The possibilities of a vertically-corrugated web as a means of reducing thermal stresses naturally have for some time been generally appreciated by designers. The stress relief to be expected is examined in some detail here. It is shown that quite shallow corrugations can be effective in reducing thermal stress and that a flange-to-web connection at corrugation-pitch intervals can offer substantial advantages over a more continuous type of connection. Arguments are presented to show why straight-sided corrugations are superior to curved ones.