近断层向前方向性地震动作用下RC框架结构易损性研究#br#

向前方向性效应是近断层地震动的重要特征之一，使得在垂直于断层方向上表现出明显的速度脉冲分量，引起结构的严重破坏。为考察该类特殊地震动作用下RC框架结构的损伤程度，基于传统的增量动力分析方法，建立考虑材料不确定性和输入地震动不确定性的结构-地震动样本，对一个12层框架结构进行地震易损性研究。利用易损性分析结果计算出结构的破坏状态概率，结合群体结构震害评估中的震害指数经验值，得到多遇地震、设防地震和罕遇地震的易损性指数。研究结果表明：近断层向前方向性地震动作用下，依据我国抗震规范设计的RC框架结构能够满足小震不坏、中震可修、大震不倒的抗震设防目标。尤其在大震作用下，结构仍处于中等破坏水平，表明结构在发生倒塌之前具备充分的富裕度。

Seismic fragility analysis for frame structure under near-fault forward directivity ground motions

The effect of forward directivity is one of the important features of near-fault ground motions, resulting in obvious velocity pulse components in the direction perpendicular to the fault, causing serious damage to structure. In order to investigate the damage degree of the reinforced concrete frame structure under this type of special ground motion, seismic fragility analysis of a 12-story frame structure was carried out based on the traditional incremental dynamic analysis，in which structure-ground motion samples considering uncertainty of material and uncertainty of inputting ground motion were constructed. Damage state probability of the structure was calculated, combined with the empirical value of the earthquake damage index in the seismic damage assessment of the group structure, the fragility index of frequent earthquake, fortification earthquake and rarely earthquake were obtained. Results show that the reinforced concrete frame structure designed according to the seismic code under near-fault forward directivity ground motions can satisfy the seismic fortification target of “no damage under frequent earthquake”, “no unrepairable damage under design-based earthquake” and “no collapse under maximum consider earthquake”. In particular, under the action of a strong earthquake, the structure is still in a state of moderate damage with enough margin before collapse.