EXPERIMENTAL RESEARCH ON PRECRACKED STEEL REINFORCED CONCRETE BEAMS STRENGTHENED WITH CFRP SHEETS

Based on the experiment of six precracked steel reinforced concrete beams strengthened with CFRP sheets, their force mechanism and failure model are discussed. The calculated formulas of bearing capacity are given. The results showed that the cracking loads of beams strengthened with one CFRP sheet, two CFRP sheets, one prestressed CFRP sheet, and two CFRP sheets with one prestressed and one normal and one CFRP sheets strengthened greater precracked beams respectively increased by 27.3%, 54.5%, 90.9%, 100% and 9.09%. The corresponding ultimate loads respectively increased by 16.2%, 27%, 28.8%, 35.1% and 14.4%. The load-deformation curves of normal and strengthened beams respectively showed three and two linear characteristics. The crack width and spacing of strengthened beams decreased, but the numbers of crack increased. The theoretical results which calculated by the formulas of bearing capacity agree well with experimental results.