ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
2. Construction characteristics and difficulties 2.1 The two-way unequal height of the lower chord of the truss in this project, how to eliminate the damage caused by unequal stress of partial trusses in the process of assembling and silk assembling is a major feature and difficulty of the project construction. The lifting point is set on the main truss on both sides of the roof, in which the main truss itself is super-long, light and large. Span steel tube truss (span 132m, height 238m, width only 1m), so in construction, we should consider not only the stability of the main truss element, but also the force shadow of the main truss on both sides during lifting process. How to divide the roof truss into blocks and reasonable lifting sequence, and control the deformation of the main truss 2 by the roof installation in its design permissible. 2.3 Compared with traditional in-situ assembly and cross-outside silk assembly, this construction technology reduces a lot of scaffolding support and large-scale machinery input, reduces the input cost of materials and equipment, and reduces a lot of work such as hoisting, assembly, welding, anti-magic and measurement and correction of 24 roof steel structures. Completion on the assembly frame reduces a lot of high-altitude work and effectively improves the overall quality and time limit of roof steel structure construction. 3. Construction process supervision assembly of small assembly units assembly of medium assembly units integral lifting closure installation unloading stress and strain monitoring 4. Technical operation points 4.1 Construction preparation 4.1.1 structure Considering the transportation problem, all roof trusses are classified by vertical webs (SFG) in the processing plant and transported to the construction site in small sections. In order to avoid the second inversion, the entry of the trusses must be based on the type.
A truss needs a complete set of stalks to enter the field to ensure the smooth assembly of the truss. (1) Whether the qualification certificate and various markings are complete or not, especially when the joints with multi-faceted intersections are out of the factory, the marking of the pipe orifices should be done with the foreign punch, which can greatly improve the efficiency of field assemblers; (2) The geometric dimensions of the rods, such as length, thickness and diameter of the pipe wall, flatness, etc. (3) Check the intersection of the rods. Whether the size and angle of the section are correct or not 4.2 small assembling units have a large span (44m and 55m). In order to facilitate transportation and assembling, each truss is divided into three units to assemble in the upper part of the truss. Temporary spot welding is used to determine the location of the segments. The assembling process is measuring positioning, manufacturing of the truss, positioning of the vertical ventral truss, and positioning of the upper and lower parts of the truss. String truss and diagonal truss assembling welding unburning checking and correcting the frame measuring and positioning of the next truss 4.2.1: the secondary truss unit is arc. Before assembling, according to the size of the truss, the outer line of the truss main pipe and the projection line 4.2.2 of the tube position at the joint should be put out on the assembly platform: the frame should be able to bear the truss. Sufficient strength, stiffness and stability should be required for self-weight of frame, load of assembled truss and other construction loads; the height of frame should be easy to weld in all positions, and the height of this project should be set at 800 mm.
Firstly, the steel tube truss main frame is mounted on the tire frame, and the chord and branch pipe are butted and welded on the basis of the outline of the truss and projection line drawn by the platform. Each cotton tire frame is set up and the bodiless and transporting convenience is also considered. 4.2.3 Assembly and lifting a vertical web to the tire frame by automobile crane, and control the connection position. After adjusting its elevation and plane position with chirp steel plate and limit plate, spot welding is carried out, and then the upper and lower chords are hoisted to the frame by the same force method for measuring and positioning, and finally the oblique webs are connected. After all spot welding is fixed, the repetition test is carried out again, and after meeting the accuracy requirements, the welding is carried out again, as shown in Fig. 5. Before installation of oblique web truss, attention should be paid to the welding of concealed welds of upper and lower chords. Because the length of the assembly section of truss is longer, considering the influence of welding shrinkage on the length of truss, the length of each section should be controlled at 3-5 mm longer than the design length.