Colliery Structures Discussion on the Paper by Mr. G. P. Bridges

In THE STRUCTURAL ENGINEER (July, 1948) Hajnal-Konyi described tests on concrete columns reinforced with square twisted steel (T.S.) and mild steel (M.S.) The tests showed that columns with T.S. have substantially higher failure loads than those with M.S. and may undergo large deformations before collapsing. Adequate warning of failure is given by gradual cracking of the concrete whereas normal tied columns reinforced with M.S. often exhibit a brittle failure, which is undesirable in any structure. Professor R. H. Evans and K. T. Lawson

The subject matter of this paper is intimately connected with the interests and activities of the Institution of Structural Engineers inasmuch as the problems in soil mechanics that we have studied in the Engineering Department of Swansea University College have originated in the panels, committees and subcommittees set up in London by the Institution. A.A. Fordham

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