“Experimental testing and analytical prediction of the behaviour of timber bolted connections subjected to fire.”

The ultimate strength of bolted and dowelled connections in timber members
at ambient temperatures have been assessed using Johansen’s yield equations in
Europe and USA. More recently, several researchers have begun to investigate the
strength of bolted and dowelled connections at elevated temperatures. Research has been carried out at the University of Canterbury to investigate the application of Johansen’s yield equations to the prediction of the failure strength of bolted connections
in fire conditions. A series of single bolted connections using steel side plates was
heated at constant temperature for several hours, then loaded to failure and used to determine the embedment strength of the wood over a range of temperatures from
ambient to 300C. The temperature-dependent embedment strengths are employed in Johansen’s equations for connections using a central steel plate as well as connections
using steel and wood side members. Comparisons are also being made with the results
of several similar connections tested in fire conditions and show considerable promise
for predicting failure of such joints. A proposal for implementation of an easy-to-use approach for the prediction of the fire resistance of bolted joints is discussed in the
paper, based on an extension of the Johansen’s yield equations to fire conditions,
including a model for the variation of the embedment strength with temperature.