SP92 This publication is a compilation of 11 papers dealing exclusively with the analysis and repairability of concrete damaged in building fires. Due to the importance of concrete and its role in the structural performance of modern buildings, the ability to deal with fire-damaged concrete is a central issue. This symposium volume combines the knowledge and experience of fire safety experts from around the world. The topics covered include the following: experience of fires in concrete structures; fires during nuclear power plant construction; assessment and repair of fire-damaged concrete; residual properties of concrete heated rapidly; and residual strength of fire-exposed reinforced concrete columns. Evaluation and Repair of Fire Damage to Concrete will give the reader substantial insight into both the problems and solutions associated with concrete which has been exposed to high temperatures.

A major three span highway bridge in Southern Ontario was 1nvYived in a construction fire while it was being widened 25 years ago. Concrete, ranging in age from 6 days to 20 years, in an abutment, the adjacent arch rings and spandrel columns was severely damaged. The structure is now revisited to assess the long term performance of the remedial works and to consider whether the investigation and repairs might have taken a different course if today's testing, analytical and repair techniques had been available then. The strengthening of the damaged arch springings and the shotcrete restored concrete sections exposed to a harsh environment have stood the test of time. The review of investigative and repair methods identifies advances made in recent years, and justifies long term confidence in o'lder procedures which are still in use.

This paper outlines the procedures adopted in obtaining information on fire-damaged concrete structures since 1975. Details are given on the information received from questionnaires and a summary of the building and construction types, damage and repairs are tabulated. The general conclusion is that concrete structures behave well under fire conditions with the majority of cases being repairable.

The present paper is intended to give an overall information on temperatures which may have occured in concrete cross-sections affected by a fire Firstly the paper contains a catalogue of circumstances and vestiges which can be found when the affected building is visited and which allow conclusions concerning the intensity of the fire and the resulting value of damages to the structural elements. For this purpose, residual contents of the building (fire load), the state of building materials, and the evident condition of the concrete structure itself are used. In the second part of the paper, general informations are given on the development of natural fires and on the parameters which in-fluence it. On the basis of two series of experiments - Metz and Lehrte - which gave temperature-time developments in compartments where wood cribs or furniture were burnt, temperature fields are presented for square concrete cross-sections affected from all sides, and for T-shaped sections affected from three sides. It is stated that the presented figures can only be rough approaches for practical work. Short, only introductory informations on residual changes of material properties due to temperature influences are added to facili-tate judgements and decisions. It stands to reason that, if findings won by this guide lead to the conclusion that the structure may be worthy to be kept, more intense and detailed investigations have to be done.

In some cases, it is necessary to evaluate and document structures which were subjected to fires during construction. Due to the lack of official regulations on the subject, the analyses and documentation on these incidences, when reported to the regulatory authorities, implied unconventional activities, both for the utility and the A/E. The paper describes several fires affecting nuclear power plant concrete structures. They were all caused by inadvertent human actions. The presence of highly combustible auxiliary cons-truction materials contributed to their propagation. It is recommended that the cost (purchase and installation) of these auxiliary materials be evaluated against the use of alter nate (noncombustible)ones before making any decision, sufficiently in advance to avoid costly and time-consuming changes that may affect a usually tight schedule. As a result of visual inspection, followed by "in situ" and laboratory tests and engineering analyses of the affected elements, some elements had to be demolished and reconstructed while others were found to be acceptable.