The first volume of Sir John Baker's The Steel Skeleton was published in 1954; volume 2 (Plastic behaviour and design), with joint authorship, was published in 1956. The two volumes give an account of the development of steelwork design, the first covering the period up to 1936, when the Recommendations of the Steel Structures Research Committee were made, and the second taking the story forward to 1954. The books are thus compounded of the history of structural design, of accounts of the important research results, and of the relevant technical advances in the theory of structures.

As soon as volume 2 of The Steel Skeleton had been completed, we wished to construct a more orthodox textbook on plastic theory; in the event, volume 1 (Fundamentals), of Plastic Design of Frames was not published until 1969, again with joint authorship. The present volume completes the original plan, and covers some topics which were not treated in volume 2 of The Steel Skeleton.

The first three chapters deal with the notion of the yield surface in the theory of plasticity; the ideas are developed simply and with reference to the frame rather than the continuum, and are applied to reinforced concrete and masonry in chapter 4. The remaining six chapters of the book return to the problem of the plane steel building frame. In chapter 5 is treated the question of elastic-plastic analysis, and in particular the calculation of deflexions.