Analysis model of crack width of partially prestressed concrete beams under fatigue loading

In order to simulate the propagation process of fatigue crack of partially prestressed concrete (PPC) beams, a numerical calculation model for the crack width of PPC beams under fatigue loading was developed. Firstly, on the base of the bond-slip relationship under monotonic loading, a fatigue bond-slip relationship of the non-prestressed reinforcement was established. Secondly, a method was presented to obtain the non-prestressed steel stress in the cracked section under fatigue loading, which took into account the effect of changing steel stress due to the stress redistribution between the different types of the tensile reinforcement and cumulative residual strains (including concrete and non-prestressed reinforcement) and area damage of the tensile reinforcement. Finally, an analytical model for estimating the fatigue crack width was developed by using the bond-slip theory. The model was illustrated by two tests (H1 and H2 series) of PPC beams under fatigue loading. The results show that good agreement between analytical and experimental results for the fatigue crack of PPC beams is observed. Meanwhile, for the beams of series H1 with the lower reinforcing index, the fatigue crack prediction is relatively conservative. Therefore, the analytical model can be applied to fatigue design and fatigue assessment. ©, 2014, Central South University of Technology. All right reserved.