Analysis of cold formed structural rack columns.

Este trabalho avalia a ocorr?ncia do modo de associado a flambagem local em pilares curtos constitu?das por perfis formados a frio tipo rack. Estes pilares possuem perfura??es para facilitar a montagem, e este trabalho considera a influ?ncia das mesmas no comportamento e no esfor?o resistente destes perfis estruturais. Os estudos foram realizados por an?lises num?ricas e experimentais, cujos resultados apresentaram boa correla??o e indicaram que as perfura??es n?o afetaram significativamente a carga cr?tica e a capacidade resistente dos pilares, apesar de influenciarem significativamente o comportamento dos mesmos, alterando o n?mero de meias ondas formadas. Observou-se ainda consider?vel influ?ncia das imperfei??es geom?tricas no comportamento da estrutura, indicando a necessidade de sua inclus?o nas an?lises num?ricas.This work presents an evaluation of local buckling in cold formed rack stub columns. These columns have perforations along their length to make assemblage easier, and this research investigates their influence in these structures behavior and resistance. Experimental end numerical analysis were carried out and their results showed good agreement and indicated that perforations in columns don't reduce significantly their buckling load and strength, but affect their buckling modes by changing the number of half waves formed in the columns . It was also observed a considerable influence of geometrical imperfections, indicating the need of their inclusion in the numerical analysis

Numerical and experimental analysis of perforated rack members under compression.

This paper presents a numerical and experimental study of uprights with rack-type perforated section in coldformed profiles, subjected to axial compression. 18 tests were performed on uprights with fixed-ends under uniform compression load to obtain the ultimate load applied, along with the measurement of the displacements. A numerical model with material and geometric nonlinearities was calibrated with the experimental tests. Next, a parametric analysis with 64 different numerical models was performed, determining the ultimate loads of the models. These results, when compared to the DSM predictions, showed that the equations of DSM are unreliable to predict the strength of this type of perforated uprights. Therefore, based on the model results, modifications were proposed to the parameters of the DSM distortional mode curve, so that it can predict the strength of the models studied