Reinforced concrete walls carrying vertical loads — minimum steel in two directions When an RC wall is designed as a compression member (as per column recommendations), what is the recommended ratio of minimum vertical reinforcement to minimum horizontal reinforcement (vertical : horizontal)?

Introduction / Context:
Reinforced concrete (RC) walls that carry vertical loads are often proportioned using column provisions with minimum reinforcement in both vertical and horizontal directions to control cracking and provide ductility. Because the principal stress and load path are vertical, minimum vertical steel is generally prescribed higher than horizontal distribution steel.

Given Data / Assumptions:

• RC wall functions primarily as a compression member.
• Minimum reinforcement percentages differ for vertical and horizontal directions.
• Code-type guidance favors more vertical steel than horizontal.

Concept / Approach:
Minimum vertical reinforcement ensures continuity for axial load, controls vertical cracking, and aids in ductility under accidental eccentricities. Horizontal reinforcement primarily controls temperature and shrinkage cracking and ties the vertical bars. Many practice guides summarize the baseline ratio of minimum vertical to horizontal reinforcement as approximately 2:1 for such walls, reflecting the dominance of vertical load effects.

Step-by-Step Solution:
Identify role of vertical bars: load sharing and crack control → higher minimum percentage.Identify role of horizontal bars: distribution/tying → lower minimum percentage.Adopt the conventional minimum ratio vertical : horizontal = 2 : 1.

Verification / Alternative check:
Many detailing schedules for compression walls target ~0.8% vertically and ~0.4% horizontally (values illustrative; check local code), maintaining a 2:1 ratio for minimums.

Why Other Options Are Wrong:
5:3 or 4:3: Do not reflect the standard simplified ratio and can overstate horizontal steel.
1:1 or 3:5: Imply equal or higher horizontal steel, which is atypical for compression walls.

Common Pitfalls:

• Using slab-wall minimums or shear-wall special seismic detailing out of context.
• Ignoring bar spacing and cover limits that may govern over minimum percentages.

Final Answer:
2 : 1