Numerical failure analysis of built-up columns composed of closely spaced pultruded FRP channels

The results of geometrically nonlinear analyses on 43 built-up Pultruded Fibre-Reinforced Polymer (PFRP) columns with closely spaced chords and intermittent interconnections are presented. A comparison between columns with the end sections entirely loaded and columns loaded at the end battens only is reported, showing no appreciable difference in the P-δ response. The effects due to variations of column length and battens spacing are then investigated. It is found that stocky columns with small battens spacing attain pre-buckling failure at the web-flange junctions of the chords for loads approximately equal to 70% of the crushing load. Slender columns fail by global buckling, whereas intermediate-slenderness columns may experience interaction between local and global buckling. A design method is finally proposed.