爆炸荷载作用下钢筋混凝土梁破坏形态有限元分析

在持续时间较长的爆炸荷载作用下，钢筋混凝土框架或梁通常会发生常见的弯曲破坏形态，但是在持续时间较短的爆炸荷载，如化学爆炸产生的脉冲荷载作用下，钢筋混凝土结构有可能在弯曲破坏发生之前产生剪切破坏。这种现象已被室内外试验所证实，其原因是脉冲荷载激发了结构中的剪力，从而使结构产生剪切破坏。为了预报钢筋单纯凝土梁在爆炸荷载下的响应破坏形态，本文提出了一种基于Ｔｉｍｏｓｈｅｎｋｏ梁理论的非线性分层梁有限元法。在材料模型中考虑了混凝土和钢盘的右面线性和应变速率效应等因素。应用这方法，本文计算分析了爆炸荷载作用下钢筋混凝土梁的动态响应以及弯曲、弯剪和剪切等不同的破坏形态，计算预报的结构动态响应和破坏形态与现场试验结果有较好的一致性。

FINITE ELEMENT ANALYSIS OF FAILURE MODES OF BLAST-LOADED R/C BEAMS

The flexural failure mode of R/C frames or beams is usually observed in case of blast loads with long duration. However, shear failure mode may occur before the flexural failure takes place in case of blast loads with short duration such as impulsive loadings induced by chemical explosion. This phenomenon is observed in both laboratory and in-situ tests. The reason is that the impulsive loading excites the shear force in the component of the structures and causes the structures fail in the manner of shear failure. Based on Timoshenko beam theory, a non-linear layered beam element is proposed in this paper to investigate the response and failure modes of blast-loaded R/C beams. Non-linear material properties, strain-rate effects of concrete and steel are taken into account in the material models. The dynamic responses and various failure modes, including flexure, flexure-shear and shear of the blast-loaded R/C beams are predicted. A good agreement between the numerical results and experimental results is reached.