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Installation and construction of bolted ball space frame in chemical coal storage yard

The bolt ball space frame structure is a new type of roof load-bearing structure, which belongs to the multi-time super static space structure system, which changes the stress state of the traditional general plane space frame structure, and can bear the load force from different directions . This kind of shell-shaped space frame structure has a beautiful appearance, strong regularity between the rods, uniform and space frame, excellent integrity, large space rigidity, all rods are connected by bolts, easy to install and operate, and stable under force . The high-altitude bulk method was used for construction in a bolted ball space frame project of a chemical coal storage yard, which ensured the quality of the project and improved the construction efficiency.

1 Project overview

The bolted ball space frame of a chemical coal storage yard is classified as Class 1, the projected area of the space frame is 180×60m, and the area of the roof part is 91.2×180m. The roof panel is made of 850 type profiled steel plate. 850-type profiled steel plate eaves around the space frame. Shot blasting and derusting of steel grid frame, second-degree anti-rust paint for steel structure.

The span is large, the horizontal span is 60m, and the construction height is high, the highest point is 28.4m. There are many high-altitude bulk operations. Except for the starting space frame, the rest of the space frames require high-altitude bulking; the roof of the cylindrical space frame has a large slope, and the slope on both sides exceeds 45°. The materials are uniform and easy to install. Compared with most projects, there are fewer types of space frame rods and accessories, and each type has a large number of sizes. The interval between steel purlins is 4m, and the main and auxiliary purlins can be processed into one type. The roof panel in the direction of arc development can be divided into four pieces.

2 process principle

In the installation and construction process of the bolted ball space frame, high-altitude scaffolding bulk space frame is used, and a sliding scaffold is set up at the lower end of the space frame installation position and used as a working platform, and single rods and node parts are assembled on the bracket. Or use a single space frame as a small unit to assemble it at high altitude. The high-altitude single-cone lifting method is: use the single-cone body as the installation unit of the space frame on the ground and assemble it, and use the installed space frame as a force-bearing platform, so that the hoisting frame can be fixed on the space frame. After the hoisting is completed, the assembly is carried out at high altitude.

3 construction method

3.1 Space frame installation

The shape of the chemical coal storage shed is a regular spherical node space frame, with a length of 180m, a span of 60m and a height of 28.4m. The overall installation scheme adopts the method of combining ground assembly and air bulk assembly. The space frame should be assembled with a crane and started on the ground to form a standard span, and then the small units at both ends will be gradually installed by the high-altitude bulk method, and the inverted triangle will be constructed from both ends at the same time.

3.1.1 The main construction process of installation

The main construction process of space frame installation is: manufacture of steel space frame in the factory → pre-embedding of embedded parts → transport of steel space frame to the site → cutting according to specifications → standard cross space frame (see the figure below for the starting grid) ground assembly and installation Position → assembly of the second space frame span → assembly of the third space frame span → assembly of the fourth space frame span.

3.1.2 High altitude bulk

(1) The high-altitude bulk method refers to the method of directly hoisting the standard “small unit” or loose parts (single rod and single node) at the design position for installation. In the process of high-altitude bulk packing, the site is required to be flat, and all the cones to be hoisted must be assembled and arranged neatly for ready assembly at any time.

(2) When assembling at high altitude, start from the ridge line, or develop from the middle to both sides, so as to reduce the accumulated deviation and facilitate the control of the elevation. The overall installation sequence is to carry out high-altitude bulk installation in two directions from the “standard grid unit” that has been hoisted in place, advance in a triangular order, install two triangles and gradually expand to intersect, that is, according to the word “person”. The shape advances, and finally closes and closes in the middle of one end. The implementation effect of high-altitude bulk packaging is shown in Figure 1.

space frame coal shed

Figure 1 High altitude bulk effect of arch space frame

3.2 Roof system installation

The final length of the roof is 95m when fully expanded. In this project, there are 6 roof panels, each of which is 16m long, and the overlapping length of the upper and lower roof panels is 200mm. The bottom board is raised 200mm and overlapped with the upper board. The roof panels are hoisted to the purlins on site by a crane and installed manually. Each board is divided into left and right sides. After the installation position is determined, the left, right, upper and lower parts must be completely aligned, and the quality inspection personnel will check and make adjustments in time for misalignment. The roof is fixed with 5 self-tapping screws, three nails are fixed to each purlin of each board, and two additional nails are added at the junction of the upper and lower boards, three nails are added on the wave crest, and two nails are added on the bottom of the peak.

3.3 Paint coating project

In order to ensure a good level of coating quality, the anti-corrosion primer is applied at the factory, and the intermediate paint and top coat are applied at the construction site. The specific painting construction process is as follows: before the semi-finished products leave the factory and arrive at the site, the overall paint of the grid frame must be inspected by the owner and the supervisor, and can only enter the site after passing the test. After the space frame cone is formed on the ground, paint construction is carried out to reduce the amount of work in high-altitude operations. Use a piece of paper to block the redundant ball holes that have not been constructed. The paint construction has basically been painted before the space frame is hoisted, and only repairs are made at the butt joints of the space frame. Make up for the damage of subsequent construction. Paint construction organizes an independent construction team. At the same time, it cooperates with the construction without affecting the overall project progress. Among the current various space structures, the space frame structure is the one with the fastest development and the widest application range. The bolt ball space frame has been widely used because of its simple production and guaranteed quality. Using the movable characteristics of scaffolding, only a small amount of scaffolding can be erected to achieve basic coverage of the grid installation position, which can greatly reduce material turnover and human resources, and has a high economic advantage. At the same time, according to the characteristics of the bolted ball joint space frame, the high-altitude bulk method is adopted for construction. This method can also facilitate the quality inspection department to conduct installation quality inspection more conveniently, and has good social benefits.