Foundation pressure distribution: For a perfectly rigid foundation base resting on a homogeneous elastic soil and subjected to a concentric vertical load, how does the contact pressure vary?

Introduction / Context:Contact-pressure assumptions depend on the relative rigidity of the footing and the soil. For a perfectly rigid footing on homogeneous soil under concentric vertical load, the conventional assumption is a uniform pressure distribution.

Given Data / Assumptions:

• Rigid foundation base (no differential deformation).
• Homogeneous supporting soil.
• Concentric vertical loading (no overturning moment).

Concept / Approach:

Rigid base implies plane sections remain plane; with symmetry and no moments, the soil reaction is uniform to balance the applied load.

Step-by-Step Solution:

Verification / Alternative check:

Flexible bases show non-uniform distributions (often more at center); presence of moments shifts maxima to edges. The stated ideal leads to uniform pressure.

Why Other Options Are Wrong:

Edges higher or center zero require eccentricity or flexibility; arbitrary shapes contradict concentric, rigid conditions.

Common Pitfalls:

Confusing rigid with flexible base assumptions; ignoring effect of eccentric loading and rocking.

Final Answer:

Uniform over the base