Method for evaluating bearing capacity of rubber shock insulation support by considering residual deformation

Abstract

The invention discloses a method for evaluating the bearing capacity of a rubber shock insulation support by considering residual deformation, which comprises the following steps of: firstly, measuring a rubber support to be evaluated, and determining an offset value of the rubber support; and then judging whether the deviation value of the rubber support to be evaluated exceeds the limit or not, if so, directly judging that the rubber support cannot be continuously used, and if not, treating the standard rubber support, and testing the bearing capacity of residual deformation to obtain the bearing capacity of the rubber support to be evaluated. According to the scheme provided by the invention, based on simple detection on the rubber isolation support in the in-service state, deformation is applied to the standard rubber support, and the standard rubber support is infinitely close to the aging state of the actual rubber isolation support to be evaluated, so that the residual bearing capacity of the rubber isolation support with residual deformation is accurately obtained; the residual bearing capacity of the rubber shock insulation support can be accurately tested under the condition that the rubber shock insulation support in the in-service state is not disassembled, the test result is accurate, nondestructive testing is achieved, and the method has important significance in engineering.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of rubber isolation bearing testing, and particularly relates to a rubber isolation bearing bearing capacity evaluation method considering residual deformation. BACKGROUND

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

[0003] However, it is worth noting that residual deformation of rubber bearings generally exists in engineering practice, which means that the rubber bearing cannot return to its original position after being affected by earthquakes, wind vibration, vehicle vibration, etc., and will bear vertical load for a long time in a state of certain deformation. This is because rubber is a flexible material that is prone to deformation under vibration, and usually cannot return to its original position after vibration. Due to different degrees of residual deformation of rubber bearings, the bearing capacity of the bearings is reduced to different degrees, and this problem has been a concern in the industry.

[0004] In the prior art, there are many schemes for testing the performance of rubber bearings, such as CN117191308A_A rubber isolation bearing performance detection device and method, which provides a device and method for detecting the performance of rubber bearings. However, this device and method do not consider the problem of residual deformation, i.e., the research object is a bearing without initial deformation; and CN113847901B_A building isolation rubber bearing lateral uneven deformation detection device and detection method, which only considers the deformation monitoring of rubber bearings, but the corresponding relationship between deformation and bearing capacity reduction is not clear.

[0005] In actual situations, rubber bearings, as flexible components, are also key nodes of deformation damage in design, and generally have residual deformation, only to different degrees. Residual deformation causes the vertical load application point to deviate from the component center, which obviously leads to a decrease in bearing capacity. However, the detection of rubber bearings is not allowed to be removed, so nondestructive testing is of great engineering significance, and an evaluation method for the residual bearing capacity of rubber bearings in service is needed. SUMMARY

[0006] To solve the above problems, the application provides a rubber isolation bearing bearing capacity evaluation method considering residual deformation, which innovates the equivalent of the bearing in actual engineering under the condition of the test bench for the rubber bearing in actual service state that cannot be removed, and evaluates the residual bearing capacity.

[0007] The specific technical scheme for achieving the purpose of the application is:

[0008] A method for evaluating the bearing capacity of a rubber seismic isolation support considering residual deformation, comprising the following steps:

[0009] Step 1, measuring the rubber support to be evaluated to determine its offset value;

[0010] Step 2, determining whether the offset value of the rubber support to be evaluated is out of limit, if it is out of limit, it is directly determined that it cannot be used continuously, if it is not out of limit, step 3 is executed;

[0011] Step 3, processing a standard rubber support and testing the bearing capacity of residual deformation to obtain the bearing capacity of the rubber support to be evaluated.

[0012] Compared with the prior art, the beneficial effects of the present application are:

[0013] (1) The scheme of the present application can accurately test the residual bearing capacity of the rubber seismic isolation support in service without disassembling it, and the test result is accurate, realizing nondestructive testing, which has important significance in engineering;

[0014] (2) The scheme of the present application is based on simple detection of the rubber seismic isolation support in service, and the standard rubber support is deformed and made to approach the aging state of the actual rubber seismic isolation support to be evaluated, so that the residual bearing capacity of the rubber seismic isolation support with residual deformation is accurately obtained.

