Back-Analysing the Bending Moment in a Concrete Diaphragm Wall

Approval for Building Regulations - and the use of ‘structural design programs’ Mr R. R. Stagg, on 20 October, expressed concern regarding what he saw as the excessive reliance, in submissions for building control purposes, on calculations as presented by computer printouts from ‘structural design programs’. This topic has been taken up in a letter from Denis Wall of Dalkey in County Dublin: Being a late entrant to building control in the Dublin area a dozen years ago, I considered that the ‘checking of calculations’ was a very barren exercise, given that the builder never sees them. Verulam

Reinforced concrete columns are now often designed by computer, but design charts are still a popular alternative. Many sets of charts have been published for different Codes of Practice over the years, by various authors, but most of those for rectangular columns (e.g. BS81lO:Part 3' and the IStructE manual²) cover only columns that are reinforced with four bars placed near their corners. A.N. Beal and F.N. Pannell

A series of experiments has been carried out in a purpose-built sand tank to assess the foundation/sand behaviour under load where the investigation is confined to the non-failure characteristics of the soil. The semi-full-scale foundation is of bolted steel box construction, instrumented to provide the contact stresses at selected points. Stresses and displacements are also measured automatically at various depths in the sand, using a dedicated computer system with a specially developed management suite of programs. The variation of displacements and stresses, once processed, are plotted against depth. The results are then compared with data from linear finite element method, using back-analysis techniques. Various parameters are then established and ascertained. R. Delpak, G.O. Rowlands and A. Siraty