Correspondence on The Use and Calibration of Design Standards for SHS Joints by J.A. Packer and Dr.

A study is presented on vibrations of a long-span lightweight floor. The floor was analysed using various different methods to see whether it would have acceptable vibration characteristics in service. The vibration characteristics were then evaluated experimentally for the floor in its bare and finished states. The site evaluation included qualitative tests to assess human reaction to vibrations induced in the floor and quantitative tests to measure the characteristics of the floor. K.P. Osborne and B.R. Ellis

Potential for catastrophe in building operations, and the question of professional responsibility In our column for 20 March, Peter Mawer posed a dilemma arising from the danger of successive piecemeal alterations to terraced properties, where the progressive removal of stabilising walls could be in danger of leading to structural instability. The professional duty of an engineer acting in relation to a particular part of the terrace could be a problem - how far should his responsibility extend? We have received a number of contributions on this interesting topic. Mr A. Aitken, from Glasgow, relates what has been his own reaction in a similar situation, taking account of his assessment of possible consequences: With regard to the item on professional duty inspired by Mr Mawer’s contribution, I should like to point out that, in practice (as opposed to hindsight), it is very difficult to decide what to do for the best. Verulam

Results are given of 35 push tests using through-deck welded studs, three types of profiled steel sheeting, and shot-fired pins, with normal density and lightweight concrete. Maximum resistances are compared with the predictions of draft BS 5950: ‘Part 3.1’, draft Eurocode 4, and two reduction formulae for the effects of rib geometry. J.T. Mottram and Professor R.P. Johnson