[0015] The present application will be further described below in conjunction with the specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a step flowchart of the method for evaluating the bearing capacity of the rubber seismic isolation support considering residual deformation of the present application.

[0017] Figure 2 It is a physical schematic diagram of the deformation treatment of the standard rubber support and the fixed deformation support in the embodiment of the present application.

[0018] Figure 3 It is a schematic diagram of the rubber support test piece after applying different deformation loads in the embodiment of the present application. DETAILED DESCRIPTION

[0019] EMBODIMENT

[0020] The rubber support to be evaluated in service in this embodiment comes from the non-iron-involved section of the second phase project of Jiangping West Road in Yangzhou City, Jiangsu Province (Ruyang North Road Interchange), which is a 2-year-old high-speed road bridge rubber support, circular, effective diameter 900mm;

[0021] In combination with Figure 1A method for evaluating the bearing capacity of a rubber seismic isolation support considering residual deformation, comprising the following steps:

[0022] Step 1, measuring the rubber support to be evaluated to determine its offset value;

[0023] This step is to obtain the offset values of the upper and lower steel plates of the rubber support to be evaluated in the two side length directions in the actual service state. Generally, the main part of the rubber support is cylindrical, and the upper and lower connecting steel plates are rectangular. At this time, in order to accurately obtain the offset, the difference d x and d y in the side length direction of the upper and lower connecting steel plates of the rubber support are measured respectively.

[0024] Step 2, judging whether the offset value of the rubber support to be evaluated is out of limit, if it is out of limit, directly determining that it cannot be used continuously, if it is not out of limit, executing step 3, specifically:

[0025]

[0026] Wherein, D a is the diameter of the rubber support to be evaluated, which can be directly measured or inquired from actual engineering data, D b is the rubber protection layer thickness of the rubber support to be evaluated, which can be directly measured or inquired from actual engineering data.

[0027] If the above formula is met, step 3 of bearing capacity evaluation of the rubber support is continued, otherwise, it is directly determined that the rubber support has overturning risk and cannot be used continuously, and should be replaced or repaired in time.

[0028] Step 3, processing the standard rubber support and testing the residual deformation bearing capacity to obtain the bearing capacity of the rubber support to be evaluated. The purpose of this step is to process the standard rubber support to make its state as close as possible to the in-service rubber support to be evaluated, specifically:

[0029] Step 3-1, determining the horizontal deformation control amount d u of the bearing capacity test according to the offset value of the rubber support obtained in step 1:

[0030]

[0031] Wherein, D u is the effective diameter of the standard rubber support used for bearing capacity test, which is 600mm in this embodiment, D a is the diameter of the rubber support to be evaluated, which can be directly measured or inquired from actual engineering data, D b is the rubber protection layer thickness of the rubber support to be evaluated, which can be directly measured or inquired from actual engineering data.

[0032] Step 3-2, based on the horizontal deformation control amount obtained in step 3-1, the standard rubber support is implemented with the deformation amount, specifically:

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

[0034] After being fixed by bolts, the lateral jack is used to apply a pushing force to the side surface of the upper connecting steel plate of the standard rubber support until the deformation amount reaches the horizontal deformation control amount d u , and is maintained for a certain period of time, which in this embodiment is 30 minutes;

[0035] In addition, in order to make the state of the standard rubber support more close to the actual in-service rubber support to be measured, in actual operation, in this embodiment, after the deformation amount of the standard rubber support reaches the horizontal deformation control amount d u and is maintained for 30 minutes, the deformed standard rubber support is also fixed and supported by steel bolts connected to the upper and lower connecting steel plates. The connection process needs to maintain the lateral jack load holding state. After the fixing is completed, the lateral jack is unloaded, as shown in Figure 2 , and is placed in a high temperature curing box for high temperature curing for several hours. The curing specification is a concrete curing box with constant temperature and humidity 40B.

