Behavior of Diagonal-Binding-Plate Shear Connector in Concrete-Filled Steel Tubular Columns

Transferring interface forces between a steel hollow section and the infilled concrete in concrete-filled steel tubular (CFST) structures usually needs careful consideration during design. This work proposed using diagonal-binding-plate shear connectors to enhance the interface shear resistance of CFST columns. Push-out tests were conducted, including a total of 13 CFST specimens with diagonal-binding-plate shear connectors along with two reference specimens. The test variables included the width-to-thickness ratio of steel tube, cross-sectional dimensions, concrete strength, and details of diagonal-binding-plate shear connectors (e.g., width, thickness, longitudinal length, and opening details in shear connectors). The research results demonstrated the interface shear resistance was effectively improved by diagonal-binding-plate shear connectors, with a maximum increase of approximately seven times compared with specimens without shear connectors. Furthermore, a finite-element model based on the Dynamic Implicit solver was developed, and parametric analysis was conducted. The load-transfer mechanism based on confinement effect of steel tube and local compression of concrete was analyzed in detail. Corresponding formulas for predicting the load capacity of diagonal-binding-plate shear connectors under local compression failure of concrete and design recommendations were proposed.