Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
(OP)
I am seeking guidance regarding the use of passive (resisting) pressures to assist in the analysis of the structural design of a stem wall. EM 1110-2-2502 allows the use of passive resistance for structural design (please see attached document). Would it be acceptable to use the net factored pressure to check the capacity of a 2 ft thick stem wall (as shown in the attached document). For example if the factored active pressure is 900 psf and the factored passive pressure is 200 psf, can 700 psf be used to analyze the wall?
I have not really seen information regarding this topic. Not sure if you can just subtract for example 200 psf from 900 psf in a 2 ft thick wall. Also, if the use of passive (resistance) pressures is allowed, should it be factored?
Thanks
I have not really seen information regarding this topic. Not sure if you can just subtract for example 200 psf from 900 psf in a 2 ft thick wall. Also, if the use of passive (resistance) pressures is allowed, should it be factored?
Thanks






RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
As 3Fan notes, it is appropriate to "sacrifice" a certain amount of resisting pressure considering the environment you are working in. I've never bought in to the trench problem though. Anyone who wantonly digs a trench in front of a retaining wall is being grossly negligent.
The retained side pressure and the resisting side pressures extend all the down to the bottom of the concrete. They don't magically disappear at the bottom of the stem.
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
I addressed that.
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
Some more recent design guides suggest using at-rest pressure for structural design instead of active. The reason for this is that we design for a factor of safety on sliding & bearing failure/settlement to prevent them from happening. If the wall doesn't move, then the pressure doesn't reduce to active. Normal (pre-failure) structural deflection of the stem isn't sufficient to mobilise the active pressure, so the stem would have to undergo hinge rotation to achieve the design assumption.
So there's a wide range in the guidance, with at-rest being at the conservative end, and (Ka minus Kp) being at the other end.
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall
That said, for the structural design of a stem wall on a soil foundation, I completely disregard passive pressure and use the average value between the at rest and active pressure: k=(ka+k0)/2.
RE: Retaining Wall - Using Passive (Resisting) Pressure in Capacity Analysis of Stem Wall