Maximum characteristic strength permitted for stirrup (shear) reinforcement in RC members

Introduction:
Stirrups (shear reinforcement) control shear cracking and provide confinement. Codes limit the yield strength adopted for stirrups to ensure adequate ductility, bendability, and anchorage at hooks.

Given Data / Assumptions:

• Shear reinforcement in reinforced concrete beams/columns.
• Characteristic yield strength options: 350–415 N/mm2.

Concept / Approach:
While high-strength steel exists, codes typically cap the characteristic strength for shear reinforcement that may be used in design calculations. This avoids brittle behavior at bends and ensures reliable anchorage with standard hook details.

Step-by-Step Solution:
1) Identify code cap for shear reinforcement strength.2) The commonly accepted maximum characteristic strength for stirrups is 415 N/mm2 (Fe 415).3) Choose the corresponding option.

Verification / Alternative check:
Detailing provisions for hooks and bends, minimum bar diameters for stirrups, and spacing limits are calibrated around Fe 415 stirrup steel.

Why Other Options Are Wrong:
350, 375, and 395 N/mm2 are below the permissible maximum; selecting them imposes unnecessary conservatism and does not reflect the cap.

Common Pitfalls:
Assuming Fe 500/Fe 550 may be used for stirrups; in many codes the design does not permit taking higher strength for shear links because of ductility and bend radius limitations.

Final Answer:
415 N/mm2