Seismic response of concrete arch dams due to different non-uniform ground motion models

This paper investigates the effects of spatially variable (non-uniform) seismic excitation incorporating incoherency effect on earthquake-induced stresses of arch dams. Coherency functions reflect the waveform variation between two different stations, which decays with an increment of distance and frequency. The response spectrum compatible non-uniform ground motions are generated utilizing the coherency functions. Besides, to study the valley shape effects and dam height on seismic responses, V-shaped and U- shaped valleys with different heights are considered. Finite element models of typical arch dams are provided, including the relevant compressible reservoirs and surrounding massed foundation rocks. Dynamic analyses are carried out for uniform and non-uniform excitations. Comparing the stress magnitudes revealed that, non-uniform ground motion inputs considering coherency functions lead to less tensile and compressive stresses than the uniform ones(identical excitation across the supports). Moreover, the stress distribution pattern depends on the utilized coherency function. Finally, the results demonstrated that the magnitude of maximum tensile stress is lower in the V-shaped valley as a general trend. Additionally, due to uniform excitation, the increase of dam height leads to an increment of tensile stresses.