砼双K断裂参数的实用解析方法

A PRACTICAL ANALYTICAL APPROACH TO THE DETERMINATION OF DOUBLE-K FRACTURE PARAMETERS OF CONCRETE

采用标准三点弯曲梁砼试件,利用试验中测得的最大荷载maxP及对应的裂缝口张开位移CMODc计算了砼裂缝亚临界扩展量caD。提出了由虚拟裂缝闭合力)(xs产生的应力强度因子cKI的实用解析方法,进而计算了砼双K断裂参数iniKIC及unKIC。采用这一方法,只需在试验中测得最大荷载maxP及对应的裂缝口张开位移CMODc、砼弹性模量及抗拉强度即可确定双K断裂参数并且无需对cKI进行数值积分。大量的计算分析表明,这一实用解析方法不但可使计算过程进一步简化,而且具有很高的精度。

Using the standard three-point bending beam specimens, the precritical crack propagation length caD was evaluated from the maximum load maxP and the corresponding critical crack mouth opening displacement (CMODc) was measured in experiments. A practical analytical method is proposed for determining the stress intensity factor cKI caused by the cohesive force )(xs along the fictitious crack zone, thereby, the double-K fracture parameters iniKIC and unKIC are determined. With this method the double-K fracture parameters iniKIC and unKIC can be easily determined using the measured maxP, CMODc, elastic module E, and tensile strength tf of a concrete material, and the numerical integration can be avoided for the calculation of cKI. Many calculations and analyses show that the newly proposed method is of high accuracy and of significance to draw up the standard testing method for the double-K fracture parameters of concrete.