NON-LINEAR RESPONSE OF A CONCRETE GRAVITY DAM SUBJECTED TO NEAR-FIELD GROUND MOTIONS

Abstract

Lifeline structures like dams should always be designed for highest safety, resisting worst forces of nature. However, events that took place across the world proved how devastating an earthquake could be, particularly in the near-field areas. Landers earthquake (1992 – Mw 7.3), Northridge earthquake (1994 – Mw 6.7), Hyogoken-Nanbu earthquake (1994 – Mw 6.8) and few more earthquake events caused damage due to near-field effects. Notable damage to Koyna dam due to Koyna earthquake (1967 – Mw 6.5), India and Shih-Kang DamdueChi-Chi earthquake (1999 – MW 7.6), Taiwan proved earthquakes and near-field effects can cause damage even to dams. In India there are several dams constructed near the active faults, which might suffer moderate to severe damage in an event of earthquake in near-field areas. In this concern, a proper study on behaviour of concrete gravity dam subjected to near-field ground motions should be performed. In the proposed study, a concrete gravity dam is selected from the National Importance Dams of India (NRLD-2009) and numerically modeled using Applied Element Method (AEM). Fault normal and fault parallel components of 5 near-field ground motion are considered as input. The behaviour of dam subjected to near-field ground motions is then studied by understanding the displacement response, and stress distribution on upstream and downstream side of the dam body.