大当量爆炸作用下预制节段拼装双层钢管混凝土墩柱的失效模式

Failure modes of precast segmental concrete-filled double-skin steel tube columns under large equivalent explosion

为提升装配式公路桥梁的抗爆防护能力,提出将双层钢管混凝土柱应用于桥梁下部结构的预制节段拼装墩柱体系。对预制节段拼装双层钢管混凝土墩柱(precast segmental concrete-filled double-skin steel tube,PS-CFDST)进行了大当量野外爆炸试验,并基于LS-DYNA软件建立了精细化有限元模型,对PS-CFDST柱在爆炸荷载作用下的动力响应和破坏过程进行了数值模拟。结果表明:大当量地面爆炸作用下,PS-CFDST柱的破坏模式表现为后张预应力筋断裂引起的墩柱整体失效,地面爆炸作用下墩柱在墩身底部接缝有较大的剪切滑移,核心混凝土的损伤主要出现在接缝处和预应力筋挤压处;预应力筋的建模方式对预制节段拼装墩柱的动力响应具有显著影响;增大轴向荷载可以减小预制节段拼装墩柱的侧向变形和墩底剪切滑移,有利于提高墩柱的抗爆性能。

In order to improve the blast resistant performance of prefabricated highway bridges,a precast segmental concretefilled double-skin steel tube(PS-CFDST)column was developed.A large equivalent field blast test on the PS-CFDST columns was conducted and a high-fidelity finite element model was established using LS-DYNA to simulate the dynamic response and failure mode of the PS-CFDST columns under blast loading.The experimental and numerical results demonstrated that the failure mode of the PS-CFDST columns under large equivalent surface explosion was fracture failure of prestressing tendons induced loss of column integrity.The PS-CFDST column exhibited large shear slippage at the column bottom segment-tofooting joint.The damage to core concrete was concentrated at the joints and contact areas between segment and prestressing tendons.The modeling approaches for prestressing tendons have a significant influence on the dynamic response of the PSCFDST columns.Increasing axial loads can effectively mitigate the column lateral deflection and shear slippage at the column bottom and it is beneficial to improve the blast resistance of the PS-CFDST columns.