Influence of strong motion duration on the seismic performance of high CFRDs based on elastoplastic analysis

Amplitude, frequency content and duration are the three main features of earthquake ground motions. The first two features have been fully considered in the seismic design of high concrete-faced rockfill dams (CFRDs). However, the role of ground motion duration on the seismic performance assessment of CFRDs remains unclear. In this paper, 40 as-recorded ground motions with a broad distribution of durations modified to match a 5% damped target spectrum are selected to investigate the influence of strong motion duration on the seismic performance of high CFRDs. A generalized plasticity model for rockfill materials, a plastic damage model for face slabs and a generalized interface plasticity model to describe the relative sliding behavior between the face slabs and rockfill are adopted for the dynamic response analysis based on a 2D 200-m-high regular CFRD. The vertical displacement, horizontal displacement, plastic shear strain and a face-slab damage index are used as the dam damage measures (DMs). The correlation coefficient R2 is selected to reflect the degree of the relationship between strong motion duration and DMs. The results indicate that the vertical displacement, horizontal displacement, and plastic shear strain are positively correlated with strong motion duration, but the face-slab damage index has a low correlation. Therefore, the influence of strong motion duration should be considered in the seismic performance assessment of high CFRDs, and the use of short durations of strong ground motion in the design and seismic performance assessment of CFRDs may overestimate dam performance.