NCEES 2008 book problem 506 Structural Depth

[maximus808]

The NCEES 2008 Errata for problem 506 Structural Depth says to use a certain configuration of steel (_l L ) two L shaped members mirrored against each other. Please bear with me as I'm going to take the trans section but am trying to to do all the problems.

The configuration states that it is 3 1/2 x 3 1/2 x 5/16 = Ag = 4.21 in^2

How did they come up with 4.21?

Also, do you think the AISC is necessary for the AM section or the CERM should be enough? Thanks.

 

[Phalanx]

According to the AISC steel manual, back to back L 3 1/2 x 3 1/2 x 5/16 have a gross area of 4.21 in^2. That's on page 1-104 of the 13th Edition.

I don't know where you would be able to find that information during the exam without have a steel manual handy. Maybe an experienced exam taker will be able to provide an opinion as to whether or not the manual is required during the morning portion.

Personally, I am taking the structural depth, so I will have the book regardless of whether or not it's required for the morning portion.

 

[dastuff]

Maybe an experienced exam taker

I found that statement funny... So if i took the test once and passed does that make me an 'inexperienced exam taker'?

You should be able to solve most of the problems using the CERM but most likely there will be a problem or two in the morning section that will require either the use of the building code or a steel manual. Although I'd expect the morning session won't use anything too difficult. You'll see problems similar to beam equations (M = wl^2/8) or looking up member properties for a quick stress calculation. Most likely you won't need up-to-date specs so you'd probably be safe borrowing or buying an old version of the code for dirt cheap on ebay.

 

[sac_engineer]

Maybe an experienced exam taker

I found that statement funny... So if i took the test once and passed does that make me an 'inexperienced exam taker'?

You should be able to solve most of the problems using the CERM but most likely there will be a problem or two in the morning section that will require either the use of the building code or a steel manual. Although I'd expect the morning session won't use anything too difficult. You'll see problems similar to beam equations (M = wl^2/8) or looking up member properties for a quick stress calculation. Most likely you won't need up-to-date specs so you'd probably be safe borrowing or buying an old version of the code for dirt cheap on ebay.

Agreed. The structural breadth will not require you to look up structural design manuals, or any other civil-specific manual. All questions can be referenced from the CERM and other exam-specific reference books (e.g. "All in One Civil PE" by Goswami).

As for the original questions: The estimated area of back-to-back angle brackets = 3.5 x 5/16 (each leg) x 4 = 4.375. The actual area based on the steel handbook is a little different, but not by much.

Good luck!

 

[civilized_naah]

As for the original questions: The estimated area of back-to-back angle brackets = 3.5 x 5/16 (each leg) x 4 = 4.375. The actual area based on the steel handbook is a little different, but not by much.
Good luck!

Since the angle leg length is measured from the back of the angle, you end up counting the square in the corner twice. So estimate the area of an angle using:

A=(L1+L2-t)xt = (3.5+3.5-5/16)x5/16 = 2.09 in^2

Therefore, for two such angles back to back: A = 2x2.09 = 4.18 (close to the actual number in AISC tables - which accounts for fillets etc.)