Browsing by Author "Santos, Lucas Manoel Cunha"
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- Critical temperature for the components of composite slabs with steel deck under fire for load-bearing ratingPublication . Piloto, P.A.G.; Balsa, Carlos; Ribeiro, Fernando; Santos, Lucas Manoel Cunha; Rigobello, Ronaldo; Kimura, Érica Fernanda AikoComposite slab made with concrete and steel deck are widely used in building structures. They also include other components, such as steel rebars for positive bending and a steel mesh for negative bending. The fire rating of this type of elements can be determined by standard fire tests, accounting for load (R), Integrity (E) and Insulation (I). This investigation deals with the fire resistance for load (R) and insulation (I), using a numerical model validated with experimental tests. This model considers material and geometric non-linear behaviour, using perfect contact between materials. The 3D finite element mesh uses solids, shells and bars, to model a simple supported composite slab with 3.2m long, 0.65 m wide and total height of 143mm, using a trapezoidal steel deck PRINS PSV73. Different load levels are simulated (live load ranging from 1.0 K/m2 to 21 kN/m2) in addition to the dead load (2.8 kN/m2). The fire resistance is determined according to standards, looking for the maximum displacement or the rate of displacement. The critical temperature of each steel component decreases with the load level. A new proposal is presented for the critical temperature of each steel component.
- Critical temperature for the components of composite slabs with steel deck under fire for load-bearing ratingPublication . Piloto, P.A.G.; Balsa, Carlos; Ribeiro, Fernando; Santos, Lucas Manoel Cunha; Rigobello, Ronaldo; Kimura, Érica Fernanda AikoComposite slabs made with concrete and steel deck are widely used in building structures. They also include other components, such as steel rebars for positive bending and a steel mesh for negative bending, preventing cracks in concrete. The fire rating of this type of elements can be determined by standard fire tests, accounting for load (R), Integrity (E) and Insulation (I). This investigation deals with the fire resistance for load (R) and insulation (I), using a numerical model validated with experimental tests. This model considers material and geometric non-linear behaviour, using perfect contact between materials. The 3D finite element mesh uses solids, shells and bars, to model a simply supported composite slab with 3.2m long, 0.65 m wide and total height of 143mm, using a trapezoidal steel deck PRINS PSV73. Different load levels are simulated (live load ranging from 1.0 kN/m2 to 21 kN/m2) in addition to the dead load (2.8 kN/m2). The fire resistance (R) is determined according to standards, looking for the maximum displacement or the rate of displacement, while the fire resistance (I) looks for the average or for the maximum temperature increase at the unexposed side. The critical temperature of each steel component decreases with the load level. A new proposal is presented for the fire resistance depending on the load level.
- Efeito do nível de carga no comportamento ao fogo de lajes mistas com chapa de aço colaborantePublication . Santos, Lucas Manoel Cunha; Piloto, P.A.G.; Balsa, Carlos; Kimura, Érica Fernanda AikoLajes mistas de concreto com chapas de aço colaborantes consistem em estruturas de concreto moldadas em fôrmas de aço que devem permanecer unidas à estrutura, agindo de forma permanente como parte da armadura para as lajes. Esta tecnologia construtiva está presente na construção civil desde os anos 80, sendo utilizada principalmente em grandes edifícios por ser uma alternativa altamente econômica quando aplicada em larga escala. As chapas de aço desempenham um importante papel na resistência mecânica destas estruturas e quando submetidas a situações de incêndio acabam por exigir uma maior atenção pois a alta sensibilidade das propriedades térmicas e mecânicas do aço quando exposto a altas temperaturas coloca em risco estas estruturas. A norma europeia EN 1994-1-2 é responsável por padronizar os métodos de projeto e de cálculo para verificação da segurança destas estruturas quando submetidas a situações de incêndio, e dela provém métodos simplificados de cálculo para projetistas. Entretanto, estes métodos simplificados não são submetidos a revisão à mais de uma década. Este trabalho apresenta o estudo do efeito do nível de carregamento sobre a resistência ao fogo das lajes mistas de concreto com chapa de aço colaborante a partir de modelos numéricos elaborados com o software ANSYS Mechanical APDL e validados com base em trabalhos experimentais já realizados por outros autores. Ao todo, 158 simulações foram realizadas e os resultados indicam correlações da resistência ao fogo destas estruturas com base no nível de carregamento e na espessura efetiva das lajes. Junto a isso, é proposto um novo modelo de cálculo para a resistência ao fogo, de lajes mistas com chapa de aço colaborante, segundo o critério de capacidade de carga (R), tendo como variáveis o nível de carregamento e a espessura efetiva das lajes.
