1 Hall project overview
The steel structure hall is divided into two parts, namely, the steel structure roof truss of 600 square meters and the double-layer bolted ball space frame roof. The horizontal projection area of the space frame is about 4500 square meters. The fire resistance level of this project is Class II, and the fire resistance limit of the steel structure is required to be 1.5 h, the use of thin coating type fire retardant coating. The space frame is in the form of an inclined quadrangular pyramid space frame, and the nodes are bolted ball nodes. The span of the space frame is 53m, the thickness of the space frame shell is about 6m, and the lower chord is supported on the concrete corbel. The roof plate of the space frame is 760 types 0.60mm thick galvanized color steel plate, the middle 50mm thick insulation cotton, and the lower plate is a 900 types 0.5mm thick thermal insulation Galvanized color steel plate. This construction organization mainly aims at the 4500 square meters bolted ball space frame, and the 600 square meters steel structure roof truss installation is relatively simple, the amount of steel is also tiny, and it can be completed mainly by truck cranes.
2 Hall construction method of space frame structure
2.1 Construction plan
Due to size limitations, the general idea of the plan is to first assemble the CH and 1-2 axis space frames on the empty ground of the 1-3 axis and the C-J axis, use an 8t crane to assemble them and then make two 8m high temporary supports, and the assembly is completed. Then use two 100T wheeled truck cranes to lift the space frame, place one end on the support, weld the support with the embedded parts, and place the other end on the temporary support. The remaining HJ, 1-2 axis space frame, use The mobile frame is used for support, and the starting span is assembled. Use this area space frame as the starting plan to use air bulk to install and complete the space frame gradually.
2.2 space frame assembly
(1) In order to reduce the accumulated error of the space frame during the assembly process, the assembly of the lower chord of the overall space frame should start from the center, assemble the vertical and horizontal axes first, and correct the size at any time. Only when it is considered correct can it be expanded from the center to the surrounding, which requires diagonal angles. The allowable error of the line (small unit) is ±3mm, the offset of the bottom chord node is 2mm, and the deviation value of the overall vertical and horizontal shall not be greater than ±2mm. (2) Check the geometric dimensions after the assembly of the overall lower chord. If necessary, use the theodolite to correct and adjust the height difference of each point with a spirit level, and make a record. (3) In order to facilitate the construction and improve the progress of the project, before the lower chord is assembled, the web rod and the upper chord rod can be seated according to the drawings and transported in place. (4) The assembly of the web rod and the upper chord should be carried out after all the lower chords are assembled, and on the basis of measuring no tolerance. The method starts from the center, and the geometric dimensions of the vertical and horizontal axes are checked at any time, and the correction is carried out to the surrounding. assembled. (5) Three points are suitable for spot welding when the space frame is assembled, and four points are suitable for those with large pipe diameters. During spot welding, arcs should not be started at any place other than the junction of the rod and the node. (6) After the space frame is assembled, weld the support, the winding suspension, and the welding ball.
2.3 Bulk installation at high altitude
The specific steps are to assemble the cones on the available field to form two types of quadrangular vertebral bodies (one is a lower chord, two lower chords, and two abdominal rods, which are hereinafter referred to as A vertebral body; one is a The chord ball, two-chord rods, and two abdominal rods, which are hereinafter referred to as B vertebrae), the completed cones are arranged in order, and the hanging cones are ready for bulk loading in the air. Install a row of A cones first, then install a row of B cones, and so on, to install the space frame.