Research On Performance Of Laminated Rubber Bearing And Response Of Isolated Long-span Viaduct And Isolated High-rise Building

With the economic development and urbanization of mankind, more and more high-rise buildings, large space structures and long-span viaducts are constructed. Wealth and population are increasingly concentrated. It will cause a greater damages and loss once subject to earthquake disaster. Long-span viaduct is a limited freedom structure. Large deformation will be occurred if it just uses the structure damping and nonlinear deformation to resistant severe earthquake. Excessive deformation will lead to serious injury or even collapse. The traditional seismic design is based on the philosophies that the structure must have sufficient strength, stiffness and ductility. The seismic force is resisted by the strength and plastic deformation of the structure members. This will make the section size and weight of the member increase. The enlarged scale causes heavier dead load and stronger earthquake response.After decades of development and application, it is proved that the isolation technology is one the most effective method in reducing seismic response and avoids earthquake disaster. At present, the application of seismic isolation in long-span viaduct and high-rise building is limited in China. The nature period of the long-span viaduct is long before isolated. The isolator will lengthen the nature period of viaduct. It is necessary to study the isolation effect on long period structures. With a high aspect ratio, the isolator in isolated high-rise building will come into the tension state because of the overturning moment cause by the earthquake. This is the most reason hinders the isolation technology application in high-rise buildings. The laminated rubber bearing is widely used in isolation design. In order to ensure the bearing undergo pure shear deformation and satisfy the rigid assumption of inner steel plate, the strength and thickness of the inner steel plate is large as much as possible. The effect of the inner steel plate thickness on stress distribution in inner steel plate and failure modes of the laminated rubber bearing is not clear.In this dissertation, several critical issues have been theoretical and experimental researched in the field of mechanical properties of laminated rubber bearings, seismic response of long-span viaduct and high-rise buildings. The main contents are as follows:(1) State of the art in the field of isolation bearing mechanical properties, isolated long-span viaduct and isolated high-rise buildings is summarized based on a large number of domestic and international research literatures. A series critical problem in isolation design is proposed. (2) Vertical compress test and compression-shear test are conducted on four full scale square laminated rubber bearings. The mechanical characteristics and effect of the inner steel plate thickness on bearings are studied. The failure mode of the bearing due to the inner steel plate bulking is discussed based on the test results.(3) Based on the rubber material characteristic test data fitting, a suitable rubber material model used in finite element analyze is chosen. And the stress distribution and deformation of the inner steel plate of the laminated rubber bearing subject to vertical compression and compression-shear states are studied using finite element method. The reason of the bearing failure due to insufficient inner steel plate thickness is interpreted based on the finite element analyze results.(4) The principle and method of isolated viaduct are introduced and the analyze model of pier plastic hinge and isolator are studied. The correction of fiber model to simulate the plastic hinge in pier is verification base on the model test of low frequency cyclic pseudo static loading on a1:10scale pier model. An analysis model using SAP2000is built based on the bearings compress-shear test and pier model pseudo static loading test. The model is verification through shake table test.(5) A full scale three dimension model considering pier nonlinear behaviors is built. The influence of soil structure interaction (SSI) on isolated long-span viaduct and the difference seismic response between resistant earthquake design viaduct and isolation design viaduct are studied using nonlinear dynamic time history analysis. Studies show that the influent of SSI is small. Isolation design without considering SSI is conservative and acceptable. The acceleration and velocity seismic response of the viaduct is significant reduced using isolation design while the displacement response is increased. The pier of isolated design remains elastic in severe earthquake, while the earthquake resistant design pier goes into plastic state. For the different height pier viaduct system, the inertial force caused by the earthquake will concentrate on the lowest pier in earthquake resistant design viaduct, however, the inertial force in isolated viaduct can be distribute on all piers through choose reasonable isolator parameter.(6) The earthquake response analysis of three20-story buildings of seismic design frame-shear wall structure, base isolated reinforced concrete frame structure and base isolated frame-shear wall structure is carried out using nonlinear time history analysis method. It is verified that the maximum story drift of the seismic design structures decreases whereas the maximum acceleration response is enlarger. The superstructure of base isolated building remains elastic state. The acceleration response of the isolated building is reduced remarkable. It is advantage to maintain function and keep people comfortable.(7) The insufficient of tensile capability of the laminated bearing is the most reason hinders the isolation technology application in high-rise buildings. In order to solve this problem, an innovation tensile-resistant laminated rubber bearing device (TRLRB) is proposed taking advantage of compressive ability to resistant the tensile force. Nonlinear dynamic analysis of an isolated high-rise building under severe earthquake loading is performed in this dissertation on study the effects of the TRLRB. The analysis results show that, the TRLRB is feasible because of the simple in both design and manufacture, and the vertical displacement of the isolation layer is reduced despite the tensile force cause by superstructure using TRLRB. The study also shows that the swing phenomenon of the isolated high-rise building is reduced remarkable and the tensile ability of the isolation layer is improved significantly. It has practical to use TRLRB in isolated high-rise building.