| In recent years, along with the booming development of transportation infrastructure in our country, more and more various kinds of large or super-large bridges and overpasses are constructed, while the application of casting-in-place construction has generated great interest because of its extensive applicability and flexibility under the constructions.This paper takes the approach spans(on Tingjiang) of Minjiang Bridge project in Langqi city of Fuzhou as an engineering example, which has such disadvantages as: high quality requirements, poor and complicated geological conditions, great difficulties in high-bracket erection and removal, many interferences and crossover operations, etc. It mainly introduces the design method and research status of high-bracket at home and abroad, and expounds detailing requirements about each member of the high-bracket in corresponding specification and code, and also discusses the stress calculation of each members and the foundation of steel tubular pile in high-bracket. Aside, it describes the construction methods and precautions of the high-bracket erection, preloading and removal. Furthermore, the force analysis of high-bracket is adopted 3D finite element model built by Midas Civil for calculation. The analysis results indicate that: the total height and the cantilever height in the upside of the lattice column can make critical contributions to the structural stability; the distance between lace bars can exert few influences on structural stability in a constant total height of lattice column when it range from a certain region, while it will decrease the structural stability with oversize-distance between lace bars; there’s no obvious variation on structural stability when there exist uneven axial force and wind load in its four lattices. In addition, material strength, initial imperfection, structure form and construction factor can also make adverse impacts on the lattice column support. |
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