Negative Bending Behavior of Steel Box Girder with Steel Fiber Reinforced Concrete Composite Deck

Abstract:

Eccentric tension tests on C50 concrete composite deck and steel fiber reinforced concrete (SFRC） composite deck specimens， together with corresponding finite element simulations based on the plastic damage model of materials were executed to investigate the axial tensile stiffness reduction and cracking characteristics of the composite deck. Furthermore， segment finite element models of continuous steel box girders with SFRC composite deck were established for parameter analysis to explore the effects of concrete material， SFRC slab thickness and reinforcement ratio on mechanical properties of main girders. The test and numerical analysis results show that the SFRC slab appears more cracks but the crack widths are much smaller. When the crack width reaches 0.10 mm and 0.20 mm， respectively， the residual contribution of the SFRC slab to the axial tensile stiffness of the composite deck is 44% and 23%， while that of the C50 slab is only 12% and 9%， indicating that SFRC slab still has a great contribution to the mechanical performance of the composite deck after cracking. The parameter analysis results show that the residual contribution of the SFRC slab to the bending stiffness of main girders is about twice that of the C50 slab at the corresponding load level with the SFRC slab crack width of 0.10 mm. When the crack width of the SFRC slab reaches 0.10 mm， the bending stiffness of main girders with 80~120 mm thick SFRC slab decreases by about 11% compared with the uncracked state. Moreover， increasing the reinforcement ratio of the SFRC slab can improve the damage degree， but it has little effect on improving the bending stiffness of main girders.