete structure model has the problem of being difficult to maintain under the same conditions. The present invention provides a concrete structure strain monitoring device to solve the above technical problems.

[0006] In order to solve the above technical problems, the present invention includes the following technical solutions:

[0007] A concrete structure strain monitoring device, the monitoring device comprising a housing, a partition plate, a strain sensor and a sensor connector;

[0008] The shell includes a steel frame arranged in a rectangular parallelepiped shape, and a bottom plate, a top plate, an end plate and a side plate arranged to enclose the steel frame;

[0009] The partition plate is arranged in the shell, dividing the internal space of the shell into a first cavity and a second cavity along the length direction; the sensor connector is arranged in the first cavity and fixedly connected to the steel frame, and the two ends of the sensor are respectively fixedly connected to the partition plate and the sensor connector;

[0010] The top plate is detachably connected to the steel frame, the second cavity is used for pouring concrete, the side plate is water permeable and thermally conductive, a sealing plate is provided in the first cavity, and elastic sealing materials are provided around the edges of the partition plate; the partition plate can move toward the first cavity under the stress of the concrete in the second cavity;

[0011] When pouring concrete, the monitoring device is buried in the concrete, and the concrete in the second cavity is poured and cured together with the concrete outside the monitoring device; when the concrete in the second cavity is strained, the partition plate is pushed to move, so that the strain sensor is compressed and the strain data is measured.

[0012] Furthermore, side panel fixings are arranged on both sides of the steel frame, and slots are formed between the side panel fixings and the steel frame, and the side panels are inserted and pulled into the slots.

[0013] Furthermore, pin ears are provided at both ends of the monitoring device;

[0014] The monitoring device is also equipped with a bracket, which includes a base and a vertical rod, and a fixing piece is arranged on the vertical rod;

[0015] The pin ear can be sleeved on the vertical rod and fixed at a preset height by a fixing piece.

[0016] Furthermore, the sensor connector includes a connecting end plate and an L-shaped connecting plate. The connecting end plate is arranged parallel to the end plate and the partition plate of the shell. One end of the L-shaped connecting plate is fixedly connected to the connecting end plate, and the other end is fixedly connected to the steel frame.

[0017] Furthermore, the monitoring device further comprises a data processor, which is connected to the strain sensor signal and is used to collect strain data ε measured by the strain sensor in the first cavity. 测 The concrete outside the shell is also buried with a strain sensor for measuring the external concrete strain ε of the monitoring device 外 ; The processor is provided with a function to calculate the strain ε related to the concrete structure stress应力相关 The calculation formula is, where

[0018]

[0019] Wherein, L is the initial length of the second cavity, and N is the gauge length of the strain sensor, which is a known number.

[0020] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: the concrete structure strain monitoring device provided by the present invention is buried in concrete during casting, and the concrete in the second cavity is cast together with the concrete outside the monitoring device, which can ensure that the physical characteristics of the concrete inside and outside the monitoring device are the same; because the side plate has water permeability and thermal conductivity, the concrete in the second cavity and the concrete outside the monitoring device have the same curing temperature and humidity;

[0021] Moreover, the concrete in the second cavity can expand and contract freely, and the strain data is measured by the strain sensor in the first cavity. In addition, the concrete strain ε inside and outside the detection device is collected by the data processor. 内 , ε 外 , can calculate the stress-related strains of concrete structures, reduce the interference of non-stress strains, and make concrete quality and safety assessment more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a top view of a concrete structure strain monitoring device in one embodiment of the present invention;

[0023] Figure 2 It is a side view of a concrete structure strain monitoring device without a side plate in one embodiment of the present invention;

[0024] Figure 3 for Figure 2 Sectional view along AA;

[0025] Figure 4 is a detailed diagram of a concrete structure strain monitoring device located at one end of a first cavity in an embodiment of the present invention;

[0026] Figure 5 is a top view of a steel frame in one embodiment of the present invention;

[0027] Figure 6 is a side view of a steel frame in one embodiment of the present invention;

[0028] Figure 7 It is a schematic diagram of three monitoring devices arranged on a bracket in one embodiment of the present invention.

