This paper describes numerical modelling of the fire behaviour of a multi-bay building having two-way reinforced concrete slabs supported by corner columns. The building consists of three bays by three bays and it is assumed that all bays of the building are subjected to fire. Two fires were used: one was the standard ISO834 fire having a 4 hour duration, while the second one was a parametric fire based on the ISO fire with the fire dying out after one hour and the temperatures decaying back to ambient after approximately another two hours. The effects of the fires in relation to the redistribution of bending moments and the development of tension field action are described.