Fast Calculation of Acceleration Responses of the Intake Tower under Near-fault Ground Motion

As an important part of hydraulic structures, the intake tower is closely related to the normal operation of the dam diversion and drainage system, while the velocity pulse of near-fault ground motion has a significant impact on the acceleration response of the intake tower structure system. In this paper, the effects of the forward-directivity pulses and the fling-step pulses on the response of hoist chamber and tower body are studied when the near fault ground motions are modulated with different intensity paramaters. Fast seismic dynamic response analysis program is constructed for the intake tower and hoist room simplified mechanical model. The acceleration response of intake tower and hoist chamber simplified mechanical model under PGA (peak ground acceleration) scaling of near-fault ground motions was investigated. PGA modulation will affect responses of near-fault ground motion. Acceleration responses of the hoist chamber are increased with the near-fault ground motions with forward directivity. It is found that the acceleration responses of structure increase as the PGA scaling index increases, while forward-directivity pulse-like ground motions have more profound effects on the acceleration responses of the hoist chamber with abrupt stiffness changes.