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

[0037] Step 3-3, based on the rubber support treated in step 3-2, the residual bearing capacity is obtained by bearing capacity test, specifically:

[0038] As shown in Figure 3 , the rubber support treated in step 3-2 is removed from the fixed deformation support, and a compression-shear testing machine is used for pressure test. The specification of the compression-shear testing machine is the same as that in the previous steps. According to the load value f u tested by the compression-shear testing machine, the bearing capacity evaluation result is obtained:

[0039]

[0040] Wherein, f u is the maximum value degree obtained by the compression-shear testing machine, and D u is the effective diameter of the standard rubber support used for bearing capacity test.

[0041] The residual deformation bearing capacity of the rubber support sample to be evaluated in service state is 5689.5kN after disassembly and experimental detection, and the residual deformation bearing capacity evaluation result of the standard rubber support treated based on the scheme of the method is 5766.4kN after residual deformation bearing capacity test, compared with the bearing capacity evaluation result 6358.5kN obtained by using the existing ordinary method:

[0042] As a non-destructive testing method of the undismounted support, the accuracy of the method reaches 98.6%, which is significantly higher than that of the ordinary evaluation method (89.7%) without considering residual deformation, and has a high engineering application prospect.

[0043] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for evaluating the load bearing capacity of a rubber seismic isolation bearing considering residual deformation, characterized by, The method comprises the following steps: Step 1, measuring the rubber support to be evaluated to determine its offset value; Step 2, judging whether the offset value of the rubber support to be evaluated is out of limit, if yes, directly determining that it cannot be used continuously, if not, executing step 3; Step 3, processing the standard rubber support and testing the residual deformation bearing capacity to obtain the bearing capacity of the rubber support to be evaluated.

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 judgment of whether the offset value of the rubber support to be evaluated is out of limit in step 2 is specifically: where D a is the diameter of the rubber bearing to be evaluated, D b is the thickness of the rubber protection layer of the rubber bearing to be evaluated; If the above formula is met, step 3 of bearing capacity evaluation of the rubber support is executed, otherwise, it is directly determined that the rubber support has overturning risk and cannot be used continuously.

4. The method of claim 2, wherein the method further comprises: The obtaining of the bearing capacity of the rubber support to be evaluated in step 3 is specifically: 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, implementing the deformation amount on the standard rubber support based on the horizontal deformation control amount obtained in step 3-1; Step 3-3, testing the bearing capacity of the rubber support processed in step 3-2 to obtain the residual bearing capacity.

5. The method of claim 4, wherein the method further comprises: 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.

6. The method of claim 4, wherein the method further comprises: The implementation of the deformation amount on the standard rubber support in step 3-2 is specifically: The standard rubber support is placed in a compression-shear testing machine, and after being fixed, a pushing force is applied to the side of the upper connecting steel plate of the standard rubber support until the deformation amount reaches the horizontal deformation control amount d u and is maintained for a certain period of time.

7. The method of claim 6, wherein the method further comprises: When the deformation amount is applied to the standard rubber bearing, the deformation amount reaches the horizontal deformation control amount d u After that, the deformed standard rubber bearing 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.

8. The method of claim 7, wherein the method further comprises: The high-temperature curing time is 72 hours, and the temperature is set to 120 DEG C.

9. The method of claim 4, wherein the method further comprises: The obtaining of the residual bearing capacity in step 3-3 is specifically: The rubber support processed in step 3-2 is tested by a compression shear testing machine to obtain the bearing capacity evaluation result: F u = D u 2 f u / d u 2 wherein f u is the maximum value in degrees obtained from the compression-shear testing machine, D u is the effective diameter of the standard rubber bearing used for the load capacity testing.

Images