Introduction to Stresses in Load-Transferring Areas of Reinforced Concrete Beams Model Strengthened with Carbon Fiber Reinforced Polymer (CFRP) Strips by an Active Method

Abstract

This research studies the introduction of stresses in load-transferring areas of reinforced concrete beams strengthened with an active method, which induces compressive stresses in the concrete by tensioning a CFRP strip at its ends using a hydraulic jack until a predicted elongation of the CFRP strip is reached and ends of the strip are secured. In this study, a finite element method was used to analyze and predict the introduction of stresses and cracking of concrete in the load-transferring areas by using load-transfer devices with different height-to-diameter ratios for the concrete material of different compressive strengths.
The finite element program “ANSYS” was adopted to create models of reinforced concrete beams, the load-transfer devices and CFRP strip using three-dimensional solid elements, considering non-linear properties of the concrete material. Results of the analyses show that diameters, height-to-diameter ratios of the load-transfer devices, and compressive strengths of the concrete materials have influences on values of the tensile and compressive stresses of the concrete induced in the load-transferring areas, which may be predicted using simple equations having the height-to-diameter ratios and diameters of the load-transfer devices as well as compressive strengths of the concrete materials as independent variables, and values of the tensile or compressive stresses of the concrete in the load-transferring areas as dependent variables.