混凝土动态弹性模量对重力坝地震反应的影响分析

现行水工抗震规范中规定,大坝混凝土动态弹性模量在静态弹性模量基础上提高30%。这一规定体现的是混凝土瞬时模量与持续模量的差异,而非加载速率的影响。根据国内相关混凝土坝设计规范,持续模量约为瞬时模量的0.67倍,亦即瞬时模量可较持续模量提高50%。本文结合不同高度的重力坝,从大坝自振特性、动位移、动应力及静动综合应力诸方面进行比较分析,论证两种动态弹性模量取值的影响。结果表明:坝体动态弹性模量提高率从30%增至50%后,对重力坝动力特性及地震反应的影响很小。

The study on the seismic response of gravity dam due to changing of dynamic concrete modulus of elasticity

According to Specification for seismic design of hydraulic structures,dynamic concrete modulus of elasticity of concrete dam should be raised by 30 percent compared with that of static,which embodies the difference between the long-term static modulus of elasticity and that of short-term.New-adopted design specification of concrete dam requires that the short-term concrete modulus of elasticity be 50 percent greater than long-term static value.In this paper,dynamic analyses of various-height gravity dams are carried out to evaluate the influence on the dynamic properties and seismic response due to above two kinds of dynamic modulus of elasticity.The results show that two dynamic modulus of elasticity have no significant influence on dynamic properties and seismic response of gravity dams.