This document discusses steel portal frames, which are low-rise structures used for industrial and warehouse buildings. They consist of columns connected by horizontal or pitched beams via moment-resisting connections. This allows the frame to act as a single structural unit and reduces bending moments in the beams. Pin joints are introduced to overcome rotational stresses from the beams to the columns. The document then discusses loads on portal frames, proper joint and foundation design, and bracing requirements. It provides specifications for typical steel sections used in portal frames and dimensions. Finally, it summarizes the steel portal frame roof design of the Turbhe Railway Station in India, which features an 84-meter long semi-circular ribbed arch roof.