No abstract

This work presents a state-of-the-art review of existing fireproof construction guidelines for dwellings against wildfires. The most important wildfire-proof construction guidelines and codes for dwellings are presented, and these are later associated with existing fire engineering chapters associated with building codes. It was concluded that the variability in this subject is very high, and the approach to classifying the thermal effects in construction still lags behind scientific consensus. Moreover, the constructive requirements depend severally on the country’s building code when assessing the fireproof requirements for wildfire. Moreover, the thermal actions of wildfires in dwellings are presented and compared with classical ISO-834 standard fire curves, in which the maximum equivalent fire exposure time can range from 2 to 4 h depending on the country’s code. The key contributions of this work consist of (i) thoroughly disseminating codes and guidelines to promote scientific discussion in order to advance the wildfire fireproof standards dedicated to WUI; (ii) emphasizing the void in current codes in order to promote conversation between future researchers.

This paper presents a numerical study on the thermal effect of the insulation of lightweight concrete in hybrid GFRP-concrete structures. In these hybrid structures, the GFRP profiles are totally covered by normal and lightweight concrete and subjected to thermal loads. The problem with GFRP structures is their weak thermal resistance, even at moderately high temperatures. To promote some thermal insulation, it is recommended to cover the GFRP profile with concrete, but this increases its weight. Therefore, lightweight concrete may be a good solution due to its insulation capabilities. For this study, the thermal loads used in the numerical campaign are based on a nominal fire-curved ISO-834, and the temperature is measured at several points. Using these temperatures, it is possible to conclude that the effect of lightweight concrete may provide structural benefits when compared with classical standard structural concrete for covering GFRP profiles using different cover values (from 5.0 cm to 2.5 cm). For this work, commercial finite element software was used for the thermal nonlinear analysis. It was possible to conclude that with lightweight concrete, it is likely to have half of the cover and still maintain the same level of insulation as regular concrete.

This paper aims to use non-linear physical analysis to calculate the displacement of beams and slabs in a cracked state. This study uses the commercial software SAP2000 to perform a numerical analysis using the finite element formulation, applying the multi-layer method. Initially, a parametric study was carried out to evaluate the vertical displacement for service loads of reinforced concrete beams and slabs using different spans, support conditions and geometry. In order to validate the finite element model, the study compared displacement values for linear analysis using Bares tables. Subsequently, simplified methods of displacement calculation in the long term are applied, using an abacus from Comité Euro-International du Béton (CEB). These values are then compared with the physically non-linear analysis in the long-term cracked state with SAP2000. Two structural codes were used in the numerical and analytical methods, Regulamento de Estruturas de Betão Armado e Pré-Esforçado (REBAP) and Eurocode 2 (EC2), to evaluate their differences in deformation control. Therefore, the main goal is to establish comparisons between the two methods of analysis in order to show that non-linear finite element modelling provides values that are lower than the analytical calculation, thus allowing greater economy in the design of structural reinforced concrete elements. In addition, it can be noted that EC2 has some inconsistencies in the design of simply supported slabs, requiring a greater thickness than a flat square slab and that indirect deformation for REBAP is underestimated for beams and, in some cases, for slabs.

RESUMO A utilização de fibras de aço no concreto vem recebendo forte atenção pela possibilidade de reduzir significativamente o consumo de barras de aço nas estruturas de concreto armado. Entretanto, ainda são poucos os trabalhos encontrados sobre a durabilidade de concreto com fibra de aço e sobre o desempenho da ancoragem das barras metálicas em concretos reforçados e submetidos a ataques de íons cloreto. Buscando contribuir para o melhor entendimento do assunto, este trabalho apresenta resultados para 12 (doze) amostras prismáticas (100x100x250) mm3. Cada amostra recebeu uma barra de aço de 8 mm de diâmetro que foram divididas em 2 (dois) grupos iguais, sendo que um grupo foi submetido ao ensaio de corrosão acelerada por imersão modificada (CAIM) e o outro não, avaliando-se os danos ocasionados pelo ataque de íons cloreto tanto nas barras quanto nas fibras de aço. Cada grupo apresentou 3 (três) amostras com 1% de fibra de aço e outros 3 (três) sem fibra, e os comprimentos de ancoragem (lb) foram de 100 %, 75 % e 50 % necessário daquele recomendado pela norma Brasileira NBR 6118. Verificou-se que não há comprometimento da perda de aderência das barras com o substrato de concreto, quando reduzido o (lb) em 25 % garantindo a funcionalidade, podendo resultar em redução de custos. Observou-se ainda que nas amostras submetidas a corrosão com fibras ou sem fibras houve perda de massa, não sendo constatado que a presença de fibras possa ter contribuído para reduzir essa perda, contudo é possível observar uma relação direta entre o menor valor de (lb) e a menor perda de massa.