粗骨料UHPC单轴拉伸性能及损伤本构模型

Uniaxial Tensile Properties and Damage Constitutive Model of UHPC with Coarse Aggregate

通过单轴拉伸试验,研究粗骨料用量和钢纤维的掺量、类型及混杂配比对粗骨料超高性能混凝土(CA-UHPC)受拉性能的影响,揭示了CA-UHPC破坏机理以及粗骨料与钢纤维的相互作用机制.结果表明:粗骨料引起的薄弱界面和空间阻隔作用削弱了钢纤维的增韧作用,CA-UHPC拉伸性能随粗骨料用量增大而降低,建议其用量不超过450 kg/m^(3);增大钢纤维掺量能改善CA-UHPC拉伸性能,且平直钢纤维的增韧作用更稳定;1.0%平直和1.0%端勾钢纤维混杂时,其与粗骨料匹配良好,钢纤维有效利用率达到25.4%,能够充分发挥混杂纤维的协同增韧作用.最后建立了考虑粗骨料和钢纤维影响的CA-UHPC受拉损伤本构模型.

The effects of coarse aggregate usage amount and steel fiber characteristics including content,type and hybrid on tensile properties of ultra-high performance concrete with coarse aggregate(CA-UHPC)were studied through uniaxial tensile test.The failure mechanism of CA-UHPC and the interaction mechanism of coarse aggregate and steel fiber were revealed.The results show that the weak interface and spatial barrier caused by coarse aggregate weaken the toughening effect of steel fiber.The tensile properties of CA-UHPC decrease with the increase of coarse aggregate content,so the recommended amount of coarse aggregate should not exceed 450 kg/m^(3).Increasing fiber content can improve the tensile properties of CA-UHPC,in which the toughening effect of straight steel fiber is more stable.When 1.0%straight and 1.0%end-hooked steel fibers are mixed,the fibers are well matched with coarse aggregate and the effective utilization rate of fibers reaches 25.4%,which indicates that the synergistic toughening effect of hybrid fibers is fully exerted.Finally,a tensile damage constitutive model of CA-UHPC is established considering the effect of coarse aggregate and steel fibers.