Concrete-Filled Steel Tube Columns Encased with Thin Precast Concrete

An experimental study was performed to investigate the axial-flexural load-carrying capacity of concrete-filled steel tube columns encased with thin precast concrete (PC). Six eccentrically loaded columns and one concentrically loaded column were tested. To prevent the premature failure of the concrete encasement, various reinforcement details such as studs, steel fiber, welded wire mesh, and cross ties were used. The maximum axial loads of the specimens agreed with the strengths predicted by current design codes, although in some specimens, the load-carrying capacity decreased immediately after the peak strength owing to early spalling of the concrete encasement. On the basis of the test results, the use of fiber-reinforced concrete is recommended to increase the ductility of columns by restraining the spalling of the concrete encasement. (C) 2015 American Society of Civil Engineers.