[0029] The numbers in the figure are as follows:

[0030] 10-shell; 11-steel frame; 12-bottom plate; 13-end plate; 14-side plate; 15-top plate; 16-sealing plate; 17-L-shaped fixing piece; 18-pin ear;

[0031] 20-partition plate; 21-elastic sealing material; 22-anchor bar;

[0032] 30-sensor connector; 31-connecting end plate; 32-L-shaped connecting plate;

[0033] 40- strain sensor;

[0034] 50- bracket; 51- base; 52- vertical rod; 53- fixing piece. DETAILED DESCRIPTION

[0035] The following is a further detailed description of the concrete structure strain monitoring device provided by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer in conjunction with the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0036] Normally, considering the hardening process of concrete, the strain of concrete structure after bearing load mainly includes: plastic shrinkage, temperature strain, autogenous shrinkage, drying shrinkage, creep strain and load strain, etc., which are the external manifestation of the comprehensive strain of concrete, that is, the strain value measured by the strain gauge at this position. However, this value cannot explain the stress state of the structure, because some strains do not necessarily lead to structural stress, mainly including strains caused by temperature difference and shrinkage. This part of strain will only generate stress in the structure when the deformation is constrained, and the magnitude of the stress generated is related to the degree of constraint. In some cases, although there is no strain, stress will still be generated. For example, when the temperature changes, the structure is constrained. At this time, although the structure has no strain, stress is generated inside the structure.

[0037] Regarding creep, in a statically determinate structure without steel bars, creep has no effect on the stress of the structure. However, in a structure containing steel bars or being over-determined, creep causes redistribution of structural stress and affects the structural stress. Therefore, this patent classifies creep as a factor affecting structural stress.

[0038] Then ε 砼 -ε 自由 =ε 应力相关

[0039] From the above formula, we can know that the concrete structure stress value under the same curing conditions minus the concrete free member strain value, the result is the strain related to the concrete structure stress. However, the difficulty lies in how to provide a device that can achieve the same conditions of curing and easily measure the concrete free strain.

[0040] This embodiment provides a strain monitoring device related to concrete structure stress. A space is constructed inside the monitoring device so that the internal concrete can deform freely. At the same time, the detection device is arranged in the concrete. The concrete inside the monitoring device and the concrete around the monitoring device can exchange temperature and humidity, ensuring that the concrete inside and outside the monitoring device are consistent in terms of material properties, curing conditions, etc.

[0041] Combination Figures 1 to 6 As shown, the monitoring device includes a housing 10, a partition plate 20, a strain sensor 40 and a sensor connector 30. The housing 10 includes a steel frame 11 arranged in a rectangular parallelepiped shape, and the steel frame 11 is welded by rectangular steel pipes or circular steel pipes or other steel sections. A bottom plate 12 is arranged at the bottom of the steel frame 11, end plates 13 are arranged at both ends, side plates 14 are arranged on both sides, and a top plate 15 is arranged on the top, so that the steel frame 11 is enclosed into a rectangular parallelepiped structure. A partition plate 20 is arranged inside the rectangular parallelepiped structure, dividing the cavity structure of the rectangular parallelepiped into two parts, front and back, which are respectively called the first cavity and the second cavity. A sensor connector 30 and a strain sensor 40 are arranged inside the first cavity, and the sensor connector 30 is fixedly connected to the steel frame 11, and one end of the strain sensor 40 is fixedly connected to the sensor connector 30, and the other end is fixedly connected to the partition plate 20. The second cavity is used for pouring concrete. In order to ensure that the concrete in the second cavity can freely expand and contract, the partition plate 20 can move toward the first cavity under the push of the concrete stress.

[0042] One of the purposes of the present invention is to ensure that the concrete in the second cavity has the same physical characteristics as the concrete outside the monitoring device. The top plate of the housing 10 and the steel frame 11 are detachable, and when the top plate is removed, the concrete in the second cavity can be poured synchronously with the concrete outside the monitoring device.

[0043] The second purpose of the present invention is to ensure that the concrete in the second cavity has the same curing conditions as the concrete outside the monitoring device, and the side plate has water permeability and thermal conductivity within the range of the second cavity, such as using a ceramic permeable plate or a magnesium oxide plate, so that the concrete in the second cavity has the same curing temperature and humidity as the concrete outside the monitoring device.

