Connection joints and calculation of high-rise steel structure beams and columns

In the joint design of high-rise steel structures, the joints connected by beams and columns are the key joints. According to the restraint stiffness of beams to columns, the joints can be roughly divided into three types: rigid joints, semi-rigid joints and hinged joints. For rigid connections, both the upper and lower flanges of the beam should be connected to the column. Hinged connection only the beam web or side steel flange is connected to the column. However, the analysis and design method of semi-rigid connection structure is not perfect at present, so it is rarely used in actual steel structure engineering.

The rigid connection between the main beam and the column in the rigid connection refers to those joints that have sufficient rigidity so that the angle between the connected components does not change before reaching the bearing capacity, and its connection strength is not lower than the yield strength of the connected components . For frames that need to resist horizontal forces, the connection between the main beam and the column should be in the form of rigid connection.

There are three structural forms of rigid connection between beam and column.

Fully welded joints, the upper and lower flanges of the beam are connected with full penetration groove welds, and the web is connected with the column flanges by fillet welds.

Bolted and welded joints, the upper and lower flanges of the beam are connected to the flange of the column with full-penetration groove welds, and the web is connected to the gusset plate on the flange of the column with high-strength bolts. The column connection is particularly frequently used in the form of construction.

For fully bolted joints, the beam flange and web are connected to the column flange with high-strength bolts by means of T-connectors. Although the installation is more convenient, the joint rigidity is not as good as the first two connection forms, and it is generally only suitable for multi-storey steel structure frames in non-earthquake areas.

When calculating the connection joints between steel structure beams and columns, the following contents are mainly checked:

1. For the connection bearing capacity of beams and columns, the connection strength is checked in the elastic stage, and the ultimate bearing capacity is checked in the elastic-plastic stage.

2. Under the pressure and tension of the beam flange, check the compressive bearing capacity of the column web and the stiffness of the column flange respectively.

3. The shear bearing capacity of the node domain.