3D Numerical Analysis of Seismic Interaction Between 3 Adjacent Bridges via Nonlinear Soil

The present study assess the effect of Structure-Soil-Structure-Interaction (SSSI) on the seismic behaviors of three dissimilar adjacent bridges by comparing their seismic responses with the seismic responses of the isolated bridges including Soil-Structure-Interaction (SSI). To this end, an extensive series of numerical analyses have been carried out to elicit the effects of (SSSI) on the seismic behavior of three dissimilar bridges with different superstructure masses. The studied bridges are based on groups of piles founded in nonlinear clay. A parametric study has performed for configurations of three bridges with superstructure masses ratios (200%, and 300%), concentrating on the influence of the inter-bridge spacing, and the geometrical position the bridges towards each other and towards the seismic exciting direction. The numerical analyses have been conducted using a Three-dimensional finite differences modeling software FLAC 3D (Fast Lagrangian analysis of continua in 3 dimensions). The results reveal a salient positive impact on the acceleration of the superstructure by considerable drop (up to 90.63%) and by (up to 91.27%) for the internal forces induced in the piles. Comparably, the influence of bridges arrangement towards the seismic loading were prominent on both of superstructure acceleration and the internal forces in the piles. The responses were as much as 27 times lesser for the acceleration and 11 times smaller for the internal forces than the response of the isolated bridge. Contrarily, the inter-bridge spacing has a limited effect on the seismic response of the grouped bridges.