huangyhg

load to a.b.
i am using this detail as a hold-down at the end of a shear wall. i got a comment on how i determined the load in the bolts; i tried a few different methods and got fairly close results. i was just curious on how you guys would determine the load in the bolts.
i'm not really sure what i am looking at, plus the material and orientation... where is the shear wall with respect to this?
mike mccann
mmc engineering
sorry i thought i wrote more, it has been a long month.
at the end of a shear wall, i am using the hss as a hold-down. this condition occurs at the end of a footing inside the wall on top of a curb. therefore, i am unable to space out the a.b. to get an even distribution, so i was wondering what method would you guys use to determine the load to each of the bolts.

i am assuming this is a plan detail, is that true? how are the anchor rods attached to the hss - are you using a thick plate?
i would probably use an equal number of anchors on both sides of the hss.
check prying action to get the tension in the closest anchor bolt. i wouldn't count on the other three to resist any tension. the right-hand sketch in fig. 9-4, page 9-10 of the 3rd edition steel manual, shows a configuration with a one-sided bolted connection resisting tension.
if the plate was thick enough, there wouldn't be any prying effects, and the tension in the closest anchor could be taken as the tension in the column.
i wanted to use an even number of bolts that was not possible at the time; we have since changed the detail. yes the first one is a plan view the second is an elevation; a plate is used to transfer the load. thanks i figured the aisc prying would be the one that would come up. anyone else have a method they use?
this is a zipper situation where failure of the first row is the only way to load the next row. the first row must be able to take the entire tension load plus prying forces.
if you "heard" it on the internet, it's guilty until proven innocent. - dcs
first bolt carries all the load.
add 30% for prying.

i disagree that the first bolt takes all the load. how much it takes is dependent on the stiffness of the column and the plate. but i do agree that it is a poor detail.
you can assume whatever you want about how the load is resisted, but you must be consistent. if you assume all the bolts are loaded equally, you must design the base plate for bending (which should not be a problem) and design the steel hss post to throw the bending induced back into the shear wall via the plywood (which could be a problem).
eccentrically loaded holddowns are frowned upon because of the moment created.
daveatkins

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