Thermomechanical simulation of prisms with concrete blocks in a fire situation

ABSTRACT

Fires in buildings are frequent in the world. Concrete blockwork masonry is a constructive system widely used in Brazil and poorly studied in a fire situation. At room temperature, the axial compressive strength of the masonry can be estimated by axial compression of prisms. In addition, by means of prisms, it is possible to represent the loss of mechanical resistance due to thermal deterioration. Thus, the purpose of the current study is to verify, in purely numeric context, the mechanical resistance of prisms with concrete blocks under compression in a fire situation, through thermomechanical simulation. Initially, the compression of the prism was simulated at room temperature with the objective of validate the materials’ properties. Posteriorly, it was adopted in the study properties based on the technical literature, at high temperatures. The boundary conditions were varied, two levels of loading were applied and cases of prism with one and two faces exposed to fire were verified. In the simulations, the application of a higher loading level, the vertical displacement restriction and the double-sided fire exposure anticipated the prism failure. The lack of rotational restraint generated a mode of rupture different from the case with rotational restraint and in less time of fire. The use of properties found in the technical literature led to a time of mechanical resistance favorable to safety.

Keywords
concrete blocks; structural masonry; high temperatures; mechanical resistance; numerical analysis