Análise numérica do comportamento estrutural de painéis pré-moldados Tilt-Up em situação de incêndio

Abstract

In response to the effects of fires, studies have been carried out on constructive and structural elements under this condition, aiming to avoid or, at least, reduce the damage caused by the fire exposure. In order to expand research on such subject, this work aims to study the stability of Tilt-Up precast concrete panels under fire condition through computational modeling by the Finite Element Method using the ANSYS program. The building use and the stability of these walls require caution when exposed to fire and must be checked. While the building use can make the environment ideal to spread the fire, stability is a matter of concern, given the high levels of slenderness ratio of the walls, as well as the possibility of changing their boundary conditions. Thus, from the numerical analysis procedure of this research, initially, graphics of the temperature distribution as a function of the wall thickness are defined in order to validate the thermal analysis. Aspects of thermal stresses in structures due to non-linear temperature variation are also addressed, in addition to the implementation of the non-linear physical behavior of concrete in ANSYS. The approach on thermal stresses shows the distribution trend of these stresses as a function of the structure cross section in a thermomechanical analysis. Then, a study of these panels under fire condition is carried out, varying the compressive strength of the concrete, the eccentricity of the load and the fire curve model, in order to evaluate their structural performance. The results show a reduction in displacements and changes in the normal stresses behavior as function of the panels thickness as the compressive strength of the concrete increases. The value of the applied axial load intensifies the bending of the panels, stresses and support reactions, while the effect of a relatively small eccentricity does not impact their structural performance. The decay phase implies a decrease in panel displacements and greater absorption of internal forces. In addition, it is concluded that the 10-meter-high panel resists the TRRF of 60 min required by the standard.