Performance Evaluation of Gravity Dams Subjected to Near- and Far-Fault Ground Motion Using Euler Approaches

Abstract

Ground motions in near source region of large crustal earthquakes are significantly affected by rupture directivity and tectonic fling. These effects are the strongest at longer periods, and they can have a significant impact on engineering structure. This paper focuses on the effects of long-period pulse of near-fault ground motions on the structural performance of concrete gravity dams. Three sets of near- and far-fault ground motion records, which have approximately the same peak ground acceleration, are selected from 1987 Superstitn Hills (B), 1989 Loma Prieta and 1994 Northridge earthquakes. As a case study, Sariyar concrete gravity dam located on the Sakarya River, which is 120 km to the northeast of Ankara, is selected to investigate the near-fault ground motion effects on dam responses. The finite element models of the dam are constituted considering dam-reservoir-foundation interaction using ANSYS software. The behavior of reservoir is taken into account by using Euler approach. To determine the structural response of the dam, the linear transient analyses are performed using above-mentioned ground motion records. In the analyses, element matrices are computed using the Gauss numerical integration technique. The Newmark method is used in the solution of the equation of motions. Rayleigh damping is considered. At the end of the analyses, dynamic characteristics, maximum displacements, maximum and minimum principal stresses and maximum and minimum principal strains are attained and compared with values obtained from analyses under far-fault ground motions recorded far away from the same sites at above-mentioned earthquakes with approximately same peak ground acceleration.