基于虚拟裂缝模型的混凝土等效断裂韧度

本文采用虚拟裂缝模型，将临界裂缝尖端张开位移ＣＴＯＤｃ作为控制参数，利用三点弯曲梁试件通过迭代求得了混凝土裂缝亚临界扩展量的临界值△ａｃ，据此求得了混凝土起裂断裂韧度ＫｉｎｉＩｃ、等效断裂韧度ＫｕｎＩｃ值。计算结果表明，随着试件尺寸的增大，△ａｃ增大，但ＫｉｎｉＩｃ、ＫｕｎＩｃ值却是与试件尺寸无关的断裂参数。这表明线弹性断裂韧度准则可应用于混凝土结构的裂缝评定。

THT EFFECTIVE FRACTURE TOUGHNESS OF CONCRETE BASED ON FICTITIOUS CRACK MODEL

Based on the fictitious crack model and Critical crack tip opening displacement CTODc, the precritical crack propagation length △a_c. of concrete was determined by means of three point bending beams. According to the calculation value of △a_c, the effective fracture toughness K~un_Ic of concrete was evaluated. It is shown that △~a_c increases with the increase of the concrete specimen size, but K~ini_Ic and K~un_Ic are size-independent and can be considered as fracture parameters of concrete. It is also found that the linear elastic fracture toughness criteria are applicable to the crack evaluation of concrete structures.