Rate-dependent Constitutive Model Of Concrete And Its Application To Dynamic Response Of Arch Dams

The dynamic tension and compression experiments of concrete are carried and according to these results, the consistency viscoplastic Drucker-Prager model and Willam-Warnke three-parameter model have been built. Finally, nonlinear seismic responses of Xiluodu arch dam are analyzed to research the effect of strain rate on seismic responses of high arch dams.Based on analyzing behavior of high arch dams, the dynamic tension and compression experiments are carried to research the effect of strain rate on the dynamic tension and compression strength of concrete, and the empirical relationships between the dynamic strength increment and the logarithm of strain rate are given. The relationships between strain rate and the elastic modulus, critical strain, Poisson's ratio and energy absorption capacity of concrete are still studied. Analyzed and compared the static and dynamic constitutive models, the relationship between the yield strength of concrete and internal variable (plastic strain or plastic strain work) and the relationship between the dynamic uniaxial tension and compression strength increment and rate of internal variable are important to building the dynamic constitutive models, so in this paper these relationships are principally and systematically studied. These works provide firm basis for establishing the dynamic constitutive model of concrete. At the same time, to research the influence of humidity of concrete on the relationship between dynamic behavior of concrete and strain rate, the concrete specimens are saturated with water for one month and the dynamic tension and compression experiments of these specimens are also carried. By contrasted these results with those of unsaturated specimens, the humidity of concrete affects the dynamic strength and dynamic behavior of concrete.According to the concept of consistency viscoplastic constitutive model and the results of these dynamic tension and compression experiments, the static Drucker -Prager model and Willam-Warnke three-parameter model are modified by considering the effect of strain rate to consistency viscoplastic Drucker-Prager model and consistency viscoplastic Willam-Warnke three-parameter model. Compared these models with experimental results, it shows that these models can well represent uniaxial dynamic tension and compression behavior of concrete. To research the effect of strain rate on dynamic behavior of concrete structures, the dynamic responses ofconcrete beams under impact loading are calculated and analyzed at linear elastic model, rate-independent and rate-dependent Drucker-Prager model, rate-independent and rate-dependent Willam-Warnke three-parameter model. It shows that the displacement, stress magnitude and distribution of beam change greatly. So, the influence of strain rate on dynamic response of concrete structures is important and inneglectable.Nonlinear seismic responses of Xiluodu arch dam are analyzed at linear elastic model, rate-independent and rate-dependent Drucker-Prager model, rate-independent and rate-dependent Willam-Warnke three parameter model to research the effect of strain rate on seismic responses of high arch dams. It shows that tension stresses become the control stresses of design and aseismic safety evaluation of high arch dams. After considering the effect of strain rate, the tension stresses and tension strength of concrete increase apparently, but the compression stresses and compression strength change very little because the compression stresses are not exceed to the compression yield strength of concrete. At the same time, the magnitude and distribution of total strain and total strain rate don't change but those of plastic strain and plastic strain rate vary greatly. The calculation results provide reference for design and aseismic safety evaluation of high arch dams.