Staad foundation advanced - foundation sizing governed by ultimate limit state load case.

Question

Hi All, 
 Here I'm facing trouble with Staad foundation advanced design. 
 Software design output displays the foundation sizing is governed by the ultimate limit state load case.....can anyone advise me on this? how can I correct this to make serviceability load case only to be considered for sizing. 
 Here in this case reactions & Load cases are considered from the Staad Pro . V8i file.

Kris Sathia · Answer

In order to calculate the bending moments and shear forces for the ultimate load combinations, the program needs to first calculate the soil pressures for those combinations. 
 If there are ultimate combinations where the vertical load is small and the bending moments are large, the footing size that is arrived at after solving the service load combinations may turn out to be insufficient for the ultimate load combinations for reasons such as 
 
 e = M/P falls outside the footing for the ultimate combination case being solved 
 Maximum soil pressure for the ultimate combination case being solved exceeds the allowable for that combination 
 Footing area in contact for the ultimate combination case being solved falls below the minimum required for that combination 
 
 If any of these violations occur, the program will increase the footing size if the design type is Calculate Dimension. If the design type is Set Dimension, the footing is treated as failed. 
 The first combination case responsible for the final footing size is set to be the critical one. So, while service load cases usually govern the size, based on the above, an ultimate combination case could govern in some situations. 
 The messages in the output pane which provide a step-by-step record of the calculations being performed should give you a clear picture of how the final footing size has been determined.