🕑 Reading time: 1 minuteThere are three different methods for design of steel structure, i.e. simple design, continuous design and semi-continuous steel design. Joints in structures have been assumed to behave as either pinned or rigid to render design calculations manageable. In simple design the joints are idealised as perfect pins. Continuous design assumes that joints are rigid and that no relative rotation of connected members occurs whatever the applied moment. The vast majority of designs carried out today make one of these two assumptions, but a more realistic alternative is now possible, which is known as semi-continuous design.