Lightweight Design of SPMT-Mounted Girder-Carrying Frame in Overpass Demolition Based on Topology Optimization
In the demolition project of four overpasses of the Beijing-Harbin expressway,including two continuous box girder overpasses(each having two equal spans of 27 m)and two continuous rigid-frame overpasses(each consisting of two equal spans of 30 m),lightweight self-propelled modular transporter(SPMT)mounted girder-carrying frame was developed,which was compact and light,and easy to be manufactured and installed as well.Based on the preliminary design of a girder-carrying frame that was composed of 16 segmental steel pipe posts and 32 tie rods,a lightweight design was carried out in Abaqus's topology optimization module,aiming to minimize the volume of the frame,and the stresses,deformation and stability of the girder-carrying frame in the preliminary design and after optimization were compared.It is shown that the girder-carrying frame maintains optimal load carrying capacity with a reduction of 19.8％of its volume,by which the number of tie rods is reduced from 32 to 12,as the segment lengths increase to 4 m,the number of segments of a steel pipe post is also reduced,further leading to the reductions of 2/3 of the connections and 1.44 t of the mass.Under the most unfavorable loading condition,slight changes in stresses are observed after the optimization of the girder carrying frame,with a maximum deformation difference of 2 mm and the threshold load factors greater than the design required 4.Then engineering practices prove that the mechanical property of the lightweight SPMT-mounted girder-carrying frame meets the requirements,though the safety factor shows a slight decrease,the safety reliability is basically the same as that before optimization.The assembly work and schedule are cut down and the economic performance is better.
overpassSPMTgirder-carrying frameAbaqus topology optimizationlightweight designfinite element methodengineering application
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维普
