内部爆炸荷载作用下钢筋混凝土板的动力响应研究

Dynamic response of reinforced concrete slab subjected to internal blast loading

对于合理预测内部爆炸荷载作用下复杂结构的动力响应,通常需要用合适的计算方法进行直接的数值模拟。采用了考虑应变率影响的钢筋和混凝土材料的动力本构损伤模型,介绍了用爆炸流体动力学软件预测在封闭空间内发生爆炸情况下结构响应的数值模拟方法。对箱型封闭空间内0.5 kg TNT爆炸荷载作用下钢筋混凝土顶板的响应进行了数值模拟研究,展示了钢筋混凝土板从混凝土开裂、钢筋断裂到板整体抛射的动态演变过程,并与试验结果进行了对比分析,内部爆炸荷载压力时程曲线、混凝土的损伤破坏和板的抛射速度与试验结果吻合较好。从中可以发现钢筋对混凝土开裂起主要抑制作用,板的开裂和碎片形成主要受脉冲压力荷载的影响,而板的抛射速度主要受气体压力荷载的控制。

In the analysis of a complex structure subjected to an internal explosion event, a direct simulation using appropriate computational technique is very necessary. This paper presents material dynamic constitutive models including the strain rate effects for concrete and steel rebar, and introduces a numerical simulation study on the prediction of structure in the confined space using a hydrocode. A reinforced concrete slab under internal explosion is analyzed using a proper coupled analysis scheme. The simulation results are compared with experimental observations. The favorable agreements are observed in the time histories of air overpressure and launching velocity of RC slab. It is found that the numerical simulation scheme incorporating an appropriate coupling at the solid-air interface proves to be capable of reproducing the shock reflection effect as well as the buildup of the gas pressure for explosion within the closed steel box, with adequate material models and suitable technique for fracture, the complicated cracking and break-up of RC components can be simulated in a rather realistic manner. The impulsive loading is responsible for the development of damage zone in the concrete and subsequent fragment size distribution, and the explosion gas loading is important in the launching velocity of RC slab.