Performance And Design Methods Of Concrete Beams Reinforced With GFRP/Steel Wire Composite Rebars

The civil infrastructures such as bridge, marine structures, waterfront, dam, tunnels are in service for many years and are subjected to aggressive environment, combined with moisture, temperature, and chlorides, resulting in corrosion of steel bars. The corrosion process causes the cumulative damage, the resistance reduction of civil infrastructures, and catastrophic disaster. Therefore, the endurance of concrete structures is the main problem to be solved in civil engineering.Due to significant advantages over GFRP rebars, namely high tensile strength, high elastic modulus, and good property of ductile, GFRP/steel wire composite rebars were manufactured to enhance the ductility and elastic modulus of GFRP rebars. The tensile strength of non-corrosion GFRP/steel wire composite rebar is larger than that of ordinary steel rebar, and the typical stress-strain relationship of GFRP/steel wire composite rebar exhibits the similar yielding characteristics to that observed for ordinary steel rebar. Therefore, GFRP/steel wire composite rebars offer a superior alternative to ordinary steel rebars in concrete structures.Based on the GFRP rebars and GFRP/steel wire composite rebars, bond behavior between GFRP rebar and concrete, bond behavior between GFRP/steel wire composite rebar and concrete, performance of concrete beams reinforced with GFRP/steel wire composite rebars, were studied in this paper. The main works of this paper is followed as:Firstly, uesing pull-out test, the effcet of rebar type, rebar component, rebar diameter, rebar surface texture, rib height, rib spacing and rib width on the bond behavior between GFRP rebars and concrete were studied. Based on analysis of the test results, design recommendations involving optimal rib spacing and rib height were made concerning optimum rib geometries of GFRP ribbed rebars with superior bond-slip performance.Secondly, due to significant advantages over GFRP rebars, namely high tensile strength, high elastic modulus, and good property of ductile, GFRP/steel wire composite rebars offer a superior alternative to ordinary steel rebars. Based on the test results of GFRP rebars, design recommendations on optimum rib geometries were also made for GFRP/steel wire composite rebars.Thirdly, 180 pull-out specimens were tested to study the influence of various parameters on bond behavior between GFRP/steel wire composite rebars and concrete. The test variables were the rebar rib spacing, rebar diameter, embedded length, concrete compressive strength, concrete cover thickness, and concrete cast depth. The test results can provide theoretical basis to determine the development length and the concrete cover thinkness, to build the model of bond-slip constitutive relationship of the GFRP/steel wire composite rebars, and to establish the related criterions.Fourthly, based on the simply-supported beams, the effects of reinforcement ratio on the cracking pattern, cracking spacing, cracking moment, cracking width, flexural performance, and load-deflection relationship were investigated. Using the teats results, the design methods of minimum reinforcement ratio, maximum reinforcement ratio, and the safety reinforcement ratio were suggested.Fifthly, based on the safety reinforcement ratio, the flexural performance of concrete beams reinforced with GFRP/steel wire composite rebars was tested. And concrete beams reinforced with GFRP rebar and steel rebar were also tested for coMParision. The design methods of cracking capacity, limit flexural capacity, and maximum crack width were suggested.Finally, based on definition the of nominal yield strength of GFRP/steel wire composite rebar, the simply design method of limit state capacity was suggested for concrete beams reinforced with GFRP/steel wire composite rebars. And the limit values of maximum crack width and defelction were also suggested.