Truncating ground motions using the VMD-Hilbert transform for nonlinear dynamic analyses

Abstract

Nonlinear dynamic analyses of engineered structures under long-duration ground motions usually require significant computational time, especially when performing incremental dynamic analyses or when developing fragility curves. This study proposes a truncation method of seismic records to reduce the computation cost of nonlinear structural analyses based on the Variational Mode Decomposition and the Hilbert Transform. The truncation-starting and -ending time instants are identified using the relative cumulative spectral energy, which is used to represent the Hilbert spectrum energy variation over time. The effectiveness of the proposed method is verified by the elastic pseudo-response spectrum, three different inelastic single-degree-of-freedom models and a multi-degree-of-freedom system. The proposed method, compared with the Arias intensity-based method, proves to be effective, not only for short-period structures, but also for medium- and long-period structures, allowing for reduction of ground motion duration of about 65% on average.