steel temperature under fire

[man chan]

The boundary conditions (heat flux and surface temperature) of a steel bar are not the same for a surface exposing to fire. On a surface, the location closer to the fire has higher heat flux and surface temperature. But in ANSYS, the boundary condition of a surface can only have one temperature (uniform temperature throughout the surface). Is it possible divide the bar into  thousands of nodes and assign different temperatures to them? For temperature measured at the centre of a surface , should I assign it to only the node in the very  centre of the surface or a few more nodes around the centre ? Will it be the same for heat flux? Is there any tutorials I can make reference to ? Much obliged .