Research On Demolishing Technology Of Long Span Lower Through Tie Arch Bridge

At present,the number of road Bridges in China has reached 912,800 and some of the Bridges built in the early stage have begun to break down or cannot meet the current transportation demand.It is necessary to dismantle and rebuild these Bridges.The construction of tied arch Bridges in China started relatively late,and there is less research on the demolition construction technology of long-span through tied arch Bridges.There are shortcomings of engineering practical demolition cases and lack of accurate theoretical guidance.In this paper,the demolition process of long-span through tie arch bridge is taken as the research object.In this paper,the demolition process of longspan through tie arch bridge is taken as the research object and its comprehensive advantages and disadvantages,possible risks in construction,stress characteristics in the demolition process and the application of BIM+VR technology in the demolition process are studied and analyzed.The main work and research results are as follows:(1)Comprehensive comparison and selection of demolishing construction technology of long span through tie arch bridge.The common demolition construction technology of tie arch bridge is summarized.Multi-dimensional qualitative and quantitative analysis is conducted on the technical difficulty of demolition,comprehensive cost,construction period and environmental impact,analyze the advantages and disadvantages of various demolition schemes and their applicable environment.The best removal method is cutting removal method,lifting removal method ranks second.(2)Risk analysis of demolishing construction technology of long span through tie arch Bridge.According to the scope of hazard sources during the demolition of long-span through tie arch bridge,the hazard sources in construction are identified.LS method and hierarchical fuzzy comprehensive analysis method are used to study the risk sources and overall risk of the demolition scheme of long-span through tie arch bridge.Through weight distribution and score assignment,the risk of cutting demolition is the lowest,and the lifting demolition method ranks the second.(3)Stress analysis of long-span lower-through tie-arch bridge in dismantling stage.According to the actual project,the most suitable demolition construction technology is selected,and the preliminary demolition sequence is drawn up according to the demolition method.In order to select the most appropriate dismantlement sequence,three dismantlement sequences are drawn up and eight states are divided.With the help of finite element software,the deflection and combined stress of the bridge body in each state are analyzed.By comparison,the relatively optimal removal sequence is to remove the whole beam in order first,and then remove the arch rib in order.The material strength sensitivity analysis of the disassembled bridge was carried out to analyze the variation of its deflection and combined stress with the increase of operating years.(4)The combination of demolition construction technology and BIM+VR.With the help of BIM modeling software Revit,the arch rib curve family library is established by using control points,and the batch parametric family library is established by other components.Then,the whole bridge model is spliced in the project library and use the volume function to establish the surrounding environment such as terrain.With the help of BIM animation software Fuzor,animation of detail component demolition and display animation of the overall bridge demolition sequence are made,and 4D construction process is established to comprehensively simulate the real demolition construction operation.With the help of VR equipment HTC Vive and Steam VR platform,the model and demolition animation can be VR,which can more truly show the demolition construction,making the whole process of demolition construction design and review online.