两层单跨缩尺RC框架结构外爆炸试验数值模拟

基于已有1/4缩尺钢筋混凝土(RC)框架结构爆炸试验,采用有限元软件LS-DYNA建立了精细化有限元模型,系统全面地分析了爆炸荷载作用下开口框架、带填充墙框架、带部分开洞填充墙框架、车库4种结构形式的动态响应行为,对爆炸冲击波超压、冲量、结构局部及整体响应情况进行了数值模拟,并与试验结果进行对比分析。结果表明:当空气、炸药网格尺寸为50 mm×50 mm时,有限元模型可以较好地预测爆炸冲击波的传播过程和结构响应情况; 框架中柱的正面反射超压模拟值呈上小下大的梯度分布; 框架中柱的冲量模拟值和试验值较为吻合,正面冲量呈上小下大的梯度分布,背面冲量在楼层位置和填充墙附近明显增大; 底层框架中柱的损伤破坏与试验接近,跨中位移模拟值和试验值相对误差小于5%; 填充墙能够阻止爆炸冲击波在结构内部传播,但显著增加中柱位置的冲击荷载和底层楼板上下表面压力差; 通过对比模拟结果与试验结果验证了数值模拟方法、网格尺寸、材料模型与参数取值的正确性与适用性,可为原型RC框架结构抗爆响应和破坏倒塌分析提供有益的参考。

Numerical Simulation on External Explosion Experiments of Two-story Single-span Scaled RC Frame Structure

Based on the existing quarter-scale reinforced concrete(RC)frame structure explosion experiments, the refined finite element model was established by LS-DYNA to analyze the dynamic response of the open frame, the infilled frames with and without opening and parking garage. The numerical simulation blast wave reflected overpressure, impulse, as well as the local and overall responses of the structure were compared with experimental results. The results show that the finite element model can well predict the propagation of blast waves and structural response when the mesh sizes of air and TNT adopt 50 mm×50 mm. The overpressure in front of the column has a gradient distribution that decreases from bottom to top. The simulated impulse on the middle column agrees well with the experimental data, and there is also a gradient distribution in front of the column, while a significant impulse increase appears near the floor and infilled wall in the back. The failure mode of lower column is consistent with the experiment, and the deviations between simulated and experimental mid-span displacement are less than 5%. The infilled wall can prevent blast waves entering the structure, but significantly increase the loads on the middle column and pressure difference between the upper and lower surface of lower level floor. The accuracy and applicability of numerical simulation method, mesh size, material models and parameter values are verified by comparing the simulated results and experimental results, which can provide a useful reference for the further study on anti-blast response and collapse analysis of RC frame structure.