Structural Analysis And Optimization Of A New Type Of Three-girder Movable Scaffolding System Bridge Building Machine

The movable scaffolding bridge building machine is a kind of construction equipment which uses two sets of corbels installed on the bridge pier column as the support,and uses the template and support system to construct the long-span bridge.It is an advanced method of bridge construction.The movable scaffolding method does not need to deal with the foundation and arrange the prefabricated beam yard.The movable scaffolding bridge building machine can easily achieve a series of constructions from bridge building to concrete pouring.Compared with the traditional design,the construction operation is simple,the automation management is high,and the bridge quality is good.Therefore,the movable scaffolding system is more and more widely used in bridge construction.The traditional movable scaffolding adopts the double main girder method,However,when the bridge deck to be poured belongs to the ultra-wide specification,the double main girder movable scaffolding is difficult to meet the construction requirements.This thesis used a new type of three-girder structure movable scaffolding bridge building machine to meet the construction requirements of ultra-wide bridges.The main research contents are as follows:(1)The downward movable scaffolding system studied in this thesis is a new type of mobile formwork system that adopts a three-beam coordinated force system,with a complex structure and high safety performance.Due to the large width of the construction bridge deckand the large amount of concrete poured,a main girder was added at the middle position to coordinate the force.The structure of each part were designed and the role of each part in the construction of the movable scaffolding systemwas introduced in detail.At the same time,the method of longitudinally moving of the new three main beam structure was discussed in detail.(2)Considered the self-weight of the movable scaffolding and the relatively large load under the pouring concrete state,in order to ensure the safety of the overall structure of the movable scaffolding,the force analysis of the main load-bearing parts should be carried out under the conditions of pouring and longitudinal movement.This thesis mainly conducted finite element analysis on the overall structure of the mobile formwork system during the concrete pouring and the longitudinal movement of the movable scaffolding.The results show that the strength,rigidity and buckling stability of the movable scaffolding system meet the requirements of the specification,and the structure design was safe and reasonable,and the finite element calculation was verified by preloading experiment.(3)The movable scaffolding is prone to equipment overturning during the movable scaffolding opening and longitudinal movement.In order to ensure the safety and reliability of the entire movable scaffolding system during the template opening process,the upper structure of the movable scaffolding was divided into three parts.The calculation of the lateral antioverturning stability shown that the overall structure of the mobile formwork meets the stability requirements.(4)The finite element calculation results shown that there were differences in stiffness and deformation between the middle main girder and the main girder on both sides,the ANSYS Workbench platform response surface optimization method was used to optimize the plate thickness of the upper and lower flange plates and webs of the middle main girder to achieve the difference between the middle main girder and the main girder on both sides.The rigidity of the main girder on both sides was matched,while reduced the amount of steel used in the main beam,the total mass of the middle main girder was reduced by 11.3%,which made the design achieve the purpose of lightening.