As someone with more of an environmental background, I have been tasked with going over a geotechnical report for a current project. In the report they state that we should provide for an allowable bearing capacity of 3.2 ksf with a factor of safety of 2.5. Where does the safety factor come into my calculations? Do I need to modify the 3.2 ksf by this safety factor or anything? Thanks in advance.
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Safety Factor
- Thread starter wpi97
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First thing I would do is to call the geotechnical consultant who prepared the report and ask if the safety factor is already applied or not.
The term "allowable" means(supposed to) that all the factors that are to be applied are applied and you can pick up the number from the report and do your work. sometimes the wording of the report may not be ideal! so a phone call will help clear things up. it may also be a good idea to clerify whether the allowable pressure is the net bearing pressure or not (it usually is). ie, is the number given the load that the soil can carry above and beyond the existing overburden or including it.
hope this helps
The term "allowable" means(supposed to) that all the factors that are to be applied are applied and you can pick up the number from the report and do your work. sometimes the wording of the report may not be ideal! so a phone call will help clear things up. it may also be a good idea to clerify whether the allowable pressure is the net bearing pressure or not (it usually is). ie, is the number given the load that the soil can carry above and beyond the existing overburden or including it.
hope this helps
For allowable bearing capacities stated in Geotechnical reports, the "safety factor" is already included. It ranges from about 2.0 to 4.0, depending upon soil conditions, expected bearing depth of the foundation, and other variables.
The 3.2 tsf given means that the footings should be sized such that the pressure exerted on the soil at the bearing level should not exceed this value. They should also be sized such that all of the footings exert essentially the same bearing pressure on the soil, while remaining below the stated allowable bearing capacity.
The 3.2 tsf given means that the footings should be sized such that the pressure exerted on the soil at the bearing level should not exceed this value. They should also be sized such that all of the footings exert essentially the same bearing pressure on the soil, while remaining below the stated allowable bearing capacity.
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