Compressive strength equation for GFRP square tube columns

In this paper, the development of a rational and comprehensive equation to determine the strength of glass fiber reinforced polymer (GFRP) pultruded square tube columns under concentric compression is presented. Material characterization and compression tests on stubs and columns were carried out in order to establish in situ properties. Square tube columns having different lengths and sections, resulting in a range of combinations of global and sectional slenderness, were tested. Material properties, critical loads, compressive strengths and failure modes are reported and comments are made on observed post-buckling behavior and interaction between crushing, local and global buckling. Column and wall imperfections are estimated and used as inputs to the proposed equation. The strength curve is plotted along with the test results, showing good agreement. Finally, a step-by-step example is presented.