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The Structural Engineer

In this paper some important conclusions are drawn from a limited number of 1/3 scale tests. Some of these are dependent on the use of a scale factor, which the authors took as ƒÄ = 1.2 when comparing their test results on a 62 mm thick model with calculations of shear capacity to CP 1 10. This should be 1.3 for 150 mm slabs according to Table 14 in the February 1976 Amendment to CP 110. Furthermore, this table is applicable only to the practical range of slab thickness down to 150 mm. The relevant scale law from beam test results (4ãh) would indicate that a ƒÄ value of 1.5 is appropriate for 62 mm slabs. Thus the 25% increase in ultimate shear stress proposed in the paper corresponds to the effect of neglecting the scale factor difference between 62 mm and 150 mm slabs. S.G.S. Feneron The importance of the slab/column connection

The Structural Engineer

Mr. Tutt reported that further results were now available. These were for 215 mm thick walls, similar in size and shape to those already reported, and for 'C' shape walls, i.e. walls supported on both horizontal edge and one vertical edge. These new results are given in Table 1.

The Structural Engineer

Following a discussion of the role of load testing in the structural appraisal of construction and of the philosophy of load testing, this paper examines recent experience of load testing of concrete floors and roofs in existing buildings in relation to the recommendations contained in BS Code of practice CP l10 The structural use of concrete. Techniques of testing building structures on site are discussed briefly. Suggestions are made for modifications to present procedures and techniques. J.B. Menzies

The Structural Engineer

Mr. W. J. Mackenzie (Slough Estates Ltd): The company I represent is a major customer of the building industry. Furthermore, being a repeat customer, it is rather more discerning and critical than many of the one-time buyers who come to the profession and to the industry for a building. We have, for some time, felt dissatisfied with the performance of the industry. The company is paying more and waiting longer for buildings, and the resulting product is inferior to what can be bought overseas, as regards both specification and aesthetics. The general standard of buildings on industrial estates around the country is poor and compares unfavourably with standards elsewhere in the world. It is essential for the customer to demand higher performance and to express his dissatisfaction.

The Structural Engineer

In the United Kingdom most highway bridges go to tender with a fully detailed design, bill of quantities, and specification. Alternative designs are permitted but, with the limited tender periods and the complications of the independent structural check recommended by the Merrison Committee and required by the Department, these are rarely offered by tenderers. However, some contractors have advocated the adoption of continental contractural methods. Design and build tendering was adopted for the Kessock Bridge only because tender prices-firstly for foundations and secondly for the whole bridge-greatly exceeded the estimates.

The Structural Engineer

'Only a few of you, my brothers, should be teachers, bearing in mind that those of us who teach can expect a stricter judgement.' Professor A.J. Harris

The Structural Engineer

This paper examines the reasons for, and the practical aspects of, load testing concrete structures, in particular floors and roofs, and the problems that have been encountered when testing in the field. It briefly discusses other types of structure, and comments on the recommended loadings. D.S. Jones and C.W. Oliver

The Structural Engineer

Castellated beams In our August column, Mr. A. Billingham posed a problem about the design of these beams in accordance with BS 449, particularly in respect of lateral buckling. Mr. A. D. Weller has responded saying: I am enclosing a copy of a letter sent to Mr. A. Billingham following his question in The Structural Engineer for August 1978. Unfortunately, the answer to his problem would require considerable research work, which may well indicate that castellated beams need restraint at close intervals. Verulam