用实用解析法计算混凝土基于裂缝粘聚力的新KR阻力曲线

DETERMINATION OF K_R EXTENSION RESISTANCE BASED ON CRACK COHESIVE FORCE IN CONCRETE USING PRACTICAL ANALYTICAL APPROACH

对三点弯曲梁混凝土试件,虚拟断裂过程区上粘聚力呈线性或双线性分布的,可以用实用解析法计算混凝土双K断裂参数及新K R阻力曲线。实用解析方法是用简单函数拟合Green函数,将粘聚力在裂缝尖端产生的应力强度因子积分算式转化为简单的算术表达式。该方法无需进行数值积分,简化了计算过程。采用不同尺寸的三点弯曲梁混凝土试件的试验结果,用实用解析法计算基于裂缝粘聚力的K R阻力曲线,与传统的数值积分计算方法对比,表明两种方法得到的K R阻力曲线很好地吻合。用实用解析法计算新K R阻力曲线具有很高的精度。

To compute double-K fracture parameters and new KR extension resistance for three-point bending beams, the practical analytical approach assumes linear or bilinear cohesive stress distribution in fictitious fracture zone. It transforms the integral expression of stress intensity factor at the crack tip into a simple algebraic expression by using a simple function rather than Green＇s function. With this method, numerical integration can be avoided and the calculation is simplified. Test results of three-point bending beams with different sizes are employed to compare the practical analytical approach with traditional numerical integration method in computing KR extension resistance based on crack cohesive force. It is demonstrated that no visible difference is observed in the KR resistance curves from the two methods. The practical analytical method has a high accuracy in computing new KR extension resistance.