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# Force-Resisting System ASCE 7-10

## Force-Resisting System ASCE 7-10

(OP)
Hi, how should i classify the force-resisting system for a building having steel columns and composite beams (Steel Deck) acting as a moment frame (no braces)? im talking of table 12.2-1 of ASCE/SEI 7-10. I'm trying to keep it as simple as i can so i'll try to use an R=3 system. Should it be considered as an "Ordinary steel moment frame" or as a "steel and concrete composite ordinary moment frame"? The thing is seismic design category is C and "steel and concrete composite ordinary moment frame" are not permited, NP, for this category but it is permited, NL, for ordinary steel moment frames.

Thanks!

### RE: Force-Resisting System ASCE 7-10

The composite moment frame business is referring to steel columns and beams generally encased in concrete. With just a composite deck slab, your system wouldn't qualify as "composite" for lateral.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

### RE: Force-Resisting System ASCE 7-10

As long as your seismic design category permits it, you can use R=3, designating it as a steel system not specifically detailed for seismic.

### RE: Force-Resisting System ASCE 7-10

#### Quote:

I'm trying to keep it as simple as i can so i'll try to use an R=3 system.

OK then - from Table 12.2-1 just use Type H - steel systems not specifically detailed...R=3 if that is the route you want to go.

If R >3 you need to select some specific type from Table 12.2-1.

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(OP)
Thanks all!

### RE: Force-Resisting System ASCE 7-10

(OP)
Hi, im back with another related question. If im choosing to design the building as "Not specifically detailed for seismic resistance" may i use equations from section 12.4.2.3 of ASCE 7-05? this is neglecting combinations with systyem overstrength factor.
In case system overstrength factor has to be considered, is it ok to consider it only for column design (12.4.3.1 LC) and ingnored (12.4.2.3 LC)for beam design? what about moment connections between beams and columns? The building is a residential 6 level regular steel moment frame building with composite steel deck.

I am doubting about this since in table 12.2-1 there actually is an overstrength factor but im not detailing specifically for seismic resistance. Does anyone know any worked out example for some guidance?

I've seen, while doing research and from the forum, seismic design is not as straight foraward as "static" design. Do you think is posible for an engineer with no seismic education backgroug to design this type of building, or is it just out of my league? I won't design anything unless i fully understand what im doing, im afraid it might take much longer than i initially thought. What do you think?

Thanks!

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