Experimental Research And Theoretical Analysis Of Hybrid Reinforced Concrete Bending Element With GFRP Bars And Steel Bars

The reinforced concrete has already got extensive use in modern engineering structure, and its durability gains more and more attention. Since 1980's, replacing steel bars with fiber reinforced polymer bars (FRP bars) in RC structures is investigated and dicussed by scholars. But FRP bars have characteristics of high tensile strength, low elasticity modulus and linearity deformation, these characteristics lead to the phenomenon of brittle failure and too large crack width and deflection of the element with FRP bars.The advantages of steel bars and GFRP bars by synthetical consideration, the concept of hybrid reinforced section is brought forward by us, 24 set of pullout bond tests on GFRP bars embedded in concrete and 10 hybrid reinforced concrete bending element with different reinforced ratio have been tested in static load experiment. The research content mainly includes:1. 72 pullout bond tests on GFRP bars and steel bars embedded in concrete have been tested. Based on the test result, bond-slip mechanism between GFRP bars and concrete is studied, GFRP bars bond behavior aspect influencing factor is analysed.2. The concept of "bars compares of cross section" is brought forward, and 10 hybrid reinforced concrete bending element with different reinforced ratio have been tested in static load experiment, the bars compares of cross section and ratio's effect on breaking modality was concerned in this experiment, involving the cracking load, the development of crack, the assuming plane sections remaining plane, load-deflection curve, and ultimate load.3. Based on the test result of 10 hybrid reinforced concrete bending element, the crack formation mechanism of hybrid reinforced concrete element is analysed. Calculation formula for maximum crack width of hybrid reinforced concrete bending element is presented. Limit value of maximum crack width is obtained for use in engineering design. Calculation method of deflection due to short-term loads of hybrid reinforced concrete bending element is presented.4. In light of extensive research progress home and abroad, calculation method of ductility coefficient applicable to hybrid reinforced concrete bending element with GFRP bars and steel bars is presented. Combine with testing results, the characteristics of the ductility of hybrid reinforced concrete bending element are analysed. 5. Using commercial finite element sofeware, ANSYS, finite element simulation of hybrid reinforced concrete bending element with GFRP bars and steel bars is accomplished. It is defining constitutive relationship of materials, selecting element, modeling method and solution method that are elaborated on in this paper, and then reliability of methods as mentioned above is testified by compared with experiment results.