Influence of Longitudinal Cracks in Bottom Flange of Concrete Continuous Box Girder

Abstract

Longitudinal crack in bottom flange is one of the most common defects in concrete box girder bridges. This paper focuses on the influence of the longitudinal cracks on the mechanical properties of box girder using numerical method. Smear crack model and strain softening model was employed to simulate cracking process. Parameter analysis was also carried out to study the effect of length, crack depth and amounts of cracks in bottom flange. The results indicate longitudinal cracks in one span have a significant effect on the transverse stress and deflection, but have little effect on the other spans. The negative effects of longitudinal cracks increase with the crack length and depth. When the crack length is up to 10% of the girder span, the deflection of the span amplifies to 13%. Compared with the length and depth, the amounts of cracks don’t have much influence on the deformation of girder but affect stress.