Discussion About The Improvement Of Pushover Loading Pattern And Method

Comparing with the traditional force-based seismic design method ,performance-based seismic design method can comprehensively assess destructiveness for the structure in the earthquake action, as well as nonlinear static analysis method (Pushover method) is an important approach to study the performance-based seismic design. At present, the research on the nonlinear static analysis at home and abroad focuses on how to consider the effect of high modes and the re-distribution of horizontal inertial force after yield for the structure. All of the load modes are unilateral loading mode, which can not consider the loading history, earthquake duration and the cumulative seismic damage on the structure. Existed research results demonstrate that energy transfer, conversion and absorption are the basic characteristics of seismic response for structure. Two-way cyclic loading Pushover analysis method used in this paper is improved from the traditional Pushover method, which can consider the displacement of the loading history and indicate the cumulative damage caused by the hysteretic energy for structure. In this paper, the research is performance through comparing the two primary pacts, which are the displacement and the hysteretic energy, respectively employing two-way cyclic loading Pushover analysis method and the nonlinear dynamic analysis method. The main contents include: the plane frame structure is equivalent to a single degree of freedom system,the nonlinear dynamic time-history analysis method is proceed respectively for the original structure and the equivalent single degree of freedom system, then, the equivalent vertex displacement time-history for frame construction is calculated against from the analysis results of the equivalent SDOF system. Analysis results manifest that the trend of the equivalent vertex displacement time-history and the vertex displacement time-history for original structure is roughly in the same, furthermore, the peak is more or less identical. So the each peak of the equivalent vertex displacement time-history is used as the target displacement of the two-way cyclic loading Pushover analysis method to progress the two-way Pushover analysis. This article introduces the link unit provided by SAP2000 to simulate the nonlinear properties for components, because link unit is non-linear element, with the hysteresis property using Pivot model as the resilience model for components. Through the two-way cyclic loading Pushover analysis, the results including the base shear against top displacement hysteresis curve, floor displacement and story drift, hysteretic energy of structure and so on are obtained to performance the seismic various assessments. By processing the two-way cycle Pushover analysis for plane frame structure and comparing the displacement and hysteretic energy dissipation obtained from the traditional Pushover analysis and the nonlinear dynamic analysis, the method presented in this paper is discussed the feasibility and reliability. The conclusion of this paper will provide a new research thought for nonlinear static analysis method in seismic analysis on the improvement of Pushover loading pattern and the discussion of loading method.