Nonlinear axial behavior of partially-confined concrete columns with embedded hexagonal FRP strips

To provide a greater mechanical efficiency of strengthening concrete by partial-embedding of composite reinforcement, the novel technique presented in this study is based on the incorporation of hexagonal FRP strips within the concrete columns. The assessment of the nonlinear response of confined concrete columns through an analytical model is a primordial procedure to optimize and to identify the adequate parameters influencing the axial compression performances of the FRP encased concrete. The influence of the different parameters of the advocated design and model on the overall axial behavior of columns have been investigated by means of a parametric study.

The emphasized results indicate that all the studied parameters have significant effects on the axial compression behavior of the confined columns, and the efficacy of confinement depends effectively on several factors, including the net spacing of the FRP strips, the width and thickness of the FRP, the compressive strength of the unconfined concrete and the level of confinement. In this respect, the ultimate stress and axial strain of confined columns can be substantially increased by increasing the amount and the number composite layers and decreasing the spacing between the hexagonal FRP strips.

Keywords: Partially confined-concrete, FRP strips, Analytical modeling, Parametric study.