A New Type Of U-rib SMA-FPB Bearing And Its Seismic Isolation In Bridges

Since the 20 th century,many strong earthquakes have occurred in various regions of the world,which has made mankind deeply aware of the destructive power of earthquakes.According to the research of many previous scholars,the traditional isolators will produce large displacement under the action of earthquake.Low frequency resonance can occur,which can damage isolators or buildings.At present,friction pendulum is widely used in engineering because of its higher bearing capacity,stability and durability.A new type of shape memory alloy(SMA)material has been widely studied and applied in practical engineering due to its unique shape memory effect,hyperelastic effect and high damping property.In this paper,we propose a new type of U-rib SMA-FPB bearing,which combines the advantages of both the FPB and the U-rib SMA.The following studies were carried out:(1)An FPB elastic model is proposed and several SMA constitutive relationships are discussed.A new U-rib SMA-FPB isolation bearing is proposed and its working principle and structure,damping constitutive relation of U-rib SMA and bearing deformation mechanism are discussed.Finally,the design essentials of U-rib SMA-FPB support are discussed.(2)Solid models of FPB and U-rib SMA-FPB supports were established by using ANSYS software.Then the hysteretic energy dissipation was simulated numerically,and the influences of design parameters such as vertical pressure,displacement amplitude,friction coefficient,bearing radius of curvature,and size of U-rib SMA-FPB supports on mechanical properties were revealed.(3)Using SAP2000 software,the finite element model of continuous beam Bridges with FPB and U-rib SMA-FPB supports was established.To the bridge structure in rare earthquake two blocks of nonlinear time history analysis,selected three kinds of far field seismic waves and three recent seismic fault,respectively along the bridge to enter and cross the bridge to the input,made of displacement,girder and pier base acceleration bending moment and other structural response analysis,research U-rib SMA-FPB bearing the isolation effect in thecontinuous girder bridge,finally it is concluded that U-rib SMA-FPB bearing the influence law of design parameters on the seismic responses of the bridge.