近场爆炸作用下节段预制拼装RC桥墩的易损性评估

Vulnerability Assessment of Precast Segmental RC Bridge Piers Under Near-field Explosion

为了评估近场爆炸荷载作用下节段预制拼装钢筋混凝土(RC)桥墩的损伤程度,首先开展了节段预制拼装RC桥墩的野外近场爆炸试验,然后建立了节段预制拼装RC桥墩的三维有限元精确化模型,以轴向剩余承载力作为节段预制拼装RC桥墩的爆炸损伤评估指标;接着探讨了近场爆炸荷载的不确定性量化,基于TNT当量和爆心距抽样的爆炸荷载研究了节段预制拼装RC桥墩的爆炸损伤程度以及损伤系数的概率分布,对近场爆炸荷载作用下节段预制拼装RC桥墩进行了易损性评估。结果表明:近场爆炸荷载下节段预制拼装RC桥墩的底节段近爆区发生局部冲切破坏,底节段残余位移最大;爆炸数值模拟与试验结果基本吻合,重启动进行轴向加载得到的轴向剩余承载力是可行的;基于TNT当量和爆心距抽样得到了节段预制拼装RC桥墩的爆炸损伤系数,不同TNT当量下的损伤系数呈对数正态分布;基于对数正态概率密度和条件概率得到了节段预制拼装RC桥墩在近场爆炸作用下的易损性曲线,可评估节段预制拼装RC桥墩在不同TNT当量下的爆炸损伤程度。所得结论可为节段预制拼装RC桥墩的爆炸损伤快速评估提供参考。

To evaluate the damage extent of a precast segmental reinforced concrete(RC) bridge pier under a near-field explosion, this study conducted a near-field blast test of a precast segmental RC bridge pier;subsequently, a three-dimensional finite element accurate model of the precast segmental RC bridge pier was established, and the axial residual bearing capacity was employed as the explosion damage evaluation index. The uncertainty quantification of near-field explosion load was analyzed, the explosion damage extent and probability distribution of the damage coefficient were studied based on the blast loading sampled using the TNT equivalent and explosion center distance, and the vulnerability of the precast segmental RC bridge pier under near-field explosion was evaluated. The results show that the precast segmental RC bridge pier has a local punching failure and the maximum residual displacement in the bottom segment under the near-field explosion test. A numerical simulation is consistent with experimental results, and the axial residual bearing capacity obtained by the restart is feasible. The explosion damage coefficient of the precast segmental RC bridge pier is obtained based on the TNT equivalent and explosion center distance, and the damage coefficient under different TNT equivalents is lognormal distribution. The vulnerability curve of the precast segmental RC bridge pier under a near-field explosion is obtained based on the lognormal probability density and conditional probability, which can be used to evaluate the explosion damage extent of precast segmental RC bridge piers under different TNT equivalents. This paper provides a reference for rapidly assessing explosion damage to precast segmental RC bridge piers.