Seismic response analysis of intake tower structure under near-fault ground motions with forward-directivity and fling-step effects: Fid-Bau Portal

Seismic response analysis of intake tower structure under near-fault ground motions with forward-directivity and fling-step effects

Chen, Xi / Liu, Yunhe / Zhou, Binpeng / Yang, Dixiong

Abstract

Abstract Forward-directivity and fling-step effects of fault rupture generally cause large amplitude and long-period velocity pulses in near-fault ground motions, which impose severe damages on structures. In this paper, 30 typical near-fault impulsive and non-pulse records were selected as the input. The 3-dimensional finite element model with material nonlinearity of a reinforced concrete intake tower structure in hydraulic engineering was established to examine its elastoplastic dynamic responses and seismic performance. The distribution features of acceleration and displacement responses of intake tower along the height under the ground motions with forward-directivity and the fling-step effects were compared. The lateral curvature was proposed as damage index to identify the damage location and to quantify the damage degree of intake tower structure, which behaves like a shear wall. Numerical results indicated that the forward-directivity and fling-step pulses lead to great nodal displacements of intake tower, and large curvatures are generated at the lower part of the structure. Moreover, the damage of intake tower subjected to near-fault impulsive records is more severe. Finally, the dynamic responses of intake tower were examined by using peak ground acceleration (PGA) and improved effective peak acceleration (IEPA) as the scaling indices of the records. It is illustrated that the dispersions of seismic responses of intake tower structure with amplitude scaling is smaller than those without scaling, and the intensity measure IEPA is more appropriate for the scaling of near-fault impulsive records than PGA.

Highlights • The elastoplastic seismic responses of intake tower structure under near-fault ground motion with forward-directivity and fling-step effects were examined. • The lateral curvature was proposed as an effective index to identify the damage location and quantify the damage degree of intake tower structure. • The fling-step impulsive ground motions more easily lead to the greater curvature and damage of lower structure of intake tower. • Intensity measure IEPA is more appropriate to scaling of impulsive records than PGA.