huangyhg

cap plates and baseplates
does anyone know where i can find a design procedure for column cap plates when beams or joists bear on them? i would also like to find a design procedure recommended for bearing plates under columns supported by a transfer girder.
thanks,

there most likely is no design procedure for some cap plates where the element (beam) sitting on the cap plate is considerably stiffer than the plate and the web or stiffeners bear directly over the web of the column. the cap plate is often just used for bolting the element to the column.
some cap plates, however, do require a thickness calculation. the one instance that i can think of is a small column bearing on a cap plate of a larger column. i am sure there are a few other instances also.
i would suggest developing the load path and reason out how the stresses would work.
look in the aisc hallow structural sections - connections manual, chapter 7 (cap plates, base plates and splices). this procedure is for hss sections, but it should give you the basis for the design you are looking for.
in my over 23 years of experience, i must say that i never came across a reference that has provisions for design of cap plate. for ordinary column cap plates, i use the following rules:
1. make plate as wide as the beam bottom flange.
2. if column is wider than beam bottom flange, then the cap plate is made larger to accommodate welding to the column.
3. select method of fastening beam to cap plate.
4. i try to match the cap plate thickness to beam bottom flange thickness.
5. for special conditions where you induce bending moment on the cap plate, then analyze it and determine plate thickness by design.
regards,
regards,
lutfi

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