考虑损伤影响的混凝土层裂试验与数值模拟

采用φ74 mm分离式霍普金森压杆(SHPB),对C20、C45、C70三种不同强度的混凝土进行了层裂试验,研究加载率和损伤对混凝土层裂强度的影响.试验结果表明:混凝土层裂强度具有明显的应变率效应,其拉伸强度增强系数DIF随应变率增大而增大,且高强度混凝土的应变率敏感性要低于低强度混凝土;当加载率过高时,混凝土中将首先出现压缩损伤使其抗拉强度显著降低.重复加载试验还表明,拉伸损伤也会影响试件内压缩波的传播.在混凝土HJC模型中引入了Tuler-Butcher损伤累积准则,对混凝土层裂试验开展了数值模拟,计算结果和试验结果较为吻合,验证了模型的有效性.

Experimental investigation and numerical simulation of concrete spalling with damage effect

The spalling tests of concrete with three different strength(C20,C45,C70)were carried out using φ74 mm split Hopkinson pressure bar(SHPB).The effects of loading rates and damage on spalling strength of concrete were studied.The results show that the spalling strength of concrete has obvious strain rate effect,and the Dynamic Increase Factor(DIF)increases with increasing strain rate.The strain rate sensitivity of high strength concrete is lower than low strength concrete.Under high loading rate,the tensile strength of concrete decreases significantly due to the compression damage.Repeated loading test shows that the tensile damage will also affect the compression wave propagation in the specimen.Combined with the HJC model,the Tuler-Butcher damage cumulating criteria was applied to simulate the spalling tests of concrete.The model is validated by the good agreement between simulation results and test data.