What are the characteristics of the connection of steel structure building components: The shape of steel structure has urban charm, and it is concentrated in the development of steel structure components.

In the steel structure building, China has the most "environment first, structure optimization, nature friendly" sustainable development strategy. While continuing to promote the industrial environment, the earth, stone, sand, wood buildings are not as good as the advantages of steel structure buildings, steel structure to maximize the conservation of resources, (energy saving, land saving, water saving, material saving) to protect the environment, reduce pollution, to provide people with a healthy, applicable and efficient use of space and nature harmonious symbiosis building. The following is a brief description; Various connection properties of steel structural parts;

First, steel structure members and characteristics

Another characteristic of steel structure members is the diversity of sections: on the one hand, the anisotropic homogeneity of steel makes it possible to be processed into various shapes, which is significantly different from the anisotropic non-homogeneity of wood: As a linear structural member, the cross-section diversity of the steel structure is incomparable to that of the wood structure, which is also the reason why there are I-beams and no "I-wood", and the connection members in the bar structure are almost all steel. On the other hand, the cross-section shape of the steel structure members also has a strong impact on the connection design. If the range of forces allows, the choice of different sections of steel can lead to different forms of connection.

Two. Constraints on connection design

There are many types of steels and their endurance varies, and the connection design is usually restricted by the following factors:

1. Source of components: Theoretically, steel structure components or connecting components have arbitrary processability, but in each specific project, structural components and connecting components are always restricted by realistic conditions. Experienced designers usually choose easy to obtain, easy to install the section steel, and design a simple and effective connection method and connection members.

2. Limitation of connection means: One of the characteristics of steel structure construction is the use of factory processing and on-site assembly. This is different from the traditional masonry and produce a large number of nodes. There are three main means of connection between various types of steel: riveting, welding and bolted. In the early days of steel structure buildings, riveting is often used, which is simple in construction, but it needs to dig out the hole on the member and reduce the section performance, and it is easy to produce concentrated stress at the node. The welded joint has a simple appearance and continuous load transfer efficiency, but the construction operation requires higher requirements. The high-strength bolted connection that appeared in the later period can also achieve the strength requirements similar to welding, and is widely used in modern steel structures.

3. The connecting components have hierarchy: there is a complex and logical hierarchical relationship between the structural systems of steel structures, and at the connection level, this hierarchical relationship is reflected in the difference between the size of the components and the sequence of installation. The purpose of connection is to achieve hierarchical transformation, and it is also the key to realize the transformation of force from three-dimensional to two-dimensional, and finally transfer to one-dimensional components. The complex connection is usually completed by the combination of three-dimensional connection component and plane connection component.

4. The plane of the connecting member: two linear structural members are always in a plane, the plane is the plane of the stress of the member, and the connecting member is often designed in this plane in order to effectively resist the stress, bending moment or shear force in this plane, such as the steel pipe and the weld of the cable are always in the plane composed of the two; In the case of the connection of multiple members, the combined plane members can correspond to the force of the three-dimensional.

Third, the prototype of the connection object and the classification of the connection

The structural construction of steel structure building includes two basic types of rod and cable, and the resulting connection mode can be divided into cable and cable connection, rod and rod connection, cable and rod connection. Regardless of plane structure or spatial structure, due to the linear characteristics of component monomers, the complexity of the structural system does not lead to more types of connections, and complex connections can be regarded as a combination of these three basic types.

1. Cable to cable connection

The cable only bears the tension in the structural system, the internal force is unchanged along the axis of the cable, and the section of the cable does not change due to the change of length. Its connection characteristics are as follows:

A. The connection at the end must be achieved by a cable.

b. The connection located in the middle of the cable can be completed by various types of fixtures.

c. The connection of multiple cables requires the design of new nodes, which are different according to the different combination methods of cables and cables: for example, the common single-layer or double-layer cable structure can appear parallel or radiation forms according to the different arrangement methods. The lightweight and effective cable mesh caters to people's common pursuit of lightness and transparency.

2. Connection between the rod and the rod

The rod appeared earlier than the cable, and the application is more widespread, because the rod can be both strained and compressed, which makes the connection design between the rod is more complicated than the cable. There are two main factors that determine the design of rod connection:

a. The intersection Angle between the rods.

b. The section form of the member. The former is determined by the structural system, and the latter can be selected or combined in the connection design stage to facilitate the design of the connection members.

In the case that the intersection Angle is not vertical, the section of the component should be carefully selected to reduce the difficulty of node design.

3. Cable and rod connection

Although the cable is in line with the material properties of steel, because it is a flexible component with only one-way tensile performance, the structural system composed of the cable and the rod can achieve the dual advantages of lightness and stability, such as the tension string structure which is very popular in large cross-field in recent years. Even in smaller span buildings, the combination of cable and rod is quite common.

Connection design according to the continuity of the cable or not, different connectors must be used to correspond: the connection at the end of the cable needs to be fixed by a series of components and rods, such connection procedure is simple and reasonable, and the application is also very common, and you can choose two different ways of cable clip welding or welding clip cable.

Four. Method of connection design

In a considerable part of steel structure buildings, the structural requirements for the form and size of the components are not very harsh, which brings considerable design room for the components and connection design. The architect's choice of the form and size of the component is closely related to the connection design or connection form. For domestic designers, the reality is often a limited choice of steel and a small number of forming connection members, so the design method is particularly important, even if these methods or means are often with pure performance color.

1. The object of decomposition is a single abstract component in the structure concept, which is often manifested as the decomposition of the number of components or the decomposition of the cross section form in the actual connection. This technique is quite common in the connection design of the rod system including the steel structure, such as the compression rod in the suspension structure is often decomposed into a combination of several rods; Columns are often broken down into beam columns and so on. Some of these decomposition is due to the need for structural forces, and some are simply to create gaps in the components to facilitate connection. The decomposition design of complex nodes is helpful to extract the basic form of the connection, so as to simplify the connection concept and integrate the node design.

2. The consideration of the form of the conversion section and the conversion of the size are also the main problems of the connection design. The purpose of the transformation is to reduce the section of the component and facilitate the connection design. The section of the member can be generally divided into two categories: tubular section (such as round steel pipe) and non-tubular section (such as I-steel). The connection between the former often requires a reduced section, such as the reduced solid steel pipe at the ball node of the grid. The connection between the latter is usually simplified, such as removing the wide wings and retaining only the height portion of the section steel, and is often combined with the decomposition design. In addition to changing the section shape of the component, it is often used to design a new node to connect the component after cutting it off along the plane perpendicular to the axis of the component. For example, in the roof frame nodes discussed above, the transformation of steel pipe section not only brings the convenience of connection, but also reflects the flexibility of node design. While expressing force transmission, sculptural modeling design is used to visualize and artistic the flow of force.

3. Integration Integration design is based on reducing the types and quantities of components, simplifying the connection methods, and emphasizing the integrity of structural forms, so that such design works often have an elegant image. This approach has two premises:

1) The force mode of each node is the same.

2) The section shape and scale of the structural members are similar. The same force mode ensures the scientific selection of similar section, and the similar section form and the approximate scale ensure the visual integrity.