Modelling Procedure:

1. Insert Ribbed Slabs and Waffle Slabs as required. Usually beam widths are at the order of 800-1000 mm and beam depths are 320 mm.
   
2. Insert slab strips. Strip must cover all continuous rib beams. If there is any discontinuity, it is required to insert a new strip. 
   
1. Strip must be in the direction of rib beams
   
2. During the design stage, the length of the designed rib beam will be calculated depending on the position of the strip (nearest beam to strip). Therefore, you may choose to insert strip along every rib beam or along the most critical one.
3.  Slab strip must set to "FE Strip" in and pick "FE span Strip" in slab strip type. (refer to snapshot below). 
   

4. When create the slab strip, ensure that correct Start/End condition is selected. Kindly refer to Working with Slab Strips – Boundary Conditions for more details.

Analysis Procedure:

1. If FE Method is preferred then perform FE Slab Analysis first.
   
2. Click on Concrete Design > Ribbed Slab Analysis. This will calculate the internal forces from existing FE Results.
   
   
3. A report will be displayed. This report summarizes the analysis results.
   
   

Design Procedure:

1. After you have performed Ribbed Slab Analysis, go to Concrete Design > Beam Reinforcement Design > Rib Beams  
   
2. The beam design menu will be shown and populated by the rib beams instead of storey beams. 
   
   
3. Design the rib beams as usual. 
   
4. Rib beams details can be accessed by clicking Detail Drawings button.
5. Number of Rib Beams designed will be equal to the number of ribbed slabs inserted. 
   
6. "Quantity" column is representing the number of ribs beams per slab. This column will be automatically populated.

For calculation and decomposition of loads on ribbed and waffle slabs, kindly refer to 
ProtaStructure Rib & Waffle Slab Loads Design Guide