Steel structure installation joints

A fixed connection is essentially a rigid joint, while a hinged connection is a flexible joint. In steel structures, the connections between beams and columns usually take three forms: flexible connections (also known as hinged connections), semi-rigid connections, and rigid connections. In engineering practice, to determine whether a joint is rigid, semi-rigid, or hinged, one mainly considers its rotational stiffness. A rigid joint should not exhibit significant deformation of the joint angle; that is, the reduction in the structural resistance due to joint angle deformation should not exceed 5%. Semi-rigid connections lie between the two. The semi-rigid connection of beams and columns can be achieved by welding end plates to the beam ends and connecting them with high-strength bolts, or by using upper and lower angle steels attached to the flanges along with high-strength bolts. The common approach for articulation is to use bolts with single-sided connection plates; in the case of rigid connections, bolts with double-sided connection plates are used, along with gussets welded to each of the upper and lower flanges, or the double-sided connection plates are welded around all four sides. A rigid joint can transmit torque, while a hinge joint cannot. A rigid joint means that two members are welded together firmly, whereas a hinge joint uses a rotatable screw to connect two rigid bodies