一般化多层偏心RC框架结构的弹塑性抗震需求

Elasto-plastic seismic demand of general multi-story eccentric RC frame structures

为研究强震作用下一般化多层强度偏心RC框架结构体系的弹塑性抗震需求。基于轴力-弯矩相互作用模型,选取4条地震动记录,对比研究刚度偏心、强度偏心和两者组合偏心对结构弹塑性抗震需求的影响程度。选取较不利的强度偏心形式,研究多层结构单层偏心、多层结构非均匀偏心、多层结构均匀偏心3种一般化偏心形式下结构的弹塑性位移、延性和楼面扭转角需求。研究结果表明:强度偏心对结构弹塑性抗震需求的影响大于刚度偏心;组合偏心对楼面扭转角的影响最大,强度偏心对延性的影响最大。一般化多层强度偏心体系中,底层偏心对结构弹塑性抗震需求的影响大于中间层和顶层偏心;结构底层具有大偏心相对于中间层和顶层大偏心工况具有更大的弹塑性抗震需求;多层均匀偏心形式最为不利。

The elasto-plastic seismic demand of general multi-story RC frame structures subjected to strong ground motions is investigated in the present paper. Based on the axial load-moment interaction model and four earthquake records, the effect of stiffness-, strengthand combined- eccentricity on the structural elasto-plastic seismic demand is compared. Employing the disadvantageous type of strength eccentricity, the elasto-plastic seismic demand of three general multi-story eccentric types is studied. The three eccentricity types include multi-story with sing-story eccentricity, multi-story with uneven eccentricities in each story, and multi-story with even eccentricities. The seismic demand is in terms of elasto-plastic displacement, ductility and floor rotatio n demand. The results demonstrate that the effect of strength eccentricity on elasto-plastic seismic demand is larger than those of stiffness eccentricity; the effect of combined eccentricity on floor rotations is largest, and the effect of strength on ductility is largest. The effect of first story eccentricity is larger than that of central and roof eccentricity; Structures with larger eccentricity in first story will experience larger elasto-plastic seismic demand comparing to structures with larger eccentricity in central or roof eccentricity; The multi-story even eccentricity type is most unfavorable.