Research On Design Method Of Transverse Joint For Precast Hollow Concrete Slab Bridge

The precast hollow-cored slab bridge has been widely promoted in highway bridge construction of our country, because its structure form is simple, the bridge parts are easy to transport and install with short construction period. But during the operation period of these bridges, there were vary degrees of damage has been found by bridge detection, the most serious and widespread damage occur in the transverse joint. The transverse joint is important part to make all hollow-cored slabs together to work. If the transverse joint was invalid, the performance of the bridge would be affected and weaken, worse to cause the single beam bearing and endanger the safety of bridge. So more and more experts begin to research on the damage of the transverse joint, the summary cause of damage has been done, they give some advices on reinforcement and improvement. But these measures didn’t thoroughly solve the problems. Therefore, with the finite element software, this article use the transverse joint as the subject of study to analysis its actual stress state and explore the methods to improvement this problem. The analysis contents are as follow:This article begins with the summary of design theory and method of precast hollow-cored slab bridge, and explores the hypothesis and error taken from simplified calculation. The analysis suggests the new type of transverse joint based on its stress characteristic.By using finite element software named ANSYS to analysis precast hollow-cored slab bridge, and simulating the actual vehicle loads, the actual stress state of transverse joint under different load case has been obtained. The results suggest that the transverse is not consistent with hinge hypothesis of the hinge-jointed plate method, its characteristics can be approximated as a semi-rigid hinge. Both vertical shear and transverse moment can be transferred by the transverse joint. In this article, distribution law of the internal stress of the joint is analyzed. The analysis show that the concrete in the joint exists multiaxial stress. Furthermore, longitudinal normal stress and transverse normal stress are too big to affect the security of the transverse joint.Some suggestions are given for the layout of the structural rebar in the joints, with the finite element software, the effect of rebar on the stress of the joint has been analyzed. Meanwhile, by comparing the distribution of structure crack from the cracking analysis, the analysis show that the rebar in the joint can limit crack extension. Through, this method can not fundamentally avoid the cracks in the bottom of the transverse joint.By comparing the analysis of improved and unimproved finite element model, some suggestions have been given to improve the design of precast hollow cored slab bridge. Meanwhile, by adding the transverse prestress into the finite element model, the transverse normal stress in the joint are reduced. The stress state of the transverse joint is improved, and the integrity and security of structure are guaranteed.