EXPERIMENTAL AND COMPUTATIONAL RESEARCH ON THE FIRE BEHAVIOR OF RESTRAINED REINFORCED CONCRETE COLUMNS – PART II

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In the eighties, the work was particularly focused in SFB (Sonder Forschungs Bereich: A special fire research activity for structural elements in Braunschweig Technical University, 1971-1986) on the development of a universal material model for normal concretes for fire case. Through a comprehensive mathematical description of the rheological phenomena at elevated temperatures, the relaxation behavior of restrained columns could be successfully predicted. It aimed at clarifying the difference, which took place between the lateral deformation behavior as well as restraint forces of calculated and measured reinforced concrete columns (RFC) under fire conditions. Such a material model was developed, in fact, through close cooperation of sub-projects A and B3 of SFB. Naturally, the use of such material model requires an immense computational treatment. Theoretical studies have shown, however, that this is worthwhile, because only by this process the fire behavior of structural concrete elements can be taken into account satisfactorily. It should be stressed here that a material model can gain confidence only if it has been tested successfully under different boundary conditions. In particular, the model must apply for the assessment of the fire behavior of structural elements in large scale. In this regard, relaxation tests on reinforced concrete columns under different boundary conditions have been carried out in the special furnace of SFB. The heating of the reinforced concrete columns have been made with respect to ISO834 Fire as well as to a simulated fire condition. The following paragraphs describe the tests and also their theoretical investigation.

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Structural fire safety , reinforced concrete columns , fire resistance , relaxation , fire behavior

Trakya university journal of engineering sciences

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Trakya university journal of engineering sciences