RC beams — trigger for side face reinforcement According to reinforced concrete detailing practice, side face reinforcement shall be provided when the overall depth (web depth) of a beam exceeds which limit?

Introduction / Context:
Side face reinforcement in deep beams helps control cracking on the exposed faces of the web where concrete is subject to restraint shrinkage and tension fields that are not fully captured by conventional longitudinal and transverse bars.

Given Data / Assumptions:

• We are checking the depth threshold at which side face reinforcement becomes mandatory.
• Standard RC detailing rules (IS-style practice) apply.
• Depth refers to the overall web depth of the beam.

Concept / Approach:
When beams are very deep, tension and shrinkage cracks can form on side faces even if shear and flexural steel are adequate. Hence a minimum side face steel area is mandated above a specified depth, typically at 750 mm, to ensure distributed crack control.

Step-by-Step Solution:
Step 1: Identify the codal depth trigger for side face steel.Step 2: From detailing rules, the trigger depth is 750 mm.Step 3: Select 750 mm from the options.

Verification / Alternative check:
Deep beam provisions universally require nominal distributed steel on side faces beyond this depth to keep crack widths within serviceability limits and to improve ductility of the web zone.

Why Other Options Are Wrong:
600, 650, 700 mm: Too low; would over-prescribe side face steel for moderately deep members.
800 mm: Too high; may permit excessive cracking before reinforcement is mandated.

Common Pitfalls:

• Confusing beam overall depth with effective depth to tension steel.
• Omitting distribution on both faces; the requirement applies on each exposed face.

Final Answer:
750 mm