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Dams and reservoirs located near populated areas represent a potential risk in the event of uncontrolled release of the reservoir water due to earthquake damage, endangering the people and properties. In the present work, the seismic performance of concrete gravity dams is studied numerically using commercially Finite Element based software ADINA (Automatic Dynamic Incremental Nonlinear Analysis). The study gives deep insight into the procedure of analysis and safety evaluation of concrete gravity dams, as well as improving its stability under earthquake loading. In the present study, the horizontal component of North Ridge earthquake was selected for analysis. The study covers a range of parameters including the effect of earthquake horizontal acceleration component, substrate soil type and strength properties of soil on the stability of concrete gravity dams. The behavior of upstream water surface under seismic shaking was also considered in the research.The results indicated that the relative uplift force, Ur, is linearly proportion to earthquake intensity. On contrary, Ur, decreases as the relative height of water in the reservoir, Hw/H, increases. The factors of safety, F.S, against overturning and sliding decrease with increasing the earthquake intensity. It was also found that sliding was the governing factor against failure.

Helical piles are used to support structures subjected to axial and lateral loads. The main object of the paper is to study the behavior of helical piles in cohesive and cohesionless soils using a full scale field testing. Then, the field test results are numerically verified using the finite element analysis software ADINA [1]. The tested piles are having two circular pitched bearing plates welded at a spacing of two and half the helix diameter welded to a solid-circular shaft. Field and numerical results showed that the most effective parameters on the helical pile uplift capacity are the embedment depth, soil strength, and number of helix, along with other parameters.

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