Theoretical and experimental investigations of the strengthening effects of glass fiber sheets on channel-shaped PGFRP beam-to-beam bolted connections

This study investigated the strengthening effects of glass fiber sheets (GFSs) on a beam-to-beam bolted connection of pultruded glass-fiber-reinforced polymer (PGFRP) profiles. A total of six full-scale specimens, including three non-strengthened and three GFS-strengthened beams, were experimentally analyzed under four- point bending. Three different end distances in the flanges from the first bolt row to the connection edge were considered (ratios between end distances and bolt diameter are double, three, and four times). The GFSs comprised glass-woven roving (0 degrees/90 degrees) and chopped strand mat (CSM) layers. The (0 degrees/90 degrees)/(CSM)/(0 degrees/90 degrees) GFS laminations were molded via the vacuum-assisted resin transfer molding (VaRTM) method and were bonded to the PGFRP surfaces for strengthening. The results indicated that the GFSs could effectively increase the PGFRP beam-to-beam connection's failure loads. The failure behavior of the GFS-strengthened PGFRP beam-to-beam connections also changed compared with that of non-strengthened specimens. Moreover, theoretical equations were proposed to predict the PGFRP beam-to-beam connections' bending failure loads and modes with high experimental matching.