What are the steps used in spread foundation design?
Following are the steps used in spread foundation design.
- Estimate dead load, live load and other loads before spread foundation design.
- Estimate service load I.e. service load = DL + LL/2.
- Decide on depth of foundation.
- Assume dimension of the foundation.
- Find plan area.
- Find net load bearing capacity.
- Estimate allowable bearing capacity.
- Ensure allowable bearing capacity is equal to or greater than the loading intensity.
- If not revise the dimension of the footings, compute the net safe bearing capacity.
- Determine the expected settlement.
- Determine the differential settlement and angular distortion.
- Ensure the settlements within the permissible limits.
- If not within permissible limits, revise footing dimensions, depth and make bearing capacity and settlement computations such that the settlements are within the permissible limits.
- Check the stability of footing to ensure safety against sliding and overturning. The factor of safety against sliding should not be less than 1.75 and not less than 2 against overturning.