Load combinations for shallow or deep foundation sizing

[callmeismail]

Dear Respected Engineers,

ASCE7-05 states:

 

1.       So, for the purpose of finding soil bearing pressure and comparing it with allowable soil bearing capacity (shortly for foundation sizing), are we supposed to use the above-listed combinations?

2.        If the above combinations are to use for foundation sizing, then do we apply the SBC overstress of 33% when lateral loads are used with gravity loads?

3.       If the above combinations are used for foundation sizing, we have to include the vertical EQ effect with the horizontal EQ effect? That's what ASCE-7 05 says, but I want to know if there is anything else.

4.       What about the following combinations? I had always thought these are the only combinations to use for sizing foundations, be it shallow or deep.

5. If the above-mentioned green load combinations are permitted to use for proportioning foundation size or finding pile numbers, do we need to include the vertical EQ effect?

Thanks all. Your valuable response is highly appreciated.

[Ayesha]

  On 8/18/2021 at 12:36 PM, callmeismail said:

So, for the purpose of finding soil bearing pressure and comparing it with allowable soil bearing capacity (shortly for foundation sizing), are we supposed to use the above-listed combinations?

Expand  

Yes.

  On 8/18/2021 at 12:36 PM, callmeismail said:

   If the above combinations are to use for foundation sizing, then do we apply the SBC overstress of 33% when lateral loads are used with gravity loads?

Expand  

This is controversial and I have seen it being used and also not being used. Normally you need to see the local building code. I recently did a project in California and they are using it there.

  On 8/18/2021 at 12:36 PM, callmeismail said:

If the above combinations are used for foundation sizing, we have to include the vertical EQ effect with the horizontal EQ effect? That's what ASCE-7 05 says, but I want to know if there is anything else.

Expand  

Yes, everything.

 

  On 8/18/2021 at 12:36 PM, callmeismail said:

5. If the above-mentioned green load combinations are permitted to use for proportioning foundation size or finding pile numbers, do we need to include the vertical EQ effect?

Expand  

Yes, for seismic loads, all effects should be there including vertical.