Evaluation of Strengthening Steel Beams Using the Technique of Carbon Fiber Confinement by a Steel Plate (CFCSP)

Abstract

Abstract This research concentrates on evaluating the effect of using two new techniques for strengthening steel beams with carbon fiber–reinforced polymer (CFRP) strips on the structural behavior of these beams at service and ultimate load stages by using a confining steel plate in two different configurations. Five steel beams with lengths of 1,500 mm were tested under a single concentrated load at midspan: the first (nonstrengthened) beam was used as a reference beam, the second beam was strengthened by only a CFRP strip located at the bottom flange (tension face), and the third beam was strengthened by only a steel plate, which is also located at the bottom flange. The first technique is represented in the fourth beam, which was strengthened by a CFRP strip confined by a steel plate welded at its ends, whereas the second technique is obtained by an amendment done on the first technique and is represented by the fifth beam, which was strengthened by a CFRP strip with the confining steel plate (welded at its ends) and glued with the CFRP strip by a suitable epoxy adhesive. Test results have shown that the first technique has led to less deflection, less tensile strain, and a higher yield load at the service load stage (i.e., elastic region), whereas the second modified technique has led to a further decrease in deflection and tensile strain and an additional increase in yield and ultimate loads, and both of those outcomes were higher than the algebraic sum of the increases resulting from beams strengthened by a “steel plate” and “CFRP strip” individually.