Failure modes of precast segmental concrete-filled double-skin steel tube columns under large equivalent explosion
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摘要: 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。
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关键词:
- 预制节段拼装双层钢管混凝土柱 /
- 大当量爆炸试验 /
- 破坏模式 /
- 预应力
Abstract: In order to improve the blast resistant performance of prefabricated highway bridges, a precast segmental concrete-filled 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-to-footing 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 PS-CFDST 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.-
Key words:
- PS-CFDST column /
- large equivalent explosion /
- failure mode /
- prestressing force
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表 1 有限元模型材料参数
Table 1. Material parameters for the finite element model
材料 材料参数 参数值 材料 材料参数 参数值 混凝土 密度 2 500 kg/m3 钢管 密度 7 900 kg/m3 弹性模量 34.5 GPa 弹性模量 206 GPa 泊松比 0.2 切线模量 2.06 GPa 无侧限抗压强度 37.3 MPa 泊松比 0.3 预应力筋 密度 7 900 kg/m3 内钢管屈服强度 315 MPa 弹性模量 200 GPa 外钢管屈服强度 416 MPa 切线模量 0.33 MPa 应变率参数C 6844 s−1 泊松比 0.3 应变率参数p 3.91 屈服强度 1 860 MPa 弹性材料(钢筋混凝土) 密度 2600 kg/m3 失效应变 0.04 弹性模量 34.5 GPa 泊松比 0.2 -
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