尖锐V型切口混凝土梁的应力强度因子研究

Study on Stress Intensity Factors of Concrete Beams With Sharp V Notches

对含尖锐V型切口构件的破坏评估通常是利用切口应力强度因子来确定,切口应力强度因子指的是切口周围渐进线弹性应力场强度.对于含尖锐V型切口构件来说,单位切口应力强度因子的大小是由V型切口角度决定.应变能量密度准则是根据一定体积内应变能的密度是否达到临界值来判断构件断裂破坏的准则,当这个体积足够小不影响Williams方程的高阶次解时,应变能量密度准则就能通过切口应力强度因子进行表示.考虑Ⅰ型荷载条件下,分别采用平均应变能量密度准则和Carpinteri有限断裂力学方法计算V型切口应力强度因子,两者的理论取值非常接近.同时通过试验,证明两种断裂准则给出的切口应力强度因子的理论值与实验数据吻合程度较好.

The failure behavior of the concrete beams with V notches is usually predicted by the notch stress intensity factor（ NSIF）,which quantify the intensities of the asymptotic linear elastic stress distributions around the notches. For a V-notched beam,the NSIF is determined by the notch angle. The strain energy density fracture criterion is used to judge the fracture failure of a member according to whether the strain energy density in a certain volume reaches the critical value. If the volume is small enough to neglect the higher-order solutions of the Williams equation,the strain energy density criterion can be used to calculate the NSIF. In view of the type-Ⅰ load condition,the theoretical NSIFs of the V notches obtained with the mean strain energy density fracture criterion and Carpinteri＇s finite fracture mechanics method respectively,agree well with each other. Moreover,both the theoretical NSIFs given by the 2 criteria are fairly consistent with the experimental results from various V-notched concrete beam specimens.