Correct Answer - Option 4 : 6.5 cm
Concept:
For isolated footing on clay, the permissible settlement is 65 mm or 65 cm.
The allowable settlement is defined as the acceptable amount of settlement of the structure and it usually includes a factor of safety.
The allowable settlement depends on many factors, including the following:
- Type of Construction
- Use of the Structure
- Presence of Sensitive Finishes
IS code specification for permissible settlement:
(i) Total Permissible settlement:
- For isolated footing on clay = 65 mm
- For isolated footing on sand = 40 mm
- For raft footing on clay = 65 - 100 mm
- For raft footing on sand = 40 - 65 mm
(ii) Permissible Differential settlement:
- For isolated footing on clay = 40 mm
- For isolated footing on sand = 25 mm
(iii) Permissible angular settlement:
- For high framed structure < 1/500
- To prevent all type of minor damage < 1/1000
Note:
For multi-storeyed buildings having isolated foundations on sand, the maximum permissible settlement is 60 mm
For multistorey buildings having isolated foundations take the higher load as compare to single-storey buildings having isolated foundations. So that deflection caused by multistorey building having isolated foundation higher than 40 mm (from the safer side).
