Concrete Retaining wall- FOS

[CROWN06]

Which code explains the limit for minimum FOS for overturning and sliding of reinforced concrete wall (and under which clause)

 

[WillisV]

IBC - I think section 1806 in 2006 version.

 

[miecz]

Interesting, that IBC doesn't specify a load case corresponding to the safety factors. It would seem that IBC 1605.3.1.2 would require all the basic combinations of ASCE7, Section 2.4.1, including combination 7, 0.6D+W+H, with a safety factor of 1.5.

 

[cedent]

Jmiec, It seems overly conservative to impose a saftey factor of 1.5 on the 0.6D+H case. I am curious how others deal with this.

 

[SteveGregory]

Doesn't the load combination 0.6D+H give a safety factor of 1/0.6 = 1.67?

 

[structuralaggie]

I have had to convince myself that D does not include the resisting force provided by the soil and use FS=1.5 for overturning and sliding. If you don't, then you get really stupid answers, especially for 0.6D+0.7E+H. There is some mention of "include in the design resistance" in section 2.3.2 in ASCE 7, but it doesn't say exactly how I have interpreted it.

 

[COEngineeer]

For calculating overturning FS and sliding, you dont factor the load at all. And you do need 1.5 F.S.

So for sliding it is the DL of wall, structure above, soil above X friction coef. >= 1.5x lateral force (area of the triangle of equivalent fluid pressure).

For OT
Moment at the toe from all the DL (wall, structure, soil above heel and toe) >= 1.5x lateral force x 1/3 H

When you are designing the reinforcement, then you need 1.6 H (or 1.7 if you are using appendix c).


Dont take anything I said for granted though because I am only an EIT

http://www.krmconsultants.com

 

[apsix]

From above;
"Moment at the toe from all the DL (wall, structure, soil above heel and toe) >= 1.5x lateral force x 1/3 H"

The 1/3H is applicable for soil forces, but not for surcharge where the point of application is at H/2.