Design focus for R.C.C. cantilever beams: At which location is the resultant design effect (bending moment and shear) critical and therefore governs sizing and detailing?

Introduction / Context:
Cantilever beams are common in balconies, canopies, and footings. Their boundary conditions produce maximum negative bending and shear at the support (fixed end), which governs reinforcement and section depth selection.

Given Data / Assumptions:

• Cantilever with a fixed support and a free end.
• Uniformly distributed load or point load at or along the span.
• Serviceability and strength checks per standard design practice.

Concept / Approach:
For a cantilever of length L with load w per unit length: maximum shear Vmax = w * L at the fixed end and maximum moment Mmax = w * L^2 / 2 at the fixed end. For an end point load P: Vmax = P and Mmax = P * L at the fixed end. Therefore, design is governed at the support.

Step-by-Step Solution:
Establish loading and length.Compute design actions; identify peak shear and moment at the fixed end.Provide top (negative) steel over the support and check shear reinforcement near the face of support.

Verification / Alternative check:
Free-body diagrams confirm zero moment at the free end and linearly increasing moment towards the support, peaking at the fixed end; shear likewise is greatest at the support section.

Why Other Options Are Wrong:

• Free end: bending moment is zero there.
• Mid-span: moments are lower than at the fixed end.
• Mid-span and fixed end equally: not true for classical cantilever behavior.

Common Pitfalls:
Insufficient anchorage/top steel over support, neglect of diagonal tension near the face of support, and inadequate cover against environmental exposure for projecting members.

Final Answer:
At the fixed end.