Steel space frame roof construction technology

1 space frame engineering situation

The roof space frame type of the university library is bolted ball joints and is placed in a square pyramid; the supporting form: multi-point support around the lower chord; the building area of the library space frame is: 1018m2 (R=36m, the main purlin is 120*60*3 square 80*60*3 square tubes are used for pipes and secondary purlins; roof panels are used (0.9mm thick YX-65-420 type vertical seam aluminum-magnesium-manganese plate + 100mm glass insulation cotton + 0.426mm thick 900 type galvanized color steel plate); The surrounding and middle glass lighting and surrounding drainage ditch of the space frame adopts 2mm stainless steel for centralized drainage; the glass in the middle lighting part of the space frame adopts 6mm+1.14mm+6mm tempered laminated glass, and the glass frame adopts 160*80*4 square tube; the material of the main material It is Q235B; the oxide scale and rust and other pollutants should be removed before the space frame members are processed. All steel space frame members should be sandblasted and rust removed, and then coated with two coats of epoxy zinc-rich primer and two coats of alkyd topcoat. Apply fire retardant paint for steel structure. To ensure construction progress and construction efficiency and reduce operating costs, the construction of the steel space frame is divided into two stages: workshop production and on-site installation. In order to ensure the dimensional accuracy and installation efficiency of components, bolt balls The parts of the space frame are made in the workshop by machine processing. The processing quality of each part is inspected, accepted and assembled in small units in accordance with the “Code for Acceptance of Construction Quality of Steel Structure Engineering” (GB50205-2001) and other relevant specifications etc..

2 Construction preparation

(1) During the construction preparation period of the steel space frame, all technical materials related to the operation should be collected as soon as possible. Including: a full set of drawings for space frame construction, a report on the mechanical properties of space frame bolts, a report on the mechanical properties of steel pipes, a report on the chemical composition of raw materials, and the qualification certificate for electric welders, etc.;

(2) Before installation, the necessary scaffolding should be built on site to lay the foundation for the construction;

(3) Before installation, the processing flow of each component of the steel space frame should be perfected, and the construction site can only be entered after the acceptance and the installation of small units have reached the standard.

3 space frame installation

3.1 Preparatory work for the installation of the space frame

Before installation, the space frame support axis and elevation should be inspected. The space frame axis and elevation orientation must be consistent with the construction drawings. The support concrete strength should be tested. After the concrete strength meets the design requirements, the installation can be continued. Build a full house of scaffolding, set out lines and plan the orientation and elevation of each fulcrum. Temporary fulcrums shall be arranged; the orientation and number of temporary fulcrums shall be checked and verified, and jacks shall be selected for temporary fulcrums to gradually adjust the height of the steel space frame.

3.2 Installation process flow

The construction of the project was started by using the high-altitude bulk method according to the site conditions. The components of the steel space frame were vertically transported to the installation platform and scattered and stacked, and then installed one by one according to the installation drawing number. In order to ensure that the installation axis of the steel space frame is in place, after the analysis, the author planned the corresponding support points and connected them to the mesh frame.

(1) The combined installation of the lower chord and the lower chord. According to the number of the top ball, fix the bottom ball first, find the center and connect it with the bottom rod, and perform spot welding after testing the diagonal dimension on the other side.

(2) Installation of the abdominal rod. When installing the web, it is necessary to calibrate the orientation of the upper chord below the chord before welding. The web rod and the top chord ball form a downward quadrangular pyramid shape. The high-strength bolts connecting the web rod and the top chord ball should be screwed together. The lower end of the web rod is connected to the bottom chord ball and spot welded, which can adjust the top chord rod.

(3) Installation of the chord. The four upper chords are assembled to form an upward four-cone system. The upper chords are installed from the inside to the outside, and the high-strength bolts must be screwed in place according to the order of the installed abdominal vertebral bodies.

4 Roof panel installation

4.1 Installation of aluminum-magnesium-manganese alloy roof panel

When placing the aluminum-magnesium-manganese alloy roof panel, you should temporarily reinforce the place where it is placed, and pay attention to placing it firmly; before installing the aluminum-magnesium-manganese alloy roof panel, install the roof bottom plate first, and then install the roof panel. Set two points in the corner and the middle to determine the entire position of the entire sky, arrange the roof panels according to the drawings, position them one by one, tap self-tapping screws, and check the verticality of the roof panels while installing; aluminum-magnesium-manganese alloy house The laying of the panel should pay attention to the perennial wind direction, and the lap joint of the rib should be opposite to the perennial wind direction; where there are markings on the roof ridge and other drawings, the roof panel should be bent up about 80 degrees to form a water retaining plate; the fixing screws should be connected with the steel plate and the steel plate. The purlin is vertical, and the line should be hung before nailing the center of the purlin, so that the nails are in a straight line; every 3 to 5 roof panels are installed, the flatness of the two ends of the panels should be checked to ensure parallel laying. Adjust in time; pay attention to the lifting and transportation of aluminum-magnesium-manganese alloy roof panels, and ensure that all panels face upwards. Roof panels must be placed near or on the purlin support points, not mid-span of the purlins. Before fixing the first roof panel, make sure its position is vertical and square, and place it correctly with other buildings. In the relative position of the components; when the first roof panel is fixed, pull a continuous alignment line at one end of the roof panel, this line and the first roof panel will become the guide line, which is convenient for the rapid installation and maintenance of subsequent roof panels. Correction, and then test each roof area in certain sections during installation, by measuring the width of the fixed roof panel, and measuring it once at the top and bottom to ensure no movement and fanning. At certain stages, such as When halfway installed, measure the distance from the top and bottom of the fixed roof panel to the completion line to ensure that the fixed roof panel is parallel to the completion line; when installing the roof panel, pay attention to protect the coating of the color steel plate from injury. It is strictly forbidden to drag the roof panel on the purlin, and the roof panel should be completely lifted and passed by hand. The installation of the layer panel on the purlin should be accurate to ensure the installation quality; Prevent water accumulation; the length of the overlapping part between the plates is not less than 200mm, and the overlapping seam is sealed with neutral sealant.