Multi-Bolted Connection Pultruded GFRP Strengthening by Glass Fiber Sheets: Influence of Bond Strength

Abstract

The multi-bolted method is typically used for pultruded GFRP (PGFRP) connections. As the capacity of PGFRP structures is governed by connection strength, many researchers have sought to improve this performance. In a previous study investigating the effectiveness of glass fiber sheets (GFSs) in strengthening multi-bolted connections, debonding failure was observed as a failure mode in various types of GFSs, including 0°/90° and ±45° with 4 and 5 bolts. The present study tested four types of specimens to characterize failure modes when PGFRP is multi-bolted with GFS strengthening. Different failure modes were observed with two different numbers of bolts. Based on the observed failure sequences and previous material properties tested, a calculation equation was proposed. The estimated strength showed good agreement with experimental results. Furthermore, the study highlights some features of the failure load (such as the type of GFS and tensile strength) as recommendations for designing strengthening of PGFRP bolted connections.