非规则结构的偶然偏心研究

目的通过算例分析考查偶然偏心对非规则结构地震效应的影响显著性．方法设计了33个单层和多层平面扭转不规则结构算例，用附加偏心距的方法考虑偶然偏心，采用振型分解反应谱法分析结构在考虑单向或双向偶然偏心前后的地震效应，以楼层最大位移、平均位移、弹性层间位移角、楼层偏心扭转角、构件地震剪力等多种地震效应作为考查指标，研究了单向或双向偶然偏心对单层和多层非规则结构的影响规律，并与偶然偏心对规则结构的影响进行了对比．结果偶然偏心的影响随结构非规则程度的增加而减小。但即使对于平面扭转特别不规则的结构，偶然偏心所导致地的震效应的增加仍然是不宜忽略的，特别是对于边缘构件更是如此．结论指出我国规范应对规则和非规则结构均按附加偏心扭矩的方法计入偶然偏心的影响．

Study on Accidental Eccentricity of Irregular Structures

The accidental eccentricity is considered for regular structures and ignored for irregular structures in seismic design according to the Chinese codes,while it is considered for both regular structures and irregular structures according to some codes such as UBC,FEMA302s,etc.So it is necessary to study the influence of accidental eccentricity on irregular structures.By considering an additional torque to calculate unilateral or bidirectional accidental eccentricities,the seismic responses of 33 single-story and multi-story structures which are irregular in plane torsion are analyzed,the influence of unilateral or bidirectional accidental eccentricities on the selected structural seismic responses,such as the maximum and average displacements,elasticity displacement angle,eccentricity torsion angle of story,shear force of columns,etc,are investigated.It is shown that,the influence of accidental eccentricity is declining with the irregular extent increasing,but the influence should not be ignored for the most irregular structures especially for the edge members of structures.It is suggested that the accidental eccentricity should be considered for the regular and irregular structures by calculating an additional torque.