Study On The Mechanical Properties Of Reinforced Concrete Beam Wrapped With GFRP Plate

Fiber reinforced polymer(FRP) is achieved wide attention and application in civil engineering due to its low weight, high strength and good corrosion resistance.To improve the durability problem of concrete structures in coastal areas and islands, one type of reinforced concrete beam wrapped with GFRP plate was designed. This kind of GFRP plate is U-shaped which provides permanent shuttering for the system and protects the reinforced concrete from corrosion. The composite action between GFRP plate and concrete can increase the load-bearing capacity of hybrid beam and reduce the amount of reinforcing steel. The global and local stability of GFRP plate can be effectively strengthened through the inner filled concrete and therefore the possibility of lateral torsional buckling and local buckling failure in the GFRP webs can be avoided. The works presented herein were as follows:1. Experimentation on flexural behavior of GFRP-RC hybrid beams and the reference RC beam were conducted. Test results showed that hybrid beams provided significant increase in flexural capacity but decrease in ductility when compared with the control RC beam.2. According to the different flexural failure modes of hybrid beams with rectangular or T-shaped section, the corresponding flexural capacity formulae were presented, based on the constitutive model of confined concrete. The agreement between experiments and analysis was good.3. Tests on shear behavior of GFRP-RC hybrid beams and the reference RC beams were conducted. Results from the tests showed that the shear strength of hybrid beams increased with the decrease of shear span ratio. The existed shear capacity models were adopted to calculate the shear capacity of hybrid beams. The agreement between experiments and analysis was good.4. The moment-curvature relation and ductility for hybrid beams were analyzed. And the short term bending rigidity formula for hybrid beams was derived.5. Exposure tests on the GFRP-RC hybrid beams under the real marine environment were conducted. The test results showed that the capacity and ductility of hybrid beams decreased significantly under the real marine environment. The deterioration mechanism of structural properties for hybrid beams was analyzed and the flexural capacity model for the deteriorated hybrid beams was proposed.