Seismic Behavior of CFT Column and Steel Pile Footings

Abstract

In this study, two column and pile-footing models consisting of concrete-filled steel tube (CFT) columns, reinforced concrete footings, and steel H-piles were designed and constructed at approximately one-fifth scale. The experimental differences between the two models were in the design details of the CFT column-to-footing connections. One connection consisted of welded studs, and the other used a base plate and stiffeners. The two models were tested in a vertical cantilever condition with cyclic horizontal forces and a constant axial load applied to the top of the column. The model footings were supported on 16 model steel H-piles simulating the pile foundation. Under imposed horizontal displacement, the two models with different CFT-to-pile-cap connection details demonstrated satisfactory cyclic behavior, with the development of full plastic hinges at the bottom of the columns. Strut-and-tie modeling analysis was carried out to show the force-resisting mechanism in the reinforced concrete footing. The study also validated a new design detail for the anchorage of steel H-piles to pile caps.