A Study Of The Theory And Practice Of The Design Of The Variant Steel Arched Girder Construction

This thesis takes a typical project--the Natatorium of the Sports Center, XuzhouNormal University--as a case to study the theory and practice of the design and theconstruction of the variant steel arched girder. After an introduction to the research on the software for the design of the variant steel arched girder construction, the creation of the structural model, the structure of the supporting seat, the design of the variant arched girder, and the measures taken to ensure the stability of the plane surface of the arched girder, the thesis goes to study the methods for the hoisting and the angle setting of the long-span arched girders, as well as the bolting of the axle pin in the hinge support. Displacement was measured after the completion of the project.In view of the external form of the roof construction, it was decided that the variant steel arched girder should be composed of a higher straddle and a lower straddle, with a stump welded between the two straddles. The straddles are two arc-shaped roofs of different curve rates, and each of the straddles is made up of segments of various curve rates.A finite-element analysis was carried out to study the stress performance of thesteel girders. In this study, STS--the steel construction design module of PKPM,a software program of China' s Institute of the Construction Science --is employedto create the construction model in order to study the construction of the supporting seat. A mechanical analysis of the variant arched girders was Implemented, with the result that consturction documents meeting mechanical requirements were designed for the hinge support, the roller support and the steel girders. Hinge joints are need for the two member bars near the roller support to ensure that no flexual torque exists.In collaboration with the worksite technicians, studies were carried out to move the girders into their place. The girders were designed to be 11 segments, 3 for the lower straddle (L1-2, welded after being put in place, L3 and L4, their lengths being 14. 421m, 17. 157m and 10. 079m respectively), and 3 for the higher straddle (L7, L8, L9-10, welded after being put in place, their lengths being 8. 85m, 12.996m, and 15. 962m respectively). Neighbouring segments are linked with bolts and welding. After the girders were segmented, guesseted plates were used with high-strength bolted oints to connect the web plates, and the higher and lower flange plates were butt-welded. Stumps were inserted and welded between the two straddles so that the girders become an integrated arched girder. A steel tubular trssed structure was vertically fixed to ensure the stability of the plane surface of the arched girder.The hoisting of the girders was achieved by the combination of a hoisting machine with scaffolding. Before the variant arch was moved into its place, scaffolds were set up under the place where the arch would be, and a clearance of 0. 8m was maintained between the scaffolds. With the help of the scaffolds, a gantry was set up, and the girder was lifted with a hand drawn chain hoist. It was essential that the lifted girder could be moved by any angle. A hand drawn chain hoist was used instead of a steel wire rope to enable the girder to be moved freelyby any angle. The suspension centers should be kept far apart but to the front as much as possible. Whether the axle pin can be smoothly bolted into the hinge support is crucial for the whole project. To achieve this goal, a prefabricated taper pin was used to induce the axle pin.Finally, after the completion of the project, a displacement measurement was carried out, and it was found that the measured displacement satisfactorily was in good agreement with the actual displacement, indicating that both the design and the execution of the project have achieved the expected goals.