Hello, I need some suggestions on a 30 ft high retaining wall. I never designed a retaining wall more than 9ft high. The wall is also part of the building, and we do not want to transfer the load to the building. I attached a preliminary geometry. Please take a look to see it makes sense and let me know your suggestions and anything I need to consider. Thanks very much!
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30 ft high retaining wall 3
- Thread starter Engin1
- Start date
MIStructE_IRE
Structural
The wall is 3 foot thick over its entire height which is unnecessary. Consider at least 3 steps in thickness.
At that height though I’d be considering a tie back system.
At that height though I’d be considering a tie back system.
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- #5
Engin1 said:
That's really the key point. You need to look at how it interacts with the building.
Doug Jenkins
Interactive Design Services
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- #7
JoelTXCive
Civil/Environmental
Is there a way to NOT connect it to the building?
1) To be able to use the active earth pressure values, the wall needs to move a little; other wise you have to use the in-situ (k_naught) earth pressures. At 30 ft of height, you might see 2 inches of movement at the top.
2) If you are connected to a building, then you do not really have a cantilevered section. You have a flat plate supported on 2 sides. This means there will be some horizontal moments and shears in the section.
At smaller scales, these issues don't matter as much, but at 30 ft height they do.
Also, as other people have mentioned, I would definitely batter one side of the wall.
1) To be able to use the active earth pressure values, the wall needs to move a little; other wise you have to use the in-situ (k_naught) earth pressures. At 30 ft of height, you might see 2 inches of movement at the top.
2) If you are connected to a building, then you do not really have a cantilevered section. You have a flat plate supported on 2 sides. This means there will be some horizontal moments and shears in the section.
At smaller scales, these issues don't matter as much, but at 30 ft height they do.
Also, as other people have mentioned, I would definitely batter one side of the wall.
Lomarandil
Structural
Lots of good advice here already. My addition is that while tiebacks are good to consider, 30ft cantilever walls are feasible. I just built one in a high-seismic zone with similar proportions.
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just call me Lo.
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just call me Lo.
- Thread starter
- #13
JoshPlumSE
Structural
Will you have perpendicular walls at the ends of the retaining / basement walls? Because I don't care how thick the wall is, it will not be as stiff as the side walls. Also, if you have a concrete slab at the top of the wall (or somewhere along its height) that will also be stiffer than the wall itself.
Not sure I understand why we can't allow the retaining wall force to go into the building at all.
Not sure I understand why we can't allow the retaining wall force to go into the building at all.
- Thread starter
- #16
JoshPlumSE,
The Wall will be 30ft long, it has perpendicular walls at the ends. It will be metal deck roof a the top. It does not have locations can fit x bracing to resist the whole retaining forces. We could allow partial forces go the building and use moment connection, but how to determine how much load will go to the building?
The Wall will be 30ft long, it has perpendicular walls at the ends. It will be metal deck roof a the top. It does not have locations can fit x bracing to resist the whole retaining forces. We could allow partial forces go the building and use moment connection, but how to determine how much load will go to the building?
- Thread starter
- #17
- Thread starter
- #19
retired13,
It has 10ft basement. It cannot taper inside the building. I am thinking to put the ties above the basement and the top to reduce the deflection of the wall. The 30ft is from the basement floor to top of the exterior grade. There is no openings on this wall. Seismic B.
It has 10ft basement. It cannot taper inside the building. I am thinking to put the ties above the basement and the top to reduce the deflection of the wall. The 30ft is from the basement floor to top of the exterior grade. There is no openings on this wall. Seismic B.
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