Masonry Walls – Slenderness check: When should the slenderness effect of a wall be considered based on effective height to thickness ratio?

Introduction:
Slenderness influences stability and compression capacity of masonry walls. Beyond a certain height-to-thickness ratio, second-order effects and risk of buckling increase and must be considered in design.

Given Data / Assumptions:

• Load-bearing or partition wall, effective height considered.
• Thickness = wall thickness including plaster if allowed by code.
• Design per typical masonry codes using slenderness limits.

Concept / Approach:

Effective height to thickness ratio (He/t) indicates slenderness. Many codes flag slenderness effects when He/t exceeds around 12 for walls, triggering reductions in compressive strength and additional checks.

Step-by-Step Solution:

Verification / Alternative check:

For He/t ≤ 12, walls behave as stocky members with negligible second-order effects; above this, sensitivity rises markedly.

Why Other Options Are Wrong:

8 and 10 are conservative thresholds but not typical triggers; 16 and 20 delay consideration of slenderness, which could be unsafe.

Common Pitfalls:

Using clear height instead of effective height, or overlooking partial fixity at slab supports.

Final Answer:

Exceeds 12 times the thickness