Experimental investigation of the behaviour of fin plate connections in fire

Accidental fires and full-scale structural tests have indicated that steel connections can be subjected to large deformations and fracture in fire. This is not currently considered in fire engineering design approaches because the connections are assumed to heat up more slowly than the structural frame members and therefore retain a greater proportion of their strength. A project at the Universities of Sheffield and Manchester has investigated the robustness of common types of steel connections when subjected to fire. In the test programme the connections were subjected to combinations of shear force and tying force, and loaded to large deformation and fracture. This paper reports on the test results on fin plate connections. The test results indicate that bolts are vulnerable to shear fracture and that failure is usually controlled by bolt shear rather than by plate bearing. Fin plate connection resistance reduces rapidly with increase of temperature. The test results are compared to values suggested by the current United Kingdom design guidance and Eurocode 3 Part 1.8. A previously developed component-based model is also used to simulate the test results.