Seismic Performance Analysis And Assessment Of R.C. Frame Structures Asymmetric In Plane

Buildings asymmetric in plane is used inevitably in practical engineering, because of the limitation of constructions field and design function. It is indicated from the earthquake damages that the damage get much more seriously in the irregular building than that in the regular ones, the cause of which is the existence of the torsional deformations. Many scholars have been so concentrating on the analysis and research on the seismic performance of eccentric buildings that much valuable conclusions were obtained. Now Pushover analysis has been successfully applied to the seismic performance evaluation of regular buildings, while little research are concentrated on high wise buildings and irregular buildings and some aspects used in Pushover procedure need to be improved. By means of applying Pushover analysis and capacity spectrum method, the seismic performance of buildings asymmetric in plane are evaluated. Conclusions obtained in this paper are valuable and important for theory research and practical engineering.The definition of buildings asymmetric in plane and torsion-resistant design method in many nations' seismic codes is introduced. The main factor and some detail method are analyzed in the calculation of torsion effects in different seismic design codes. Then, the basic principle and development survey of Pushover analysis method are summarized, and the whole models and element models used in the static plastic analysis are given. Several suggestions on the using and loading directions of lateral load through expanding Pushover analysis to 3-D models in ETABS are obtained. The basic principle and application conditions of capacity spectrum method are introduced by the example of seismic performance evaluation on one building asymmetric in torsion. It is concluded that target displacement is different when loading in opposite directions and the difference is getting more obvious with the increasing of eccentricity and plastic deformation. Based on thecombination between modal decompose response spectrum method and Pushover analysis, the capacity spectrum is modified on solving target displacement considering model coupled effects. One four-storey R.C. structure asymmetric in torsion is operated and its target displacement is solved by use of the new method. The calculation result is compared with that of non-linear time history analysis and the result precision is good enough for piratical engineering.