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Safety evaluation is an important task to verify the performance of a dam during its service. For an old dam, the material properties vary from the designed value significantly affecting structural performance. This study investigates the effects of material properties of dam concrete and foundation rock on the structural behavior of an old concrete arch dam during operation. The dam safety is evaluated by using a three-dimensional finite element model (FEM). All main loads, such as water pressure, dam self-weight, and thermal load, are considered in the analysis. An existing 54-year-old concrete arch dam, located in a tropical climate region in Thailand, is employed as a case study. The analysis results show that deformation modulus of the foundation, modulus elasticity of concrete, and the variation of reservoir water level during operation are key factors affecting the dam response. With a deformability modulus of foundation and elasticity modulus of dam concrete, which are about 20 GPa and 44.2 GPa, respectively, a good agreement in dam deflections between the analysis and the current monitored data from plumb line equipment can be obtained. It should be noted that the material properties are different from the designed value significantly. Finally, safety evaluation can be properly conducted based on current material properties. [ABSTRACT FROM AUTHOR]

The aim of this study is to present an evaluation of the thermal load effects on the behavior of a concrete arch dam in Thailand. A Three-Dimensional Finite Element model for the thermal transient analysis was implemented to determine the thermal distribution in the dam body. Environmental conditions, such as reservoir water temperature at all depths, ambient temperature, and solar radiation were considered in the analysis. Then, structural analysis was conducted to evaluate deflections and stresses in the dam caused by the temperature profile. The thermal analysis results indicated that the upstream face is strongly affected by reservoir water temperature, while air temperature and sunlight mostly affect the downstream and crest faces. The solar radiation increases the concrete surface temperature by about 2 ℃ to 7 ℃ above the ambient temperature and causes nonuniform temperature distributions on the dam faces. Though prior literature shows significant effects of seasonal temperature variations on dam behavior, the structural analysis results in this paper show that the thermal loads contribute very little to the stresses and deflections of a dam in Thailand. [ABSTRACT FROM AUTHOR]