循环荷载下橡胶混凝土的断裂特性

Fracture behaviors of rubber concrete under cyclic loading

为了研究循环荷载下橡胶掺量对混凝土断裂力学性能的影响,对5种不同橡胶掺量(0、5%、10%、15%、20%)的带缺口混凝土梁分别开展了单调和循环加载断裂试验。根据断裂试验获得的荷载裂缝口张开位移(P-CMOD)曲线计算了橡胶混凝土的断裂能和耗散能,结合典型橡胶混凝土试件的破坏形态,综合分析了加载工况及橡胶颗粒掺量对混凝土断裂力学性能及能量耗散的影响规律。结果表明:随着橡胶掺量的增加,橡胶混凝土强度和弹性模量逐渐降低,而断裂能值逐渐增大。在循环加载工况下,混凝土耗散能随循环加载过程的持续逐渐累积过程与裂缝口张开位移的累积过程类似,损伤破坏过程呈现“三阶段”特征。总耗散能随橡胶掺量增加而增加,但始终不超过其断裂能。

In order to study the influence of rubber content on the fracture mechanical properties of concrete under cyclic loading,monotonic and cyclic loading fracture tests are carried out on five kinds of notched concrete beams with different rubber content(0,5%,10%,15%and 20%).According to the load-crack mouth opening displacement(P-CMOD)curves obtained by fracture tests,the fracture energy and dissipated energy of rubber concrete are calculated.Combined with the failure modes of typical rubber concrete specimens,the influence of loading conditions and rubber particle content on the mechanical properties and energy dissipation of concrete is analyzed comprehensively.The results show that with the increase of rubber content,the strength and elastic modulus of rubber concrete decrease gradually,while the fracture energy increases gradually.Under cyclic loading,the continuous and gradual accumulation of concrete dissipated energy with cyclic loading is similar to the accumulation of crack mouth opening displacement,the damage and failure process also presents a"three-stage"characteristic.The total dissipated energy increases with the increase of rubber content,but it does not exceed the fracture energy.