Bolted glass-fibre-reinforced plastic joints

Abstract

Test results are presented for single fastener glass-fibre-reinforced plastic (GFRP) members connected with GFRP threaded rods, steel threaded rods, and steel bolts. Twenty-eight joints were tested in tension and thirty-five were tested in compression. For some of the tests, a GFRP pipe was used as a protective sleeve for the threads of the steel and GFRP threaded rods. The effect of fastener strength and stiffness on the load carrying capacity of the joints is reported. The major findings for both the tension and compression tests were that joints constructed with a GFRP threaded rod had approximately half the strength of joints constructed with a steel threaded rod. Also, joints constructed with a GFRP threaded rod and GFRP pipe sleeve were at least a third stronger than joints constructed with a GFRP threaded rod alone. The GFRP members used consisted of a pultruded glass fibre sheet, which was composed of symmetrically stacked, alternating layers of identically orientated unidirectional E-glass fibres and randomly orientated E-glass continuous strand mat. The maximum load carrying capacity decreased with increasing angle of loading with respect to the unidirectional fibres, but this was more pronounced for the tension tests than for the compression tests. For the tests performed, it was sufficient to finger tighten end nuts; indeed, tightening end nuts by a half turn-of-the-nut slightly decreased the strength of the joints. Key words: glass-fibre-reinforced plastic, connections, fibreglass bolts, experimental.