New mandatory-language design standards – ASCE 74 and CEN/TS 19101 in the United States and Europe, respectively – address the structural design of pultruded GFRP structures. This paper focussed on the local flange buckling and web buckling limit states of members loaded in concentric axial compression promulgated in these standards. Parametric evaluations of the concentric axial-induced local buckling provisions of ASCE 74 and CEN/TS 19101 are presented. The assumption of web or flange rotational restraint – whether simply-supported, as assumed in ASCE 74, or rotationally restrained by the flange-web junction, for which more complex provisions are permitted in CEN/TS 19101, is shown to have a large impact on calculated local flange or web buckling capacity. It is additionally shown that the calculated design capacity based on simply supported conditions does not provide the same degree of conservativeness depending upon whether flange or web buckling controls behaviour. An alternative, semi-empirical approach to conservatively estimating the local buckling capacity accounting for rotational restraint of the flange-web junction(s) is presented which offers a simplified approach for ASCE 74 to address this behaviour or an alternative to CEN/TS 19101 C5.5.