T-beam proportioning guideline in building floors: The width of the rib (web) of a T-beam is generally kept within which range relative to effective depth d?

Introduction / Context:
In monolithic slab-beam floors, the beam acts as a T-beam with the slab providing the flange and the stem (rib) forming the web. Reasonable rib proportions help ensure adequate shear capacity, bar anchorage, and economy while controlling congestion.

Given Data / Assumptions:

• Floor system with cast-in-place T-beams.
• Effective depth d set by bending and serviceability.
• Rule-of-thumb proportioning for preliminary design.

Concept / Approach:
Common practice keeps the rib width as a moderate fraction of depth to balance shear area and reinforcement detailing. A range of about 0.30 d to 0.50 d is frequently adopted in preliminary sizing before final checks on shear, deflection, and bar spacing/cover drive the exact dimension.

Step-by-Step Solution:
Select a rib width that prevents excessive shear stress (too narrow) yet avoids unnecessary concrete (too wide).Adopt 0.30 d to 0.50 d as a reliable preliminary range for most building floors.

Verification / Alternative check:
Detailing constraints (minimum bar spacing, cover, stirrup placement) commonly fall within this envelope, confirming practicality in construction.

Why Other Options Are Wrong:
0.15 d to 0.20 d: Often too narrow, leading to high shear stresses and bar congestion.0.25 d to 0.35 d: Lower bound can work but upper bound may be tight for heavy loads.0.50 d to 0.70 d: Usually over-wide and uneconomical for typical buildings.

Common Pitfalls:

• Fixing rib width without checking stirrup fit and clear cover.
• Ignoring flange effective width limitations when sizing T-beams.

Final Answer:
0.30 d to 0.50 d