Fire performance of bolted connections in laminated veneer lumber
This paper describes an investigation into the fire performance of bolted tensile connections in laminated veneer lumber (LVL) made from radiata pine. The capacity of the bolted connections depends on the embedding strength of the wood and on the yield moment of the bolts. The purpose of the research was to investigate the relationship between the failure load of LVL timber and the time to failure of the connections when exposed to fire. An experimental investigation was carried out on the axial tensile strength of three types of bolted connection that utilised either wood or steel splice plates. Some specimens were tested at ambient temperature while similar specimens were tested in fire conditions with a constant applied load. In addition, single-bolted connections were tested under constant elevated temperature conditions to determine the embedment strength of the LVL. Connections with no steel plates, or with steel plates slotted between the timber members performed better than those with exposed steel. A simplified design approach based on an extension to the Johansen formulae such that the embedment strength of the LVL depends upon the temperature in the bolt has been proposed for the fire resistance of connections.