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Early-age thermal cracking in
a wall on a stiff foundation |
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A principal reason for the update was to align the design with the requirements of Eurocodes, in particular EN1992-3, which will replace BS8007 for design of liquid retaining structures. The technical work was undertaken by Dr Phil Bamforth under contract to CIRIA. He was supported by an expert Steering Group and Dr Steve Denton of Parsons Brinkerhoff provided specific expertise in the Eurocodes.
The revised guidance suggested that the Eurocode advice was un-conservative in some circumstances and proposed measures to reduce the risk accordingly. Following the publication of CIRIA C660, the author observed that some of the basic assumptions behind the cracking model of BS8007 (and which has been adopted by EN1992-3) may be incorrect, particularly in the way in which restraint is assumed to affect crack widths in members subject to continuous edge restraint.
A new concept was proposed and it is this which is the subject of the current study supported primarily by the ICE, with additional support from the Highways Agency and the Concrete Centre.
The project, being undertaken by Dr Phil Bamforth and Parsons Brinkerhoff, is aimed at developing a model (primarily) for early-age thermal cracking that reflects more reliably the cracking mechanism and in particular the role of the boundary conditions (restraint) in the distribution and size of cracks within a member.
The model will be tested against field observations, published data and using FE analysis. A basis for a new design approach will be developed, aimed at being applicable for controlling cracking under any conditions of restrained contraction.
For further information please contact Dr Phil Bamforth (E-mail: phil.bamforth@btopenworld.com).
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