Experimental Research On Flexural Performance Of Concrete Beam Reinforced With High-strength Rebars

With the development of rebar strength, the rebar stress during the normal use state, which has the main relationship with the crack and stiffness, also increase continuously. But the formula in current code is obtained according to experimental data of HPB235 and HRB335. So it is hard to say that the crack width and deflection during the normal use state can meet the requirement when high strength rebars are used.In order to achieve the international level and popularize the high strength rebars (400Mpa and 500MPa), systematic experimental research should be done to research the concrete member performance with high strength rebars. Through the flexural performance experiment of four concrete beams reinforced with 400MPa new style rebars and four concrete beams reinforced with 500MPa rebars, the paper evaluates the suitability of the current standard about crack, stiffness and flexural strength.The experiment result data show that the rebars can yield when the beam reaches its ultimate strength. So the strength of 400MPa new style rebars and 500MPa rebars can be fully used when determining the flexural strength. According to the data of this experiment and some previous experiments, the paper regresses a new formula for average crack spacing. Further, the paper obtains the new formulas for average crack-width and the maximum crack-width under short-term load. The deflection values obtained in the experiment of concrete beams reinforced with 500MPa rebars are close to those values obtained according to the current code, so the formula for stiffness is not revised in this paper.