Model Studies Of Composite Building Frame Behaviour In Fire

A series of analytical studies is presented on the behaviour of an unprotected plane composite steel-concrete frame under fire scenarios which occur across single storeys of the structure. The main purpose is to assess the effectiveness of using various types of sub-assembly in predicting the structural behaviour in fire. The studies are based on modelling a full-scale experimental multi-storey frame in which some fire testing is to take place shortly, and in part originate from a programme of analyses in which the authors have participated whose aim has been to determine the test parameters required. For the basic modelling studies the frames and subframes are assumed to be rigidly connected, but the effect of the semi-rigidity of real connections is also investigated. The analyses are all performed using a program NARR2, whose most recent development has been the capability to take into account strain reversal whenever it happens. This allows an assessment of the residual effects on the frame members after a local fire has been extinguished and the frame has returned to ambient temperature.