Effect of Ground-Motion Duration on Seismic Fragility Analysis of Clay Slopes

Duration is one of the most important characteristics of ground motions. Yet, its effect on slope seismic fragility remains ambiguous. This study performs dynamic analyses on a 15 m homogeneous earth slope using 30 long-duration and 30 short-duration ground motions with the material point method. PGA and Ds5-75 are selected as optimal intensity measures. Scalar and vector fragility functions are developed. Results indicate that long-duration ground motions reduce slope capacity by about 31%. Differences between scalar and vector fragility are more significant under long-duration excitations. A vector-based fragility approach using [PGA, Ds5-75] is recommended to capture duration effects.