Perfomance-based Seismic Design And Seismic Fragility Analysis Of Steel Frame Structure

The self-centering damper has moderate energy dissipation capacity and good reset ability.The structure with self-centering damper can reduce residual deformation earthquake.Performance-based seismic design method could make the structure meet the different performance target under different earthquake.Performance-based seismic design of passive control structures could be used to determine the mechanic parameters according to different performance objectives.Seismic fragility analysis method,based on the concept of performance-based seismic design,is used to evaluate the conditional probability of reaching or exceeding the limit state of the appointed structure under the given seismic parameters.In this research,the calculating formula of additional stiffness for the self-centering damper is given,and the corresponding selecting principle is completed.Meanwhile,for the structures with self-centering dampers,performance design method based on capability spectrum method is completed by considering the total effect of additional stiffness and additional damping ratio to such structure.Seismic fragility analysis is conducted to passive control structure with self-centering dampers.Finally,energy-based seismic design method is completed in the passive control structure with self-centering damper.This research mainly had done work as follows:(1)The performance design method of passive control structure with self-centering dampers based on component deformation and capacity spectrum method is introduced,according to principle of self-centering dampers.The method also includes the calculation of target performance point based on spectral displacement and equivalent damping ratio,obtain the additional damping ratio according to equivalent damping ratio.According to the mechanical model and energy dissipation characteristics of SMA damper,the formula of the additional damping ratio is proposed,and the damper parameters are determined by the additional damping ratio.Meanwhie,a 20-floor Benchmark steel frame structure is selected for the seismic performance design based on capability spectrum method and performance analysis of passive control structure with SMA self-centering dampers are carried out for performance evaluation.(2)Seismic fragility analysis is carried out on the passive control structure with such damper to study the energy dissipation effect of the damper.The seismic fragility analysis based on the incremental dynamic method is introduced,and the corresponding procedure is given.A great deal of time history analysis have been conducted in ABAQUS software for 9-floor Benchmark steel frame structure or such structure with dampers and the corresponding IDA curves is obtained.From the time history analysis results,seismic fragility curves for uncontrolled structure and passive control structures are obtained,and they are transferred to the corresponding minor,moderate and major earthquake seismic fragility matrices under eight degree seismic precaution,to estimate the improvement of the damper to seismic behavior of structure quantificationally in the respect of probability.(3)Energy-based seismic design method is carried out the passive control structure with self-centering damper.The energy spectra for energy-based seismic design,including the spectral input energy,cumulative hysteresis energy ratio and the normalized equivalent velocity spectrum for the single-degree-of-freedom system are briefly introduced.Finally,a 20-floor Benchmark steel frame structure is selected for energy-based seismic design to estimate the improvement of the damper to seismic bahavior.