Light steel structure is a new type of structure developed on the basis of ordinary steel structure.
Compared with ordinary steel structure, it has better economic index. Light steel structure is not only light weight, steel consumption, construction speed, and it has a strong seismic capacity, and can improve the overall seismic performance of the house. It is a kind of structure widely used in industrial plant.
Light steel structure by the foundation beam, column, purlin, layer and wall composition
Light house of monolayer USES portal type frame commonly
Roof truss
网架
The form of portal frame
The form and characteristics of rigid frame
1, the use of light roof, not only can reduce the size of beam and column section, the foundation is also reduced.
2, in the multi-span building can be made into a ridge of large double slope roof, for the long slope surface drainage to create conditions. The intermediate column can reduce the span of the beam, thus reducing the cost. The middle column adopts the up and down hinged swing column made of steel tube, which occupies little space.
3, the lateral stiffness of frame with purlin support to ensure that the longitudinal rigid components, and reduce the width of flange.
4, rigid frame can be used variable section, section and bending moment is proportional; When changing section, the height and thickness of web and the width of flange can be changed according to the need to make the best use of materials.
5. The web of the rigid frame can be designed according to the effective width, that is, partial web instability is allowed and its post-buckling strength can be used.
6. Vertical load is usually the designed control load, but when the wind load is large or the house is high, the role of wind load should not be ignored. In the light roof door rigid frame, the earthquake action does not have the control effect generally.
7. Support can be made lighter. It is connected to the web directly or with a horizontal nodal plate, a tensioned round steel may be used.
8. All structural components can be manufactured in factories with a high degree of industrialization. The component units can be divided according to the transportation conditions, and the units can be connected with each other by bolts on the site, which is convenient and fast to install, and the construction amount of civil engineering is small.
Connection of beam and column and splicing of beam
For the connection between the beam and the column of portal frame, the end plate can be vertically placed (FIG. A), diagonally placed (FIG. B) and horizontally placed (FIG. C). Cross beam splicing should make the end plate perpendicular to the outer edge of the member (figure d).
Rigid frame column foot
It is advisable to adopt flat-plate hinged leg (FIG. A, b) for steel structure of light housing with portal frame. Rigid column legs may also be used when necessary (FIG. C, d).
bracket
The structure of the leg is shown in the figure
Roof truss
The structural form of roof truss: the structural form of roof truss mainly depends on the use of roofing materials and housing. Mainly to triangular roof truss, triangular arch roof truss and shuttle - shaped roof truss, flat slope trapezoidal steel roof truss
Light steel roof truss and ordinary steel roof in the essence of how much difference, the design principle of the two is the same, but light steel roof truss rod section size is smaller, connection structure and use conditions are slightly different.
Trapezoidal roof frame articulated support node
Purline
Purline form: purline should be preferred to use solid belly component, also can use hollow or lattice structure component. Purlins are generally single span simply supported components, solid belly purlins but also continuous components.
Hollow purline: hollow purline is composed of Angle steel upper and lower chord and battening plate welding, its main characteristic is less steel, can reasonably use small Angle steel and sheet steel, because the battening plate spacing is more dense, assembly and welding workload is larger, so less application.
Lattice purline: lattice purline can adopt plane truss, space truss and bottom support purline.
Solid belly purline
1, channel steel purline
There are two kinds of ordinary channel steel purlins and light channel steel purlins. Purlin of ordinary channel steel (FIG. A); Because the thickness of the profile is thicker, the strength can not be fully developed, with a larger amount of steel. Light channel steel purlin is improved than ordinary channel steel purlin, but it is still not ideal.
2, high-frequency welding light h-shaped steel purline; Light h-beam welded with high frequency (hereinafter referred to as "light h-beam") is a kind of light beam produced with foreign advanced technology (FIG. B), which has the advantages of thin web, good bending rigidity, relatively close inertia moment between the two spindle directions, flat flange plate and easy connection.
3, roll groove shape cold bending thin-walled steel purlin: roll groove shape (C shape) cold bending thin-walled steel purlin (figure C) cross section interchangeability is large, widely used, with less steel, easy to manufacture and install.
4. Z-shaped cold-formed thin-walled steel purline with coiling edges: z-shaped with straight coiling edges (figure d) and z-shaped with oblique coiling edges (figure e). Its main plane x axis stiffness, as purlin deflection is small, with less steel, easy to manufacture and installation. Inclined coil side Z - shaped steel can also be stacked when storage, occupying less space. When the roof slope is large, this kind of purlin is widely used.
Purlin connection structure
Purlin and roof should be connected reliably to ensure that the roof can prevent the lateral instability and torsion of the purlin, which is especially important for solid belly purlin without checking the overall stability.
Purlin and pressure plate roof connection, should be used with rubber gasket self - tapping screw.
Purlin pull and support: each other by bolt connection.
Purlin in the roof (frame) arrangement and use
1, in order to make the roof truss chord does not produce bending moment, purlin should be located in the roof truss chord node. When the inner gutter is used, the side purlin should be as close as possible to the gutter.
2, belly purlin section should be perpendicular to the roof slope surface. For channel steel and z-shaped steel tans, it is advisable to point the upper flange tip (or roll edge) towards the ridge to reduce the torque caused by eccentric roof load.
3, truss purlin upper chord should be perpendicular to the roof truss upper chord, and the belly and lower chord should be perpendicular to the ground.
4. Ridge purlin scheme: double purlin scheme shall be adopted for solid belly purlin, and roof ridge purlin can be connected with channel steel, Angle steel or round steel (see the figure below). When truss purlin scheme is adopted at roof ridge with single purlin, although the steel quantity is less, the purlin types are more and the structure is complex. Therefore, it is advisable to adopt double purlin in general.
