Web crippling of pultruded GFRP built-up sections

Web crippling is a critical premature failure of pultruded glass fiber reinforced polymer (GFRP) composites. One solution is to combine several sections to form a built-up section to carry the web crippling load. However, there is no existing study on the web crippling behavior of built-up sections under transverse loading. This paper presents an experimental and analytical study on the web crippling behavior of built-up I-shaped sections. The I-shaped sections were made by connecting two single channel sections back-to-back. Two connections methods were used including adhesive bonding and mechanical bolting. The bolt arrangements including number of bolt rows in the longitudinal direction, bolt spacing were varied to understand their effects on the web crippling behavior. The built-up sections were tested under two loading conditions of ITF and ETF, and the failure modes, load–displacement curves, and web crippling capacities were reported. Finally a section integrity enhancement coefficient was introduced in the analytical model to predict the web crippling capacity of built-up I-shaped sections and the predictions agreed well with the experimental results. This study contributes to the understanding of web crippling behavior of built-up sections made with pultruded GFRP sections.