Analysis of heat transfer mechanisms on hollow concrete masonry units under standardized fire conditions

Resumo

Concrete structural masonry is widely used on high-rise buildings in Brazil. Through the past decades
some effort on research in the topic have been made but there is still a need for research on masonry fire safety.
This is reflected in the lack of a Brazilian National Standard regarding masonry under fire conditions. In this
context, it is of interest to assess the influence of the cavities present in concrete masonry units (CMU) on thermal
behavior. This paper uses ABAQUS software to perform numerical simulations and assess the relative importance

of radiation and convection inside cavities in concrete masonry units under standard ISO 834-1:1999 fire condi-
tion. Radiation between cavity surfaces and fluid convection are considered using coupled fluid-solid transient heat

transfer analysis. The simulation procedure is validated using available experimental data on literature. After vali-
dated, parametric analysis is performed through simulations using different concrete emissivity values on cavities.

Results show that when concrete cavity surface has high emissivity value the radiation dominates the solution and
air flow has negligible effect in the heat transfer inside the cavities.