考虑混凝土应变率变化的高拱坝非线性动力响应研究

提出一种新的应变率相关的混凝土非线性弹塑性损伤模型。采用此模型对混凝土拱坝的非线性地震响应作了分析。在综合考虑坝-地基-库水动力相互作用和坝缝非线性接触的基础上，着重研究了混凝土应交率相关效应及加载历史对混凝土极限强度等重要参数及拱坝响应的影响，并与采用不考虑应交率影响的混凝土损伤模型计算结果进行了对比分析。结果表明，拱坝考虑横缝作用后的坝面应变率分布不同于整体拱坝。应交率分布形态不仅可以很好地表征拱坝的振动形态，而且对于高拱坝的动力响应的影响也不可忽略。

Seismic analysis of arch dam with joints based on a new strain-rate-dependant plastic damage model

A new 3-dimensional strain rate-dependent damage constitutive model for massive concrete is proposed by introducing strain rate-dependant plastic damage variables as internal variables that vary with strain rates, and is applied in the seismic analysis of massive concrete structures. The effects of strain rates induced by seismic excitations on the tensile strength, compressive strength and plastic behavior are taken into account. Consistent with thermodynamic requirements, a strain-driven formalism is adopted. The nonlinear seismic responses of arch dams were computed using this model, and the dynamic interactions among dam-foundation-reservoir as well as the nonlinear dynamic contact of joints were included . The effects of strain rates and loading history on concrete limit strengths and strains are discussed, and the seismic responses of arch dams are compared with the results given by the corresponding rate-independent damage model. It is shown that the distribution of strain rates are different different parts and different times through seismic history which cause the tensile or compressive strength varing. The distribution of strain rates can not only influence the vibration modes of dam, but also have significant effects on the dynamic damage of arch dams.