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Failure of pultruded GRP single-bolt tension joints under hot-wet conditions.

Research output: Contribution to journalJournal article


Journal publication date1/02/2007
JournalComposite Structures
Number of pages7
Original languageEnglish


An experimental study of the effects of hot–wet conditions on the load carrying capacity of pultruded GRP (glass reinforced plastic) single-bolt tension joints has been carried out. The bolted joints were failed in tension after being immersed in water at three temperatures for two periods of time. Two joint geometries, defined in terms of end distance and width to bolt diameter, were tested with the pultrusion and tension axes coincident. The reductions in the load capacities of the joints due to the hot–wet conditions were quantified and shown to be very large. For example, it was found that more than 60% of the load carrying capacity of a single-bolt tension joint was lost after being immersed in water for 6.5 weeks at 60 °C. This temperature is lower than the manufacturer’s recommended maximum service temperature for this type of pultruded GRP material.

Bibliographic note

This paper, together with three companion papers by the same authors, has increased understanding of the design of pultruded GRP connections in hostile environments. The information provided therein has impacted on the design of joints between pultruded GRP profiles, which are used increasingly to the replace timber structural members, in industrial forced induction cooling towers throughout Europe, Asia and the Americas. (contact: DWitcher@Strongwell.com, Chief Structural Engineer, Strongwell (the major US pultruder). RAE_import_type : Journal article RAE_uoa_type : General Engineering