Soil pressure

Why doesn't soil bearing change when I edit slab reinforcement?

Answer: Nonlinear cracked-section analysis must be performed for rebar to affect the stiffness of a model. This may be accomplished as follows:

• Choose the source of reinforcement which the software should use to calculate cracked-section properties. Options are available through Run > Cracking Analysis.

• Create load cases through Define > Load Cases, assign various load patterns, then select the Nonlinear Cracked Analysis type.

• Use these load cases to check pressures and compare against allowable limits.

• Modify the model as necessary and re-analyze until bearing stresses are acceptable.
  
  
  • NOTE – If a beam is added, the effect will depend on such factors as its location and stiffness.
    
    
  • NOTE – Increasing mat thickness is typically more efficient than adding reinforcement when looking to improve bearing pressure distribution.

See Also

• Modeling uplift and foundations on soil supports article

• Cracking section

How do I report the foundation soil pressures?

Extended Question: The Soil Pressures – Enveloping Summary table is organized by Panel, but these labels do not match my foundation Area Labels. How do I find which foundation corresponds with which panel? Can I print a table of the results for enveloped soil pressures per each foundation Area?

Answer: To identify panel location and geometry, select Tables > Results Summary > Panel Geometry. To obtain pressures based on area objects, select Tables > Nodal Results > Soil Pressures. An envelope load combination may be created to obtain results based on area objects.