Research On Nonlinear Contact And Damage States Of Hinge Joints In Slab Girder Bridges

According to the data,the total number of highway bridges in China reached 805,300 by 2018,of which Jiangsu Province ranked first among provinces and cities in the number of highway bridges with a total of 71,235 bridges.In terms of the bridge span proportion,the number of medium and small span bridges reaches more than 90%,which plays a vital role in the transportation system.Prefabricated concrete plate girder bridges are the main type of small and medium-span bridges.Hinge joint disease is one of the main diseases of such bridges.Once the performance of hinge joint decreases,the integrity of bridge superstructure will decline sharply.When the decrease becomes severe,it will lead to the phenomenon of"single girder under loading",which directly affects the safety and serviceability of the structure.Therefore,it is necessary to systematically study the disease of hinge joint and the performance state of hinge joint.In this paper,the hinge joints diseases of plate girder bridges in Jiangsu province of Beijing-Shanghai Expressway in recent years are counted,and the hinge joints diseases are analyzed from two dimensions:time and space.Elasto-plastic numerical simulation of girder plate and hinge joint is carried out using ABAQUS finite element software.The failure modes and characteristics of single girder and girder hinge system are analyzed.On this basis,the parameter analysis of the non-linear contact performance between the old and new cast concrete of hinge joints is carried out.The deformation characteristics of the hinge joints under the tensile-shear state and the tensile-compressive-shear state are studied,and the damage state of the hinge joints is preliminarily defined.At last,the hinge joints of specific expressway bridges are tested without traffic closing,which provides a reference for the rapid inspection of hinge joint damage state.The work shows that from the perspective of the proportion of diseased holes and diseased location,the probability of white-precipitin and whitening of hinge joints disease is greater for bridges with larger spans.White-precipitin and whitening are the most common types of diseased hinge joints.Most diseased hinge joints have not yet developed to the extent of seepage and deslurry.Hinge joints diseases are more likely to occur at the end of girders,and edge hinge joints have the highest probability of diseases.In the process of gradual increasing static load,the failure of hinge joints begins at the bottom of midspan,and after cracking of adjacent hinge joints,the cracks appear in pairs in midspan.As the increase of the static load,the cracks develop symmetrically toward both ends of the girder.When the cracks develop to 1/3 of the distance between the two ends,the surface of the pavement and the joint of the hinge and the pavement begin to crack.With the continuous development of the cracks,the phenomenon of "single girder under loading" is finally formed.Parametric analysis shows that under the tensile-shear state and tensile-compressive-shear state,the interfacial bond strength,tangential bond strength,the slip corresponding to the peak stress and the bond slip rigidity have no obvious influence on the failure process of the hinge joint.The spot test of the performance of the two bridge hinge joints shows that the hinge joints of the two bridges are still in good condition or under a slightly damage state.