钢筋混凝土梁式构件抗爆分析的改进等效单自由度方法

爆炸荷载作用下钢筋混凝土梁式构件可能会出现多种破坏模式,主要有弯曲破坏、直剪破坏和弯剪联合破坏等。现有结构构件抗爆分析方法主要考虑爆炸荷载下结构构件的弯曲破坏,对直剪破坏和弯剪联合破坏研究较少,尤其缺少快速准确的抗爆分析方法。基于等效单自由度模型理论,改进了钢筋混凝土梁抗爆分析的直剪单自由度方法,提出了直剪、弯剪联合破坏的判定准则,给出了两种破坏模式下钢筋混凝土梁动态响应的计算方法。进一步考虑爆炸荷载作用下钢筋混凝土梁的弯曲破坏、直剪破坏和弯剪联合破坏,提出钢筋混凝土梁式构件抗爆分析的改进等效单自由度方法,并给出了其分析步骤。该方法可以直接评估爆炸荷载下钢筋混凝土梁式构件的破坏模式,并计算其动态响应。通过有限元软件LSDYNA数值模拟了不同爆炸工况下钢筋混凝土梁式构件的动态响应和破坏模式,与改进的等效单自由度方法的计算结果进行了对比,验证了提出的改进等效单自由度分析方法的正确性。

Improved equivalent single degree of freedom method for blast analysis of RC beams

RC beams may be damaged with different failure modes subjected to blast loads. The possible damage modes include flexural failure, direct shear failure, combination of diagonal shear and flexural failure. A dynamic analysis method of structural components under blast loads mainly considers the flexural failure mode and ignores direct shear failure and combination of diagonal shear and flexural failure. Therefore, a quick and accurate blast analysis method for different failure modes is still lacking. In this paper, based on an equivalent single degree of freedom (SDOF) model theory,equivalent SDOF models considering direct shear failure and combination of diagonal shear and flexural failure for RC beams are improved, and the failure criteria and calculation method for the dynamic response of RC beams exhibiting both the direct shear failure and combination of diagonal shear and flexural failure are proposed. Furthermore, considering the combined failure modes, an improved equivalent SDOF method for blast analysis of RC beams is proposed. The procedure for blast analysis of RC beams based on the improved equivalent SDOF method is also presented. The improved method can directly evaluate the failure modes of RC beams under blast loading and calculate structural dynamic responses. Different failure modes and dynamic responses of RC beams under different blast loads are simulated based on software LS-DYNA. The comparison between the simulated results and results calculated from the improved equivalent SDOF method proves that the proposed equivalent SDOF method is valid.