Within prestressed concrete construction______________?
Show answer Hide answer
Answer: B. forces of tension and compressions remain unchanged but lever arm changes with the moment
Explanation
Prestressed concrete members utilize high-strength tendons that remain under constant high tension. Under normal working loads, internal forces of tension and compression stay relatively constant and balanced. Applied external bending moments are resisted primarily by adjusting the internal lever arm between forces. Prestressing introduces deliberate permanent compressive stresses into concrete before applying service loads. The internal lever arm is the physical distance between the resultant compressive and tensile forces. This structural mechanism keeps the entire concrete cross-section uncracked under normal service loads.
Prestressed concrete is widely used in long-span bridge girders, parking structures, and airport runways. This behavior allows prestressed beams to be shallower and lighter than conventional reinforced concrete beams. Engineers rely on this constant-force principle to analyze serviceability and deflection behavior accurately. Claiming both internal forces change incorrectly implies conventional reinforced beam behavior in prestressed members. Stating that tension and compression change while the lever arm remains unchanged contradicts prestressed mechanics. Assuming all internal forces and lever arms remain completely static ignores how members react to applied moments.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Formwork surfaces to vertical columns, walls, and structural members are generally removed following______________?
Show answer Hide answer
Answer: A. 24 to 48 hours
Vertical formwork surfaces carry minimal self-weight structural loads immediately after the concrete hardens. Concrete develops sufficient early cohesive strength within twenty-four to forty-eight hours to stand unsuppor...
Q2. Hoop stresses generated in a spherical dome by a crown point load are_______________?
Show answer Hide answer
Answer: B. tensile everywhere
A concentrated load at the crown of a spherical dome pushes downward, causing meridional compression and circumferential expansion. This circumferential expansion stretches the horizontal ring elements outward in all dir...
Q3. Reinforced concrete footings resting on soil must maintain an edge thickness no less than______________?
Show answer Hide answer
Answer: B. 150 mm
Reinforced concrete footings transmit heavy column loads safely into the supporting subgrade soil layer. A minimum edge thickness of 150 mm provides enough cross-sectional area to resist diagonal shear stresses. This thi...
Q4. Symmetrically reinforced concrete sections experience shrinkage stresses in the concrete and steel respectively equal to_______________?
Show answer Hide answer
Answer: B. tensile and compressive
Concrete naturally shrinks as excess mixing water evaporates and chemical hydration reactions proceed over time. In symmetrically reinforced sections, the rigid steel bars physically restrain this natural concrete volume...
Q5. Per IS : 456 – 1978, what is the maximum allowable distance between structural expansion joints________________?
Show answer Hide answer
Answer: C. 45 m
Thermal expansion and contraction occur continuously as ambient temperatures fluctuate throughout seasonal cycles. Long concrete structures accumulate significant dimensional changes that induce high internal thermal str...
Q6. In cantilever T-shaped retaining walls, the main reinforcement in the stem is positioned on______________?
Show answer Hide answer
Answer: C. the inner face in one direction
In cantilever T-shaped retaining walls, the stem acts as a vertical cantilever with earth pressure on the inner face, placing the main tension reinforcement on the inner face in one direction.