On the Local Buckling of Pultruded GFRP I-Section Columns
Gisele G. Cintra1; Daniel C. T. Cardoso1; Janine D. Vieira2
1 Pontifical Catholic University of Rio de Janeiro (PUC-Rio); 2 Federal Fluminense University
doi:10.20906/CPS/CILAMCE2017-0568
Resumo
Glass-fiber reinforced polymers (GFRP) have contributed to advance civil engineering due to its several advantages over traditional materials, including their corrosion resistance, lightweight and versatility in section geometry and properties. The pultrusion process has reduced the manufacturing costs, increasing the quality control and becoming a fast and economical method of producing GFRP profiles. To spread and encourage the use of the material and allow for safe structural design, considerable research has been conducted worldwide to develop standard provisions. Although modern, the preliminary versions of these documents still contain old-fashioned conservative equations for prediction of local buckling critical stress of I-section columns and, therefore, additional studies on the local buckling behavior are still necessary. This paper aims to present the results of an experimental program on the local buckling behavior of GFRP I-section columns conducted at PUC-Rio. Characterization tests were made to determine the material properties and thirty-two stub columns having three different flange-to-web ratios, overall lengths and walls end-condition were tested under compression. With the aid of the software GBTUL, based on the Generalized Beam Theory, so-called signature curves (critical stress versus length) were obtained and lengths were determined to ensure 'pure' local buckling. Experimental data are reported and a discussion on the observed behavior is made, including strength, pre-buckling behavior, post-buckling reserve of strength and the influence of length and end-conditions in the critical load. It is also shown that the use of traditional Southwell plot technique leads to greater critical loads and an alternative procedure considering post-buckling behavior is proposed to determine the bifurcation load.
Palavras-chave: Local buckling; Pultrusion; Orthotropic Materials; GFRP