Analysis of the assessment methods of reinforced concrete beams in fire conditions proposed by NBR 15200

Bolina, Fabrício Longhi; Baques, Benno; Tutikian, Bernardo Fonseca; Rodrigues, João Paulo C.

doi:10.1590/s1983-41952018000600008

Cited by 2 publications

(8 citation statements)

References 9 publications

(14 reference statements)

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“…In this analysis, the closest reinforcement to the heated face was considered. It is worth mentioning that this is a foundation of the tabular method along with width beams and level load (Bolina et al. , 2018; Silva, 2011).…”

Section: Parametric Analysis Resultsmentioning

confidence: 99%

“…The study showed that hyperstatic beams had gains of up to 30 min in fire resistance time compared to isostatic beams. Furthermore, in the analyzed cases, the tabular method resulted in TRRF values higher than the verified TRFs (Bolina et al. , 2018).…”

Section: Introductionmentioning

confidence: 91%

“…The divergence occurred close to the time when the temperature in the tensile flexural reinforcement reaches 500 8C. According to the tabular method, this temperature is considered critical for the safety of reinforced concrete structural elements (Bolina et al, 2018) (Silva, 2011), which is justified by the fact that, for temperatures higher than 500 8C, the steel of the reinforcement has practically no resistance, failing to contribute to the strength of the reinforced concrete element. It is worth mentioning that the critical steel of 500 8C temperature corresponds approximately to the combinations of actions in fire conditions is 70% of combinations of actions in normal conditions.…”

Section: Trf Of Reinforced Concrete Beamsmentioning

confidence: 99%

“…Several studies evaluated and compared the methods of structural elements' verification of reinforced concrete in a fire situation (Associação Brasileira de Normas T ecnicas (ABNT), 2013; Pol ıcia Militar do Estado de São Paulo/Corpo de Bombeiros, 2011a, b). In this context, Bolina et al (2018) analyzed the influence of connections on the TRF of reinforced concrete beams. The study showed that hyperstatic beams had gains of up to 30 min in fire resistance time compared to isostatic beams.…”

Section: Introductionmentioning

confidence: 99%

“…The main disadvantage of this method is that it results in shorter fire resistance times than more complex methods (e Silva and Moreira, 2021; Albuquerque and Silva, 2013). This is because, usually, the tabulated methods do not take into account the real conditions of loading, design and behavior of the structure and can produce less economical results concerning more refined methods (Bolina et al. , 2018).…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the TRF of reinforced concrete beams through thermal and thermostructural analysis

Nicoletti

Oliveira

Souza

et al. 2023

JSFE

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PurposeIn the analysis of structures in a fire situation by simplified and analytical methods, one assumption is that the fire resistance time is greater than or equal to the required fire resistance time. Among the methodologies involving the fire resistance time, the most used is the tabular method, which associates fire resistance time values to structural elements based on minimum dimensions of the cross section. The tabular method is widely accepted by the technical-scientific community due to the fact that it is safe and practical. However, its main criticism is that it results in lower fire resistance times than advanced thermal and thermostructural analysis methods. The objective of this study was to evaluate the fire resistance time of reinforced concrete beams and compare it with the required fire resistance time recommended by the tabular method of NBR 15200 (ABNT, 2012).Design/methodology/approachThe fire resistance time and required fire resistance time of reinforced concrete beams were evaluated using, respectively, numerical models developed based on the finite element method and the tabular method of NBR 15200 (ABNT, 2012). The influence of the following parameters was investigated: longitudinal reinforcement cover, characteristic compressive strength of concrete, beam height, longitudinal reinforcement area and arrangement of steel bars.FindingsAmong the evaluated parameters, the covering of the longitudinal reinforcement proved to be more relevant for the fire resistance time, justifying that the tabular method of NBR 15200 (ABNT, 2012) being strongly and directly influenced by this parameter. In turn, more resistant concretes, higher beams and higher steel grades have lower fire resistance time values. This is because beams in these conditions have greater resistance capacity at room temperature and, consequently, are subject to external stresses of greater magnitude. In some cases, the fire resistance time was even lower than the required fire resistance time prescribed by NBR 15200 (ABNT, 2012). Both the fire resistance time and the required fire resistance time were not influenced by the arrangement of the longitudinal reinforcements.Originality/valueThe present paper innovates by demonstrating the influence of other important design variables on the required fire resistance time of the NBR 15200 (ABNT, 2012). Among several conclusions, it was found that the load level to which the structural elements are subjected considerably affects their fire resistance time. For this reason, it was recommended that the methods for calculating the required fire resistance time consider the load level. In addition, the article quantifies the security degree of the tabular method and exposes some situations for which the tabular method proved to be unsafe. Moreover, in all the models analyzed, the relationship between the span and the vertical deflection associated with the failure of the beams in a fire situation was determined. With this, a span over average deflection relationship was presented in which beams in fire situations fail.

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Section: Parametric Analysis Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

Section: Trf Of Reinforced Concrete Beamsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of the TRF of reinforced concrete beams through thermal and thermostructural analysis

Nicoletti

Oliveira

Souza

et al. 2023

JSFE

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Efectos Del Fuego Sobre La Resistencia De Elementos Estructurales De Hormigón Armado: Una Revision De Literatura

et al. 2021

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El fuego en la estructura hace que aumente la temperatura de la superficie del hormigón, reduciendo así su resistencia a la compresión, flexión y el módulo elástico. Aunque el hormigón tiene un conductor más pobre que el acero, la alta temperatura constante en la superficie provoca el calentamiento gradual en su capa interior. Como material de construcción, el hormigón se usa ampliamente debido a su alta resistencia al fuego, es esencial para resistir uno de los desastres más severos que una estructura puede soportar en su vida. El presente documento tiene como objetivo realizar una revisión sistemática de los efectos que tiene el fuego en las propiedades mecánicas y térmicas de las estructuras de hormigón armado. Se revisaron 50 artículos publicados en base de datos indexadas entre los años 2011 y 2021, distribuidos de la siguiente manera: 28 en Scopus, nueve en Web of Science, ocho en Scielo, tres en ScienceDirect y dos en EBSCO, referentes al hormigón resistente al fuego, temperaturas altas, propiedades mecánicas y conductividad térmica. Para poder comprender el impacto que tiene el fuego en la resistencia de elementos estructurales de hormigón armado se presentaron los resultados de estudios elaborados en el ámbito. Se concluye que los principales efectos del fuego sobre el hormigón armado fueron: 1) disminución en la adherencia entre el hormigón y el acero 2) rotura del hormigón y 3) reducción de la resistencia del hormigón y el acero. Palabras claves: conductividad térmica – efecto del fuego en el hormigón armado – propiedades mecánicas del hormigón armado

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Analysis of the assessment methods of reinforced concrete beams in fire conditions proposed by NBR 15200

Cited by 2 publications

References 9 publications

Evaluation of the TRF of reinforced concrete beams through thermal and thermostructural analysis

Evaluation of the TRF of reinforced concrete beams through thermal and thermostructural analysis

Efectos Del Fuego Sobre La Resistencia De Elementos Estructurales De Hormigón Armado: Una Revision De Literatura

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