huangyhg

anchorage into concrete pier / pier sizing
hello everyone,
here is the dilemma. i have a typical building with base shears. the building has steel columns connected with anchor bolts to piers. the piers are reinforced with longituinal reinforcing and has stirrups that ties it all together. i have been trying to determine the anchorage requirements based on aci requiremnts (appendix d).
for example, i have a 10" w section, with say a base shear of 35 kips. what happens when i run through the calculations is that concrete breakout strength is always governing, and it tells me i need like a 4'x4' pier to prevent failure. this is rediculous. all the examples given don't have a typical column to pier connection, and its hard to figure out what is going on.
i think the reason my pier is so big is that there is no consideration of the pier steel reinforcing strength in shear.
does anybody know a good referece example i can follow, or what i am forgetting to consider here. any adivce will help.
steven
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you come face to face with a dilemma that has engineers scratching their heads viz a viz the aci appendix d anchor bolt shear provisions which in my view is unworkable, overly ponderous, and in need of a major overhaul to bring sanity back into something we all thought we know how to do, but alas, no more.
in my view, use pci design handbook for your anchorage design until appendix d is done in on its own petard.
pumpdady ,
follow the steps given in aisc "design guide-1( second edition).
you always can specify deeper embedment, which is close to development length to increase the capacity of the bolts. in this way you do not have to increase the dimension of the concrete section.
also design guide 7 (industrial structures). you need to figure out how to use reinforcing to take the loads instead of plain concrete-- the aisc design guides give some examples.
i use pier ties, spaced 2" oc, as required at the top of the pier, to resist horizontal load.
daveatkins

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