Seismic performance of grouted CFDST column base: Investigation and design method

Abstract

This paper investigates the seismic performance of the grouted concrete-filled double skin steel tubular (CFDST) column base. Two column base specimens are tested under compression and lateral cyclic load, with analysis focused on investigating the failure modes, load-displacement relationship, strain distribution, deformation patterns, and the degradation of strength and stiffness. A finite element model is established, validated and employed for analysing the deformation and internal force. Three types of failure modes are identified, namely, the flexural failure at the CFDST column, the pullout failure of the grout, and the punching shear failure of the grout. These failure modes vary depending on parameters such as the embedment depth and the compressive strength of the grout. At shallow embedment depths, pullout failure at the grout becomes more prominent. Conversely, insufficient compressive strength of the grout enhances the risk of punching shear failure at the grout. A design method is proposed by parametric analysis, encompassing the flexural resistance calculation and structural detailing recommendations.