EXPERIMENTAL INVESTIGATION ON R.C. BEAMS RETROFITTED IN FLEXURE AND SHEAR BY PRETENSIONED STEEL RIBBONS

The experimental results of three and four point loading tests on reinforced concrete beams strengthened by angles and/or pre-stressed stainless steel ribbons (CAM system) are presented. The stainless steel prestressed ribbons play the role of adjunctive transversal reinforcement as well as confine the structural element. Six flexural critical beams and nine shear critical beams were tested. In the first group four beams were retrofitted with bottom stainless steel angles and transversal ribbons, with two different spacing. In the second group three specimens were retrofitted by wrapping the beam with the ribbons, while three specimens were strengthned by perforation of the beam beneath the slab height, and by partially wrapping the beam by inserting the ribbons through the hole, in order to simulate a strengthening performed without drilling of the slab. The test results prove the effectiveness of the retrofitting system for both the flexural and shear critical beams.