Study On Effect Of Internal Forces Of Closure Pattern For Arch Bridge With Cable Hoisting Method

Consedering arch brigdes constructed in China and aborad,the main arch construction method include supporter cast-in-situ method,cable hoisting method,stiff skeleton method,cantilever casting method and swivel construction method.In China,theoretical analysis and engineering application research on the construction of cable hoisting method have started since 1960 s.It has been widely used in concrete arch bridge,steel arch bridge and concrete filled steel tube arch bridge,and has been applied well in suspension bridge and cable stayed brige too.The main arch closure has two different ways called large part closure and setting the closure section.But we rarely carry out deep studies about the impact of closure on arch deformation and internal force,lacking the knowledge of mechanical characteristics of the multi segmental cable arch bridge.So,this paper carries out the following research work:1 Aiming at few segments and multi segments hoisting methods,based on the idea of no stress state closure,analysing the influence of two kinds of closure on internal force and deformation of the main arch ring theoretically.2 Theoretical study and data analysis show that in terms of arch bridge with less segment hoisting without considering influence of shrinkage and creep of concrete,the elastic compression deformation occurs at the maximum cantilever end under the combined action of the dead weight of the cable and the cantilever beam,which will make the length of the closure segment is greater than the length of the unstressed length and ensure the closure of the closure segment and the length of unstressed length equal by lowering the elevation.At the same time,it also need to adjust the size of the closure,to achieve unstressed closure.3 In terms of arch bridge with multi segment hoisting,the vault is in a horizontal state,and it satisfies the curvature continuity of the stress free state method.Therefore,it also need to adjust the size of the closure,to achieve unstressed closure.In view of the closure length and the curvature don't meet the requirements of the closure for unstressed state method.By studying the unstressed closure algorithm,we can well meet the unstressed length of the closure segment.4 Taking the five crane staggered Gorge Bridge(75m span)and eighteen crane bridge(180m span)of hippocampus for example,I used MIDAS/Civil software to calculate the arch internal force under two kinds of closure,and compared internal force,deformation of the main arch under self weight.In this paper,theoretical derivation was verified.