- Effect of the load level in the fire resistance of composite slab with steel deckingPublication . Balsa, Carlos; Santos, Lucas Manoel Cunha; Piloto, P.A.G.; Kimura, Érica Fernanda Aikoconsists of cold-formed profiled steel deck which acts as a permanent formwork to the concrete topping. Normally, this composite solution requires the addition of other components such as steel rebars (placed within the ribs) for positive bending and steel mesh for negative bending, preventing cracks in concrete, see Figure 1. Due to the external reinforcement provided by the steel deck, composite slabs generally require less additional reinforcement and less concrete as well, resulting in slender slabs. In addition, the reduction of the construction time, elimination or reduction of struts and the simplicity of installation, are other advantages of composite slabs in comparison to conventional flat concrete slabs. The composite action between the concrete and the steel deck is generally achieved by indentations or embossments in the steel deck.
- Effect of the load level in the fire resistance of composite slab with steel deckingPublication . Balsa, Carlos; Santos, Lucas Manoel Cunha; Piloto, P.A.G.; Kimura, Érica Fernanda AikoThe composite slab with steel decking is widely used in every type of buildings and requires fire resistance, in accordance to regulations and standards. The concrete is usually reinforced with a steel mesh on the top and may also be reinforced using individual rebars. The fire assessment should consider the criterion for stability (R), Integrity (E) and insulation (I). The scope of this investigation concerns the fire rating for the R and I criteria. Numerical simulations with finite elements were developed, using ANSYS, to find out the thermal and mechanical effects of standard fire exposure. The fire resistance criteria for loadbearing (R) depends on the maximum displacement (D) or on the rate of displacement (dD/dt), while the fire resistance for insulation depends on the maximum or average temperatures in the unexposed side. A literature review from different investigations is presented [1] [2]. The results of the numerical simulation are compared with experimental results to validate the model [3]. The results are also compared with the simplified method proposed by Eurocode 4-part 1.2 [4].
- Effect of the load level on the resistance of composite slabs with steel decking under fire conditionsPublication . Piloto, P.A.G.; Balsa, Carlos; Santos, Lucas Manoel Cunha; Kimura, Érica Fernanda AikoThe fire resistance of composite slabs with steel decking, in Europe, is usually defined using simple calculation models provided by the Eurocode EN 1994-1-2. For assessing the methodology of these simple calculation methods, a new advanced calculation method is presented, using the software ANSYS. The numerical model is first validated with experimental data reported on bibliography and then a parametric analysis is conducted to better understand the effect of the load level on the composite structure under fire. The validation of the simulations consisted of three different models: the first model considers perfect contact between the steel deck and the concrete topping, and the two following models consider the existence of an air gap between these materials, acting as a thermal resistance on the temperature field through the thickness of the slab. The numerical results show good approximation to the experimental results, mainly when using the non-perfect contact model, reaching 3.88% and 16.91% of difference with respect to the insulation and load-bearing criteria, respectively. Based on the validation models, a parametric study is presented, modifying the load level from 10% up to 75%. New simple calculation models are presented to define the fire resistance of composite slabs, considering the load level, and the debonding effect between the concrete and the steel deck.
