Studies On Perfomance-based Seismic Design Of Steel Frame Structure With Self-centering Damper

The self-centering damper has moderate energy dissipation capacity and good reset ability.The structure with self-centering damper can weaken the seismic response of structures,dissipate seismic energy and reduce the residual deformation after the earthquake.Performance-based seismic design method provides a variety of seismic performance targets for the owners to choose.It is convenient for the structural design to achieve different performance levels under the seismic action of different risk levels.The concept of performance-based seismic design is applied to the field of seismic design of passive control structures.This can be used to design the damper layout and parameters for the expected seismic performance target.In this paper,an energy-based performance index was proposed.The selfcentering damper is applied to the performance-based seismic design of the passive control steel frame.The effects of additional stiffness and additional damping ratio of the self-centering damper are considered in the design.The selected topic has strong practical engineering application value.This research mainly had done work as follows:(1)The performance index based on energy is proposed and the performance level quantification and performance target based on energy index are given.On the basis of summarizing the standard performance level division at home and abroad,the ratio of seismic cumulative hysteretic energy demand to structural hysteretic energy dissipation capacity is proposed as an energy-based performance index.Based on the known energy index limits,the corresponding performance level limits of each level is obtained by interpolation.Finally,the performance level of grade 5 based on the energy index and the seismic performance target for the passive control structure are given.(2)The seismic performance design of steel frame with self-resetting damper is improved based on capability spectrum method.Through the performance analysis of the uncontrolled structure,the additional damping ratio needed to achieve the expected performance goal is defined,and the damper is initially arranged in combination with the displacement response of the uncontrolled structure.Finally,the damper parameters are designed and the passive control structure is formed.In order to consider the influence of the additional stiffness of the damper,the capability spectrum curve considering the additional stiffness of the damper is obtained by the nappe analysis of the controlled structure with the added damper.The improved seismic performance design based on capability spectrum method considers the influence of additional stiffness and additional damping ratio of the damper from two aspects.(3)The method of calculating the distribution of energy dissipation layers in multimodal analysis is improved.The calculation of energy spectrum and energy demand ratio spectrum is introduced.By comparison with time history analysis found that the more the calculation method of modal pushover analysis because of not considering structure of reciprocating vibration when the weak positions are more likely to cumulative damage and generate energy concentration,too small to estimate the energy consumption of relatively weak layer,thus put forward through the cumulative damage amplification factor to consider the effect of relatively weak layer and thus improve modal pushover analysis method.The comparison of time history analysis shows that the improved multi-mode analysis can improve the calculation accuracy of energy dissipation layer distribution.(4)A design flow of seismic performance based on energy index is proposed for the steel frame with self-centering damper and an example is given to illustrate the practicability of the design process.The energy spectrum and the improved multi-mode nappe analysis method are applied to the performance-based seismic design of passive control structures.The damper is initially arranged by the distributed control between the energy dissipation layers.The damper parameters are designed by the energy dissipation formula of the damper and the passive control structure is formed.