Abstract:This paper is concerned on the development of a computational model based on finite element procedures for advanced analysis capable of estimating the behavior of reinforced concrete and composite steel-concrete plane structures exposed to fire. The program implemented is called NASEN, the specific thermo-structural module is used to analyze structures under fire conditions. The effects of geometric nonlinearity, material nonlinearity and nonlinear thermal gradients are incorporated into the model, as well as … Show more
“…In [22], a developed computer model based on the finite-element method for advanced analysis capable of assessing the behavior of reinforced concrete structures exposed to fire is offered. The calculations were carried out in the NASEN software package, which is used to analyze structures under fire conditions.…”
Section: Literature Review and Problem Statementmentioning
A finite-element model for the heat engineering calculation of fireproof reinforced concrete slab has been built, which is designed to assess the fire resistance of unprotected reinforced concrete structures. A feature of the model is the correct choice of types of heat transfer in the cavities of reinforced concrete ceilings. An algorithm that includes experimental and calculation procedures in determining the fire resistance of unprotected reinforced concrete structures has been applied. The initial, boundary conditions for the construction of the model were formulated; the thermophysical properties of materials were substantiated. Thermal calculation of fireproof multi-hollow reinforced concrete ceiling under conditions of fire was carried out. The adequacy of the developed finite-element model was checked. A satisfactory convergence of experimental and calculated temperatures with an accuracy of 10 % was established, which would suffice for the engineering calculations.
The model built makes it possible to assess the fire resistance of unprotected reinforced concrete structures. Thus, there is reason to argue that the model constructed can partially or completely replace the experimental assessment of fire resistance, provided that the construction and setting of the model parameters are correct
“…In [22], a developed computer model based on the finite-element method for advanced analysis capable of assessing the behavior of reinforced concrete structures exposed to fire is offered. The calculations were carried out in the NASEN software package, which is used to analyze structures under fire conditions.…”
Section: Literature Review and Problem Statementmentioning
A finite-element model for the heat engineering calculation of fireproof reinforced concrete slab has been built, which is designed to assess the fire resistance of unprotected reinforced concrete structures. A feature of the model is the correct choice of types of heat transfer in the cavities of reinforced concrete ceilings. An algorithm that includes experimental and calculation procedures in determining the fire resistance of unprotected reinforced concrete structures has been applied. The initial, boundary conditions for the construction of the model were formulated; the thermophysical properties of materials were substantiated. Thermal calculation of fireproof multi-hollow reinforced concrete ceiling under conditions of fire was carried out. The adequacy of the developed finite-element model was checked. A satisfactory convergence of experimental and calculated temperatures with an accuracy of 10 % was established, which would suffice for the engineering calculations.
The model built makes it possible to assess the fire resistance of unprotected reinforced concrete structures. Thus, there is reason to argue that the model constructed can partially or completely replace the experimental assessment of fire resistance, provided that the construction and setting of the model parameters are correct
This article presents a numerical formulation based on finite element procedures for application in nonlinear thermo-mechanical analyses of steel planar structures under fire condition. The mechanical properties of structural elements degrade when subjected to high temperatures, resulting in significant reductions in strength and stiffness. Under these conditions, the structures present complex behaviors associated with nonlinear models, requiring an advanced mathematical analysis. As such, a computer program called NASEN has been developed to investigate the behavior of steel structures subjected to fire, considering the effects of geometric and material nonlinearity, as well as the thermal gradients acting on the cross-section. The solution strategy is based on sequential coupling of numerical processes. Initially, the two-dimensional thermal field is determined, followed by an assessment of structural behavior. In each solution step, corrective processes are implemented to ensure convergence of the temperature and displacement nodal vectors. Numerical experiments are performed in order to evaluate the accuracy and capacity of the computer program. Results are compared with experimental tests and computer simulations found in pertinent literature. The program shows good agreement with reference solutions, indicating its accuracy and applicability for the cases studied.
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