This book is an authoritative account of the latest developments in fire performance and fire resistant design of thin-walled steel structures. It provides a comprehensive review of recent research, including fire tests of thin-walled steel structural members and systems, numerical modelling of heat transfer and structural behaviour, elevated temperature material properties, methods of improving fire resistance of thin-walled steel structures, and performance based fire resistant design methods. Worked examples navigate the reader through some of the complexities of this specialist subject. This is the first book devoted to the fundamental principles of this emerging subject, as thin-walled steel structures are increasingly being used in building construction. It will be valuable to fire protection engineers who want to optimise fire resistant design of thin-walled steel structures, and specialist manufacturers needing to control fire resistance of thin-walled steel structural systems, as well as to the research community.