Tests on web crippling strengthening of pultruded glass fibre reinforced polymer sections

Web crippling failure is critical for pultruded glass fibre reinforced polymer (GFRP) sections under concentrated bearing load due to their low material strength in transverse direction. This paper examined two approaches to enhance the web crippling strength of pultruded GFRP sections, through CFRP strengthening or steel tube strengthening. Experimental studies were conducted on the strengthened GFRP square hollow sections (SHS) of two different dimensions. Two loading conditions, end-two-flange (ETF) and interior-twoflange (ITF), were applied to investigate the effect of loading position on the web crippling behaviour. It was found that the web crippling capacity of GFRP section was effectively improved by up to about 85% using CFRP strengthening, and by up to about 4 times using steel tube strengthening.