Author: Bloomer, D A
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Bloomer, D A
The Structural Engineer, Volume 71, Issue 16, 1993
Safe loads on hangers for timber joists Dr J. B. Bellamy believes that there is a need for the clarification of the criteria for designing joist hangers, and explains how he sees the design considerations: There appears to be a widespread misunderstanding among suppliers of builder’s metalwork as to what is the safe working load on built-in joist hangers. It is common to see figures in sales literature which are many times those set out in the relevant Code of Practice, BS 6178: Part I 1990. For example, one supplier quotes loads ranging from 14.7 to 37.8 kN compared with l.9 to 3.1 kN in the standard. At first sight, this could be taken as being due to improved designs, but closer examination suggests that the majority of suppliers offer very similar products. A few minutes spent calculating stress levels reveals that, in normal applications, the factor governing capacity is the crushing strength of the masonry, not the strength of any element of the metalwork. Verulam
This year, 1993, marks 50 years from the introduction of the pretensioned, prestressed railway sleeper. This paper describes some history of the early development of prestressed sleepers and links the design development with that of our Codes. The success of the prestressed sleeper is self-evident, but the paper does emphasise the successful way in which the prestressed sleeper copes with a most hostile working environment and provides an insight into the development of our design methods for prestressed concrete. H.P.J. Taylor