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TWf GUIDANCE

Rebar stability – technical guidance

The Temporary Works Forum (TWf) has published revised guidance, Temporary condition of reinforcement cages prior to concreting: Part 2 – Technical guidance (Ref.: TWf2021: 01, November 2022). A copy can be downloaded (free) from: LINK

SYNOPSIS

Prior to being encased in concrete a reinforcement cage should be considered as an item of temporary works. This guide (‘Part 2’) has been produced to supplement ‘Part 1’ (Ref. TWf2020: 03) by providing further detailed engineering explanation of the issues involved. It also provides design guidance for cages assembled in their final position on site and those pre-fabricated and requiring lifting, transporting and positioning in their final position.

GENERAL

Until a cage is encased in concrete it is a temporary structure made from vertical, longitudinal, diagonal and transverse bars which are generally connected with tying wire, though sometimes welded connections may be used. Tying wire does not contribute to the final strength of the reinforced concrete structure but plays an important part in cage stability prior to concreting. Cages can be pre-fabricated in workshops off-site (especially if welded intersections are preferred), pre-fabricated on-site and lifted into place or assembled in-situ. All these options are susceptible to inaccuracies and variations in workmanship to some extent.

REMINDER

The following publication is withdrawn: Stability of Reinforcement: Cages Prior to Concreting (TWf2013: 01, October 2013).

This TWf Safety Bulletin - whilst superseded by this guide - may still provide useful background information: Stability of reinforcement prior to concreting (TW15.116, 16.10.15, LINK).

Further information can be found here, LINK (Work in progress).


David Thomas
TWf Director and Company Secretary
11.11.22