anominal
Structural
- Jul 10, 2009
- 40
I've run across two different methods for designing tension reinforcement in the heel of a reinforced concrete cantilever retaining wall. The methods produce dissimilar designs. Each method considers the heel as a cantilever, with a fixed base at the rear face of the stem. The big difference is how the design moment is calculated; the design moment in "Method A" is calculated using the weight of the heel and soil on the heel acting downward, but neglects the soil bearing pressure acting upward; i.e. the heel has no support from the underlying soil. "Method B" does consider the soil bearing pressure acting upward.
I think it's clear that Method A is more conservative than Method B, but I have been advised that Method A is incorrect. Contrary to the advice I received, I've read that Method A is more appropriate because the reinforcing will be designed to withstand tilting of the wall. I have also seen Method A in older text books.
I'm interested to know if other engineers consider upward soil pressure when they design heel reinforcing. The difference in the design moment is significant, and using Method A will produce a design with more reinforcing steel in the footing top mat.
I think it's clear that Method A is more conservative than Method B, but I have been advised that Method A is incorrect. Contrary to the advice I received, I've read that Method A is more appropriate because the reinforcing will be designed to withstand tilting of the wall. I have also seen Method A in older text books.
I'm interested to know if other engineers consider upward soil pressure when they design heel reinforcing. The difference in the design moment is significant, and using Method A will produce a design with more reinforcing steel in the footing top mat.