外包钢套加固震损双层高架桥框架式桥墩地震易损性分析

Seismic vulnerability analysis of seismic-damaged double-deck viaduct frame piers reinforced by steel sheathed

基于OpenSees开源程序分别建立对比试件、外包钢套加固试件、中度预损加固试件、重度预损加固试件的有限元模型,进行了低周往复荷载试验模拟,试验结果验证了模型的可行性。选取20条天然地震波,基于增量动力分析法建立桥墩易损性曲线,以峰值加速度(peak ground acceleration,PGA)中位值定量评估外包钢套加固震损桥墩的地震易损性;改变缀板间距、外包钢含钢率,对其加固效果的影响进行了评价。结果表明:在轻微、中度、重度和完全破坏状态下,中度预损加固试件的PGA中位值分别提高了35.2%、51.7%、67.0%和73.5%,重度预损加固试件的PGA中位值分别提高了32.4%、44.6%、56.1%和67.9%。缀板间距对外包钢套加固效果影响有限,外包钢含钢率对加固效果影响较大,为满足经济和加固效果要求,外包钢含钢率建议取值为2.86%。

Based on OpenSees open-source program,finite element models of comparison specimens,steel sheathing reinforced specimens,moderately pre-damaged reinforced specimens,and severely pre-damaged reinforced specimens were established respectively.Low-cycle reciprocating load test simulations were carried out,and the feasibility of the model was verified by comparing with the test results.Twenty natural seismic waves were selected to establish the vulnerability curves of bridge pier based on incremental dynamic analysis method.The seismic vulnerability of a bridge pier strengthened with an enveloped steel jacket was quantitatively evaluated by the median value of peak ground acceleration(PGA),and the influence of the spacing of the plates and the steel content of the cladding steel on the reinforcement effect was evaluated.The results indicate that in the damage states of mild,moderate,severe and complete destruction,the median values of PGA of moderate pre-damaged reinforced specimens are increased by 35.2%,51.7%,67.0%and 73.5%,respectively,while those of severe pre-damaged reinforced specimens are increased by 32.4%,44.6%,56.1%and 67.9%,respectively.The distance between the fixings has a limited effect on the reinforcement effect of the cladding steel,but the steel content of the cladding steel has a greater influence on the reinforcement effect.In order to meet the requirements of economy and reinforcement effect,the recommended value of the steel content of the cladding steel is 2.86%.