- Influence of load-level and effective thickness on the fire resistance of composite slabs with steel deckPublication . Santos, Lucas Manoel Cunha; Piloto, P.A.G.; Balsa, Carlos; Kimura, Érica Fernanda AikoComposite slabs with steel deck have been used on building construction due to its fast-and-easy crafting that brings economic outstanding alternatives to architects and engineers on large-scale steel framed constructions. At room temperatures and in Europe, the designing procedures of composite slabs are defined by Eurocode 1994-1-1. When it comes to the fire safety analysis of these elements, the designing procedure requires more attention due to the direct exposition of the steel deck to fire, affecting the overall bending resistance. This importance is presented in Eurocode 1994-1-2, taking in consideration the integrity, insulation and load-bearing criteria. In this work the thermal and mechanical behavior of composite slabs with steel deck exposed to standard fire ISO 834 are studied through numerical simulations using Finite-Element Method (FEM). The model was previously validated with one experimental test from literature. The ANSYS Mechanical APDL software was used to develop a parametric study, simulating four different geometries with different load levels, comprehending a total of 126 thermal and mechanical simulations used to determine the correlation between load-level and fire resistance. As result, a new simplified method is proposed for the load bearing fire resistance of composite slabs, considering the effect of the effective thickness and the load level. The fire resistance decreases with the load level and increases with the thickness of the concrete. A new proposal is presented to determine the fire resistance, based on these two parameters.
- Three-dimensional numerical modelling of fire exposed compositew slabs with steel deckPublication . Piloto, P.A.G.; Balsa, Carlos; Ribeiro, Fernando; Santos, Lucas Manoel Cunha; Rigobello, Ronaldo; Kimura, Érica Fernanda AikoComposite slabs with reinforced concrete and cold-formed profiled steel deck are very popular and reduce the building construction time. The steel deck acts as a permanent formwork to the concrete topping. Usually, the concrete is reinforced with individual rebars placed within the ribs for positive bending, and a steel mesh on the top for negative bending and to prevent concrete cracking. The fire rating of these building elements involves the analysis of different criteria, namely load bearing (R), integrity (E) and insulation (I). The integrity is easily verified, due to the construction method. The other two metrics require the development of experimental fire tests, the application of simplified calculation methods or the development of advanced calculation models. This investigation introduces 3-D numerical validation models for load bearing (R) and insulation (I) criteria. Parametric analyses are developed to investigate the effect of the load into the fire resistance (R) and critical temperature of the steel components (deck, rebar and mesh), as well as the effect of the concrete thickness on the fire resistance from the insulation standpoint (I). The advanced calculation model consists of a non-linear analysis for the thermal and structural behaviour. Both thermal and mechanical models consider perfect contact between materials. For the thermal model, an alternative model is used, with an air gap included between the steel deck and concrete topping to simulate debonding effects. For the mechanical model, the live load level changes from 1.0 kN/m2 to 21.0 kN/m2, and the dead load presents a constant value of 2.8 kN/m2. The fire resistance is determined according to standards, based on the maximum displacement or the rate of displacement. The critical temperature of each steel component decreases with the load level. A new proposal is presented for the critical temperature of each steel component and for the fire resistance according to the insulation criterion.
- Validation models on the fire resistance of composite slab with steel deckPublication . Piloto, P.A.G.; Balsa, Carlos; Ribeiro, Fernando; Rigobello, Ronaldo; Santos, Lucas Manoel Cunha; Kimura, Érica Fernanda AikoConcrete slabs with profiled steel deck are slabs that use steel deck as a permanent form work,and reinforced concrete placed on the top.Thefire rating of this type of elementis determined by standard fire tests, accounting for load bearing(R), integrity(E) and insulation(I). In this work, different composites labs are numerically teste du sing the standard fire curve ISO834 to evaluate the insulation criterion(I) and the load bearing criterion(R). Three-dimensional numerical simulations are performed using the Finite Element Method to investigate the thermal effects of standard fire explosure.