Prestressed Concrete MCQ with answer and solution

Concept

Shear crack propagation in prestressed concrete

Formula

NONE

Step-by-step solution

1. In prestressed concrete beams, diagonal cracking occurs when principal tensile stresses exceed the tensile strength of concrete. 2. The principal tensile stress and distribution of shear stresses depend significantly on the web thickness and section geometry. 3. Thus, the propagation of shear cracks in a prestressed concrete member depends upon the shape of the cross-section of the beam. Answer: D

Explanation

Shear cracking in prestressed concrete members occurs when principal tensile stresses exceed the tensile strength of concrete. The magnitude and distribution of these web shear stresses depend directly on the geometry and cross-sectional shape of the beam. Consequently, the shape of the cross-section dictates how shear cracks form and propagate, making option D correct.

Why the other options are wrong

A) Tensile reinforcement resists flexural bending stresses rather than determining the path of diagonal shear cracks. B) Compression reinforcement improves beam ductility and reduces long-term creep without governing shear crack propagation. C) Shear reinforcement limits crack width after formation, but web geometry primarily governs initial crack propagation.

Shortcut

Shear crack propagation in prestressed members depends on the beam cross-section shape.

Common mistake

Assuming shear crack propagation is governed solely by shear reinforcement rather than cross-sectional shape and web geometry.