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Steel Designers' Manual - 6th Edition (2003)
834 Foundations and holding-down systems
For heavily-loaded columns or those carrying large moments resulting in high
compressive forces the bedding should be fine concrete using a maximum aggregate
of 10 mm size. The usual mix is 1 : 1 1 /4:2 with a water–cement ratio of between 0.4
and 0.45 (this is not suitable for filling the bolt tubes as it is too stiff; a pure cement
water mix has suitable flow properties and is usually used). It also has high shrinkage
properties and should be allowed to set fully before continuing with the
bedding. A cement mortar mix is often used for moderately-loaded columns. A suitable
mix would be 1 : 2 1 /2. Weaker filling than this should only be used for lightlyloaded
columns where the erection packs are left in position and transfer all the
load to the foundation.
In order to facilitate the compaction of the bedding material, holes are cut in the
baseplate of the order of 50 mm diameter or more, near to the centre of the plate,
in order to allow the escape of air pockets and to ensure that the bedding reaches
to centre.
Further reading for Chapter 27
British Constructional Steelwork Association/The Concrete Society/Constructional
Steel Research and Development Council (1980) Holding-Down Systems for Steel
Stanchions.
British Standards Institution (1997) Structural use of concrete. Part 1: Code of practice
for design and construction. BS 8110, BSI, London.
British Standards Institution (2000) Structural use of steelwork in building. Part 1:
Code of practice for design – Rolled and welded sections. BS 5950, BSI, London.
Capper P.L. & Cassie W.F. (1976) The Mechanics of Engineering Soils, 6th edn. E.
& F.N. Spon Ltd.
Capper P.L., Cassie W.F. & Geddes J.W. (1980) Problems in Engineering Soils.,
3rd edn. E. & F.N. Spon, London.
Lothers J.E. (1972) Design in Structural Steel, 3rd edn. Prentice Hall, Engleword
Cliffs, NJ.
Pounder C.C. (1940) The Design of Flat Plates. Association of Engineering and
Shipbuilding Draughtsmen.
Skempton A.W. & McDonald D.H. (1956) The allowable settlement of buildings.
Proc. Instn Civ. Engrs, 5, Part 3, 727–68, 5 Dec.
Skempton A.W. & Bjerrum L. (1957) A contribution to the settlement analysis of
foundations on clay. Géotechnique, 7, No. 4, 168–78.
Terzaghi K., Peck R.B. & Nesri G. (1996) Soil Mechanics in Engineering Practice,
3rd edn. Wiley, New York.
The Steel Construction Institute/British Constructional Steelwork Association
(2002) Joints in Steel Construction. Simple Connections. SCI/BCSA.
Tomlinson M.J. (2001) Foundation Design and Construction, 7th edn. Prentice Hall,
Harlow.
A series of worked examples follows which are relevant to Chapter 27.