Study On Construction Control Of Half-Through Tied Arch Bridge

Tied arch bridge with a long span is an arch-beam combination system bridge, which gives full play to the characteristics of compressive behavior of arches and flexural behavior of beams. The construction process is long and complex. So, the rigorous control of construction is the guarantee of achieving design objective of the tied arch bridge. Dongman Bridge in Shenyang as an instance, many problems on construction control technique for the tied arch bridge are discussed in this paper, including:the calculation method of tied arch bridge construction simulation, construction monitoring, incremental launching construction technology, error analysis in the rib-hoisting process, closure construction of arch Ⅲ, optimization calculation of suspension member transversal girder construction, the hoisting sequence and construction technology of suspension member transversal girder and suspender tension control.This paper introduces calculation method of tied arch bridge construction simulation, and forward-analysis method is adopted to simulate the entire construction process. The steel arch ribs and suspenders are calculated under the construction process and dead loads, and the result meets the requirements and shows that bridge structure is safe and reliable.The characteristics of incremental launching construction technology, the construction process and the construction control are discussed and studied in detail. Reasonable jacking force and pulling force are determined by finite element analysis under different construction conditions. Construction monitoring results and theoretical calculations agree well. This kind of incremental launching construction technology of frame structure which is suitable for the climate conditions of northern china (great seasonal temperature difference) can be used as reference for the safety construction of similar structure.Based on the analysis of construction control error in the rib-hoisting process, the methods of reducing the error and the requirements of hoisting construction control are proposed.At the same time, because of the two-way (longitudinal and transverse) closure in arch Ⅲ and the characteristics of small spacing, short length, big linear stiffness of the three transverse braces at arch top, shrinkage stress of weld between transverse braces and arch ribs will adversely affect the structure. The closure construction of arch Ⅲ is discussed.Because of small lateral stiffness and poor lateral stability of suspension member transversal girder, prestressed tension sequence is adjusted in accordance with the internal force analysis results in the construction phase. Meanwhile a set of measures such as braced plane frames between suspension member transversal girders is adopted to optimize the structure internal forces, which makes construction stress decrease sharply before the consolidation of suspension member transversal girders and the bridge decks, thereby improving the safety reserves in the construction process.Combined with the characteristics of suspension member transversal girder construction, the hoisting sequence of suspension member transversal girder is determined. This paper summed up the various technical problems encountered in the hoisting construction, and put forward the corresponding technical measures. Finally the research and discussion with this technology are listed in detail, which can be used as reference for the safety construction of similar structure.In order to eliminate the difference of suspender force under dead loads, this paper gives the correction equation of absolute elevation method for elevation control, which achieves the control requirements that the outer suspender force is the same as inters under dead loads.