Study of the Effect of Soil-Pile-Structure Interaction on the Seismic Response of Steel Diagonal Grid Structures with Emphasis on Soil Liquefaction Phenomenon

The transition from internal frame structures to external systems like diagonal grids has enhanced both shear resistance and aesthetic value in tall buildings. These external systems effectively distribute load-bearing elements around the perimeter, utilizing triangular grid networks to optimize structural and architectural performance. However, a significant challenge in seismic regions is the liquefaction of loose sandy soils, which can cause severe settlement and lateral displacement. This research examines steel diagonal grid structures, focusing on soil-pile-structure interaction and liquefaction effects. A symmetric four-story model was developed using SAP۲۰۰۰ and modeled nonlinearly in OpenSees, incorporating near-field and far-field soil domains, piles, and structural elements. Results indicate that longer piles (۲۸-۳۰ meters) with diameters over ۱.۲ meters reduce roof displacement by up to ۴۲%, while increasing shear forces and bending moments within the piles, maintaining foundation rotation within acceptable limits (less than ۰.۰۰۲ radians). In contrast, shorter piles (۱۲ meters) decrease shear and axial forces but lead to increased roof displacement and inter-story drift, with increases up to ۴۳%. Notably, under liquefaction, these shorter piles show a relative drift reduction of up to ۶۲%. The findings stress the importance of a balanced design approach that considers both structural displacements and internal stresses, advocating for the integration of geotechnical and structural factors in seismic design for innovative systems like diagrids. Recommendations include refining design codes to impose specific limitations on pile dimensions to address nonlinear liquefaction effects.

کلیدواژه ها:

Soil-pile-structure interaction ، Diagonal grid steel structure ، Seismic response ، Liquefaction of soil