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

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.