Yong-tai-wen Railway Yandang Large Composite Arch Bridge Construction Key Technologies

Based on the construction of Yandangshan Composite Arch Bridge of the Yong-Tai-Wen Railway Project, this paper systematically elaborates the manufacturing of the 2-90m composite arch bridge, which crosses over a highway, assembly of its steel beams, top pulling of the 184m-long steel beam, and accurate lifting and closure of large-tonnage composite steel beams. It is carefully studied how the steel box beams and steel box arches are sectionally processed in the plant, and what technologies are used in the site welding, site assembly, top pulling, accurate lifting and closure of heavy beams and linear control of the arches. The main contents of the paper are summarized as follows:1. Process of steel box beams and steel box arches1) After consideration of several plans on how to manufacture the steel beams and arches, we propose to control the process in sections and blocks, which solves the size problem during the processing and transportation and guarantees the quality of manufacturing and beam assembly.2) Dimensions and internal sizes of the beams are effectively guaranteed through demonstration, research and implementation of the general plan on how to assemble the steel beams. In particular, the method of straight loading and inclined assembling effectively solves the problems in accurate beam size control which may occur due to welding contraction and elastic deformation of the tyres under heavy loading.3) Quality Control (QC) is adopted to ensure the quality of welding ring of the steel beams and thus the whole welding quality is effectively controlled. And meanwhile quality control technology is developed for the ring welding of single-box multi-room steel box beams.4) The high-frequency ultrasonic hammering techniques eliminates the welding residual stress during the railway steel bridges manufacturing, improves the test results of weld fatigue strength, resolves the problems of residual stress concentration caused by intensive welding of the steel beams, and effectively improves the quality of bridge.2. Top pulling technology of the 180m-long steel box beam of the 2-90m composite arch bridge1) On the basis of finite element analysis and advantages of the existing steel truss hoisting and tunnel bridge incremental launching, a construction technology is proposed that is to assemble the steel box beams on scaffolding and position the assembled beams by top pulling method.2) The most advanced top-pulling equipment, ZLD-150 continuous jack, accelerates the construction schedule, and ensures smooth top pulling, avoids moving of the main piers affected by the frequent dynamic-static friction. Controlling points are set on the front and rear ends of the beams so as to guarantee the accuracy of top pulling.3) Adjustable hydraulic bearing is designed for the sliding system. By adjusting the height of the support points, force and stress control of the beams is achieved and thus the quality of the box beams is guaranteed after top pulling.4) Dynamic correction method is applied to correct deviation and limit movement. The forces are balanced while the jacks on both sides of the beams are turned on. But due to altitude error and uneven texture of the sliding board, the steel beams will rotate inevitably. Dynamic control of the forward direction can be achieved by putting small lateral forces on the beams that rotate during uniform moving. Thereby, progress and efficiency are improved and the steel box beams are ensured to be placed accurately in one time.3. Assembling of the steel box beams of the 2-90m composite arch bridge1) Compare various cable cranes, truck cranes and gantry cranes for the major arches and determine the gantry crane program as final.2) Finish the support design for the rib assembling of the major arches.3) Systematically study the installation, adjustment, welding and closure of the ribs the major arches and ensure smooth installation of the major arches.In the end, the paper introduces the research contents, innovative approaches adopted, main conclusions, research results, and value and significance of promotion.