A method for evaluating bearing capacity of rubber seismic isolation support considering residual deformation

Abstract

This invention discloses a method for evaluating the bearing capacity of rubber seismic isolation bearings considering residual deformation. First, the rubber bearing to be evaluated is measured to determine its offset value. Then, it is determined whether the offset value of the rubber bearing to be evaluated exceeds the limit. If it exceeds the limit, it is directly determined that it cannot continue to be used. If it does not exceed the limit, a standard rubber bearing is processed, and the bearing capacity of the residual deformation is tested to obtain the bearing capacity of the rubber bearing to be evaluated. The solution of this invention is based on a simple inspection of rubber seismic isolation bearings in service, and applies deformation to a standard rubber bearing, making it infinitely close to the aging state of the actual rubber seismic isolation bearing to be evaluated. This accurately obtains the residual bearing capacity of the rubber seismic isolation bearing with residual deformation. It can accurately test the residual bearing capacity of the rubber seismic isolation bearing without removing it from service, and the test results are accurate, achieving non-destructive testing, which has important engineering significance.

Description

Technical Field

[0001] This invention belongs to the field of rubber seismic isolation bearing testing, specifically relating to a method for evaluating the bearing capacity of rubber seismic isolation bearings that takes into account residual deformation. Background Technology

[0002] Currently, seismic isolation technology has been fully developed and widely applied. Circular rubber seismic isolation bearings have become the most widely used seismic isolation technology due to their advantages such as stable performance, clear force transmission structure, and no difference in performance in all horizontal directions. They have played an important role in major projects such as the Beijing New Airport and the Hong Kong-Zhuhai-Macau Bridge.

[0003] However, it is worth noting that residual deformation is common in practical engineering applications. This means that after experiencing earthquakes, wind vibrations, vehicle vibrations, etc., the rubber bearing cannot return to its original position and continues to bear vertical loads under a certain degree of deformation. This is because rubber is a flexible material, which is prone to deformation under vibration and usually cannot completely return to its original position after the vibration ends. Due to the varying degrees of residual deformation in rubber bearings, the bearing capacity is reduced to varying degrees. This issue has always been a concern in the industry regarding experimental and evaluation methods.

[0004] In existing technologies, there are many schemes for performance testing of rubber bearings. For example, CN117191308A, "A Performance Testing Device and Method for Rubber Seismic Isolation Bearings," provides a device and method for testing the performance of rubber bearings. However, this device and method do not consider the problem of residual deformation, that is, the rubber bearing under study is a bearing without initial deformation. Another example is CN113847901B, "A Lateral Uneven Deformation Testing Device and Method for Building Seismic Isolation Rubber Bearings," which only considers the deformation monitoring of rubber bearings, but the correspondence between deformation and the decrease in bearing capacity is currently unclear.

[0005] In practice, rubber bearings, as flexible components, are also key points for deformation and damage in design, and residual deformation is common, albeit to varying degrees. This residual deformation causes the point of application of vertical loads to shift from the component's center, obviously leading to a decrease in load-bearing capacity. However, rubber bearings cannot be removed for inspection. Therefore, non-destructive testing is of significant engineering importance, necessitating a method for assessing the residual load-bearing capacity of rubber bearings in service. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a method for evaluating the bearing capacity of rubber seismic isolation bearings that considers residual deformation. For rubber bearings that cannot be disassembled in actual service conditions, this invention innovates a method that is equivalent to a bearing in actual engineering under test bench conditions and evaluates the residual bearing capacity.

[0007] The specific technical solution for achieving the objective of this invention is as follows:

[0008] A method for evaluating the bearing capacity of rubber seismic isolation bearings considering residual deformation includes the following steps:

[0009] Step 1: Measure the rubber bearing to be evaluated and determine its offset value;

[0010] Step 2: Determine whether the offset value of the rubber bearing to be evaluated exceeds the limit. If it exceeds the limit, it is determined that it cannot continue to be used. If it does not exceed the limit, proceed to step 3.

[0011] Step 3: Treat the standard rubber bearing and conduct a load-bearing capacity test on the residual deformation to obtain the load-bearing capacity of the rubber bearing to be evaluated.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] (1) The solution of the present invention can accurately test the residual bearing capacity of the rubber seismic isolation bearing without removing it in service, and the test results are accurate, realizing non-destructive testing, which is of great significance in engineering.

[0014] (2) The present invention is based on a simple test of the rubber seismic isolation bearing in service and applies deformation to the standard rubber bearing, making it infinitely close to the aging state of the actual rubber seismic isolation bearing to be evaluated, so as to accurately obtain the residual bearing capacity of the rubber seismic isolation bearing with residual deformation.

