Installation quality control of space frame engineering (Part 2)

2.3 Quality control in the installation stage

According to the structural characteristics of this project and the actual situation of the site layout, in order to speed up the installation progress of the space frame and to cooperate well with the main structure, the installation of the space frame is divided into two areas, and the upper and lower parts are assembled at the same time.

2.3.1 Determine the process flow. Construction preparation – laying out positioning – erecting temporary supports – shelving adjustable rings – assembling space frame – inspection – correction – welding supports – inspection – painting – acceptance.

2.3.2 Prepare for installation. According to the compiled installation plan, draw the complete assembly diagram, and indicate the node ball number, coordinates, bar number, and length according to the design drawing. Check the technical disclosure records and safety education records for all personnel participating in the installation. Level and tamp the temporary platform area where the space frame  is assembled; check the specifications and quantities of the rods and balls entering the field, and conduct quality inspections on the balls and rods in strict accordance with the specifications. The space frame is seated according to the drawing and transported in place.

2.3.3 Reasonably arrange the installation sequence. Preliminary stakeout is carried out on site to determine the preliminary position of each intersection point and fix it with temporary supports; then accurately stake out to adjust the position and height of each support, and make records to ensure that they are at the same elevation. Use the theodolite for precise setting out, and pop up the crosshairs at the fulcrum to ensure that the plane is accurate. To control and check the coordinate positions of space frame nodes, set 4 control points in each area.

2.3.4 Installation implements process control. When assembling, first install the space frame to be installed in this area into small parts on the ground, lift it to the working platform with a tower crane, install it on the support of the column top or beam, and then temporarily fix it. The installation sequence of the upper chord of the space frame should be passed from the inside to the outside, and the tightening of the upper chord and the ball should be carried out in sequence with the tightening of the web and the lower chord. Use the above method to conduct a comprehensive inspection every 2-3 installations, and follow this method until all installations are completed. In order to shorten the installation period as much as possible, after the network frame is installed at a certain distance, the installation of the roof purlins will be followed in time, and the three-dimensional cross operation of each process will be implemented. During the whole space frame installation process, the bolts are tightened in place, and no gaps that can be observed by the naked eye are allowed on the contact surface of the sleeve; the rods are not allowed to have more than the specified bending; the surface of the installed space frame parts is free from damage, no depression, and it is easy to install. , The check mark is accurate, and the wrong installation is found to be replaced in time; during the installation process, control the key indicators such as the offset value of the space frame node center, the length error of the single cone space frame, the offset value of the support center, and the height difference between adjacent supports; quality inspection Personnel are prepared with theodolites, levels, steel tapes and auxiliary lines, cones, steel rulers, etc. to measure axes, degrees and dimensions at any time, and make records.

In order to reduce the accumulated errors in the assembly process of the space frame, the assembly of the overall space frame starts from the center, the vertical and horizontal axes are assembled first, and the size is corrected at any time. After the error is correct, it is expanded from the center to the surrounding.

3 quality results

3.1 Sampling inspection results of bolt balls and accessories

According to the national standard and “High Quality Carbon Structural Steel Technology”, a total of 18 groups of bolt balls were selected, and the measured stress section and ultimate tensile bearing capacity of the work were all in line with the regulations; the allowable deviation of the sealing plate, cone head, sleeve, and rod All are within the standard control value.

The test results are all qualified.

3.2 After the space frame is installed, the deflection test result is 96mm, far less than the specification value of 245mm (controlled by 1/250 of the span).

4 Summary

1) For the bolt ball node space frame project, the quality of the bolt ball process is the key. Manufacturers that meet the requirements strictly follow the national standards for processing, material testing, and protection of the finished product, especially the quality of the thread.

2) Reasonable process organization is very important. From the early on-site inspection, the laying of the backing plate to the later installation of the space frame, the rational organization of each process, the three-dimensional intersection, and the division and cooperation of different types of work are the keys to success.

3) Strict process inspection and quality control are the guarantee for the successful installation of the space frame.

4) The human factor is also very important. People are the main body of management. The quality of people and the strength of quality awareness have a great impact on ensuring the quality of the project. From ordinary installation workers to technical management personnel, there are checks at all levels and division of labor Responsible, strong technology, strong sense of responsibility, to ensure the steady progress of space frame installation.