Flexural and Shear Strengthening of RC Beams with Large Openings by Steel or CFRP Plates

Abstract

Existence of transverse openings in the web of reinforced concrete beams is usually used to provide paths for required ducts and pipes which are necessary to accommodate essential services like water supply, sewage, air-conditioning, telephone and electricity. However providing an opening in the beam reduces its stiffness, which decreases the overall strength. The provision of openings through the beam depth, changes its simple mode of behavior to a more complex one depending on the size, shape and location of openings. Repair and strengthening of an existing structure may be essential in many cases such as increasing the stiffness of the beams due to making transverse openings in the web of beams after construction. An experimental test program of fourteen RC beams with large openings were strengthened by using additional layers of externally bonded steel plates or CFRP Plates with different techniques then tested by four-point bending test. The behaviors of the tested specimens were investigated with and without strengthening and compared to identify the effectiveness of each method and material of strengthening to increase the flexural and shear strength of beam with different opening location. The research shows that strengthening using CFRP Plates were more effective than using steel plates.