Yongxiu Frame Tied Arch Bridge Construction Monitoring Key Technologies

The Yongxiu super large bridge located at Nanchang-Jiujiang intercity railroad, the main bridge is a rigid-framed tied arch bridge with a span of 31.75+128+31.75m, the arch and piers are consolidated, the beam and piers are separated. The arch bears the most load, beam only bears load between joints as bridge floor system.It is the first time to apply this type of the structure in railway bridge. In order to coordinate the project construction and the study of key subject on the Railway Ministry's research and development, construction monitoring of the background project in this paper is researched as main content,the linear control of the beam and arch, tensioning method and monitoring for the tensile force of rod are included in it, trying to make the linearis and force state of the finished bridge accord with the design requirements.The main results are as follows:1. According to designed stucture and construction technology of beam first and arch late determined by construction unit, the finite element model of the Yongxiu rigid-framed tied arch bridge is established which including design analysis model and construction monitoring model and finite element model of temporary supports for the main beam and arch. Relevant mechanical analysis are carried out and rationality and reliability of designed stucture and construction temporary supports are checked out using the model in the paper.2. Based on the influence matrix method, the paper deduces the calculation method and formula for the jack tensile force of rod considering the suspender tension of rigid-framed tied arch bridge which is used construction technology of beam first and arch late, according to the tension technology for single or double or more hanger rod stretched in the same time. The paper provides the definite arithmetic linking the engineering example and discusses the key question for application.3. Tension number, tension sequence and tension order of the rod are all analysed. Four schemes containing the design scheme are comparatively analysed as theoretical basis for construction unit when choosing stretching plan of hanger rod. combining practical stretching plan of hanger rod and based on the method in the thesis, effective tensioning force in the beginning tensioning and adjusting tensioning stage is provided. In addition, monitoring of whole procedure is carried on.4. Constructions monitoring about the linear and performance of the main beam, main arch, main pier, tied bar, hanger rod and temporary supports are taken place, and favorable monitoring effect is obtained. The advice that no further adjusting tensile force of tied bar and hanger rod is needed to putted forward based on the finished structure.