It has been nearly 20 years since CHINA applied seismic isolation technology to building structural engineering in 1992. Dampers, oil dampers, etc. Among them, the most mature technology and the most common application are laminated rubber shock-isolation bearings. Among the seismic isolation buildings that have been built in the world today, more than 80% use laminated rubber seismic isolation bearings, which are the main components of the seismic isolation system, although their research has not been interrupted.
The laminated rubber shock-isolation bearing is composed of thin steel plate and thin rubber sheet. The molecular chain of the rubber material is broken under the action of light, heat, oxygen, ozone and mechanical stress, and the performance decreases and shows aging. Since the rubber shock-isolation bearing is placed at the bottom of the building, it is necessary to consider the differences in climate in various regions, such as heat resistance in the south, cold resistance in the north, and ultraviolet radiation resistance in the plateau area. Correlation and aging performance research is important. At present, there are only literatures on the temperature dependence and heat aging of the 300-type rubber isolation bearing, and there are very few literatures on the temperature dependence and aging resistance of the large-diameter rubber isolation bearing. However, temperature and aging resistance are important factors affecting the long-term use of rubber isolation bearings, and are important means to evaluate the performance stability of isolation bearings. Therefore, the research on small-diameter isolation bearings has limitations, which restricts the promotion of isolation technology. And development. In this paper, 12 600-type rubber shock-absorbing bearings are used as the test body, and the relationship between its performance and temperature and heat aging is studied through experiments, and the heat-resistant aging test of tens of days is used for extrapolation calculations, and the heat resistance of 60-100a is obtained. Aging performance, and the long-term aging resistance performance of the rubber shock-isolating bearing was evaluated.
1 Experimental device and test body
The performance test device of the test body in the study is a 20 000 kN electro-hydraulic servo loading system, see Figure 1. The vertical output force reaches 20 000 kN, and the horizontal output force reaches 2 000 kN; during the horizontal shear strain test, the vertical pressure is kept constant, the loading speed is 3-8 mm/s, the loading adopts sine wave, and the sampling frequency is 2 Hz．Its temperature control adopts automatic temperature control equipment with length, width and height: 2 m×1.5 m×1.8 m, and temperature: 22°C to 42°C. The thermal aging test was completed in a thermostat with a controlled temperature of 100°C.
The test body is 12 600-type laminated rubber shock-isolation bearings, of which: LRB type is 7 bearings with lead cores, and RB type is 5 bearings without lead cores. The structure is shown in Figure 2. The main parameters are shown in Table 1.
2 Test content
2.1 Benchmark performance test
Before each test, 12 test bodies (LRB type and RB type) were subjected to a benchmark performance test with a vertical design load of 15 MPa (4 241 kN), content: vertical pure compression performance, horizontal performance.
2.1.1 Vertical pure compression performance
The vertical pure compression test is to determine the vertical stiffness and vertical deformation of the isolation bearing, and the cycle is within ±30% of the design load value, and the number of cycles is 4 cycles. The vertical load value is collected by the oil pressure sensor, and the vertical displacement is collected by the CLP50 displacement sensor, and the collection time interval is 0.5S.
2.1.2 Horizontal performance
The horizontal performance test is to determine the horizontal equivalent stiffness, post-yield stiffness, yield force and damping characteristics of the isolation bearing. In the research, a compressive stress of 15 MPa (4 241 kN) was applied vertically to the pre-test body, and then a restoring force with a horizontal shear strain of 100% (±120 mm) was applied to it, and the frequency was 0.02 Hz for 4 reciprocating cycles, as shown in Table 2. .
2.2 Temperature-related performance test
After the benchmark performance test, the 3 LRB-type and 3 RB-type test bodies were subjected to temperature-dependent tests, see Table 3 for details.
2.3 Thermal aging performance test
After the benchmark performance test, the 6 (RB and LRB type) test bodies were subjected to heat aging test according to Table 4, and the benchmark performance test was carried out again after the aging test bodies were parked for 72 h. Before the aging test, the compressive stress correlation and shear strain correlation tests were carried out on the LRB-600-J bearing in the test body; after aging, the same content test and the unidirectional 350% ultimate deformation test (vertical Axial load 15 MPa=4 241 kN, horizontal displacement: -420 mm), see Table 5 and Table 6 for details. At the same time, 120 repeated cyclic loading tests (vertical load: 15 MPa, horizontal displacement: ±120 ram) were carried out on the RIL-600-L bearing in the test body after the aging benchmark performance test, and then the benchmark performance test was carried out again to compare Performance rate of change.
