Percorrer por autor "Silveira, Matheus Bez da"
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- Computational modeling of the thermal effects on composite slabs under fire conditionsPublication . Balsa, Carlos; Silveira, Matheus Bez da; Mange, Valerian; Piloto, P.A.G.This paper presents finite element thermal models to evaluate the thermal behavior of composite slabs with steel deck, submitted to standard fire exposure. Composite steel/concrete slabs are a mix of a reinforced concrete layer with a profiled steel deck reinforced by steel bars between its ribs. The resulting transient and non-linear thermal problems are solved numerically with threedimensional multi-domain finite element models. The models were developed for normal weight concrete and lightweight concrete, and for different steel deck geometries (trapezoidal and re-entrant). The results of the numerical simulations are used to present a new calculation method to determinate the temperatures on the steel deck components and on the rebars and, consequently, to determine the bending resistance of composite slabs under fire conditions.
- New developments on the bending resistance in composite slabs with steel deck under firePublication . Silveira, Matheus Bez da; Piloto, P.A.G.; Balsa, Carlos; Dias, Gustavo LacerdaComposite steel/concrete slabs can be considered a union of a reinforced concrete layer located above a profiled steel sheet which may or may not be reinforced by steel bars. This configuration allows lightness in the structure, whereas the negative mesh located on the top side of the slab needs to resist only against the concrete shrinkage; the profiled steel deck with the reinforcement bars is responsible for resisting the sagging moments. The main objective of this work is to investigate the fire effect on the bending resistance of the composite slab with steel deck, comparing the behavior of Normal Weight Concrete (NWC) and Light Weight Concrete (LWC) when submitted to standard fire. The Eurocode 1994 1-2 is responsible for providing the guidelines for structural design of composite slabs under fire conditions. This standard presents a simplified calculation model to determine the slab sagging moment. However, it neglects some important effects occurring during a fire situation, such as the air-gap effect and the influence of the concrete layer h1. In order to optimize the calculation model presented by Eurocode 1994 1-2, a parametric study was performed using trapezoidal and re-entrant steel decks geometries. This study comprises two trapezoidal models (Confraplus 60 and Polydeck 59s) and two reentrant models (Multideck 50 and Bondek) with different thicknesses for h1. This analysis consists of a non-linear transient thermal analysis using the finite element method, performed on two different software: ANSYS and MATLAB. Based on the average temperature of each component, new coefficients and calculation proposal for annex D of Eurocode 1994-1.2 are presented, and the slabs reduction load-bearing capacity is determined. By analyzing the results provided by this study, it was possible to conclude that Eurocode 1994-1.2 simplified calculation method produces a lower temperature field than the parametric curves and the New Calculation Proposal, thus confirming the current analytical method produces unsafe results. A comparison of the estimated temperatures between the New Proposal and the temperatures of Eurocode 1994-1.2 showed an average variation of 6% for composite slabs with trapezoidal profiles and 10% for composite slabs with re-entrant profiles, and this effect is intensified for the initial fire resistance classes, which can reach up to 40%. The variation in temperatures also leads to variations in the reduction of the resistant capacity of the slabs; when comparing the two analytical models, the variation is around 3% to 20% for most fire resistance classes and can reach up to 50% for the initial rating times of 30 min and 45 min.
- New developments on the bending resistance in composite slabs with steel deck under firePublication . Piloto, P.A.G.; Silveira, Matheus Bez da; Balsa, Carlos; Dias, Gustavo LacerdaThe main objective of this work is to investigate the fire effect on the bending resistance of the composite slab with steel deck, comparing the behavior of Normal Weight Concrete (NWC) and Light Weight Concrete (LWC), when submitted to standard fire. The bending resistance of these two composite slabs is affected, primarily, by their mechanical properties, but also by their thermal properties [1][2]. The analysis is based on a finite element model, used to solve the non-linear transient analysis of composite slabs. Based on the average temperature of each component, the reduction load bearing capacity is determined, for specific fire ratings (R30, R60, R90 and RI20). The numerical mode1s are simulated using the ANSYS and MATLAB software, to verify the effect of using different modelling techniques.