Influence of fire resistant steel bars on the fire design of simply supported reinforced concrete beams

Resumo

The exposure to fire conditions can cause damage to reinforced concrete structures by reducing their
strength. As a result, even today these accidents cause irreparable material and immaterial losses. Therefore, it is
understood that the technological improvement of structural elements is essential for the advancement of fire safety
engineering. A form of improvement that has been studied in recent years are the steels with enhanced fire
behavior, or “fire resistant steels”, as they are usually known. These special metallic alloys are able to maintain
their mechanical properties for longer when exposed to high temperatures and are already applied to metallic
structures, although their contribution to the performance of reinforced concrete structures is still poorly
understood. The present research seeks to evaluate the influence of this type of material on the fire design of simply
supported reinforced concrete beams using a methodology that adapts the tabular method to verify these structures.
The developed methodology is similar to those presented in NBR 15200 (ABNT, 2012) and Eurocode 2 (CEN,
2004) and considers the use of the improved steel in replacement to the conventional tensile reinforcement. The
study is essentially theoretical and numerical, through the use of the finite element software Super TempCalc, and
the results achieved have shown that there can be a reduction in the minimum dimensions required for beams’
cross-sections by the aforementioned codes if the fire resistant steels are used.