7-May-07 – v5 1 Fire performance of bolted connections in laminated veneer lumber (LVL) P.H. Lau Arup Fire, Perth, Western Australia, Australia T. Chuo Beca Fire International, Wellington, New Zealand P.J. Moss † , A.H. Buchanan University of Canterbury, Christchurch, New Zealand M. Fragiacomo University of Sassari, Alghero, Italy SUMMARY 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. 1 INTRODUCTION Fire is unpredictable and dangerous, especially in residential buildings. The effect of fire on timber structural members is very complex because of the large number of variables involved. Once ignition has occurred, then a layer of char forms as the wood burns. A structural wood member will lose load capacity as the wood is converted to charcoal which has no strength. The thickening char layer protects the remaining wood, resulting in a predictable rate of charring below the surface. The rate of development of this charred layer determines how long the member can continue to carry load before the strength of the remaining unburned wood is exceeded. A thin layer of heat-affected wood below the char layer will have reduced strength and stiffness. In recent years, a number of research papers have been published on the influence of temperature on the mechanical properties of wood [e.g. 1-4]. Research has also been carried out into the performance of joints in timber members when subjected to fire temperatures [e.g. 5- 9]. Particular research into the embedment strength of wood at elevated temperatures has also been carried out by Moraes et al [10, 11]. They carried out embedment tests at temperatures ranging from 20ºC to  Correspondence to: Peter Moss, Department of Civil Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand † Email: peter.moss@canterbury.ac.nz