Design and Construction of Welded Portal Frame Warehouse Building Designed by the Plastic Method Dis

Sir,-We welcome this paper by Dr. Wood because for the first time in an official publication the nonproportionality of the stanchion moments with the load, for increase of loads above the design loads, is recognised and the irrational basis of the theory published by the Steel Structures Research Committee is clearly demonstrated.

The method presented here is applicable only to portal frames with hinged base columns, but as about 80 per cent. of every-day portal design comes under this category, it must be agreed that this fact does not seriously affect its usefulness to the designer. J.F. Horridge

This month's letters discuss foundations in shrinkable ground and highlight a survey on structural optimisation in practice.