Study On Cracking Resistance Of Assembly Type Hollow Slab Bridge Applied Transverse Prestressing

Assembly hollow slab bridge was commonly adopted in domestic middle and small span highway Bridges.But during the actual application,Because of the various factors of design,construction and operation,hinge joints disease is increasingly outstanding.According to the analysis of the literature and site investigation,the joint disease may be due to the hinge cracking caused by temperature,and then vehicle load accelerated the development of the disease.In order to solve such problems,based on the idea of transverse prestressing to improve the load transverse distribution of bridge and prepress concrete to prevent crack.the paper try to apply transverse prestressing for the slab bridge,and study the crack resistance of assembly hollow slab bridge after applying transverse prestressing,The main research content is as follows:For transverse prestressing to improve the load transverse distribution of bridge,the paper based on the articulated slab girder theory,using the general finite element software ABAQUS to create hollow slab bridge finite element model.Compared the load transverse distribution coefficient calculated by finite element method and the articulated slab girder theory,to verify the accuracy of the model calculation.Using the model analysis studies about the parameters which impact the load transverse distribution coefficient,such as the value of transverse pre-stress imposed,the distance between two pre-stressed bar and the location on the cross section of hollow slab.The results show that the transverse prestressing can improve the bridge load transverse distribution,but the effect is limited.In theory,prestressing in the transverse for assembly type hollow slab bridge,to make prestressing on the section of hinge joints,improve the load condition of the hinge joints,thus eliminating the tensile stress on the section of hinge joints,and avoid cracking.To studies the distribution law of prestressing on the section of hinge joints after prestressing in the transverse,reference to the test of Yu Bo doctoral thesis ABAQUS finite element model is set up,the result compare with the relevant test data,to prove the calculation accuracy.Then using the model analysis studies about the main parameters which impact the prestressing distribution,Summarize and present the preliminary calculation method of transverse prestressing.In view of the cause of the joint disease,the paper also study on vehicle load and temperature gradient,the main factor that result in the crack of the hinge joints,and then study the crack resistance of assembly hollow slab bridge after applying transverse prestressing.According to the model analysis know that:vehicle loads caused smaller values of the transverse tensile stress on the section of hinge joints;Positive temperature gradient produce larger transverse tensile stress mainly acting on the interface between the deck and hollow slab,the deck and hinge joints.because of the shortage of new to old concrete interfacial interaction,it's easy to result in the crack of the hinge joints.Negative gradient temperature effect on the top of the bridge deck produce the transverse tensile stress greater than tensile strength of concrete,result in the crack of the bridge deck.Actual bridge model is established,compare the transverse prestress before and after the transverse prestressing is applied,the results show that the applied of transverse prestressing is helpful to eliminate tensile stress produced by the load,and improve the crack resistance of the bridge.Finally,analyzing the load particularity of skew bridge during apply the transverse prestressing and the main influencing factors such as the skew angle parameters,then design the skew bridge transverse prestressing and research the crack resistance of skew bridge transverse prestressing.