Experimental investigation and analytical method for DSPC piers under cyclic loading

With the development of bridge construction in high-traffic areas, there is a growing demand for pier design that combines excellent mechanical performance with ease of construction. Double steel plate concrete composite structure (DSPC) is a reasonable option for such requirement, since the inner and outer steel plates can provide strong bearing capacity and serve as formwork for in-filled concrete. To investigate the seismic behavior of DSPC pier, five tests on 1:2 scaled specimens representative of 30-meter span bridge piers were conducted under axial compression of approximately 0.1 compression ratio and lateral cyclic loading. The detailing included head studs and tie bars, connecting the double steel plates and in-filled concrete. The failure mode, load-deflection curve, strain distribution, and other key indexes were discussed afterwards. The result revealed that DSPC piers exhibit excellent seismic performance with great load bearing capacity and ductility. The failure modes were controlled by outer steel plate and welding seam fractures, while the studs and tie bars remained functional. The findings demonstrate the feasibility of DSPC piers for seismic design. Regarding the impact of four parameters: a 45° change in loading direction reduced bearing capacity by 9.4 % with minimal impact on deformation; increasing the height-to-width ratio reduced ductility factor by 11 % with minimal impact on strength; reducing steel plate thickness significantly weakened both capacity and deformation; decreasing the hollow ratio by 0.133 reduced capacity by 3.2 % without affecting deformation. Finally, a simplified calculation method to predict the bending capacity of DSPC section is proposed, subjected to eccentric compressive loads in any loading angle. Upon further verification, the predicted results agree well with experimental data, as well as with the results from broader parametric study using the fiber section model method and considering varying material properties.