Reinforced lightweight concrete filled steel tube columns

Together the merits of CFST columns, inclusive high restrained to concrete, improve the buckling for steel tube, high compressive and bending strength, enhancement of fire and earthquake performance and quick construction, thus, save time and cost, RLWCFST columns are used in structural applications with higher strength/weight ratio and minimize in column size thus reduce self weight. Factors, such as the concrete core condition, the slenderness and the steel tube wall thickness, have a considerable impact on the performance of LWCFST columns, especially in the behaviour after yield.To survey the compression conductof the steel tube infill with reinforced lightweight concrete columns (RLWCFST), 18 specimens, including 6 LWCFT and 12 RLWCFST, were tested under concentric loading. The parameters which are considered include:: steel tube yield strength and thickness, slenderness ratios, reinforcing bar diameter. The experimental results show that a RLWCFST column has excellent load bearing capacity, post-peak behaviour and load deformation characteristics, with high ductility than LWCFST. Increment in tube thickness led to higher stiffness, ductility, confinement effect and toughness.RLWCFST columns show an increment in load capacity and confinement with reduces of L/D ratio. The measured ultimate load of the specimens is compared with identical values achieved by two international codes (AISC 360-16 and EC4-1994). It shows a good foretelling of EC4 and a conservative estimation of AISC.