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RE: Minimum steel connections

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Title: RE: Minimum steel connections

>AISC ASD specification section J1.6 calls for steel connections to be
>designed to support a minimum load of 6 kips (LRFD section J1.7 specifies 10
>kips).  Lacing, sag bars and girts are excepted from this requirement.  Are
>there any other exceptions explicity given?

I think the basic intent of the provision is just that the structure be robust. The usual detail to which it is applied is a shear connection. There are probably a lot of cases other than those given where the exception could be made, but I don't really see a need to exempt a lot of connections.

Practical considerations for field constructability in just about every detail will normally mean that the 6-kip requirement in ASD (10-kip requirement in LRFD) is not all that hard to live with. Other factors, like the "soon-to-be-law" OSHA 2-bolt minimum rule for field connections also ease the compliance with a minimum reaction.

From an economy standpoint, the minimum reaction does not make much of a difference. Changing plate and angle thicknesses and putting in two bolts where one might be good enough for the load do not have much of a diseconomy as long as the nature of the connection is not changed. Moreover, it definitely helps the field guys to have enough holes to use their drift pins and put bolts in at the same time. Erector friendly equals lower cost.

As a simple rule of thumb for similar details, if the number of fittings is the same, the cost is about the same. This is so because it takes just about the same amount of labor to make all the fittings regardless if there are a few more holes to put in ... the angle-master, for example, just plugs away making clips after it is set up.