Determination Of Key Process For Construction Control Of Half-through Composite Beam Steel Arch Bridge

The beam-arch composite bridge combines the characteristics of arch and beam,with large vertical stiffness,low requirements on geological conditions,strong span capacity and beautiful shape,which is widely used in bridge construction,especially in urban bridges.Steel-concrete composite beam combines the advantages of two materials and is easy to construct,which currently is promoted vigorously in bridge construction.In this paper,a five-span continuous half-through steel-concrete composite beam steel arch bridge with a span of 35m+ 100m+ 150m+100m+35m was taken as the engineering background.Based on the finite element analysis software Midas/Civil,the full-process simulation calculation of the full bridge was established.Researched the modeling method of the steel-concrete composite section,researched the calculation method of suspender tension considering the suspender tension sequence,and the construction process of suspender tension,tie bar and the installation of bridge deck were determined,to achieve the theoretical completion state of bridge,ensure safety of bridge construction and make structure stress more reasonable in the construction process.The main work of this article is as follows:1.Three methods were used to build the model of steel-concrete composite section.By comparing the advantages and disadvantages of different modeling methods and comparing the calculation results of internal force and deformation,it pointed out that the modeling method using section conversion had the advantage of fast calculation speed.However,it was uneasy to simulate the construction of bridge deck,and the internal force distribution in bridge deck couldn’t be calculated.The plate element was used to simulate bridge deck,and established the plate-beam combination element,which could best reflect the actual internal force and deformation of bridge deck.2.Considering the mutual influence of suspenders,the sequence of suspender tension was introduced into the influence matrix,and the simplified formula of suspender tension in construction was derived by using the influence matrix method under any suspender tension sequence.Combined with the calculation of suspender tension in actual engineering,the application of the simplified formula was introduced.3.Based on the calculation and analysis of different suspender tension processes,by comparing the suspender tension,suspender force,structural stress and deformation,and considering the principle of safety,applicability and construction convenience,a reasonable suspender tension process was finally determined.In addition,considering the horizontal reaction at the pier bottom and the stress on the bridge deck,the original tie bar tension process was adjusted to ensure that the structural deformation would be gentle and the stress would be reasonable during the bridge construction.4.Through simulating and calculating two kinds of bridge deck installation methods and five kinds of bridge deck installation sequences,analyzed and compared internal force,deformation and horizontal reaction force of pier bottom.It pointed out that the construction method of pouring wet joint while installing bridge deck would make the tensile stress of bridge deck too large after completion of bridge.The sequence of installing bridge deck from the center of arch foot to both sides at the same time could significantly reduce Reaction of pier bottom.