This Digest is part of a suite of related documents containing guidance for the construction industry on structural fire engineering design. The intention is to produce performance based guidance that brings together fire engineering and structural engineering providing a framework within which designers are free to develop site specific solutions based on real performance criteria. The Digests contain information complementary to the existing and emerging fire engineering codes and standards. Each Digest may be used in isolation or as part of the full integrated suite. Owing to its high thermal conductivity exposed steel will increase in temperature very quickly during a fire, losing strength and stiffness. The designer must ensure that any building will maintain its stability for a reasonable period should any accidental fire occur. This Digest presents the current available design tools to ensure stability of steel framed buildings during a fire. Results from tests on a full-size building at Cardington have been used to develop a new design method for composite floorplates. These tests also give a better understanding of connection behaviour during a fire. 8 pages.