Load-bearing Capacity of Nailed Joints Exposed to Fire

Nailed joints with wood members were exposed simultaneously to standard fire and constant load. Different loads were applied in the range of 0.1 to 0.6 of the estimated failure load at normal temperature. Measurements of the rate of charring and the temperature were used to determine the temperature profiles and further to estimate the reduction in the strength properties. The test results are compared with calculations based on the theory of K. W. Johansen. Three different relations between the reduction of embedding strength and the temperature were investigated. For one of these relations, the theory agrees well with the results obtained in the fire tests. The results of the calculations also show that there is a considerable reduction of the embedding strength during the first period of fire.