Analysis of the cause of bursting on bottom slab of long span prestrssed concrete box girder bridge

Based on an accident of bursting and crack of bottom slab of one continuous box girder bridge during construction, the damage mechanism was analyzed using spatial finite element method. Parameter analysis on main factors influencing the vertical stress state of bottom slab of cantilever casting prestressed box girder segment closure and nearby segment was carried out. Then stability performance of box girder segments with cracked bottom slab were studied. It is concluded that radial force of bending prestressing strand and additional radial force with its deviation from the design position were the main reasons for bursting cracks in box girder bottom slabs, and the final failure form of bottom slabs was unstable destruction.