huangyhg

code question
the governing code is boca 96 and i've been asked by a building official about highrises. he said he read somewhere that "all (seismic) connections in a high rise building must be fully restrained", and asked me if thats correct.
i dont recall reading that in any code, and i thought connection design was up to the engineer, not the buliding code.
any thoughts or insights on this? maybe someone else has read something similar?
also, what qualifies as "high rise"? anything over 240 feet?
perhaps the b.o. is thinking of aisc seismic provisions section 7.2 which requires slip-critical joints for the seismic system. or aisc specifications section j.11 which requires pretenstioned bolts for buildings taller than the prescribed heights.
the word "restrained" in code lingo is usually focused on fire resistance (see the underwriter's labs book). restrained beams are those which, as they have a portion of them heated, are restrained longitudinally against thermal expansion.
some work has been published recently that argues that most all beams in buildings can be considered restrained as the floor deck is not all heated simultaneously and restraint is provided by it to the beams.
the boca national building code, 1996 edition, section 403.1 defines high-rise structures as "...all buildings having occupied floors more than 75 feet (22860 mm) above the lowest level of fire department vehicle access." varies exceptions include airport traffic control towers, open parking structures and stadiums to name a few.
i also see nothing in this book (boca) that relates to a "restrained" seismic connection and as you suggested would leave that up to the designing engineer.
brian k. willis, pe

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