Investigation on bond behavior in post-tensioned RC slabs

This study investigates the effect of various parameters including concrete compressive strength, prestressing load level, CFRP strengthening, and tendon eccentricity on the load capacity and bond behavior of post-tensioned RC slabs strengthened with CFRP. The load-displacement behavior was experimentally determined and the results were verified. A follow up FEM study was performed on concrete-CFRP interfacial stress and strain distributions, as well as CFRP slippage and damage evolution contours. Based on the results, tendon eccentricity has the greatest effect on load capacity of slabs. Besides, increasing the prestressing load level increases the secant flexural stiffness, but decreases ductility. A 54% increase in prestressing load results in a 64% enhancement in slab stiffness. Also, the yield and maximum loads increase by increasing prestressing load. This is particularly advantageous in slabs strengthened with thinner CFRP laminates, at which slippage of the laminate is very common.