Numerical Investigation of Cold-Formed Purlins with Longitudinal Stiffeners in Shear

Abstract

Presenta una investigación numérica sobre el pandeo por cortante y la resistencia a cortante de correas de acero conformadas en frío con rigidizadores de alma longitudinal inclinada. Basado en el método de elementos finitos (FEM) y el uso del software ABAQUS/Standard, esta investigación implica el desarrollo de un modelo numérico del novedoso equipo de prueba de actuador dual, que permite el estudio de corte de correas CFS con alta relación de aspecto (corte lapso/profundidad de red). Posteriormente, se han realizado simulaciones FEM-ABAQUIS en canales con rigidizadores de alma longitudinal inclinados y relación de aspecto 2,0. Más precisamente, se simularon cinco canales de alma rigidizados con diferentes alturas de refuerzo y un ancho constante de 5,0 mm junto con un canal de referencia adicional sin rigidizar. La relación entre las entradas, los rigidizadores longitudinales inclinados del alma y las imperfecciones geométricas iniciales, y las salidas, el modo de falla, el pandeo por cortante y la resistencia al cortante, se analizaron en profundidad para comprender mejor el comportamiento a cortante de los canales de alma rigidizada con respecto al canal no rigidizado.

In the steel building industry, Cold-formed steel (CFS) members have a variety of applications, being purlins one of particular interest, these structural members are usually used to transfer roof desk loads to the structural frames. CFS enables to manufacture of purlins in different complex shapes, and one of them are channels with longitudinal web stiffeners. It is known that the addition of longitudinal web stiffeners increases the shear strength capacity of CFS channels; however, it is not evident in how much. In that sense, this thesis presents a numerical investigation on shear buckling and shear strength of CFS purlins with inclined longitudinal web stiffeners. This research involves the development of a numerical model of the novel Dual Actuator Test Rig, which enables the shear study of CFS purlins with high aspect ratio (shear span/web depth). This stage of the investigation is based on the Finite Element Method (FEM) by using the software ABAQUS/Standard. Afterwards, FEM-ABAQUS simulations have been performed on channels with inclined longitudinal web stiffeners and aspect ratio of 2.0. More precisely, five stiffened web channels with different stiffener depths and a constant width of 5.0 mm were simulated along with an additional reference unstiffened channel. The relationship between the inputs, inclined longitudinal web stiffeners and initial geometric imperfections, and the outputs, failure mode, shear buckling and shear strength, were deeply discussed to understand better the shear behaviour of the stiffened web channels and its correlation with the unstiffened channel. Furthermore, the FEM outcomes were subsequently plotted against Direct Strength Method (DSM) shear curves, to verify the accuracy of the numerical results and the reliability of the current DSM shear equations.