Experimental Study On Cracking Resistance Of Prestressed High-strength Reinforced Concrete Beams And Finite Element Analysis

A smaller tensile stress will cause concrete to crack because of concrete has a low strengthagainst tension, not only check flexural capacity but also a further check cracking load andcrack width in the normal service condition when used of high-strength RC beams.Prestressed high-strength RC member can make the best of high-strength concrete andreinforce bars, it has good crack resistance and high stiffness, used of the great span bridge,super tall building and special structure can reap the better social and economic benefits.In order to study crack resistance of prestressed high-strength reinforced concretebeams, An experimental study including12prestressed high-strength concrete beams withHRBF500reinforce bars were carried out under static loading.6beams were used by C80and6beams were used by C100, Observed experiment phenomenon for the members fromcracking to achieved the flexural ultimate strength and deflection; analyzed theprestressing loss; used the finite element soft ADINA simulated the crack propagation anddistribution, cage of reinforcement stress, deflection change, i.e.; discussed by the nominaltensile stress method for the control of short-term maximum crack width; and thecalculation results of this method was compared with the results calculated using theformulas given in Chinese, American and European concrete codes. The cracking strength,short-term maximum crack width, average crack spacing and width under differentprestressing strength ratio and different reinforcement ratio were analyzed, and to testwhether the formulas for calculation the crack resistance and crack width in the currentconcrete structure design code GB50010-2010are suitable for prestressed high-strengthreinforced concrete beams.The result indicate that the prestressing loss value was12percent of tension controlstress, ADINA simulated the crack propagation and distribution, cage of reinforcementstress, deflection change were agree well with the experimental, the load-deformationrelation and strain results has better tally with test results; The test results of cracking loadare agreement well with the calculation results based on formulas specified in the code fordesign of concrete GB50010-2010; the precision of nominal tensile stress method could beproved by inducing the effect of average crack spacing, and the calculation results isinclined to be safe; in the case of the12specimens, the European concrete codes EN1992-1-1:2004has the highest calculation precision, and then is the Chinese concretecode GB50010-2010, and difference between the test and calculation results of theAmerican code ACI318-08is the largest; However the test results of average crack spacingand maximum crack width are smaller than the calculation results by the code. Whereasthe average crack width is greater than the calculation results. A revised formula aboutaverage crack spacing is proposed, i.e., the concrete elongation with crack width influencecoefficient to0.85and reduced short-term crack width expansion coefficient to1.44，themethod can improve the accuracy of the formulas.