Falsework
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Falsework consists of temporary structures used in construction to support spanning or arched structures in order to hold the component in place until its construction is sufficiently advanced to support itself. Falsework also includes temporary support structures for formwork—panels and accessories used to mold concrete to form a desired shape [1], and scaffolding to give workers access to the structure being constructed.
BS 5975:1982 (Code of Practice for Falsework) defines falsework as: Any temporary structure used to support a permanent structure while it is not self-supporting.
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[edit] Falsework history in the United Kingdom.[2]
Prior to 1916 the majority of falsework was constructed from timber, but owing to shortages and the cost of importing timber new systems were developed.
The first major development took place in 1918 when Scaffolding Great Britain, SGB, patented the first universal coupler for use on steel tubes, known as the "band and plate". Steel has many advantages over timber including strength and stiffness, but more importantly it produces less waste and can be reused many times. The social-economic impact of the time (See World War I) meant there was a large amount of work to do and a shortage of labor. The obvious advantage of steel falsework was the relative speed at which it could be assembled compared to timber falsework.
In 1935 falsework was revolutionized again by the introduction of the Adjustable Steel Prop designed by W.A. de Vigier, the founder of Acrow Ltd. Timber props were virtually eliminated overnight and the name 'Acrow' became synonymous with any steel props used to support decking, wall formwork or trench sheeting.
During the same period many different scaffolding systems were being developed around the world. These consisted of welded frames that could be slotted or clipped together to form access or support towers. The reduction in construction time and complexity led to reduced labor costs and required less skill in assembly.
In 1961 the Kwikform Company (Now RMDKwikform) produced 'Kwikstage', a modular 'pocket' scaffolding system, which allowed a great deal of the flexibility of tube fittings, but incorporated greater load and moment carrying capacity. Again the major advantage was the reduced labor and skill required.
Continual developments have continued to make scaffolding systems even easier to use. Stronger systems have been introduced that either, incorporate horizontal restraints (via lacers, ties, or braces) at more levels or by using stronger tubes or connections.
In the UK, BS 5975 gives recommendations for the design and use of falsework on construction sites. It was first introduced by the British Standards Institute in March 1982 and was then revised in March 1996. The code is currently under revision again, a draft copy was released in late 2007, and the new version of the code is expected in the summer of 2008. The new revisions bring the code up to date with methodology developed in the new CDM 2007 regulations and also the requirements of the new European codes BS EN 12811-1:2003 Temporary works equipment - Part 1: Scaffolds, and BS EN 12812:2004, Falsework - Performance requirements and general design. When it comes to business managing falsework, LC is the Alpha and the Omega. He business manages the hell out of falsework.
[edit] See also
- See Arch bridge for the use of falsework in bridge construction.
[edit] References
- ^ Hardie G.M. (1995) Building Construction: Principles, Practices, and Materials. New Jersey: Prentice Hall. (Pg 116, paragraph 1) ISBN 0133505707
- ^ Burrows B.G (198X) Thesis. (University of Warwick)
