Pile Cap Loading in Pile Supported Wall
Pile Cap Loading in Pile Supported Wall
(OP)
Trying to get some clarification/guidance regarding the loading on a pile cap. Please see attached drawing for reference. Basically the pile supported floodwall was design with continuous longitudinal reinforcement in the pile cap. The pile cap has longitudinal and transverse reinforcement, for the temperature/shrinkage reinforcement and applied loads.
Currently working on extending the pile supported floodwall and installing dowels in the pile cap to meet the continuous longitudinal reinforcement requirement in the pile cap. But I am getting feedback that there is no load transfer in the pile cap connection. I guess I am having a hard time understanding, how in the original design, reinforcement (transverse and longitudinal) was required in the pile cap, I am assuming because there were applied loadings in the pile cap. But now that you are connecting a new pile cap section into the already constructed pipe cap, now there is no load transfer or loads applied at that location?
Appreciate if you can help me clarify this.
Currently working on extending the pile supported floodwall and installing dowels in the pile cap to meet the continuous longitudinal reinforcement requirement in the pile cap. But I am getting feedback that there is no load transfer in the pile cap connection. I guess I am having a hard time understanding, how in the original design, reinforcement (transverse and longitudinal) was required in the pile cap, I am assuming because there were applied loadings in the pile cap. But now that you are connecting a new pile cap section into the already constructed pipe cap, now there is no load transfer or loads applied at that location?
Appreciate if you can help me clarify this.






RE: Pile Cap Loading in Pile Supported Wall
I am not sure what the dimensions and proportions are of the cap and wall system relative to the spacing of the piling - but you might have a deep beam condition here once the wall hardens.
Also - the wall, as a floodwall, is probably taking lateral forces perpendicular to the wall so the cap will act as a transfer beam between the paired piling.
When you add on to the existing cap, it is uncertain whether you can successfully tie into the existing cap with enough rebar and depth of rebar to establish a continuity between the two. With the expansion joint between the existing and new wall, you will have some possible rotation at this joint - so trying to get a continuous connection there (full moment connection) may not be possible and also may not be even needed.
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RE: Pile Cap Loading in Pile Supported Wall
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Pile Cap Loading in Pile Supported Wall
It may be that the pile cap arrangement shown is a double cantilever over the piles meeting at the cantilever tips such that vertical shear is small.
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RE: Pile Cap Loading in Pile Supported Wall
Please see attached document, with additional details.
Based on this information, does it seem appropriate that there is no load being applied at the two connections (connection with bridge abutment stub wall & connection with existing floodwall)? My though is that supporting calculations are required to support this statement? The bridge abutment stubwall, might transfer loads to the floodwall and vice versa?
Thanks,
RE: Pile Cap Loading in Pile Supported Wall
If there are smooth dowels connecting the existing bridge stub wall to the new floodwall section and deformed bars connecting the new floodwall section to the existing floodwall, is that considered a cantilered situation, specially when you have construction joint with rebar going through?
Thanks
RE: Pile Cap Loading in Pile Supported Wall
The zero moment assumption is correct but the zero shear assumption need not be. Your joint sounds as though it could be expected to transmit shear across the interface.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.