Energy-Based Seismic Design Method Of K Type Steel Eccentrically Braced Frame Under Nearfault Earthquake

The near-fault earthquake can bring large energy to the building in a short time with its strong velocity pulse and long pulse period,which causes the structure damage.The current seismic design method is an elastic design method mainly based on strength,which considers little about the inelastic behavior of structure.Structures designed by this method may be not safe under near-fault earthquake.It is important to put forward a more reasonable seismic design method,which can fully consider the characteristics of near-fault earthquake.This paper introduces the maximum effect cyclic energy spectrum,and proposes a performance-based seismic design method of K type steel eccentrically braced frame under far field earthquake according to the energy balance equation.This method selects part of the seismic input energy as the design basis,and clearly corresponds the characteristics of near-fault earthquake,which is clear in concept,convenient and practical.Ten-story and fifteen-story K eccentrically braced steel frames with three spans were designed using the method above.10 near-fault ground motion records were selected respectively to evaluate the seismic behavior of the two structures by pushover and nonlinear time history analysis.The results show that the structure takes on the ideal progressively plastic mechanism,and the yield displacement keeps stable while not far from the design value.The inter-story drift of structures,under frequent,intermediate earthquake and rare earthquake level,can meet the requirement of Code for Seismic Design of Buildings.The deformation and hysteresis energy along the height of structures,is uniformly distributed.The reasonably and reliability of this seismic design method is verified.