Soil-Structure Interaction Effects on the Buckling Behaviour of Braced Multi-Storey Steel Frames

Abstract

This study investigated the influence of soil stiffness on the global buckling behaviour of braced 10-storey high steel frame structures. The structural stability of three types of bracings (x-bracing, v-bracing, and single cross bracing) was studied when subjected to gravity and wind actions. On the assumption of an elastic sandy soil deposit that can be described using the soil's elastic properties (modulus of elasticity and Poisson's ratio), the soil-structure interaction effects were modelled and compared using the continuum finite element (CFE) approach and Winkler's support approach. The findings reveal that, regardless of the modelling approach utilized, soil stiffness impacts the critical buckling load of steel frames under gravity loads. It was observed that the difference in the gravity load buckling factor of the frames for loose and stiff soil deposits was larger than 70%. In general, the buckling load factors (BLF) decreased with lower soil stiffnesses, but at greater soil stiffnesses, they converged to the value of theoretical pinned support. Furthermore, the buckling load for lateral loads was discovered to be affected by the modelling approach. With increasing soil stiffness, Winkler's model converged quickly to a pinned support condition for lateral loads, but the CFE technique converged slowly.