无黏结预应力装配式框架结构地震易损性分析

Seismic fragility analysis of unbonded post-tensioned fabricated RC frame structures

为研究无黏结预应力装配式框架结构的抗震性能,首先采用有限元软件Open SEES中的梁柱节点单元模拟无黏结预应力梁柱节点,并与试验结果进行验证.然后,按照场地条件选取18条地震动记录,以预应力筋屈服和最大层间位移角作为结构的损伤指标,建立地震需求模型.最后,采用IDA方法对一栋6层无黏结预应力装配式框架结构和现浇框架结构进行易损性分析,得到两种结构的IDA曲线和易损性曲线.研究结果表明:在水平地震作用下,柱截面尺寸和配筋相同、梁截面尺寸和受弯承载力相同时,在防止倒塌性态点处,装配式结构的最大层间位移角和地震动强度指标均小于现浇结构;当地震动强度较小时,装配式框架结构和现浇框架结构的抗倒塌能力接近,但随着地震动强度的增大,在防止倒塌性态点处,装配式框架结构的抗倒塌能力比现浇框架结构弱.

To investigate the seismic performance of unbonded fabricated frame,a numerical model of the beamcolumn connection was built in Open SEES. The comparison between test results and numerical analysis proved the effectiveness of the numerical model. Eighteen different ground motions were employed in the seismic fragility analysis according to the site conditions. The maximum story drift and tensile force in prestress strands were chosen as the damage indexes. Through IDA analysis for two 6-story frame structures,i. e. the common RC frame and unbonded fabricated frame,the IDA curves and fragility curves were obtained. According to the analysis,the unbonded fabricated frame can sustain ground motion record with smaller intensity index than the common RC frame with the same configurations,i.e. the cross-section of column,reinforcement ratio etc. Under small earthquake,the two frame structures present similar performance, while under strong earthquake, the collapse resistance performance of common RC frame is better than that of the unbounded fabricated frame.