by Steel structure connection – a steel structure is made of prefabricated materials (steel) fabrication, which is processed into components in the factory and then assembled on site.
Therefore, the connection node between components is an important part of forming steel structure and ensuring the safe and normal operation of the structure.
The basic principles of designing steel structure connection are: reasonably design the connection to ensure that the node has sufficient bearing capacity and appropriate node stiffness, To transfer internal force at the node.
In the specific design, the connection joints shall be calculated according to the internal force response of the structure or member generated by the load design value.
Correctly calculate the bearing capacity of nodes The internal force (or transmitted) is the premise to ensure the safe force transmission of the joint, and the selection of appropriate connection mode and the arrangement of connectors according to the force transmission mechanism of the joint connection depend on the load characteristics borne by the structure or member, the member section shape at the connection, the member size, the scale of the connection area, the joint stiffness requirements, the structural requirements of different connection modes, the possibility of construction, etc Many factors.
The basic connection mode of steel structure is welding connection (Metallurgical type), which makes the metal melt at high temperature and form a whole.
Welding materials are used: arc welding, gas welding and electroslag welding.
Welding materials are not used: resistance welding fastener connection (mechanical type) bolt: ordinary bolt: refined bolt (grade A and b) high strength bolt: rough bolt (grade C) rivet: nail connection: (shooting nail, self tapping screw, welding nail) others (chemical type) strong glue: directly bond parts chemical slurry anchor bolt: the anchor bolt and anchor foundation are combined into a whole through structural glue, which is used for the connection between steel members and concrete members.
1.
Characteristics and advantages of welding: simple structure – members of any shape can be directly connected without auxiliary parts, saving labor and materials – convenient processing, no drilling, no weakening of section, and fast construction Speed – it can be operated automatically.
The connection has good tightness, large stiffness and good integrity.
Disadvantages: the material is easy to become brittle, resulting in residual stress, residual deformation and welding defects, which have adverse effects on the fatigue and stability of steel structure.
It depends more on the skill level of welders.
When the quality inspection requirements are high, the inspection workload is large.
The most basic connection mode of modern steel structure is the most widely used.
2 Characteristics and advantages of bolt connection: simple construction, convenient assembly and disassembly, high requirements for Installers,) friction type high-strength bolt connection has good dynamic performance, fatigue resistance and easy to prevent crack propagation.
Disadvantages: material consumption, weakening of opening section, high requirements for bolt hole processing accuracy.
3.
Characteristics and advantages of rivet connection: good plasticity and toughness, good dynamic performance, disadvantages: material consumption The heating riveting process is extremely labor-consuming.
At present, it is rarely used in the connection of load-bearing steel structures.
4 Characteristics of bolt (welding) nail connection the bolt connects the steel plate with the concrete plate.
The bolt bears the shear force.
The basic connection mode is compared with the welding connection form and characteristics [arc welding] the welding material is used after power on (welding rod or wire) and weldment generate electric arc and melt welding materials to form weld.
It is necessary to use welding rod: manual arc welding: q235-e43 series, q345-e50 series, q390-e55 series.
When different steel grades are connected, it is appropriate to use welding rod suitable for low-strength steel – the quality is not easy to guarantee, which is used for automatic welding on site (semi automatic) submerged arc welding: q235-h08, H08A, H08MnA welding wires, Q345, q390-h08a, H08E, H10Mn2 – with uniform quality, good plasticity and impact toughness.
CO2 gas (instead of flux) and welding wire are used for factory welding of regular components.
The arc melts the welding wire to form a weld.
CO2 gas protects the welded metal from contact with air [electroslag welding] use the resistance generated by the current through the slag to melt the filler metal and base metal, and form a connection after solidification [gas welding] use the flame formed by the combustion of acetylene in oxygen to melt the electrode to form a weld – for the welding of thin steel plates and small structures Resistance welding: using current to heat the metal through the surface of the welded parts to be welded, to melt through pressure – for thickness of 12mm steel and thin walled steel welding, do you know so much knowledge about the steel structure industry? I have been concerned about the WeChat official account of the steel structure alliance, and every day can receive wonderful articles.
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