Fragility Analysis of Silos with Different Height-to-Diameter Ratios under Mainshock-Aftershock Seismic Sequences

This study utilized ABAQUS finite element software to develop three-dimensional reinforced concrete silo models with height-to-diameter (H/D) ratios of 2.5, 2.0 and 1.4, representing typical engineering configurations. A systematic investigation was conducted using incremental dynamic analysis (IDA) and cloud computation method to evaluate the seismic response of silos under individual mainshock and mainshock-aftershock sequences. A typical cylindrical silo was selected as the prototype, and the full silo condition was considered to analyze the maximum inter-story drift ratio responses under varying peak ground accelerations (PGA). Probabilistic seismic demand models (PSDMs) and fragility curves were subsequently developed. The results demonstrate that: (1) Under mainshock-aftershock sequences, silo structures exhibited significant stiffness degradation, increased dispersion in IDA curves and earlier entry into the nonlinear stage. (2) Decreased H/D ratios correlate with deteriorated seismic performance of silos, evidenced by reduced IDA curve slopes, significantly increased exceedance probabilities across damage states and accelerated damage progression, indicating a transition in failure modes from ductile to brittle failure. (3) Mainshock-aftershock sequences substantially elevated structural damage probabilities, with larger diameters further exacerbating risks. This research elucidates the cumulative damage mechanisms of silos under mainshock-aftershock sequences, provides theoretical foundations for seismic design and recommends incorporating aftershock effects into current codes.