[0015] The present invention will be further described below with reference to specific embodiments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the steps in the method for evaluating the bearing capacity of rubber seismic isolation bearings considering residual deformation according to the present invention.

[0017] Figure 2 This is a physical schematic diagram of the deformation treatment of the standard rubber bearing and the fixing of the deformation support in an embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram of rubber support specimens subjected to different deformation loadings in an embodiment of the present invention. Detailed Implementation

[0019] Example

[0020] The rubber bearing to be evaluated in service status in this embodiment comes from the non-railway section of the second phase of Jiangping West Road Project (Runyang North Road Interchange) in Yangzhou City, Jiangsu Province. It is a high-speed bridge rubber bearing that has been in service for 2 years. It is circular with an effective diameter of 900mm.

[0021] Combination Figure 1A method for evaluating the bearing capacity of rubber seismic isolation bearings considering residual deformation includes the following steps:

[0022] Step 1: Measure the rubber bearing to be evaluated and determine its offset value;

[0023] This step is to obtain the offset values ​​of the upper and lower steel plates of the rubber bearing to be evaluated in two side length directions under actual service conditions. Generally, the main body of the rubber bearing is cylindrical, and its upper and lower connecting steel plates are rectangular. In this case, to accurately obtain its offset, the difference d between the upper and lower connecting steel plates of the rubber bearing in the side length directions is measured respectively. x and d y The tools used can be plumb lines and measuring rulers.

[0024] Step 2: Determine if the offset value of the rubber bearing to be evaluated exceeds the limit. If it exceeds the limit, determine that it cannot continue to be used. If it does not exceed the limit, proceed to Step 3, which is as follows:

[0025]

[0026] Among them, D a The diameter of the rubber bearing to be evaluated can be directly measured or obtained from actual engineering data. b To determine the thickness of the rubber protective layer of the rubber bearing to be evaluated, it can be directly measured or actual engineering data can be consulted.

[0027] If the above formula is met, proceed to step 3 to continue assessing the bearing capacity of the rubber bearing; otherwise, it is determined that the rubber bearing is at risk of overturning and cannot be used. It should be replaced or repaired in a timely manner.

[0028] Step 3: Treat the standard rubber bearing and conduct a residual deformation bearing capacity test to obtain the bearing capacity of the rubber bearing to be evaluated. The purpose of this step is to treat the standard rubber bearing to make its condition as close as possible to that of the in-service rubber bearing to be evaluated. Specifically:

[0029] Step 3-1: Determine the horizontal deformation control amount d for the bearing capacity test based on the offset value of the rubber bearing obtained in Step 1. u :

[0030]

[0031] Among them, D u The effective diameter of the standard rubber bearing used for load-bearing capacity testing is 600 mm in this embodiment. a The diameter of the rubber bearing to be evaluated can be directly measured or obtained from actual engineering data. b To determine the thickness of the rubber protective layer of the rubber bearing to be evaluated, it can be directly measured or actual engineering data can be consulted.

[0032] Step 3-2: Based on the horizontal deformation control amount obtained in Step 3-1, apply this deformation amount to the standard rubber bearing, specifically as follows:

[0033] The standard rubber bearing is placed on a compression-shear testing machine. The standard rubber bearing used here should be the same model as the in-service rubber bearing to be evaluated to ensure more accurate evaluation results. The upper and lower connecting steel plates of the standard rubber bearing are square; in this embodiment, its side length is 1200mm. The compression-shear testing machine used in this embodiment is a UTM-500 testing machine. The lifting capacity of the lateral jack is not less than 10t.

[0034] After being secured with bolts, a thrust is applied to the side of the upper connecting steel plate of the standard rubber bearing using a lateral jack until its deformation reaches the horizontal deformation control amount d. u And maintain it for a certain period of time, in this embodiment 30 minutes;

[0035] Furthermore, in order to make the state of the standard rubber bearing more closely resemble that of the actual in-service rubber bearing under test, in actual operation, in this embodiment, when applying this deformation amount to the standard rubber bearing, the deformation amount is such that it reaches the horizontal deformation control amount d. u After maintaining this position for 30 minutes, the deformed standard rubber support is then fixed in place by connecting it to the upper and lower connecting steel plates using steel bolts. During the connection process, the lateral jacks must be kept under load. Once the fixing is complete, the lateral jacks are unloaded. Figure 2 As shown, it was placed in a high-temperature curing chamber for several hours of high-temperature curing, with the curing specifications being a constant temperature and humidity 40B for concrete curing chambers.

[0036] In this embodiment, the specific high-temperature curing time is 72 hours, and the temperature is set to 120°C.

