Debonding behavior and interfacial stress in carbon fiber-reinforced polymer plate-strengthened top flange of box-girder bridge

THE INTERFACIAL STRESS IN A CARBON FIBER-REINFORCED POLYMER (CFRP) PLATE FOR STRENGTHENING THE TOP FLANGE OF A BOX-GIRDER BRIDGE WAS THEORETICALLY INVESTIGATED. ACCORDING TO THE FORCE ANALYSIS RESULTS FOR THE BOX-GIRDER STRUCTURE, THE MOST UNFAVORABLE FORCE AREA WAS SELECTED FOR MODELING ANALYSIS. USING THE SIMPLIFIED BEAM MODEL, A CFRP PLATE–CONCRETE INTERFACIAL-STRESS CALCULATION MODEL WAS DERIVED, AND A CLOSED-FORM SOLUTION FOR THE CALCULATION MODEL WAS OBTAINED. EQUIVALENT SIMPLIFIED TEST SPECIMENS WERE DESIGNED ACCORDING TO THE BOX-GIRDER STRUCTURE TO VERIFY THE RELIABILITY OF THE THEORETICAL MODEL. THEN, FOUR-POINT BENDING TESTS OF THE SAMPLE WERE PERFORMED. IN THESE TESTS, THE DEBONDING FAILURE MODES AND STRAIN IN THE CFRP PLATE WERE EXAMINED. THE CFRP PLATE–CONCRETE INTERFACIAL STRESS WAS CALCULATED ACCORDING TO THE STRAIN DATA OF THE CFRP PLATE IN THE EXPERIMENTAL TESTS. THE EXPERIMENTAL RESULTS WERE THEN COMPARED WITH THE THEORETICAL RESULTS. FURTHERMORE, THE CORRESPONDING INTERFACIAL STRESSES WERE CALCULATED AND COMPARED ACCORDING TO THE DIFFERENT LOAD LEVELS SPECIFIED IN THE CODE. A SERIES OF THEORETICAL AND EXPERIMENTAL COMPARISONS WERE PERFORMED TO VERIFY THE RELIABILITY OF THE PROPOSED CFRP–CONCRETE INTERFACIAL STRESS CLOSED-FORM SOLUTION MODEL.