Influences of fire resistant concrete structure (FGU2003/004)
Overview
Background & policy context:
The nature of concrete-based structures means that they generally perform very well in fire. However, concrete is fundamentally a complex material and its properties can change dramatically when exposed to high temperatures. The principal effects of fire on concrete are loss of compressive strength and spalling – the forcible ejection of material from the surface of a member.
Though a lot of information has been gathered on both phenomena, there remains a need for more systematic studies of the effects of thermal exposures. The response to realistic fires of whole concrete structures presents yet greater challenges due to the interactions of structural elements, the impact of complex small-scale phenomena at full scale, and the spatial and temporal variations in exposures, including the cooling phase of the fire.
Objectives:
The main aim of the project is to test the influence of the porosity of the concrete with the proposed test program as well as the thickness of component on the spalling of the concrete in case of fire. The project will analyse the newest findings published in scientific literature and the project findings will be verified using the fire tests.
Methodology:
The following methods will be used: Literature review and subsequent laboratory tests on specially prepared test specimens.
It is suggested to discover the influence of porosity and component humidity on the fire resistance through two test series. The tests will be based on further knowledge of literature on evaluations as well as a defined temperature. In the first phase the available information in literature, which concern the mentioned subject, will be evaluated. It is thus guaranteed that no double determination will occur. Qualitative statements could set up the right priorities. Plates with different w/z-ratio and air-content will be manufactured. These are going to be tested in fire tests on their fire resistance. The humidity of the plates are constant. Parallel to the samples of the first test, samples with higher bending resistance will be produced. Like that it is guaranteed that the influence on the concrete prescription do not have to be considered on the comparison on the results. The prescription, which show the highest fire resistance in the first test will be tested in the second test with a higher bending resistance.
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