| This thesis takes Jingkai District Bridge, a steel truss beam and flexible arch railway bridge, as background which is located in Hefei Southern Ring Railway included in Hefei-fuzhou Railway. The arch erection schemes and stability of the sructural members are studied, measures for improving structural performance are presented, and detailed stress of crucial members as well as reinforcing schemes are researched.First, construction methods of steel truss beam bridges and incremental launching construction method of steel truss beam and flexible arch bridge are reviewed. A finite element model of whole bridge is established with MIDAS/CIVIL2006, a finite element analysis software, with detailed simulation of components including steel truss beam, arch, floor system and falsework, et al of the bridge. Then, three arch erection schemes are studied which are’erecting the arch closed at apex after launching the beam’,’erecting the arch closed at springing after launching the beam’, and’launching the beam and arch after arch closed at springing’, with consideration of the procedure and period of construction, structural deformation and stress for crucial cases, and unstressed closure method for the arch. Based on analysis and comparation,’erecting the arch closed at apex after launching the beam’is chosen as a preferred scheme. In addition, according to related standards, overall stability of members during the construction is analyzed by programming, based on stress results calculated through finite element method. What’s more, measures are presented for improving structure stress by adjusting the relative height of base plates during construction. Moreover, based on shell elements and block elements, detailed models for members with larger stress are established for calculating and analyzing stress, and the distribution and extreme value of stress are studied. Through comparision and analysis of reinforcing schemes, optimum schemes are presented. |
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