超高性能水泥基复合材料弯拉作用下虚拟应变硬化机制分析

Pseudo strain hardening model of ultra high performance cementitious composites under flexural loading

根据Tjiptobroto的工作,假设初始裂纹为最终失效裂纹,引入非初始裂纹纤维基体间的部分剥离能耗散项和单位失效面上随机纤维有效根数,依据初始裂纹总耗散能与非初始裂纹耗散能的平衡准则,研究了水泥基复合材料的多裂纹扩展失效机制。根据超高性能水泥基复合材料特性,修正和简化了各能量耗散项,建立了基于能量平衡准则的超高性能水泥基复合材料多裂纹开裂失效机理的理论模型,用以预报该材料的裂纹扩展规律。数值预报了Tjiptobroto实验模型的多裂纹扩展数目和能量耗散项,并与其实验结果进行了对比,吻合较好。表明对具有高弹模钢纤维的超高性能水泥基复合材料引入部分剥离能项是必要的。本文中的理论模型也可作为超高性能水泥基复合材料初裂承载能力和极限承载能力预报的理论参考。

According to Tjiptobroto＇s research, the multiple cracking failure mechanism of cementitious composites was studied based on the energy dissipation equilibrium criterion between the initial cracking and non- initial cracking. The partial debonding energy at non-initial cracking and the number of random effective fibers were inserted with the assumption of the initial crack as the final failure crack of the structure. All the energy terms related in the model were modified and simplified according to the properties of ultra high performance cementitious composites （UHPCC） and a theoretical model of multiple cracking propagation of UHPCC was constructed to predict the crack propagation based on energy equilibrium criterion. The number of cracks and energy dissipation terms of Tjiptobroto experiment specimens were predicted. The comparison with the test results showed good agreement. It is suggested that the partial debonding energy term is necessary for UHPCC with high modulus of elasticity of steel fiber. The model can be a theoretical reference for predicting the initial cracking loading capacity and the ultimate limit loading capacity of UHPCC.