Study On Hysteretic Behavior Of Multifunctional And Adaptive Double Friction Pendulum Bearing

Double friction pendulum bearing(DFPB)is one of the spherical sliding isolators.The DFPB can provide relatively larger displacement compared with the traditional friction pendulum bearing(FPB)with same dimensions as the DFPB.Therefore,the DFPB has attracted extensive notice of researchers and engineers.However,the conventional DFPB has some shortcomings such as low seismic resistance redundancy and poor displacement limitation and re-centering capacities.To overcome the above deficiencies,a new type of multifunctional and adaptive double friction pendulum bearing(MADFPB)consisting of shape memory alloy(SMA)cables and DFPB device is presented in this dissertation.By using experimental investigation and numerical simulation,the hysteresis behavior of the MADFPB is systematically researched.The main contents and results of the thesis are described as follows:(1)The configuration of the novel MADFPB is formed by uniformly arranging superelastic SMA cables between top plate and the bottom plate of the proposed isolator.Similar to the pure DFPB,the MADFPB implements isolation mechanism and energy dissipation through sliding friction.Furthermore,the MADFPB realizes effective displacement control and additional energy consumption by means of the SMA cables,which are important to prevent the isolators from damages under strong earthquakes.(2)The mechanical properties of SMA wire and SMA cable specimens were tested,The effects of loading times,loading frequency and displacement amplitude on mechanical parameters of the SMA components were summarized.The results show that both SMA wire and SMA cable specimens can provide stable hysteresis curves,and have excellent superelastic performance.(3)MADFPB specimen were designed and fabricated,and their mechanical properties were studied experimentally.The influence of different vertical pressure,displacement amplitude and loading frequency on the mechanical properties and hysteresis characteristics of the isolator specimens were investigated.The hysteresis behavior of the MADFPB specimens and the corresponding DFPB specimens were compared and analyzed.The study reveals that both MADFPB and DFPB could provide stable and full hysteretic loops.During the sliding process of the MADFPB,the SMA cable can play a good role in bidirectional displacement control by virtue of the superelasticity.,which evidentally improves the energy dissipation ability and adaptability of the traditional DFPB.(4)By using the ABAQUS software,the finite element models of the afore mentioned MADFPB specimens were established.Based on the cases identical to the experiment study,the quasi-static cycling test for the MADFPB specimens were numerically simulated.The simulated results were compared to the experimental results.The investigation indicates that the experimental results are in good agreement with the simulated results.