Practice Test Unit 2 SDD - III

Prestressed concrete beam fails suddenly without war

• failure of concrete in compression<br />zone
• failure of concrete in tension zone
• failure of steel in tension

Failure of under reinforced prestressed concrete beam is preceded by

• very few cracks near centre of span
• very little deflections
• large number of cracks with large deflections

Failure of over-reinforced prestressed concrete beam is characterised by

• large number of cracks with large deflections
• explosive failure due to crushing of concrete in compression zone
• sudden failure due to fracture of steel in tension

The moment of resistance of a rectangular section depends upon

• ultimate strain in concrete
• area of high- tensile tendons
• tensile stress in concrete

In a prestressed beam with bonded tendons, the value of tensile stress in steel at failure stage of beam is influenced by beam at failure according to IS: 1343 is limited to a value of

• the compressive stress in<br />concrete
• effective reinforcemen t ratio
• neutral axis depth

The maximum effective reinforcement ratio of a bonded prestressed<br />concrete

• 0.15
• 0.4
• 0.25

The ultimate flexural strength of post-tensioned beams with unbonded tendons depends upon

• characteristic tensile strength of prestressing steel
• effective stress in tendons after all losses
• tensile strength of concrete

The moment of resistance of a prestressed beam is generally higher if it is

• post- tensioned with bonded tendons
• post- tensioned with unbonded tendons
• pretensioned

Transfer of prestress in pretensioned members is due to

• bearing on end face
• shear resistance
• bond between concrete and<br />steel

The transmission length at the end of a pretensioned member depends upon

• tensile strength of concrete
• diameter of the high- tensile wire
• ultimate tensile strength of steel