[0044] The third purpose of the present invention is that the concrete in the second cavity can freely expand and contract. In order to reduce the friction between the concrete and the shell 10, an isolation layer is provided inside the shell 10 of the second cavity. The isolation layer can be a plate made of the same material as the side plate. The contact surface between the isolation layer and the side plate is smooth. The isolation layer can also be other lining materials to isolate the concrete from the shell 10 and reduce the resistance of the concrete expansion and contraction. In addition, the elastic sealing material 21 provided around the partition plate 20 can not only ensure the sealing around the partition plate 20, but also ensure that the partition plate 20 can move freely.

[0045] It should be noted that since the strain sensor 40 is arranged in the first cavity, in order to ensure the measurement accuracy of the strain sensor 40, concrete and water cannot penetrate into the first cavity. Therefore, a sealing plate 16 is arranged in the first cavity for sealing. Since the partition plate 20 needs to move within a certain space, a flexible sealing material is arranged around the partition plate 20 for sealing to prevent concrete and water from entering the first cavity.

[0046] As an example, when pouring a large concrete component, the monitoring device is placed at a preset position, the top plate is removed, and the concrete inside and outside the monitoring device is poured simultaneously. When the concrete fills the second cavity, the top cover is installed. After the concrete pouring is completed, the large concrete component is cured. Since the side plates are permeable and thermally conductive, the concrete inside and outside the monitoring device have the same curing conditions. When the concrete in the second cavity is deformed, the partition plate 20 is pushed to move toward the first cavity. The partition plate 20 pushes the strain sensor 40, and the strain sensor 40 has the same displacement as the end of the concrete.

[0047] In a specific embodiment, two pairs of L-shaped fixing members 17 are provided on both sides of the steel frame 11. The four L-shaped fixing members 17 form a slot in which the side panels are inserted and withdrawn. The side panels and the top panel are removed to facilitate the simultaneous pouring of concrete. After the concrete is poured, the side panels are inserted into the slots, and then the top panel is installed to separate the concrete in the second cavity from the concrete outside the monitoring device.

[0048] In a specific embodiment, since the partition plate 20 needs to move synchronously with the concrete in the second cavity, it is necessary to ensure a firm connection between the two. An anchor bar 22 is provided on the side of the partition plate 20 facing the second cavity. One end of the anchor bar 22 is fixed to the side of the partition plate 20, and the other end points to the second cavity. After the concrete is poured, the anchor bar 22 is buried in the concrete, so that the partition plate 20 is integrally arranged with the concrete. When the concrete in the second cavity is free to expand and contract, the partition plate 20 is synchronously driven to move, so that the strain sensor 40 is synchronously deformed. In addition, an anchor bar 22 can also be provided on the inner side of the end plate of the second cavity to ensure a firm connection between the concrete member in the second cavity and the end plate.

[0049] In a specific embodiment, pin ears 18 are provided at both ends of the monitoring device, and the monitoring device is also equipped with a bracket 50. The bracket 50 includes a base 51 and a base 52, and the bottom of the base 52 is fixedly connected to the base 51, and a fixing member 53 is provided on the base 52. The pin ears can be sleeved on the base 52 and fixed at a preset height by the fixing member 53. The vertical rod can be a threaded rod, and the fixing member can be a nut. Further, a plurality of monitoring devices are vertically spaced on the bracket 50, and each monitoring device is adjusted to a suitable height by the fixing member. The monitoring device provided in this embodiment is suitable for strain monitoring of large-volume concrete structures with a relatively thick thickness, and can directly measure the strain state of the concrete structure at different depths, thereby improving the monitoring efficiency and accuracy.

[0050] In a specific embodiment, the sensor connector 30 includes a connecting end plate 31 and an L-shaped connecting plate 32. The connecting end plate 31 can be a rectangular plate. The connecting end plate 31 is arranged parallel to the end plate 13 and the partition plate 20 of the shell. One end of the L-shaped connecting plate 32 is fixedly connected to the connecting end plate, and the other end is fixedly connected to the steel frame of the shell. An elastic sealing material 21 is arranged between the L-shaped connecting plate and the partition plate 20 to ensure the movement of the partition plate 20. Due to the arrangement of the L-shaped connecting plate, the distance between the connecting position of the connecting end plate on the shell and the partition plate 20 can be reduced. When calculating the strain, the distance between the connecting position of the connecting end plate on the shell and the end plate of the second chamber can be approximately equal to the initial distance of the second chamber, which is convenient for calculation.

