Concrete construction practices: construction joints are generally provided at which of the following positions or conditions?
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Ain concrete wall at sill level of windows
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Bwhere bending moment and shear force are small
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Cwhere a member is supported by another member
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Dat 18 m spacing in very large structures
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Eall the above
Answer
Correct Answer: all the above
Explanation
Introduction / Context:Construction joints are planned discontinuities in concrete work to accommodate interruptions. Proper placement avoids structural weakness and ensures load transfer.
Given Data / Assumptions:
- Monolithic construction is ideal but often impractical.
- Joint positions are chosen to minimize adverse effects.
Concept / Approach:Joints should be at locations of minimum stress (low BM and SF), at support points, or at natural breaks (like window sills). In large continuous structures, spacing rules like 18 m apply.
Step-by-Step Solution:(a) Walls: sill level joints are convenient and aesthetic.(b) Structural members: joints at low stress regions are safe.(c) Supports: natural cut-off point.(d) Long structures: spacing provides control.Thus, all apply.
Verification / Alternative check:IS 456 provides guidance for joint placement at low stress zones and architectural breaks.
Why Other Options Are Wrong:
- No option is wrong; all are valid placement criteria.
Common Pitfalls:
- Providing joints at high stress regions, leading to cracks or leakage.
Final Answer:all the above