Dynamic Properties of Mass Concrete Obtained From Dam Cores

The dynamic properties of concrete are an important consideration in the analysis and review of the safety of structures such as concrete dams. Concrete tests can be designed to predict the behavior of a structure under various static and dynamic loading conditions. In laboratory tests, different dynamic conditions are modeled by varying the strain rate at which the test is performed. Thus, the strain rate of the tests is key to the interpretation of results. The U.S. Bureau of Reclamation is particularly concerned with the performance of its dams when subject to earthquake loads. For approximately fifteen years, Reclamation’s laboratory core test programs typically include dynamic tests performed at strain rates corresponding to seismic loads. This paper summarizes the results of a Reclamation research project designed to provide a broad database of the behavior of mass concrete from existing dams under dynamic loading conditions that simulate earthquake loadings. Laboratory tests performed on cores at both traditional, static loading conditions (strain rates of 10^-6 to 10^-4) and dynamic loading conditions (strain rates of 10^-3) are compared. Dynamic and static measurements of compressive strength, modulus of elasticity, compressive failure strain, Poisson’s ratio and splitting tensile strength are summarized. In some cases, the core size or moisture condition among similar samples was varied to determine if either of these parameters affected test results. Linear, elastic assumptions that are typically used for finite element analyses of structural deformation and structural failure are reviewed for these data.