[0037] Step 3-3: Conduct a bearing capacity test on the rubber bearing after the treatment in Step 3-2 to obtain its residual bearing capacity. Specifically:

[0038] like Figure 3 As shown, after the rubber support is treated in step 3-2, the fixed deformation support is removed, and a compression-shear testing machine is used for pressure testing. The specifications of the compression-shear testing machine are the same as those in the previous steps. The load value f is determined according to the test load value of the compression testing machine. u The bearing capacity assessment results were obtained:

[0039]

[0040] Among them, f u D represents the maximum degree obtained from the compression-shear testing machine. u This refers to the effective diameter of the standard rubber bearing used in the load-bearing capacity test.

[0041] In this embodiment, after disassembling the rubber bearing sample to be evaluated in its service state, the experimental test showed that its residual deformation bearing capacity was 5689.5 kN. However, the method described in this embodiment, after processing a standard rubber bearing and testing its residual deformation bearing capacity, yielded a result of 5766.4 kN. This is significantly higher than the bearing capacity assessment result of 6358.5 kN obtained using existing conventional methods.

[0042] As a non-destructive testing method for unremoved supports, the accuracy of the method of this invention reaches 98.6%, which is significantly higher than that of ordinary evaluation methods that do not consider residual deformation (89.7%), and has great potential for engineering applications.

[0043] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for evaluating the load bearing capacity of a rubber seismic isolation bearing considering residual deformation, characterized by, Includes the following steps: Step 1: Measure the rubber bearing to be evaluated and determine its offset value; Step 2: Determine whether the offset value of the rubber bearing to be evaluated exceeds the limit. If it exceeds the limit, it is determined that it cannot continue to be used. If it does not exceed the limit, proceed to step 3. Step 3: Treat the standard rubber bearing and conduct a load-bearing capacity test on the residual deformation to obtain the load-bearing capacity of the rubber bearing to be evaluated: Step 3-1. Determine the horizontal deformation control amount d of the bearing capacity test according to the offset value of the rubber support obtained in Step 1 u ; Step 3-2: Based on the horizontal deformation control amount obtained in Step 3-1, apply the horizontal deformation control amount to the standard rubber bearing; Step 3-3: Conduct a load-bearing capacity test on the rubber bearing after the treatment in Step 3-2 to obtain its residual load-bearing capacity.

2. The method of claim 1, wherein In the step 1, in order to accurately obtain the offset value, the difference d in the length direction of the upper and lower connecting steel plates of the rubber support is measured x and d y .

3. The method of claim 2, wherein the method further comprises: The step 2, determining whether the offset value of the rubber bearing to be evaluated exceeds the limit, specifically involves: ； Among them, D a D represents the diameter of the rubber bearing to be evaluated. b The thickness of the rubber protective layer of the rubber bearing to be evaluated; If the above formula is met, proceed to step 3 to assess the bearing capacity of the rubber bearing; otherwise, it is determined that the rubber bearing is at risk of overturning and cannot be used.

4. The method of claim 1, wherein The horizontal deformation control amount d in step 3-1 u Specifically, ； where D u is the effective diameter of the standard rubber bearing used for the load test, D a is the diameter of the rubber bearing to be evaluated, D b is the rubber protection layer thickness of the rubber bearing to be evaluated.

5. The method of claim 1, wherein In step 3-2, the horizontal deformation control of the standard rubber bearing is specifically implemented as follows: The standard rubber bearing is placed on a compression-shear testing machine and fixed. A thrust is applied to the side of the upper connecting steel plate of the standard rubber bearing until its deformation reaches the horizontal deformation control amount d. u And maintain it for a certain period of time.

6. The method for evaluating the bearing capacity of rubber seismic isolation bearings considering residual deformation according to claim 5, characterized in that, When the deformation amount of the standard rubber support is implemented, the deformation amount reaches the horizontal deformation control amount d u After that, the deformed standard rubber support is fixed and supported, and is put into a high temperature curing box for high temperature curing for several hours, and the curing specification is constant temperature and humidity of the concrete curing box.

7. The method of claim 6, wherein the method further comprises: The high-temperature curing time is 72 hours, and the temperature is set at 120℃.

8. The method of claim 1, wherein the method further comprises: The process of obtaining the residual bearing capacity in step 3-3 is as follows: The rubber bearing treated in step 3-2 was subjected to a compression-shear testing machine to obtain its load-bearing capacity evaluation results: F u =D u 2 f u / d u 2 Among them, f u D represents the maximum degree obtained from the compression-shear testing machine. u This refers to the effective diameter of the standard rubber bearing used in the load-bearing capacity test.

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