Analysis on Probability of Web Cracking Risk of Box Girder Bridge Based on Traditional Prestress Tensioning Technology

The model of principle tensile stress in webs of box girder bridge varying with time using traditional vertical prestressing technology is developed.Considering the randomness and time variation of the strengths of concrete and reinforcement,the allowance stress of principle tensile stress in webs is taken as limit state,a probabilistic model of web cracking of box girder bridge is developed using traditional prestressing technology.Based on Monte-Carlo simulation method,the cracking risk of webs over service time is calculated,and the relative parametric sensibility is analysed.It is found that(1) based on the design parameters,the maximum probability of cracking of webs in designed service time is 1.49%.The sensibility analysis shows that the longitudinal spacing of finishing reinforcement,the anchorage deformation and the reinforcement shrinkage have a maximum influence on cracking of web,the influence of assembling deviation angle is second,and the quantities of stirrups have a lowest influence on web cracking of box girder bridge.