Effect of soil properties and foundation embedment depth on dynamic behavior of structures with different slenderness ratios

Abstract

Soil-structure interaction (SSI) is of critical importance for high-rise buildings, dams, bridges, nuclear power plants, silos, chimneys, and water tanks, where seismic performance depends particularly on soil conditions. Furthermore, in embedded structures, embedment can alter the period, stiffness, damping capacity, and responses of the soil-structure system. The main objective of this study is to examine the effects of aspect ratio (2, 4, and 6), soil conditions, foundation embedment ratio (0, 0.5, 1, and 1.5), and earthquake frequency content (2 high, 2 medium, and 2 low) on the dynamic behavior of structures by considering SSI. For this purpose, finite element models of the soil-structure systems were constituted, and the employability of these models was demonstrated through substructure approaches. Seismic analyses were performed, and relative displacements, interstory drifts, stresses, and accelerations were examined. It was seen that the increment of aspect ratio and soft soil conditions elongate the periods, and significantly increase the displacements and interstory drifts. In general, with the increment in the embedment ratio, the reductions in the displacements and stresses were observed. It was determined that softening of the soil does not always lead to a decrease in internal forces, and due to the combined effects of many parameters, soil softening also has the potential to increase internal forces. The results revealed that the seismic behavior cannot be controlled by a single parameter, and the mutual interaction among soil type, earthquake frequency content, embedment ratio, and aspect ratio can produce effects on responses that are contrary to expectations.