Masonry has superior fire resistance properties stemming from its inert characteristics, and slow degradation of mechanical properties. However, once exposed to fire conditions, masonry undergoes a series of physio-chemical changes. Such changes are often described via temperature-dependent material models. Despite calls for standardization of such models, there is a lack in such standardized models. As a result, available temperature-dependent material models vary across various fire codes and standards. In order to bridge this knowledge gap, this paper presents three methodologies, namely, regression-based, probabilistic-based, and the use of artificial neural (ANN) networks, to derive generalized temperature-dependent material models for masonry with a case study on the compressive strength property. Findings from this paper can be adopted to establish updated temperature-dependent material models of fire design and analysis of masonry structures.
Masonry is an inert construction material with favorable thermal and mechanical properties. While masonry is widely used in buildings, the fire performance of this material has not received much attention over the years. This continues to hinder the understanding of the fire behavior of masonry. To bridge this knowledge gap, this study presents the results of an experimental campaign carried out on concrete masonry blocks (CMUs) to investigate fire-induced degradation of the compressive strength of CMUs under elevated temperatures and post-fire conditions. In this campaign, steady-state tests were conducted; wherein standard-sized CMUs are exposed to a heating scenario ranging from 25 to 800 C followed by cooling to ambient temperature. In addition, these tests were also complimented with a thermogravimetric (TGA) analysis to arrive at a comprehensive understanding of the degradation of the strength property of masonry. Results from the tests clearly show that the degradation in CMUs is lower than that typically observed in normal strength concrete. Furthermore, our findings also infer that masonry is capable of retaining a larger percentage of strength when tested under post-fire conditions as opposed to being under heating.
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