Space truss structure
A spatial structure composed of several rods connected by nodes in a certain grid form. It has the advantages of spatial force, light weight, large stiffness and good seismic performance. It can be used as the roof of stadium, cinema, exhibition hall, waiting hall, stadium stand awning, aircraft hangar, two-way large column distance workshop and other buildings. The disadvantage is that the joint on the node of the rod more, the production and installation of more complex plane structure.
Classification of network structure
There are many kinds of net structure, which can be classified according to different standards.
First, according to the structure of the network frame itself can be divided into: single-layer network frame structure, two-layer network frame structure; Three layer network frame. Among them, single-layer and three-layer network frames are suitable for the cases with a small span (no more than 30m) and a particularly large span (more than 100m), respectively, and have few engineering applications in China.
Second, according to the construction materials are divided into: steel mesh frame, aluminum mesh frame, wood mesh frame, plastic mesh frame, reinforced concrete mesh frame and composite mesh frame (such as the combination of steel mesh frame and reinforced concrete slab), among which steel mesh frame has been widely used in China, and composite mesh frame can also be used as floor layer structure.
Three, according to the supporting situation can be divided into: peripheral support, four-point support, multi-point support, three-side support, side support and mixed support form.
Four, according to the different composition, can be divided into four categories:
1, cross truss system network frame;
2. Triangular cone system network frame;
3. Four-angle cone system network frame;
4, hexagonal cone system network frame.
The fourth classification method is a popular one in China.
In the form of
There are 11 forms of network structure in our country get different degrees of application, the following from the composition and characteristics of the 11 forms of network structure to be introduced.
First, the cross truss system network frame
The first category is the grid structure composed of two or three groups of plane trusses, which is called the cross truss system (see figure). This is one of the simplest and earliest forms of grid structure. It is developed and evolved on the basis of cross beams. The upper and lower chords of this kind of net frame are equally long. Generally, web bar can be designed as "pull bar system", that is, long bar (inclined bar) under tension, short bar (vertical bar) under compression, inclined bar and chord Angle should be between 40 degrees to 60 degrees. Among them, the vertical rod is the common plane truss of each group. This kind of net frame commonly has 2 kinds of forms.
The system of cross truss is divided into two - way and three - way.
Two, three Angle cone system network frame
The second category is suitable for square, rectangle, triangle, trapezoid, hexagon, octagonal and round plane shape buildings.
Which is divided into: triangular cone frame, take out the triangular cone frame, honeycomb triangular cone frame.
Three, four Angle cone system network frame
The third category is composed of four Angle cone structure, there are five forms, respectively: square four Angle cone structure, square take out four Angle cone structure, inclined put four Angle cone structure, checkerboard shape four Angle cone structure and star shape four Angle cone structure.
Four, hexagonal cone system network frame
The fourth major category is composed of hexagonal cone (heptahedral) network frame structure, known as the hexagonal cone system network frame. Its basic unit element is 6 chords, the hexagonal taper that 6 chords form (can invert or be put). One of the main forms of this kind of net frame is the hexagonal cone net frame.
Structure is introduced
Rod design and joint construction
The cross section of the truss structure should be calculated according to the strength and stability. In order to reduce the calculated length of the pressure bar and increase its stability, additional sub-bar and support bar can be used. The joints of the plate type and double shell type net frame made of steel are mainly in three forms: cross plate joints, welded hollow ball joints and bolt ball joints. The cross plate joint is suitable for the grid structure of the shaped steel member, the connection between the member and the joint plate is made by welding or high-strength bolt. Hollow ball joints and bolt ball joints are suitable for the net structure of steel pipe members. The joints of the single-layer shell frame should be able to withstand bending internal forces. In general, the steel consumption of the joints accounts for 15 ~ 20% of the steel consumption of the entire steel frame structure.
Construction of the installation
The construction and installation methods of the grid structure are divided into two categories: one is the integral jacking method, the integral lifting method and the integral hoisting method assembled on the ground; The other one is bulk, block and block assembly and high-altitude sliding assembly.