3 Test results and analysis
3.1 Benchmark Performance
The benchmark performance test results of 12 test bodies are shown in Table 7. Its vertical stiffness analysis calculation formula is as formula (1):
Among them: Ecv is the modified compression elastic modulus (MPa) of the laminated rubber bearing, Ecv=Ec·Ev/(Ec+Ev); Ev is the elastic modulus of rubber material volume constraint (MPa); Ec is the laminated rubber bearing Compression elastic modulus (MPa), Ec=E(1+2kS21; E is the standard elastic modulus of rubber material (MPa); k is the hardness correction coefficient of rubber material; S is the first shape correction coefficient of the laminated rubber bearing. Data processing and analysis in the test
取测试数据中第三次循环结果，计算如式(2)：
水平性能分析采用双线性模型计算分析[6]，由图3所示，图中Keq为水平等效刚度；H。。为等效阻尼比；Kd为屈服后刚度；Qd屈服力；δ1、δ2为水平变形位移，计算式如下：
图中曲线是LRB支座试验所得双线性恢复力特性滞回曲线，虚线是RB支座恢复力特性曲线．曾襄7知，经基准性能试验两种类型支座的竖向刚度试验值分别相近似，变化区域在一21.1％～+3.3％之间；RB型支座的水平等效刚度很接近；LRB型支座的水平性能中屈服后刚度、等效刚度、屈服力、阻尼比同样分类相近似，与设计值偏差在15％之内。
3.2温度相关性能
图4给出RB和LRB型6个试验体支座在竖向载荷15 MPa(4 241 kN)下水平剪应变为100％(±120 mm)时温度相关性的等效刚度、屈服后刚度、屈服力及等效阻尼比的试验结果曲线及竖向性能的结果曲线．温度对试验体支座水平刚度及屈服力的影响采用式(3)、(4)表示：
式中：丁。为标准常温状态下20℃；T为试验温度；K为水平刚度．图4(a)为试验体(RB和LRB型)支座等效刚度与设计式的对比，知其与设计式曲线趋势相近，RB型支座+40℃时等效刚度偏离设计式+5.5％，温度一20℃时偏离设计值一3.2％；LRB型支座+40℃时等效刚度偏离设计式达+2.0％，温度一20℃时偏离设计值为一0.9％，阻尼比在+40℃时偏离设计式为一11.5％，温度一20℃时偏离设计值为+17.8％．反映出温度对支座的等效刚度及阻尼均具有不同程度的影响，低温使阻尼增大，支座耗能能力显著上升，高温则使其降低．图4(b)、(c)为LRB型支座屈服后刚度、屈服力与设计式的对比，知屈服后刚度及屈服力曲线均与其设计式趋势相一致；+40℃时其屈服后刚度与设计式偏离为+8.5％，温度一20℃时偏离为+10.1％；而+40℃时其屈服后力与设计式偏离为一5.9％，温度～20℃时偏离为＋0.4%；图4（d）为RB和LRB型支座的竖向刚度与温度相关性曲线，知其变化趋势有相同性；温度对竖向刚度存在一定的影响，低温令其刚度增大，高温则使其减小。
3.3热老化相关性能
结 论
(1)研究表明600型(RB和LRB)叠层橡胶隔震支座温度在一20℃～+40℃内变化时，竖向刚度变化趋势具有相同性，随温度的升高刚度下降，低温令刚度增大．其等效刚度与设计式相近似；LRB型支座屈服后刚度、屈服力与设计式趋势相一致，随温度的升高而降低；阻尼比随温度的升高而减小，显示低温阻尼增大耗能特性强，高温耗能性降低．
(2)600型(RB和LRB)试验体支座老化后，经基准性能试验表明，竖向刚度变化率小具有稳定性．RB型支座经老化等效刚度降低；LRB型支座经老化等效刚度、屈服后刚度趋于降低，而屈服力、等效阻尼比显上升趋势(耗能性增大)．
(3) The performance comparison test before and after the aging (100℃×336 h) of the LRB-600 test body support shows that: with the increase of the compressive stress, the equivalent stiffness and stiffness after yielding have a similar trend and decrease; while the equivalent damping ratio, Yield force was increasing. With the increase of shear strain, the equivalent stiffness, equivalent damping ratio and post-yield stiffness all decreased, while the yield force increased slightly. After the aging of the test body, when the vertical load is 15 MPa and the horizontal shear strain is 350% (--420 mm) ultimate deformation, there is no abnormal split layer and crack in the appearance of the test body.
(4) The reference performance of the LRB-600 test body support after aging at 100°C×240 h and its reference performance before aging and after 120 repeated cycles of loading, and its ultimate deformation of 350% before and after aging at 100°C×336 h After comparison of the benchmark performance, it is known that the aging time has a considerable influence on the benchmark performance of the rubber bearing. Long-term aging causes the horizontal benchmark performance of the bearing to decrease, and the vertical performance tends to increase; after the horizontal benchmark performance test after 350% ultimate deformation and 120 cycles, the horizontal stiffness decreases and the damping ratio increases, indicating that aging promotes the damping of the lead core bearing increase.
There are not many studies on the temperature correlation and aging performance of large-diameter rubber shock-isolators at home and abroad. This study reflects that the performance of rubber shock-isolators produced in my country is stable, and the performance indicators all meet domestic regulations, national standards and even Japanese construction standards. The requirements of seismic isolation design provide an important basis for the popularization and application of seismic isolation technology in the field of construction engineering.
