Joint design is one of the important contents in steel structure design.Before analyzing the structure, the form of joint should be fully considered and determined.The most common situation is that the final design node is not exactly the same as the form used in the structural analysis model, which must be avoided.According to the transmission characteristics of the node, the node is divided into rigid node, hinge node and semi-rigid node.It is advisable for beginners to choose the first two methods, which can be analyzed by simple and quantitative methods.

            The difference of connection has a great influence on the structure.For example, although some rigid joints have no problem in bending moment, they will produce large rotation in structural analysis, which is not consistent with the assumption.The harmfulness of actual engineering deformation is greater than the calculated value.

            There are generally two methods of node connection: equal strength design and actual force design. Beginners can choose the former safely.It can also be done automatically using the post-processing part of structural software.

The specific design mainly includes the following contents:

            Welding: in terms of weld size and shape, there are mandatory provisions, which should be strictly observed.The selection of electrode shall be suitable for the material to be connected to the metal.E43 corresponds to Q235, Q345 and E50 correspond to each other.Q235 and Q345, low strength should be selected instead of E50 weld.Welding design.The center of gravity of the weld shall be close to the center of gravity of the connecting parts.Other details can be used to adjust the specification of the welded structure.

           Bolt connection: the form of riveting is rarely used in construction engineering.The common bolt has poor shear performance and can be used in secondary structure.High strength bolts are used more and more widely.The two strength grades are usually 8.8s and 10.9s.According to the stress characteristics, pressure type and friction type are divided.The two methods are different.Minimum size M12.High strength bolt is often used in M16 ~ M30 design.Super large bolts should be used carefully in design.Self tapping screw is used for secondary connection between steel plate and thin wall steel.In the low-rise wall panel house, it is also commonly used for the connection of the main structure.