A Study on Seismic Performance and Fragility of Gravity Dams with Various Monolith Shapes Using Nonlinear IDA

Vulnerability assessment of gravity dams against destructive phenomena such as earthquakes is important. Vulnerability assessment and prediction of dam’s damage due to earthquakes with variety of intensities can provide helpful information that would be very useful and effective in the proper management of probable crises. One of the useful tools in assessing earthquake damage of concrete dams is the production of their fragility curves. Due to the vulnerability of concrete dams to tensile cracking, a new concept of damage index according to tensile cracking has been developed. Because of dependency of fragility curves to limit states of engineering demand parameters, limit states have been defined according to tensile cracking in dams. Studies on the production of fragility curves of concrete gravity dams are very limited and mostly not comprehensive in a way fragility curve are normally produced only for one type of dam or with one height and one configuration. In this paper, fragility curves have been generated for three gravity dams with different base width (L) and height (H), i.e. Pine Flat dam (United States), Koyna dam (India) and Shafarood dam (Iran). It was shown that Shafarood dam with (L/H) ratio equals to one has better performances under seismic excitation than Pine Flat and Koyna dams that their (L/H) ratios are 0.8, 0.7, respectively.