【摘要】 混凝土结构在使用过程中,都要遭受地震、爆炸、冲击等动态荷载作用,在动态荷载作用下,混凝土的动态特性及损伤特性将发生很大改变。通过在MTS试验机上对普通混凝土受拉试件在应变率10-5/s～10-1/s范围内进行动态单轴直接拉伸试验,以切线模量的退化来量度损伤,从损伤的角度把混凝土受拉应力-应变上升段曲线分为3个阶段,即初始损伤未发展阶段、损伤稳定发展阶段、损伤不稳定阶段。研究表明,随着应变率的变化,损伤未发展阶段的最大应力水平也随之增加。同时分析了动态荷载下混凝土的抗拉强度、弹性模量、临界应变及泊松比的变化,结果表明混凝土的弹性模量和泊松比随着应变率的增加变化不大;混凝土的抗拉强度、临界应变与应变率之间呈线性关系,并给出了抗拉强度、临界应变受应变率影响的经验公式。更多还原

【Abstract】 Concrete structures unavoidably are subjected to dynamic loads,e.g.,seismic load,blast load,impact load,etc.There are distinctive changes in the dynamic behaviors and damage behaviors of concrete under dynamic loads.Dynamic direct tensile tests of plain concrete specimens are carried out on MTS,with the axial strain rate ranging from 10-5/s to 10-1/s.Defining the damage of concrete with the reduction of tangent modulus,the damage evolution of concrete is divided into three phases:undeveloped damage phase,steadily developing damage phase and unsteadily developing damage phase.It is found that the maximum stress ratio of undeveloped damage phase increases with the strain rate.Tensile strength,elastic modulus,critical strain and Poisson’s ratio of concrete under dynamic load are also analyzed.Results show that the elastic modulus and Poisson’s ratio are independent of the strain rate.The tensile strength and critical strain of concrete increase approximately linearly with the logarithm of strain rate,and the experiential relationships between strain rate and tensile strength and critical strain are established.更多还原