Pier Cap Shear Design

[struct1954]

What is standard practice for a rectangular pier cap shear design? The pier is a multi-column pier. When I use the Simplified Procedure for Nonprestressed Sections, using a beta of 2, my shear capacity is around 460. If I use the General Procedure, which calculates beta to be 1.1, my shear capacity is around 260. Also, I have been reading about the strut and tie method but several articles I've read say that isn't standard practice. What are some experiences with this?

 

[BridgeEI]

We only use strut tie in hammerhead type piers or special circumstances. Our designs are typically done like you state except we use the beta theta equations. Somewhere in that chapter it tells you the limits of using the beta of 2 and theta of 45.

 

[gwynn]

Whether or not to apply the strut and tie method depends on whether deep beam theory applies or not. If you are approaching, or under, a span to depth ratio of 2:1 then you should use the strut and tie method.

I assume you are in the USA. In Canada, CSA S6 still allows the use of the simplified method for non-prestressed components, but most provincial authorities require using modified compression field theory. No comment on Beta values, as under the Canadian codes they top out at 0.4 so they are clearly a different animal.