Experimental study on the seismic behavior of T-shaped high-strength double skin composite wall with steel truss

In this paper, the seismic behavior of T-shaped high-strength double skin composite walls (DSCWs) with steel truss was investigated. Five T-shaped specimens fabricated with Q460 steel and C60 concrete were tested under combined axial and cyclic lateral loading, and the effects of the axial compression ratio and aspect ratio were taken as the main design parameters. The experimental results showed that all specimens exhibited a flexural failure, but with different failure mechanisms under positive and negative loading. The flange-free boundary component was identified as critical to the seismic response, because either crushing of the infill concrete or fracture of the steel in this region led to the loss of load-carrying capacity. A clear shear lag effect was also observed in the flange. The use of high-strength materials enabled the specimens to achieve high load-carrying capacity, stable strength and stiffness, and good energy dissipation capacity. Overall, increasing the axial compression ratio enhanced the peak load and initial stiffness of the specimens but reduced the displacement ductility, whereas increasing the aspect ratio decreased the peak load while improving ductility. Direct application of the flexural-capacity methods in JGJ/T 380–2015 and ANSI/AISC 360–22 resulted in clear loading-direction-dependent deviations. In addition, a simplified formula for evaluating the flexural capacity of T-shaped DSCWs was proposed by accounting for the strength enhancement of confined concrete and the effect of steel fracture.