[0051] It should be noted that the monitoring device further includes a data processor, which is connected to the strain sensor 40 for collecting the strain data ε measured by the strain sensor 40 in the first cavity. 测 A strain sensor is also embedded in the concrete outside the housing 10 to measure the concrete strain ε outside the monitoring device. 外 , the processor is used to calculate the stress-related strain ε of the concrete structure 应力相关 ,in,

[0052]

[0053] Wherein, L is the initial length of the second cavity, and N is the gauge length of the strain sensor 40, which is a known number.

[0054] The above formula 1 is deduced as follows:

[0055] The external concrete strain is denoted as ε 外 , the strain of the internal concrete is recorded as ε 内 , the strain measured by the strain gauge is recorded as ε 测 , the initial length of the second cavity is recorded as L, and the gauge length of the strain sensor 40 is recorded as N. According to the deformation coordination, it can be known that:

[0056] ε 外 ×L=ε 测 ×N+ε 内 ×L; (2)

[0057] That is, ε 外 ×L-ε 内 ×L==ε 测 ×N;

[0058] Thus we get:

[0059] Since the monitoring device is buried in the concrete during operation, the concrete strain ε outside the monitoring structure is 外 This is the ε mentioned above. 砼 , while the concrete structure inside the monitoring structure can expand and contract freely, ε 内 is the strain of the unconstrained free expansion member, which is the ε in the previous text 自由 .

[0060] Therefore, Formula 3 can be transformed into:

[0061]

[0062] Therefore, the monitoring device provided in this embodiment only needs to collect data from the strain sensor 40 in the first cavity and the strain data of the concrete outside the monitoring device to automatically calculate the accurate value of the strain related to the stress of the concrete structure, thereby improving the accuracy of monitoring the stress state of the concrete structure.

[0063] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A concrete structure strain monitoring device, characterized in that: The monitoring device comprises a housing, a partition plate, a strain sensor and a sensor connector; The shell includes a steel frame arranged in a rectangular parallelepiped shape, and a bottom plate, a top plate, an end plate and a side plate arranged to enclose the steel frame; The partition plate is arranged in the shell, dividing the internal space of the shell into a first cavity and a second cavity along the length direction; the sensor connector is arranged in the first cavity and fixedly connected to the steel frame, and the two ends of the sensor are respectively fixedly connected to the partition plate and the sensor connector; The top plate is detachably connected to the steel frame, the second cavity is used for pouring concrete, the side plate is water permeable and thermally conductive, a sealing plate is provided in the first cavity, and elastic sealing materials are provided around the edges of the partition plate; the partition plate can move toward the first cavity under the stress of the concrete in the second cavity; When pouring concrete, the monitoring device is buried in the concrete, and the concrete in the second cavity is poured and cured together with the concrete outside the monitoring device; when the concrete in the second cavity is strained, the partition plate is pushed to move, so that the strain sensor is compressed and the strain data is measured.

2. The concrete structure strain monitoring device according to claim 1, characterized in that: Side panel fixing members are arranged on both sides of the steel frame, and a slot is formed between the side panel fixing members and the steel frame, and the side panel is inserted and pulled into the slot.

3. The concrete structure strain monitoring device according to claim 1, characterized in that: Pin ears are provided at both ends of the monitoring device; The monitoring device is also equipped with a bracket, which includes a base and a vertical rod, and a fixing piece is arranged on the vertical rod; The pin ear can be sleeved on the vertical rod and fixed at a preset height by a fixing piece.

4. The concrete structure strain monitoring device according to claim 1, characterized in that: The sensor connector includes a connecting end plate and an L-shaped connecting plate. The connecting end plate is arranged in parallel with the end plate and the partition plate of the shell. One end of the L-shaped connecting plate is fixedly connected to the connecting end plate, and the other end is fixedly connected to the steel frame.

5. The concrete structure strain monitoring device according to claim 1, characterized in that: The monitoring device further comprises a data processor, which is connected to the strain sensor signal and is used to collect strain data ε measured by the strain sensor in the first cavity. 测 The concrete outside the shell is also buried with a strain sensor for measuring the external concrete strain ε of the monitoring device 外 ; The processor is provided with a function to calculate the strain ε related to the concrete structure stress 应力相关 The calculation formula is, where Wherein, L is the initial length of the second cavity, and N is the gauge length of the strain sensor, which is a known number.

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