Experimental investigation of octagonal partially encased composite columns subject to concentric and eccentric loading

Partially Encased Composite (PEC) column is one of the recent achievements in the field of composite columns. This paper presents a combined experimental and theoretical study on the mechanical performances of six octagonal PEC columns subjected to axial compressive and bending moment loading. The major different between them was the concrete reinforcement details. The parameters studied in the experimental and numerical study were the type of reinforcement details and the failure mode. The results were presented as load-deformation and moment-rotation curves. In the analytical phase, the experimental results in the compressive loading were compared with those obtained from CSA S16-14 and EN 1994-1-1 equations. The comparison of the code equations given in CSA S16-14 and EN 1994-1-1 revealed that the equation in CSA S16-14 underestimates the capacity. Also, theoretical relationships were used to estimate the compressive capacity and the behavior of laboratory models in order to find the confinement coefficient of concrete.