Analysis Of The Bearing Capacity Of The Pile And Caps With Cracks Of A Railway Bridge During Construction

Cracks of the5th and6th Pile and Caps of a railway bridge under construction were found when concrete of the caps and the entity area of the pile shafts had been cast. The cracks on the opposite sides of the5th Pile and Cap were staggered far away, but that of the6th Pile and Cap were not staggered far away. In this paper3D finite element analysis of the two piles and caps has been finished and the influence of the cracks on the bearing capacity of the pile caps, the pile shafts and the pile foundations has been studied. The main work and the results are as follows.1. The simulating method of finite element analysis of reinforced concrete with cracks is studied. The concrete pile shafts and caps are divided into several domains according to the ratio of reinforcement. Dispersive type of reinforced concrete element is used. Two finite element models of the5th pile shaft and cap have been established. One is with cracks as it has been and the other is without cracks. Three finite element models of the6th pile shaft and cap have been established. The first is with cracks as it has been, the second assumes that two pairs of cracks on the opposite sides of the cap have been cracked into "+" sharp. The third is without cracks.2. Finite element analysis of the two models of the5th pile shafts and cap under the worst vertical load case and the combination of vertical load and braking force has been finished. The results show that little influence happens of the cracks on the stress condition of the pile cap, the pile shaft and the pile foundations. The stresses of the concrete and the stresses of the reinforced rebars in all directions of the cracks of the two models are much smaller than the bearing capacity.3. Three dimensions finite element analysis of the three models of the6th pile shaft and cap under the worst vertical load case has been finished. The results show that even the two pairs of cracks on the opposite sides of the cap have been developed into "+" sharp, the stresses of the pile cap, the pile shaft and the pile foundations have changed a little. The stresses of the concrete and the reinforced rebar in all directions of the cracks of the three models are still much smaller than bearings capacity.4. Suggestions are given according to the study results. The cracks of these two piles and caps should be sealed to avoid the decreasing of durability.