Improving Resistance of Gravity Dam to Seismic Wave by Using Stepped Base

This study analyzes the possible modes of seismic wave for concrete gravity dams and damage occurring in body where two dam sections are taken as a case study. Model (1) is typical section dam, while model (2) provided with specified steps at its base. The design waves included Operational Base Earthquake (OBE), Maximum Design (MDE), Credible (MCE) levels. body-foundation-reservoir water interaction system analyzed by numerical analysis software (ABAQUS). main conclusion shows that model's underground motion loadings have noticeable increase displacement distribution within first model, especially higher mode compared to model. Damage Index value was equal 0.357 MCE wave, which does not appear second time occurs faster than (2). Consequently, significantly reduces different intensity levels on amount transmission body.