Council for their financial support, to the staff of the Atlas Computer SS ratory, Chilton, for their extremely efficient service, and to iiss P. Sage for reproducing the drawings included in this thesis with such great care,The Author is especially indebted to his wife for her tolerance and understanding during the preparation of the thesis, and for ae many long hours she spent typing the manuscript. Oi ONL Ee Nie Synopsis Acknowledgements Contents Notation CHAPTER INTRODUCTION Set Criticism of elastic design methods 132 Limitations of simple plastic design 2g) Proposed design method CHAPTER HISTORICAL REVIEW OF RELATED WORK BAe : 2.3(b) Frame instability 2 oth Recent design and analysis methods