Seismic behavior of L-shaped concrete-filled steel tubular columns with reinforcement stiffeners

Three L-shaped concrete-filled steel tubular (CFST) column specimens including one reinforcement stiffened column and two non-stiffened columns were fabricated and researched by quasi-static experiment. The reinforcement stiffener and axial compressive ratio were key factors to be studied for their influencing regulation in the experiment. Combined with finite element analysis of software OpenSees, failure modes and hysteretic properties of specimens were investigated. The mechanism of reinforcement stiffeners and the confinement effect provided by L-shaped tube were also studied. The results reveal that: the reinforcement stiffeners can effectively postpone steel tube’s local buckling and restrain separation of steel tube from concrete at concave corners to guarantee the interaction of steel tube and concrete; with the axial compressive ratio varying from 0.3 to 0.6, the energy dissipation capacity and the ductility of non-stiffened L-shaped CFST columns decrease; compared with non-stiffened L-shaped CFST columns, reinforcement stiffened L-shaped CFST columns have positive effect on failure mode, energy dissipation capacity and ductility under the same axial compressive ratio; the finite element analysis results can basically reflect the seismic behavior of the specimens under cyclic loading.