mmarlow
Structural
- Aug 17, 2018
- 77
Hello,
I have a project where a customer wishes to tear down and existing boat house and build a new one on its foundation. With limited information we are assuming that the concrete foundations have the same width at the bottom as they do the top (2'-0") and that it is reinforced.
We know the following:
Subgrade modulus
Bearing capacity
f'c
Reinforcing wasn't found during concrete tests -- assuming un-reinforced.
The reason for the columns is that there are proposed concrete planks on the second floor.
The question is:
I have checked the existing foundations with approximate loading based on the proposed framing layout as a beam on elastic foundation. The bearing capacity seems to check out. The bending/flexure is what concerns me. I'd like to know if it is appropriate to analyze the foundations as plain concrete beams per (ACI 318 14.5.2.1). or the MOR x Sx (which is almost the same equation). The current structure is quite small, and quick checks look as if flexure due to service loads would not have exceeded the ACI Plain concrete flexural strength requirements. So flexure cracking has presumably not occurred.However, this has not been confirmed. Please see the attached PDF.
Any insight on whether the plain concrete formulas would be appreciated. We have proposed the use of helical piers without much luck.
Thank you
-MMARLOW EIT
I have a project where a customer wishes to tear down and existing boat house and build a new one on its foundation. With limited information we are assuming that the concrete foundations have the same width at the bottom as they do the top (2'-0") and that it is reinforced.
We know the following:
Subgrade modulus
Bearing capacity
f'c
Reinforcing wasn't found during concrete tests -- assuming un-reinforced.
The reason for the columns is that there are proposed concrete planks on the second floor.
The question is:
I have checked the existing foundations with approximate loading based on the proposed framing layout as a beam on elastic foundation. The bearing capacity seems to check out. The bending/flexure is what concerns me. I'd like to know if it is appropriate to analyze the foundations as plain concrete beams per (ACI 318 14.5.2.1). or the MOR x Sx (which is almost the same equation). The current structure is quite small, and quick checks look as if flexure due to service loads would not have exceeded the ACI Plain concrete flexural strength requirements. So flexure cracking has presumably not occurred.However, this has not been confirmed. Please see the attached PDF.
Any insight on whether the plain concrete formulas would be appreciated. We have proposed the use of helical piers without much luck.
Thank you
-MMARLOW EIT
