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Design and Construction of Light Steel Structure Cladding System (Part 1)

In recent years, light steel structures have been widely used in factories, small exhibition halls, and office buildings due to their low steel consumption, short design and installation time, and high degree of industrial production. This promotes the development of the steel structure enclosure system from simplification to diversification, which in turn leads to changes in new design ideas and new construction methods.

The cladding system of light steel structure mainly includes wall system, roof system, lighting belt, edge wrapping and flashing, gutter and insulation cotton, etc. The cladding system is one of the most important components of the light steel structure, which determines the appreciation of the building’s appearance, the waterproof and thermal insulation effects of the building.

1 Design and construction of roof and wall systems

1.1 Classification of color board enclosure system

The color board enclosure is divided into: single-layer board, EPS sandwich board, BHP color steel board, GRC wall board, polyurethane sandwich board, glass wool on-site composite sandwich board, rock wool sandwich board.

According to the construction method, it is divided into: finished composite board and on-site composite board. On-site composite board connection methods are divided into: lap joint board, occlusal board, concealed buckle board.

According to the material, it is divided into: galvanized color steel plate, titanium gold plate, galvanized color steel plate, aluminum alloy plate profiled plate, stainless steel plate profiled plate, copper plate.

1.2 Design Considerations

On-site composite panels are widely used in light steel structures due to their low processing cost and relatively mature construction technology. 0.376t and 0.5t thick galvanized paint color panels are used for colorful roof panels.

The slope of the roof affects the discharge of rainwater from the roof. The slope of the roof should be 1/8-1/20 during design, and the larger value should be selected in areas with a lot of rain (see CECS102:98 for details). In addition, the slope of the roof and the used It is related to the type of roof panel. Generally, the slope requirements for exposed nail-type panels are relatively large, and the requirements for concealed panels are relatively small.

The roof panels of large-span steel structures should adopt concealed buckle-type color steel plates. In a large number of engineering applications, the concealed buckle color steel plate shows the following advantages: (1) Avoid excessive deformation of the roof panel caused by temperature difference, and self-tapping screws are cut off. (2) In rainy areas, the temperature deformation of exposed self-tapping screws in typhoon areas, the vibration of wind loads, and the aging of rubber pads are very easy to cause corrosion and water leakage of the plates. The above-mentioned conditions can be avoided by using hidden buckle mining steel plates. For roofs with a single slope length greater than 60 meters, it needs to be processed into two panels to form expansion joints between the panels, connected with Detai cover sheets, which can slide with the color panels to solve the problem of temperature deformation.

1.3 Precautions for construction

During construction, for large-span roofs, the color board needs to be a whole piece of forming board. Because the crane hoisting the board is easy to cause the deformation of the board, so the crane is generally not used for installation, and the color board is hoisted semi-obliquely by a hoist.

2 Design and construction of day lighting panels

According to the material, the lighting board can be divided into glass fiber reinforced polyester lighting board, honeycomb or solid board made of polycarbonate, etc. According to the shape, it can be divided into glass fiber reinforced polyester lighting board (referred to as FRP lighting tile) with the same waveform as the roof panel. ) and other flat or curved lighting panels.

Different lighting panels have different fixing methods. Polycarbonate lighting panels are fixed with aluminum profile fasteners, and corrugated lighting panels are fixed with lighting panel brackets and self-tapping screws, and then sealed with glue. The position of the daylighting panel is generally set in the middle of the span. The lighting board is connected with self-tapping screws and must have a cover. The solar panel has a large deformation in cold and heat, and is easy to be cut by self-tapping screws. Therefore, the solar panel should have a larger hole at the place where the self-tapping screws are punched. When installing the daylighting board, the flexibility of the daylighting board should be considered.

There is no need to overlap the lighting board within 12m, and it needs to be overlapped if it exceeds 12m. The length of the overlap is 200-400mm, and two layers of sealant are applied to the overlap. Type, ordinary profiled steel plate, generally do not consider virtual trimming, directly fix it with the color plate with self-tapping nails, and apply sealant, and the occlusal plate needs to be trimmed.

The lap joints in the longitudinal direction of the lighting panels should be set near the sandalwood bars, and the roof waterproof treatment must be internally coated with sealant.

Lap joint of daylighting panels to color panels: exposed screw roof panels or concealed fastening roof panels, the effective width of the lighting panels should be reserved, and long self-tapping screws are used to fix the peaks of the lighting panels, taking into account the thermal expansion of the lighting panels Cold shrinkage is not the same, so pre-punched holes should be used for the lighting board (8mm holes are suitable), and reinforced waterproof gaskets should be placed under the self-tapping screws to prevent the lighting board from cracking at the screw after thermal expansion and cold contraction.