ENERGY-BASED FORMATION OF MODAL PUSHOVER METHODAND ITS APPLICTION
ZOU Zhong-quan1 ; HE Guo-jing2
1. School of Civil Engineering and Architecture, Central South University, Changsha 410075, China; 2. School of Civil Engineering, Architecture & Mechanics, Central South University of Forestry and Technology, Changsha 410004, China
Abstract： An improved method that directly establishes the capacity curve based on energy increments is submitted for modal pushover analysis (MPA). Applying the energy-balance equation of linear and nolinear system, it is proved that while the structure is loaded with modal related load, the total input energy is fully transformed to the absorbed energy by the corresponding SDOF system. The relationship between the energy increments and the spectral displacement increments as well as the spectral acceleration increments are deduced, hence the capacity curve is directly obtained. The properties of the equivalent SDOF system are evaluated from the capacity curve, and the seismic responses are calculated with the capacity curve and response spectrum. A large span continuous frame bridge with tall piers in seismic zone is analyzed with the submitted method. The results show that the capacity curves obtained with the proposed method are more stable than those obtained with conventional method, thus the deficiency of multi-definition or distortion for conventtional method is corrected.
2010, Vol. 29 
