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RC Wall Under Strength for Shear
- Thread starter Ericson66
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Similar to the shear friction, there are tensile forces on each side of the shear plane, that is where the T's coming from. I don't think truss analogy is appropriate, or adequate to address the problem here. Mohr's circle, yes, and engineering mechanics should be the best resource for answers.
Blackstar123
Civil/Environmental
Are you considering the combine shear force due to dead + soil? Because the shear force produced due to gravity and soil loads will have opposite sign. This will also help in reducing the shear force.
Considering just about every major concrete design code in the world suggests that axial compression improves shear strength, I think we might believe them. Shear is caused by a combination of shear strain and flexural tensile strain, and axial compression reduces the flexural tensile strain.
I cannot believe that a 1m thick retaining wall will fail in shear if it is adequately reinforced for flexure. Are you sure the flexure reinforcement is correct, and that your shear calculations are correct?
I cannot believe that a 1m thick retaining wall will fail in shear if it is adequately reinforced for flexure. Are you sure the flexure reinforcement is correct, and that your shear calculations are correct?
So, shear failure mode does not exist for gravity load column, rather shear failure occurs only for column subjects to uplift force?!
Compressive force helps horizontal structural elements such as beams if applied in the geometry center, or off center in direction opposite to the gravity loads that produces bending, by limit the development/intensity of the flexural stress. If it is applied in manner contrary to stated above, flexural stress increases, and shear failure occurs that leads to ultimate failure of the element under concern.
The concept above can apply to vertical members too, but more useful in the retrofit practice than during the normal design phase. We had core through concrete gravity dam/retaining walls to install anchors/pre-stressing strands to increase base shear resistance, and resist over turning force to stability those structures. It is an effective and viable method, but costly.
Compressive force helps horizontal structural elements such as beams if applied in the geometry center, or off center in direction opposite to the gravity loads that produces bending, by limit the development/intensity of the flexural stress. If it is applied in manner contrary to stated above, flexural stress increases, and shear failure occurs that leads to ultimate failure of the element under concern.
The concept above can apply to vertical members too, but more useful in the retrofit practice than during the normal design phase. We had core through concrete gravity dam/retaining walls to install anchors/pre-stressing strands to increase base shear resistance, and resist over turning force to stability those structures. It is an effective and viable method, but costly.
BridgeSmith
Structural
Who said that? Concrete subjected to axial compression has greater capacity in shear than concrete under no axial load and concrete in tension. It not only makes intuitive sense, but as rapt reminded us, the effect is recognized and quantified in all the major concrete design specs.
Rod Smith, P.E., The artist formerly known as HotRod10
Rod,
For compression failure, review the linked document. Link
(I must apologize to jayod for proving wrong link in my response. Mistake corrected.)
For argument on effect of compression on flexural members, see the sketch.
Do you mind to offer a code provision (besides shear friction and passive shear capacity at soil-structure interface) that support your statement, so I can realize my mistake. Thanks.
For compression failure, review the linked document. Link
(I must apologize to jayod for proving wrong link in my response. Mistake corrected.)
For argument on effect of compression on flexural members, see the sketch.
Do you mind to offer a code provision (besides shear friction and passive shear capacity at soil-structure interface) that support your statement, so I can realize my mistake. Thanks.
I think it's time to stop the side tracking argument, and go beck to the central topic.
I believe the OP has somehow noticed the deficiency from design review. As the construction is in its early stage, he's looking for the most viable/reliable, and less painful corrective action. As the problem does not limit to the wall base, it extends to the upper support as well, I couldn't find any good solution from my memory bank, but to support the idea of adding buttress to beef up the wall. Also note, other than the questionable at rest earth pressure (seems it's only a concern to me), I doubt the lack of ground water condition at some 90' below grade. Therefore, positive strengthening, in my view, is the best way to proceed.
I believe the OP has somehow noticed the deficiency from design review. As the construction is in its early stage, he's looking for the most viable/reliable, and less painful corrective action. As the problem does not limit to the wall base, it extends to the upper support as well, I couldn't find any good solution from my memory bank, but to support the idea of adding buttress to beef up the wall. Also note, other than the questionable at rest earth pressure (seems it's only a concern to me), I doubt the lack of ground water condition at some 90' below grade. Therefore, positive strengthening, in my view, is the best way to proceed.
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