Prediction of global buckling loads of doubly symmetric pultruded FRP columns subjected to concentric compression

摘要

This paper presents an improved closed-form solution to determine the global buckling capacity of axially loaded pultruded fiber-reinforced polymer (PFRP) columns with doubly symmetry cross sections based on the original solution recommended by Eurocode 3 (EC3). In this improved solution, a newclosed-formequation to determine the reduction factor for global buckling of doubly symmetric PFRP members under axial compression is developed, based on the Ayrton-Perry formula and observed initial out-of-straightness of PFRP members measured by other researchers. Recognizing that data on initial imperfections may be unavailable, a second new empirical closed-form equation is derived to predict the global buckling loads of doubly symmetric PFRP columns based upon the experimental data. Validation of the two explicit solutions taking into account the influence of geometric imperfections of doubly symmetric PFRP shapes is performed by both comparison to experimental data and comparison with validated numerical simulations. In addition, compared with the five closed-form solutions available in the literature, the two proposed solutions exhibit higher accuracy in predicting the global buckling capacity of concentrically loaded PFRP columns with doubly symmetry cross sections. Parametric studies are further conducted, and the influences of the main parameters on the performance of corresponding solutions are discussed. The two proposed solutions can facilitate the global buckling analysis and design of doubly symmetric PFRP columns under concentric compressive loading.