Seismic Behaviors of Concrete-Filled T-Shaped Steel Tube Columns

Abstract

Concrete-filled special-shaped (L-shaped, T-shaped, and cross-shaped, and etc.) steel tube column is a type of member in which concrete is poured into special-shaped steel tube so that steel and concrete support loads together. It improves the seismic behaviors of reinforced concrete special-shaped columns due to the better confining effects provided by the steel tube. A test research on the seismic behaviors of one concrete-filled T-shaped steel tube column with pseudo static method is presented and the load-displacement curve and skeleton curve are provided. Series of steel bar stiffeners were welded onto the steel tube in order to postpone the buckling of steel tube and to enhance confining effects. A numerical analysis program was developed using a fiber-based method. The constitutive model of concrete employed the modified Mander model, and that of steel employed a bi-linear model considering the Bausinger effect. The numerical analysis program was verified by the test results and parametric analysis was carried out, in which the influences of the ratio of axial compression stress to strength, steel tube thickness and concrete strength were mainly discussed. The following conclusions are obtained: with the increase of the ratio of axial compression stress to strength, the bearing capacity of member increases and the energy dissipation capacity improve, while the ductility deteriorates. With the increase of steel tube thickness, the initial rigidity, bearing capacity, ductility and energy dissipation capacity improves simultaneously. With the increase of concrete strength, the bearing capacity increases, the energy dissipation capacity improves, while the ductility deteriorates.

Experimental Study on Seismic Behavior of Concrete-Filled L-Shaped Steel Tube Columns

“…Experimental results indicate that the CFLST columns hold considerably high stiffness, favorable ductility, and that stiffeners can make hysteretic curves plumper and then enhance the ductility of CFLST columns. Pseudo static experiments of three T-shaped columns (Wang et al 2009), including one non-stiffened CFTST column, one indented-shaped reinforcement stiffened CFTST column and one T-shaped RC column indicated that CFTST column had higher strength and better energy dissipation capacity compared with RC column, but lower strength and smaller energy dissipation in comparison with CFTST column with indented-shaped reinforcement stiffeners.…”

Behaviour of T-shaped stiffened concrete-filled steel tubular stub columns after uniform and non-uniform fire exposure

“…The drawbacks mentioned above determine that the SCFST column is mainly applied to multi-story structures at low seismic intensity zones, thus the outer steel tube is thin to achieve favourable economic effects, which may result in severe local buckling of the SCFST column (Yang et al, 2012). In this regard, several solutions have been proposed in the literature, such as binding bars (Zuo et al,2018), battlement-shaped bars (Liu et al, 2018a), tensile bar stiffeners (Wang et al, 2009; Xu et al, 2019), setting steel plate stiffeners along the horizontal direction (Liu et al, 2018b), and multi-cell combination used to strengthen the confinement on internal concrete (Tu et al, 2014). As reported by the above researchers, the bearing capacity of the stiffened column increases by 6%-53% compared with the unstiffened column, and the ductility has a greater increase, reaching 54%-650%.…”

Flexural Capacity of Cross-Shaped Concrete-Filled Steel Tubular Column–Steel Beam Joints with Side-Plate Connections

“…Specially shaped concrete-filled steel tubular columns are produced by pouring concrete into these steel tubes. Because of the synergy between the steel tube and concrete, CFSTs have the advantages of high bearing capacity, good plasticity, improved seismic performance, convenience of construction, and they can help improve the space utilization inside a building [9][10][11]. Specially shaped concrete-filled steel tubular column-steel beam joints transfer forces in the frame structural system.…”