Estabilidade e Resistência de Colunas em Perfis U Pultrudados Reforçados com Fibra de Vidro sob Falha Global

Abstract

The construction industry is constantly seeking the development and improvement of materials that can meet its needs in a more complete way. Currently, composites are gaining visibility in this sector, as they are an arrangement arising from constituents with different characteristics, which result in a material with properties superior to those that originated it.

Glass fiber reinforced polymers (GFRP) have several advantages, including structural efficiency, durability in aggressive environments, diversity of cross-sections, lightness, high strength, easy and quick installation, among others, that have encouraged the use of this constructive system in different sectors. This material, unlike steel, has different mechanical properties on each axis and when it comes to fiber reinforced profiles, these characteristics are susceptible to variation according to fiber content, resin type, void volume and manufacturing mode, making them more complex in predicting behavior. Furthermore, according to Cintra (2017), the use of slender profiles combined with a low modulus of elasticity leads to important instability problems (e,g,, buckling).

In this context, the current work presents, through a numerical-computational study, on the performance of fixed-ended columns consisting of U-profiles formed from GRPs under global failure mode by flexural-torsional or flexural. The first step consists of the careful selection of columns (geometry and lengths) to be evaluated, using the GBTul program (according to the Generalized Beam Theory). At this stage, ten cross sections are obtained, and a total of forty-eight columns are chosen.

After that, the FEM (Finite Element Method) is applied via Ansys computational/commercial code for non-linear physical and geometric analysis, using shell elements (Shell 181), to simulate the structural behavior of buckling, post-buckling and ultimate resistance. The results obtained, namely equilibrium trajectories, buckling modes and the resistance defined by a collapse criterion, are analyzed for a better understanding of the performance of this type of composite.

Among the main conclusions of this research are the studied GFRP columns subjected to F_m did not present post-buckling resistance, while those subjected to F_MT exhibited a notable energy reserve, reaching, in some cases, values ​​higher than 1,8 P_cr; Furthermore, the initial failures occurred close to f_cr, and for all cases of Fm the load at the time If =1 is smaller than f_cr.