混凝土梁式构件弹性模量的应变率效应研究

The strain rate effect of elastic modulus of concrete beam

首先给出了梁式构件三点弯曲振动时材料弹性模量和跨中截面应变率的表达式,通过三点弯曲梁测试装置研究了素/钢筋混凝土梁弯曲振动时跨中最大应变率与动态弹性模量的关系,并进一步通过试验结果拟合出了考虑应变率效应的素/钢筋混凝土梁弹性模量提高系数的表达式。试验结果表明:在梁式构件的三点受弯振动中,随着跨中最大应变率由1-0 5/s增长到10-3/s,素混凝土梁的弹性模量增长了大约7.8%,钢筋混凝土梁的弹性模量增长了约10%。另外,由得到的拟合曲线和其他模型对比可知,应变梯度的存在一定程度上影响了混凝土材料弹性模量的应变率效应。

Concrete is a typical rate-sensitive material.According to different strain rate,the dynamic elastic modulus is increased in different level compared to elastic modulus with quasi-static strain rate and the strain rate effect of material could lead to the strain rate effect of members.In this paper,expressions of elastic modulus and stain rate of mid-span section were given,in the meanwhile,3-point bending beam damping experiment of concrete beams were carried out and the fitted curve of enhanced coefficient of elastic modulus was provided by analysis of experimental results considering strain rate effect.The experimental results show that the elastic modulus of plain concrete beam was increased by about 7.8% and the elastic modulus of reinforced concrete beam was increased by about 10% when maximal strain rate of mid-span was increased form 10-5/s to 10-3/s.In addition,the strain rate effect of elastic modulus was decreased by the presence of strain gradient due to the comparison of fitted curve and other models.