Where can I find the basic rules of structural systems? (e.g. when to use Mom. Frame, Br. Frame etc)

[drucurl]

Ok so this is a bit of a n00b question but can someone direct me to a resource or book that explains clearly when to use certain structural systems?
I don't specialize in structures but I can analyze them and design them (following the codes isn't that hard)
What I often don't know is WHY I'm doing certain things.


For instance, in industrial structures I generally use braced frames. This is because you can get away with smaller members and connections.
However I'd like to truly understand the reasons why and when (for example) Moment Connections are required and when Braced Connections can be used.
Also I understand the structural implications of pinned foundation connections vs fixed, but I'd really like some clarity on what are the best circumstances to use either.

Thanks in advance.

 

[GeorgeTheCivilEngineer]

These are the sorts of decisions engineers make. There's no perscribed answer for what structural form to use in a given situation. The decision is driven from a mix of economics (structural efficiency), architecture and practicality.


"I don't specialize in structures but I can analyze them and design them (following the codes isn't that hard)"

Codes of practice aren't rule books and there are many situations they don't adequately cover. Beware using COPs blindly.

Anyway, to more directly answer. Use moment frames when you can't brace.

 

[Struct123ure]

Like George said, always use braces unless the architecture makes it so that you can't in which case you would use a moment frame. Moment frames are inefficient and expensive so stay away. In Industrial buildings nobody cares about architecture compared to a public library.
Foundations pined vs fixed think of it as iterative. You can assume that the foundation is fixed, but then you have to detail it such in the case of concrete make sure the rebar is properly spliced and developed, in the case of steel base plate column, make sure the anchor bolts are spaced and designed for the full fixed load. If you can't get it to work then you assume its pinned and re-analyze the loading that you need to design it for.
Most of the time just assume everything is pinned (refer back to the moment frame vs braced ). You can jump through many hoops, but unless you run your own business you won't see a dollar more and you'll deal with more stuff on the construction site.
In terms of choosing material for your structural system, whatever is cheapest in your area is best. In my experience concrete has a more stable price, steel can sometimes be cheaper but by the time design is done and construction starts steel can increase by 50% in price due to market forces and all of a sudden it would have been cheaper to build in concrete. Wood is more expensive unless you are talking about stick frame residential.