撞击荷载下钢筋混凝土柱动力响应的数值研究

为了研究撞击荷载下钢筋混凝土柱的动力响应,该文基于有限元软件LS-DYNA建立了钢筋混凝土构件碰撞模拟分析的数值模型。对经典钢筋混凝土梁落锤试验进行数值模拟,分析表明该数值模型能够较好的模拟钢筋混凝土构件碰撞过程中的撞击力和变形发展。基于该模型该文研究了不同因素对刚体碰撞钢筋混凝土柱动力变形和撞击力的影响,包括撞击体速度、质量和形状,钢筋混凝土柱纵向配筋率、配箍率和混凝土轴心抗压强度以及材料应变率。分析表明钢筋混凝土柱在撞击作用下的破坏模式主要包括：局部损伤型、整体破坏型和局部破坏型。影响撞击力曲线变化的因素可分为三种：撞击体自身的因素,影响柱体刚度的因素和影响柱体材料强度的因素。各种因素对撞击力峰值、撞击力平台值和撞击持时分别具有不同的影响规律。这些规律将为建立建筑结构倒塌分析的简化撞击力模型提供参考。

NUMERICAL INVESTIGATION ON DYNAMIC REPONSE OF REINFORCED CONCRETE COLUMNS SUBJECTED TO IMPACT LOADING

To study the dynamic response of reinforced concrete (RC) columns subjected to the impact loading, a numerical model is established for the impact analysis of RC structural members based on the LS-DYNA finite element code. The typical drop hammer tests on RC beams are simulated so as to confirm that the impact loading and structural deformation can be accurately captured via the developed model. Based on the model, the effect of various factors on the impact load and the structural deformation of the RC columns is investigated. The factors are the velocity, the mass and the shape of the impactor, the longitudinal and transverse reinforcement ratios of the columns, the strength of concrete and the strain rate of material. Three typical damage modes of the RC columns subjected to impact loading are found from the numerical analysis, including a local damage mode, a global bending failure mode and a local shear failure mode. The factors which influence the impact loading can be classified into three types, i.e., the impactor-related factor, the column-stiffness-related factor and the column-strength-related factor. The effects of these factors on the peak load, the average load and the duration of the impact action are discussed for the purpose of providing a valuable reference to establish the simplified impact loading model for the impact-induced collapse analysis of building structures.