Steel moment frames consist of columns and beams joined by a combination of welding and bolting. The Welded Flange connection is one of the most common moment frame joints. This typically consists of a welded shear tab for vertical loading and the beam is usually connected using bolts. This is the “moment connection”, which can be seen in the picture below.
Most modern high-rise, mid-rise and low-rise building use moment frames to resist the lateral loading which occur with high winds or moderate earthquakes. Wind causes external lateral loading while moderate earthquakes cause internal lateral loading. Current building codes want the building to remain elastic or return to its original shape when lateral loading stops. Moment frames are important because they are meant to resist the lateral loading caused by the frame bending.
Moment frames provide the flexibility needed to meet the demands of lateral loading requirements. While the design of moment frames can be time consuming and labor intensive in the end it could be worth it.