拆除爆破数值模拟中钢筋混凝土构件的建模及参数取值方法

Simplification and Parameter Selection of Reinforced Concrete Component for Numerical Simulation of Demolition Blasting

采用数值模拟方法对钢筋混凝土结构的拆除爆破方案进行分析时,数值模型的简化和参数的选择对模拟结果和计算效率的影响十分显著,这影响拆除爆破数值模拟结果的可靠性。根据目前有限元法的技术水平,对钢筋混凝土构件数值模型的典型建模方法进行了评价,建议在建立大型数值模型时可忽略箍筋,但需考虑箍筋对素混凝土极限强度和应变的影响。基于拆除爆破现场试验数据,分析了楼房支撑区钢筋混凝土立柱的应变时程曲线和应变率时程曲线。实验结果显示:构件破坏过程中应变率存在强烈的波动性。数值模拟中采用应变率相关的本构模型时,应变率的强烈波动可能导致材料性能变化过于复杂,因此建议可采用应变率不相关本构模型,并应根据结构破坏阶段的平均应变率对材料参数进行取值。综合考虑箍筋效应和应变率效应,提出了拆除爆破数值模拟时混凝土和钢筋的参数确定方法,以及以最大应变为主的单元失效控制方法。

When the numerical simulation method is used to simulate the demolition blasting plan of reinforced concrete structure,the simplification of the numerical model and the selection of parameters have a significant effect on the simulation reliability and calculation efficiency.According to the current of finite element method,the typical modeling methods of reinforced concrete components are evaluated.It is suggested that stirrups should be neglected in the large-scale numerical model,but the influence of stirrups on the ultimate strength and strain of plain concrete should be considered.Based on the field test data of a demolition blasting project,the strain time history curve and strain rate time history curve of reinforced concrete columns in the support zone of buildings are analyzed.The results show that there is a remarkable fluctuation of strain rate in the failure process.When the strain rate dependent constitutive model is used in numerical simulation,the fluctuation of strain rate may cause the variation of material properties to be too complex.It is suggested that the strain rate independent constitutive model should be used,and the material parameters should be selected according to the average strain rate in the failure process.Considering the effect of stirrup and strain rate,the method to determine the parameters of concrete and reinforcement in the numerical simulation of demolition blasting is proposed,and the method to control the erosion of element based on the ultimate strain is proposed.