Comparative study on mechanical performance of bolted joints with steel and fibre reinforced polymer bolts

Abstract

This paper presents a comparative study on single-bolted double-lap joints with steel bolts and glass fibre reinforced polymer (GFRP) bolt. Three types of steel bolts including plain, galvanised and stainless and a newly developed GFRP bolt were considered. Two preload levels were practiced in the experiments, i.e. snug-tight and full-tensioning. The torque-preload relationships for different types of bolts were investigated in reference to international standards. It was found that galvanised bolt showed the highest efficiency of torque conversion into bolt preload, while the GFRP bolt the lowest. Static experiments and finite element (FE) analysis were then conducted and the mechanical performance of bolted joints with steel and GFRP bolts in shear were comparatively studied in terms of failure modes, load-displacement and load-strain responses. Similar joint stiffness or capacity was found for the joints with GFRP or steel bolts under snug-tight condition. High preload level can significantly increase the joint capacity by up to 89.2% for bolted joints with steel bolts while only 9.8% for GFRP bolted joints. The developed FE modelling considering contact behaviours and pretension can well predict the mechanical behaviour of single-bolted double-lap joints including initial slip.