In the eighties the work was particularly focused in SFB (SonderForschungsBereich: 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 in case of fire. 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 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 subprojects 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 ISO830-fire as well as to a simulated natural fire condition. The following sections describe the tests and also their theoretical investigation.
|Yayımlanma Tarihi||15 Aralık 2017|
|Yayınlandığı Sayı||Yıl 2017, Cilt 18, Sayı 2|