With 500mpa Reinforced Polyline Pre-tensioned Prestressed Concrete Beams Force Performance

In the present, the pre-stressed reinforcement in pre-tension construction members is generally the bars of straight line, It is difficulty to arrange the strand wires based on the actual bending moment envelope curve. Based on the above situation, a kind of fold-line pre-stressed reinforcement style is put forward in the pre-tension pre-stressed concrete constructions, the implementation of fold-line pre-tension ties the pre-stressed strand wires to the broken line, the steel stranded wire bends upwardly in the end of the beams according to the design request, To make the pre-stressed wires tie with beam's actual stress adapts by this realization structure acts according to the bending moment envelope curve, achieved the goals of enhancing the construction members' performance and save materials .The standard value of HRB500 steel bar's tensile strength is 500MPa. It is a new type steel bar which has many merits, such as high-strength and strong ductility. To take the fold-line pre-tension pre-stressed concrete structure and the 500MPa steel bars to unify may enhance the crack resistance of the component and reduces the distortion, simultaneously can enable the 500MPa steel bar high strength to display. This kind of structure has been used prevalently in foreign countries. But it hasn't been taken in by new Code for design of concrete structures (GB50010-2002). In order to take the internationalization into reality as soon as possible and popularize this new kind of steel bar in engineering area of our country, the experiment researches should be done on the main characteristic of 500MPa reinforced flexural members.The experiment of research shows that the fold-line pre-tension pre-stressed beam with 500MPa high strength steel bars have enough ductility. The fold-line pre-tension pre-stressed beam with 500MPa high strength steel bars accorded with plane cross-section assumption. The bearing capacity of flexure member can be calculated by the formula of cross-section in the Code for design of concrete structure (GB50010-2002). The result shows that when f_y =450MPa, the fold-line pre-tension pre-stressed beams with 500MPa high strength steel bars have enough safe capacity. Under limit state of serviceability, the research of the fold-line pre-tension pre-stressed beam with 500MPa high strength steel bars shows that the flexural members' width of cracks and deflection can be calculated by formulas in existing Code for design of concrete structures (GB50010-2002). Because the 500MPa steel bar's working stress (under the limit of serviceability) is larger than other bars in existence, we suggest that a checking computation to the width of cracks of the flexural members should be given.With the whole testing and the final destruction shape of the fold-line pre-tension pre-stressed beam with 500MPa high strength steel bars, the fold-line pre-tension pre-stressed beam performance to be stable and display the good ductility distortion characteristic in the later period of loading .