Prestressed Concrete MCQ with answer and solution

Concept

Tendon profile in prestressed concrete cantilevers

Formula

NONE

Step-by-step solution

1. Cantilever structures experience maximum negative bending moment at the fixed support. Answer: D

Explanation

In a prestressed concrete cantilever structure, the maximum hogging bending moment occurs at the fixed support and decreases towards the free end. The prestressing tendon is profiled parabolically to counteract this bending moment distribution across the cantilever span. Consequently, a parabolic profile with its lowest point positioned near the free end optimizes stress distribution, making option D correct.

Why the other options are wrong

B) Inclining tendons upward from the support reduces their effective depth where hogging moment is maximum. C) Inclining tendons downward increases tension on the upper side where hogging occurs.

Shortcut

Cantilever prestressed tendons stay near the top at the support where maximum negative bending moment occurs.

Common mistake

Selecting option B or C by confusing the cantilever tendon profile with a simply supported beam profile or assuming a straight profile.