Tying capacity of web cleat connections in fire, Part 2: Development of component-based model

The companion paper has reported the results from a test programme in which web cleat connections were subjected to various combinations of shear, tying and moment actions at elevated temperatures. These tests showed that web cleat connections have very good tying resistance and rotational capacity, mainly due to the large deformation of which the web cleats are capable. In this paper a mechanical model is developed to predict the behaviour of web cleats subjected to tying forces. This model considers the formation of four plastic hinges on each angle and the effect of the angles opening in enhancing their resistance. It is capable of representing the action of the angles in component-based models for web cleat connections, in which algorithms for other components, including bolts in tension, bolts in double shear and holes in bearing, are already available. Failure criteria determined from the tests have been introduced into the models for components such as web cleats and bolts in double shear. This enables the component-based assembly to predict the occurrence and the sequence of connection failure. The behaviour of the connection predicted by the component-based model shows good correlation with the test results, which indicates that the developed model can be adopted in structural frame analysis to consider connection failure.