爆炸作用下钢绞线斜拉索破坏模式和剩余承载性能试验

Experiments on Damage Modes and Residual Capacity of Strand Stay Cables of Cable-stayed Bridge Subjected to Blast Loading

为研究爆炸荷载作用下斜拉桥钢绞线斜拉索的破坏模式和剩余承载性能,开展了8根15.7-7钢绞线斜拉索试件的野外爆炸试验以及爆炸损伤钢绞线的静力轴向拉伸试验,得到了钢绞线斜拉索在接触爆炸及近距离爆炸作用下的破坏形态和损伤钢绞线的剩余承载力;并根据断丝数量和承载力损失定量比较了高密度聚乙烯护套(HDPE)、单层钢管护套(SST)、双层钢管护套(DST)以及泡沫铝夹层钢管护套(FAFST)4种不同防护措施的抗爆防护效果。研究结果表明:在接触/近距离爆炸作用下,钢绞线斜拉索的损伤破坏主要表现为正对爆炸作用区域部分钢丝断裂和局部横向变形;采用FAFST防护可以有效地改善钢绞线斜拉索的破坏程度,HDPE防护效果有限;相较于无防护的祼索,SST与DST防护反而加剧了斜拉索试件的损伤程度;爆炸损伤钢绞线的剩余承载力与剩余钢丝数量成正比。基于试验结果和回归分析方法,提出了爆炸损伤钢绞线斜拉索剩余承载力评估的实用公式,可以在爆炸灾害后根据钢绞线断丝破坏情况,快速评估斜拉索的剩余承载能力。

To investigate the damage modes and residual bearing capacity of strand stay cables subjected to explosions,an experimental study including field blast tests on eight 15.7-7 strand stay cable specimens followed by axial tensile tests on the blast-damaged strands were carried out.The damage modes of the strand stay cable specimens under contact or close-in explosions were observed,and the residual load-carrying capacities of the blast-damaged strands were obtained.Four different protective measures,including high-density polyethylene(HDPE),single steel tube(SST),double steel tube(DST),and foamed aluminum filled steel tube(FAFST),were considered in the experiments,and their effectiveness in blast protection of strand stay cables were quantitatively compared based on the number of fractured wires and the loss of load-carrying capacity.The experimental results indicate that the strand stay cables under contact or close-in explosions are likely to suffer localized damage,including wire fracturing and local lateral deflection in the region directly facing the detonation.The damage of the specimens protected with FAFST was clearly improved,while the protective effect of HDPE was limited.The damage of the specimens with SST and DST was even worse than that without any protective measures.The residual load-carrying capacities of the blast-damaged strands were proportional to the number of remaining wires.Based on the experimental results,an empirical formula was derived through regression analysis to predict the residual load-carrying capacity of steel strands subjected to explosions,which can be used for rapid assessment of the residual-bearing capacity of strand stay cables after blast hazards.