When designing profiled metal sheeting and decking at the ultimate limit state, the conditions at the internal supports, where the bending moment interacts with the support reaction force, are critical. Design code provisions for estimating the moment of resistance over an internal support are known to be inadequate and the problem is aggravated if account is taken of the redistribution of bending moment accompanied by post-yield buckling. This paper shows that the performance at the internal support can be predicted by finite element analysis and that continuing the analysis into the drooping post-yield range allows a relatively simple pseudo-plastic design method to be developed.