Thickness Design And Stress Analysis On Approach Pavements Of Jointless Bridges

The approach pavement of jointless bridge uses CRC or CRC+AC composite pavement structure. With the characteristics of continuously reinforced concrete pavement allow jointless work, so the jointless bridge further cancels the expansion joints of the road and bridge. By the transverse cracks open, the approach pavement absorbs the deformation of the beam caused by temperature drop. The design of approach pavement should control crack width and spacing in the design specification range. The bridge, approach slab and approach pavement will be integrated into a whole in this design, which can realize jointless.The stress state of approach pavement is very complicated, and approach pavement is affected by not only vehicle load and temperature load, but also the shrinkage deformation of jointless bridges influenced by the temperature. This paper focus on the structure characteristics combining with the existing research results and takes the approach pavement for the research object. The finite element method was applied to study the stress condition. The main research works are done as follow:(1) Introducing the current CRC and CRC+AC composite pavement research situation at home and abroad, summarizing the research results of the total jointless bridge structural system.(2) Approach pavement with transverse trench lugs finite element models is established. This paper analyzes the mechanical performance of approach pavements under the effect of temperature drop effect and leads to the conclusion that the distortion of the main beam is the main influencing factors of CRC layer stress of reinforcement. The change rule of stress of reinforcement and slab stress are analyzed under thickness, variable modulus and steel ratio.(3) This paper proves that the first pre-cut crack symmetrically arranged is the critical load position of the approach pavement under the effect of the contraction distortion of the main beam, vehicle load and temperature load. The influence rule of stress of reinforcement and slab stress are analyzed with the change of pavement structure parameters such as the thickness and modulus of AC layer, the thickness and modulus of CRC layer and longitudinal steel ratio.(4) This paper analyzed the bearing capacity performance of approach pavement. Under the effect of vehicle load and temperature load, this paper studied the sensitivity of the slab stress of approach pavement with the change of pavement structure parameters. And this paper put forward the thickness design method of the CRC layer of approach pavement. The design method combines the design method of continuously reinforced concrete with the mechanical characteristics of approach pavement itself. The results offered a theoretical basis of structural design of approach pavement.