Analysis And Experimental Study On Nonlinear Mechanical Properties Of Series Isolation System

With the rapid development and application of isolation technology,it is a common phenomenon that the series isolation system(SIS)composed of lead-core laminated rubber bearing(LRB)connected to the top of cantilever column(RC column)in basement is used as isolation layer.Under earthquake action,especially in the long holding time or nearly pulse type faults under the action of earthquake ground motion,RC column will appear at the bottom of the nonlinear cumulative damage caused such as stiffness and strength degradation,which connected with the isolation bearing formed by serial mechanical performance of vibration isolation components change,assuming RC column is still at the bottom of the rigid components,will not be able to correctly describe the components of true stress of composite bearings.It is lack of series isolation component to the overall mechanical properties and testing research,in order to be able to the mechanical properties of the series isolation components have a more in-depth cognition,establish the series isolation component performance state indicators,for the tandem structure provided a reference for practical engineering design,this thesis made the following aspects of content:(1)The stress state and basic theory of series isolation members are deduced and analyzed,and the horizontal stiffness of LRB under four different boundary conditions is given,so as to further deduce the horizontal stiffness of series isolation members.At the same time,a refined model of multiple series isolation components is established by using ABAQUS software,and the hysteretic curve,LRB stress distribution and damage characteristics of RC columns were discussed and analyzed to prepare for subsequent research.(2)Presents a series of LRB isolation components between the RC column and the deformation coordination equation of introducing the slenderness ratio of axial compression ratio and two parameters,with displacement Angle limit state as performance indicators,analyzes the slenderness ratio of axial compression ratio and performance condition,the influence of series isolation components series isolation components are pointed out in the state of different performance bearing shear strain along with the change of axial compression ratio and slenderness ratio,The critical value of slenderness ratio corresponding to different coaxial pressure ratio is given when the bearing fully plays its working performance,that is,the bearing reaches the ultimate deformation state.The rationality of the performance index parameters is verified by the test results,which provides a quantitative index for the practical engineering design of series isolation structures.In this thesis,considering that the axial compression ratio commonly used in engineering is generally between 0.2 and0.5,in order to ensure the overall safety performance of series isolation components,it is suggested that the slenderness ratio of cantilever column in basement should be within 10.4.(3)Five groups of series isolation components under different working conditions were studied by pseudo-static test.The test results were compared with the established finite element model and the performance state interval of the series isolation component.Verify the validity and rationality of the finite element model and the performance state of the series isolation member.At the same time,the nonlinear mechanical properties such as force-displacement relation,strength,horizontal stiffness,ductility and energy dissipation capacity of series isolators are analyzed.