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Good catch McEngr. I'm stumped, too. The problem seems to have dead and live load acting upwards.

Unless I'm reading it wrong, SERM is doing it correctly (and in a way that jibes with your attachment), although they seem to have made a mistake in flipping their L1 and L2 terms in the equations vs what they show in Figure 1.25 (but proceed to use the correct numbers in the calcs). Just...

Thanks for the catch on the erata, Hank. Yeah, with that graph McEngr noted in mind, my procedure is usually to calc Ts=Sd1/Sds. If T<Ts, then 12.8-2 controls by inspection. If Ts<T<Tl, then 12.8-3 controls by inspection. Just a minor shortcut / timesaver (on the order of a few...

Dave, your instinct is correct. They're being a little cute with their terms, but what they're driving at is "pound for pound", all else being equal, the moment frame will give you the most drift because it's the least stiff inherently. Keep in mind for other potential questions, though, that...

@Rhoadies: FWIW, just ran across an example problem in "Structural Engineering Solved Problems, 5th ed.". Problem (Ch.6, problem 1.3) deals with seismic load path into, through, and out of a 2-story light frame system of diaphragms, collectors, blocking, and shear walls, and asks to determine...

Nevermind. Plasticity doesn't equal loss of flexural capacity, just large strains and thus energy dissipation. Derp.

A theoretical question, not a code-based question, because I think my brain's on vacation today: How can it be deemed desirable to have a plastic hinge form at the base of a shear wall? Doesn't a hinge at the fixed end of a cantilever imply instability since there's nowhere else for forces to...

Vm=2Mn/h

Hmmm. Not sure I'm following, sorry! For a shear wall, the strength of the wall(s) for determining story shear strength would be based on ACI 11.9.5, 11.9.6, or 21.9.4.1 (in-plane shear strength of walls), wouldn't it? Let me know where you're finding reference to "shear resulting from the...

Pretty sure that makes sense to me, kevo. Thanks! That's why you get paid the big bucks around here (of course, by "the big bucks" I mean "with many thanks"). Not gonna spend too much more mental energy on it. If it comes up on the exam, I'll tip my cap to them and move on.

Correct: footings do not require minimum shear reinf. when 0.5*phi*Vc < Vu < phi*Vc. See ACI 11.4.6 exception (a). On the second question, I've never designed a pier such that it can't transfer its compression via bearing (don't think that's a good practice), so haven't looked into this...

You're right, and I now see the circlular logic you're talking about, and I now have the same question!

Adding...a weak beam at a level or a weak base plate connection at the foundation can control over nominal flexural strength of the column when looking at determining story strength.

Yes: V = 2Mp/h for an individual column. Similar to the check for flexural shear in an EBF link (which of course won't control when e<1.6Mp/Vp). Also similar to the ACI check you mentioned.

I read it that the resulting design force on the collector would become 1.25*design force = 1.25*Omega*Eh (in most cases as you mention).

...what is it? Or more specifically, how does it affect design? I understand it has to do with how active and severe a nearby fault is, but don't see where or whether it affects the process of calc-ing design parameters and forces. Isn't this already taken into account in the probabilities...

Good catch. Nothing in the SDPWS commentary on that section. I checked another source: "Design of Wood Structures, 6th ed." by Breyer et al, which is generally considered a good source on wood design. On page 10.35 regarding anchorage forces he says, "It will be recalled that the (shear wall...

I noticed the same thing (though not from NCEES - in SEAOC V1 they do a wood shear wall tie down example where they use the gravity load at the top of the wall to help resist against net uplift on the tie down, also in contradiction to the SERM approach). However, Williams didn't pull the more...

No problem - I'll have plenty of ?? for you I'm sure once I get into seismic detailing. This studying has been my intro to parapets, too, since doing almost exclusively heavy industrial bldg's IRL, the extent of our architectural features starts and stops with a "flash as required" note on the...

Adding - the other good news is that getting comity from an SE state will be really easy now, since they all accept this exam, and almost all (CA is one big exception) have no (or very minor) additional requirements. No more old days where you had to take additional boatloads of additional...