Determination of dowel-bearing strength of laminated bamboo at elevated temperatures

Abstract The Eurocode Yield Model to calculate the load capacity of dowel-type fastener connections is commonly adopted at normal temperature and in fire. The dowel-bearing strength of bamboo and timbers are required for the use of the calculation method. A total of 100 laminated bamboo specimens are employed to study the effect of temperature and grain direction on the dowel-bearing strength by the steady-state test method. With the temperature increasing from 20 °C to 250 °C, the embedding strength decreases gradually for both grain directions. But due to the evaporation of inherent water and glass transition of hemicellulose and lignin, the load-displacement curves of laminated bamboo have a turning point at 100 °C and 150 °C. For laminated bamboo perpendicular to grain, the embedding load rises linearly with the displacement, and a continuous increase is witnessed after yielding. And it shows obvious brittleness regardless of the increase in temperature. Four different typical failure modes have been observed, each two for one kind of grain directions. The yielding load of laminated bamboo is determined by the 5% diameter off-set method in different temperature ranges. By comparing different national standards and literature, the formula for embedding strength and the reduction factor with temperature are established at normal and elevated temperatures. This paper gives a valuable reference to calculate the bearing capacity of a dowel-type connection and predict structural performance under fire exposure.