Nonlinear Dynamic Response of a CC-RCC Combined Dam Structure under Oblique Incidence of Near-Fault Ground Motions

Jiawen Zhang,Mengxi Zhang,Bowen Shi,Mingchao Li,Qiaoling Min,Lingguang Song

doi:10.3390/app10030885

Abstract

The velocity pulse contained in near-fault ground motions have a tremendous impact on dam safety. Previous studies have mainly focused on the response of dams under near-fault seismic records without considering the obliquely incident seismic waves. In this study, the structure–soil interaction (SSI) is taken into consideration, and the nonlinear behavior of a conventional concrete roller-compacted concrete (CC-RCC) gravity dam under near-fault pulse records and non-pulse records is investigated with consideration of the obliquely incident P waves. On the basis of the dam site conditions, three groups of near-fault pulse records are chosen, and three corresponding non-pulse records are fitted by their acceleration response spectra. Combining with the viscous-spring artificial boundary, the wave input method is proposed to transform the near-fault seismic records into the equivalent nodal forces at the boundary of the foundation. The concrete damaged plasticity model is used for the nonlinear analysis. The results show that the pulse ground motions are more destructive than the non-pulse motions. The nonlinear behavior of the dam varies with the incidence angle of P waves and generally reaches a maximum at 60° and 75°, the worst damage occurs at the interface between different materials of the dam, and the spatial variation of its damage is very obvious under near-fault seismic records with various incidence angles. Therefore, the effect of the angle of obliquely incident seismic waves and near-fault pulse effect should be considered comprehensively in the seismic analysis of dams.

Highlights

The meizoseismal area in southwest China is rich in water energy resources [1], and the problem of selecting sites for high dams and large reservoirs is “difficult to avoid”
Some of the high dams that have been built, are under construction, or in the planning stage are located near the seismic fault zone [1], which is subject to complicated rules of near-fault ground motions
This study investigates the nonlinear dynamic behavior of the concrete roller-compacted concrete (CC-RCC) gravity dam under near-fault pulse and non-pulse seismic records, and considers the effect of the seismic incident angles

Summary

Introduction

The meizoseismal area in southwest China is rich in water energy resources [1], and the problem of selecting sites for high dams and large reservoirs is “difficult to avoid”. Some of the high dams that have been built, are under construction, or in the planning stage are located near the seismic fault zone [1], which is subject to complicated rules of near-fault ground motions. Near-fault earthquakes occur within 20 km of the fault and include displacement and velocity pulses, as well as permanent ground displacement [2,3,4], their characteristics are remarkably different from those of far-fault earthquakes. Several major earthquakes in the last twenty years, such as Northridge (1994), Kobe (1995), Chi-Chi (1999), and Iran (2003), and especially the Wenchuan earthquake in China (2008) and the earthquake in Haiti (2010) have confirmed the remarkable impact of velocity pulses contained in near-fault seismic records on building damage [5,6,7,8,9].

Methods

Results

Conclusion