爆炸移除钢筋混凝土框架柱抗倒塌性能数值模拟

基于已有的爆炸移除钢筋混凝土框架柱的实验数据,利用有限元软件AUTODYN建立了一个分离式与整体式相结合的4层2跨钢筋混凝土框架结构的三维有限元模型,并采用三阶段分析法,对爆炸移除钢筋混凝土柱的结构动力响应和破坏形态进行了数值模拟,且考虑炸药、空气与结构的流固耦合作用和应变率对材料的动态本构特性的影响.在爆炸移除短边中柱与角柱两种工况下,计算得到的柱破坏形态和梁柱节点动态位移与实验结果吻合较好,还分析了柱内纵筋对RC框架结构的动态响应的影响以及柱的破坏失效过程.计算结果表明:对发生塑性和弹性变形区域分别采用分离式和整体式建模,不仅保证了钢筋混凝土框架柱的爆破作用过程数值模拟的真实性和适用性,又大量缩短了计算时间,可为今后爆炸荷载作用下RC框架的参数影响分析和连续倒塌破坏模式控制提供参考.

Numerical Simulation on Collapse Behavior of RC Frames with a Column Removal under Blast Loads

Based on the existing experimental investigation on RC frame with a column removal, the three-dimensional finite element simulation with a combination of separated and integral models for a four-story two-span RC frame structure was established by using the finite element software AUTODYN, and analyzed through three stages. The effect of gas-solid interaction was considered to simulate the dynamic response and failure modes of RC frame due to the removal of reinforced concrete columns under explosion loads. In the numerical simulation, the strain rate effects were also taken into account for the dynamical constitutive behaviors of the materials. In the case of the failure of the corner column or the short side column under blast loads, the failure modes of the column and the dynamic displacement of the beam-column joints from FE models agreed well with the experimental results. Meanwhile, the failure process of the column removal and the influence of the longitudinal-steel in the column on the dynamic response of the RC frame structure were examined. Moreover, the simulation results indicate that the way adopting separated and integral models in the plastic and elastic deformation region, respectively, not only ensured the authenticity and adaptiveness of the simulation of the RC frame under column removal, but also reduced substantial computational effort. Therefore, this developed model can provide a reference for the further studies on the parametric analysis and collapse mode control of RC frame structures under blast loads.