EXPERIMENTAL STUDY ON FLEXURAL BEHAVIOR OF PRESTRESSED STEEL REINFORCED ULTRA-HIGH STRENGTH CONCRETE BEAMS

The prestressed steel reinforced ultra-high strength concrete beam is a new type composite beam that consists of ultra-high strength concrete, steel structures and prestressed technology. Fourteen specimens were tested to investigate the flexural behavior of prestressed steel reinforced ultra-high strength concrete beams. Test results such as failure mode, failure mechanism, and crack development in the beams are studied. The test results indicated that the bearing capacity of the specimens reduced dramatically after the maximum strength was reached due to the brittle failure of ultra-high strength concrete. But the embedded steel beams increased the ductility of the specimens. The specimens reached the yield strength when the longitudinal rebars yielded and reached the ultimate strength when the concrete in the compression area crushed. The mid-span section of specimens followed the plane section assumption until the load reached 0.9. The finite element program ANSYS was used to simulate the prestressed steel reinforced ultra-high strength concrete beam, and the slip between steel and concrete was ignored in the analysis. The cracking load, yield load, and ultimate load from the analysis model agreed with the experimental results well, which verifies the correctness of the finite element model.