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Installation Quality Control of Space Frame Engineering (Part 1)

1 Basic situation

A project with a construction area of 3333m3, the foundation is made of concrete independent foundation, the main body is a two-story frame structure, the roof adopts a space frame structure with bolt ball nodes, the projected area of the space frame structure is 3200m2, and the specifications of the space frame structure rods are from ф48×3.5_ф159×6, and the material is Q235B steel pipe, bolt ball specifications from ф100-ф280, material is Q235B steel, sealing plate, cone head, support, backing plate are made of Q255B steel plate and steel pipe.

2 Quality Control Measures for Bolt Ball Node Space Frame Project

The total construction period of the space frame structure project is 35 days. After deducting the space frame design, preliminary structural inspection, support blanking, support embedding and other ancillary projects, the actual space frame installation time is 20 days. The installation work is in the cold December. According to the actual situation, some rods, sealing plates, supports, backing plates, etc. are adjusted to be made on site. How to install the bolted ball joint space frame project with high quality and efficiency under unfavorable conditions is for The provision of working surfaces for the follow-up curtain wall project is the focus of project management. In order to grasp the installation quality of the bolt ball joint space frame project, the installation quality control is mainly carried out from three aspects, namely, the quality control of the preliminary preparation and auxiliary work, the on-site processing quality control, and the bolt ball joint space frame assembly quality control.

2.1 Preliminary preparation and auxiliary work quality control

2.1.1 On-site copy test. In order to grasp the quality of the project and improve work efficiency, the copying and surveying work is entrusted to a professional surveying and mapping company. With the pouring of concrete beams and columns, the surveying and mapping company will carry out simultaneous copying and testing, measure and set the fulcrums on the design drawings on the beams and columns, release all the fulcrum positions, and draw cross lines; the space frame installation unit will process on-site according to the copying and testing results Production, installation by professionals, after all supports are installed, the surveying and mapping company will conduct re-measurement, and the supervision company will carry out measurement and composite, and record the lofting data for filing.

2.1.2 Material sampling and testing. The material inspection is divided into two parts. The manufacturer inspects the bolt balls, rods, steel plates, etc., and the supervisors go to the factory to supervise. The bolt balls are formed by die forging of 45# steel, and the quality of the raw materials is in accordance with “High Quality Carbon Structural Steel Technology” (GB699_88 ) standards, conduct inspections, conduct spot checks according to 5% of the bolt balls of each specification, and use magnetic particle inspection technology and 10 times magnifying glass for visual inspection; compare the thread and thread tolerance of screw holes with “GB196-81” and “GB197-81” According to the 6H level accuracy standard, the diameter, roundness, distance between the ball end surface and the center of the ball of each specification are tested with standard thread gauges at a ratio of 5%, using tools such as vernier calipers, height gauges, and mandrels. High-strength bolts are manufactured by professional manufacturers, and the manufacturers provide inspection reports. After the materials enter the site, the supervisory unit checks the factory certificate and test report, conducts a visual inspection of the bolts on the spot, and uses a 10-fold magnifying glass to conduct spot checks visually. The contents include: whether there are bolts Sampling checks for cracks, damage, thread size, geometry, etc. Sampling inspection is carried out on some materials, the bolt ball is matched with the bolt, and 3 groups of bolt ball joints are taken and entrusted to a qualified unit to carry out the tensile strength pull-out test.

2.1.3 Check the erection of the scaffolding and springboard of the whole hall. The height of the second floor ranges from 11.5 to 19.6 meters, and the quality of the scaffolding is crucial to the smooth installation of the space frame structure. The general contractor entrusts a professional company to set up the scaffolding, organizes the space frame installation unit to make a disclosure, and strictly controls the vertical and horizontal rows, vertical bars, and diagonal bars of the scaffolding in strict accordance with the grid installation requirements. The strength and rigidity meet the requirements. Afterwards, the general contractor organizes professional companies and grid companies to check and accept, and the supervisory unit conducts spot checks, and then assembles space frame after compliance with the regulations.

2.1.4 Embedded bearings. Check the disclosure records against the design drawings; before pouring concrete on beams and columns, workers use theodolite and level to measure the control points on the beam and column measurement line, and draw cross lines; the installers determine the height and position of the support, and Embed the support in the concrete; the supervisory company will compound the result of copy test and installation.

2.2 On-site processing and production quality control

In order to ensure the construction period, some materials are processed on site, such as backing plates, sealing plates, cone heads, sleeves, and some rods, etc., so their quality control is the key to management. The first is material control: the backing plate, sealing plate and cone head are made of Q235 steel, the sleeve is made of 45# steel; the sealing plate is processed by cutting, and the cone head is formed by die forging gold. The second is inspection control: use a 10 times magnifying glass to visually inspect the backing plate, sealing plate, cone head, sleeve, etc., randomly check 5% of each specification, and not less than 10 pieces, and there must be no cracks, overheating and scale; The geometric dimensions of cones, sleeves, etc. are inspected with vernier calipers, dial indicators, etc., and 5% of each type is spot-checked, and no less than 10 pieces are in compliance with the regulations; welds are inspected by ultrasonic flaw detection, in accordance with the “Steel Structure Construction and Acceptance Specifications” ( GB50205) Secondary quality standard, inspection quantity, random inspection of 5% of each type of rod, and no less than 5 pieces;

The tensile strength test shall be carried out on the welds between steel pipe rods and sealing plates or cone heads, and the bearing capacity requirements stipulated in the appendix of “Quality Inspection and Evaluation Standards for Space Frame Structure Engineering” (JGJ78-91) shall be followed, and the number of rods of the same specification shall be equal to or less than 300 pieces. For a batch, each batch of 3 pieces is randomly selected as a group for spot checks. The inspection method is to entrust the inspection agency to use a tensile testing machine for inspection.