Experimental and numerical investigation of the seismic performance of concrete-filled steel tubular composite columns with UHPC plates

To study the seismic performance of concrete-filled steel tubular composite columns with UHPC plates. The pseudo-static tests were carried out on five specimens with the longitudinal distance of the column limbs and thickness of the UHPC plates as test parameters. Subsequently, a nonlinear finite element model of such com-posite columns was established based on OpenSees, and the calculation method of lateral bearing capacity of the specimen under compression-bending load was proposed. The results showed that the longitudinal distance of the column limbs significantly influenced the lateral bearing capacity as well as the initial stiffness of the specimens. The longitudinal distance of column limbs was increased from 250 mm to 650 mm, and the lateral bearing capacity as well as the initial stiffness of the specimens were increased by 246.0 % and 488.5 %, respectively. The thickness of the UHPC plate was increased from 50 mm to 100 mm, the lateral bearing capacity of the specimen was increased by 32.2 %, while the cumulative hysteretic energy consumption was reduced by 45.05 %. Keeping the same axial pressure ratio, the initial stresses in the column limb steel tubes of the concrete-filled steel tubular composite columns with UHPC plates specimens were higher compared to those of the concrete-filled steel tubular composite columns with ordinary reinforced concrete plates specimens, resulting in poorer ductility. The established nonlinear numerical model accurately captured the hysteretic performance of the specimen. Moreover, the proposed lateral bearing capacity calculation method has high accuracy and can predict the lateral bearing capacity of such structures well.