Explain the various modes of failure encountered in prestressed concrete beams subjected to bending moment shear and torsion.
Q) Explain the various modes of failure encountered in prestressed concrete beams subjected to bending moment shear and torsion. Prestressed concrete beams subjected to combined bending, shear, and torsion fail through distinct modes categorized by their dominant cause: flexural tension/compression, shear cracking (diagonal tension/compression), or torsional cracking. Modes of Failure in Prestressed Concrete Beams Flexural Failure (Bending): Fracture of Steel (Under-reinforced): Occurs when the prestressing steel yields or fractures before the concrete crushes. The beam undergoes large deflections, providing warning. Compressive Failure (Over-reinforced): Occurs when the concrete in the compression zone crushes before the steel yields. This is sudden and brittle. Failure due to Premature Yielding: Occurs when, if the concrete in the tension zone cracks, the strength of the beam relies completely on the reinforcement, leading to rapid steel yielding. Shear Failure: Diagonal Tension ...