The design of reinforced concrete structures is an increasingly prevalent topic given society's recognition of the benefits of durability, safety and economy that a well-designed project can provide in light of ABNT NBR 6118 (2023). However, depending on the size and use of the building, it will be necessary that, in addition to the aforementioned standard, the building can meet the fire resistance requirements, considering the fire situation in the design of structural elements. In this context, beams have typical support characteristics and, depending on the building, sizing it to resist fire becomes essential for the stability of the structures. In this scenario, ABNT NBR 15200 (2012) establishes the requirements when it comes to the design of reinforced concrete structures exposed to fire. Knowing the importance that the topic presents in everyday life, and motivated by the deepening of knowledge on the subject, the present work sought to size and analyze a double-supported reinforced concrete beam from a building for commercial use in a normal situation, according to NBR 6118 (2023) and, subsequently, check the sizing of the structural elements considering the fire situation, as recommended by ABNT NBR 15200. To do this, we carry out the sizing of the beam in the Ultimate Limit State (ELU) and Service Limit State (ELS) according to the procedures adopted by ABNT NBR 6118 (2023) and the design and verification of compliance with the Fire Resistance Time (TRF) and the Required Fire Resistance Time (TRRF), based on the recommendations given by the NBR 15200 criteria, being used to verify the TRF and TRRF the tabular, graphic and simplified methods. It was possible to verify that the graphical and simplified methods are more economical than the tabular method, although the latter is the simplest to use based on the characteristics of ABNT NBR 15200 (2012).
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