STAAD.Foundation - Moment Capacity Check

Question

When checking a Mat Foundation Job, after: analysis; Moment Envelope Generation and Design Parameters; one can use the Moment Capacity Check . One can enter the reinforcing and materials parameters and then check capacity vs. the moment diagram. I've noticed the following issues when plotting the Plot Capacity Diagram : 
 
 It doesn't appear that a Phi factor is used (0.9*Mn) - I've compensated by defining the Fy of the steel to be (0.9*60 = 54 KSI) to calculate the correct Moment Capacity. 
 The program does not calculate the bottom steel capacity correctly for the bottom cover; it seems to use the top cover in all its calculations, so I've just entered the worst case cover for all layers. 
 
 Are there potential problems with the program or am I missing something? I'm using StaadFoundation V8i (SELECT series 4), Release 05.03.00.32 
 Thanks for any input

Sye · Accepted Answer

I checked both the issues and you are correct. The software is only using the top cover and is also reporting the nominal capacities. I have communicated both issues to our development desk and we will get this addressed in the release coming out next month. Thanks for bringing it to our attention. 
 As a temporary workaround, you may want to use the top cover option even when you choose slab face as Longitudinal Bottom/Transverse Bottom. For the capacity, you may use 0.9x fy but also ensure that you change Fc to 0.9xfc too as otherwise a slight error would be introduced in the calculation of the depth of the equivalent stress block.