Pier Design

Hi,

I am in the midst of designing a bridge substructure which includes a solid wall pier.
AASHTO 7.3.1 says that it is to be designed as column about the weaker axis and as a "Pier" about the stronger axis.
If I am missing the obvious here I am sorry but I dont see a single reference in the code as to how to design " as a Pier", now, designing as column is straight forward.
I have in the past when working on similar elements designed them as deep beams cantilevering above the footing but that was when working with ACI, there is no mention of deep beams in AASHTO or I am missing it. I have looked in all my texts but there are no examples or...
I would really appreciate it if any one of you could help out by seggesting design methods or references.

Much Thanks

 

[Dinosaur]

I looked up this reference and I find it confusing as well. The only interpretation I can use which makes any sense is that when determining the minimum reinforcement limits (as in 8.17) use the weak axis dimensions. Assuming the wall is sufficiently long, design it to resist diagonal shear cracks and ignore bending in the strong axis.

Good Luck

 

[originator]

I modeled it on PCACOL only to arrive at biaxial moment interaction since it does not qualify to be designed as a column, (0.1f'cAg) is more than the applied loads. i think regardless of wording it is still a flexural member in strong direction(or column) it is just that it does not deform and transfers everything in shear in its plane. and one should be in the codes good graces if flexure and shear are satisfied.
thanks for the response.

 

[edward1]

In the many solid pier designs that I have done the controlling design has been by moments produced by all the forces in Chapter 3 of AASHTO. However, if one has a solid pier of height greater than 100 feet then you must look at the PDELTA effect in design.