Numerical investigation on seismic behaviour of aged concrete gravity dams to near source and far source ground motions
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Numerical investigation on seismic behaviour of aged concrete gravity dams to near source and far source ground motions Soumya Gorai1 · Damodar Maity1 Received: 3 September 2019 / Accepted: 25 September 2020 © Springer Nature B.V. 2020
Abstract This study presents a numerical investigation on the seismic behaviour of aged concrete gravity dams under near source and far source ground motions. Two-dimensional formulation of a concrete gravity dam is carried out implementing the finite element technique, considering full reservoir and rigid base condition. Degradation of concrete properties due to hydro-chemo-mechanical effects and the influence of sediment layers are taken into account to calculate the response of the dam-reservoir coupled system at different ages. Two near source and far source ground motions from real earthquake events are selected for time-history analysis. Seismic performance evaluation is also carried out to assess the probable damage level of the dam. The outcomes of this study show the variation of seismic response of the dam over the ages and the necessity of considering the aging effect, e.g. degradation of concrete and influence of sediment layers, in the inspection of seismic safety issues of concrete gravity dam. This study also reveals the critical effect of near source ground motions on concrete gravity dams at later ages. Keywords Dam-reservoir system · Seismic analysis · Finite element method · Degradation of concrete · Influence of sediment depth · Near source and far source ground motions
1 Introduction Ground motions, recorded in the proximity of an active fault (the range of upper limit of fault distance is 20–60 km), are generally considered as near source (or near fault) ground motions (Stewart et al. 2002; Li and Xie 2007). However, this definition does not reflect the main features of near source ground motions. The significant characteristic of near source ground motions is the long-period pulse(s), which appear prominently in velocity and/or displacement time history (Fig. 1a). These pulses are generally originated by “forward-directivity” (Bray and Rodriguez-Marek 2004) and “fling-step” (Yadav and Gupta 2017) effect. Whereas, far source (or far fault) ground motions do not * Soumya Gorai [email protected] 1
Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
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(a) Gilroy #3, Gillroy Sewage Plant (near source)
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Fig. 1 Illustration of near source and far source ground motions recorded during Loma Prieta earthquake
exhibit such pulse-type characteristics
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