高温下钢筋混凝土梁抗冲击性能的细观数值分析

Mesoscale simulations of the impact resistance performance of rein-forced concrete beams exposed to high temperature

结合混凝土细观结构特征,考虑高温下钢筋和混凝土细观组分力学性能退化行为及材料的应变率效应,建立了钢筋混凝土梁细观数值分析模型,研究了高温经历时间和落锤冲击能量对钢筋混凝土梁抗冲击性能的影响.主要分析了高温下钢筋混凝土梁在冲击荷载作用下的破坏过程、冲击力时程、支座反力时程和跨中位移反应.研究结果表明:细观数值模型由于考虑了细观组分的非均质性,获得了较为合理的温度场分布;随着加热时间的增加,混凝土梁在冲击荷载作用下破坏更加严重,冲击力持续时间和跨中最大位移增大,但是冲击力峰值减小;随着冲击能量的增大,钢筋混凝土梁的剪切破坏更加严重,冲击力峰值增大,跨中最大位移随冲击能量增大而线性增加.

Considering the degradation of the mechanical properties of steel and concrete under high temperature and the strain rate effect of the materials, a mesoscopic numerical analysis model of reinforced concrete beam are proposed based on the meso-structure of concrete. The influences of fire duration time and impact energy on the impact resistance behavior of concrete beams in fire are discussed. In this paper, the failure process of reinforced concrete beam subjected to impact load, the impact force time history, the reaction time of support and the displacement response in the middle span are analyzed. The results show that the mesoscopic numerical model can well simulate the heat transfer process of each components of concrete. With the increase of heating time, the concrete beam under the impact load is more serious, meanwhile the duration of the impact force and the maximum displacement of the span increase, but the impact force peak decreases; with the increase of impact energy, the shear failure of concrete beam is more serious, and the impact force peak increases. The maximum displacement increases linearly with the impact energy.