You run two independent models, one for ultimate load combinations to design lateral elements, in which the level of cracks are based on one of the 3 methods prescribed in chapter 6 (ACI 318). For service load combinations which will be needed for drift, the factors allowed to be increased by...
Treat each story differently, the bottom enclosed building (internal coefficient ±0.18) and the top story as an open building with (internal coefficient =0), see Figure 28.3-3 in ASCE 7-22. The second floor seems to me a concrete slab? so rigid diaphragm, consider torsion. The roof seems to be...
Could you press (Ctrl + W), tick "end release" at section properties, Ok and show screenshot? To me the beam with negative moment have unreleased end (at least for major axis, M3 in ETABS assuming default local axis definition).
All the loads should be considered simultaneously for stability check. If it enclosed, with flat roof, will develop negative pressure. ASCE 7 gives leeward coefficients as a function of length to width, and roof pressure as a function of height to length (the length is parallel to the wind...
The effective length (kz) is 0.85 times the half diagonal length considering the radius of gyration in the z-axis, rz and (kx = ky = 1.0) times half length in rx and ry (see screenshot from El-Tayem and Goel). All the three limits (0.85 * (L/2) /rz), (0.85 * (L/2) /rx) and (0.85 * (L/2) /ry) to...
It makes uplift check more sense though (0.9 Dead vs 0.6 now and fluid either 0.75 or 1.5), however, with changing MRI, results maybe will be worse than current combinations to check uplift. I tried to use it to design hydrostatic slab, but I thought will be difficult to convince Building...
For interior reentrant, wind separation is far from happening, so no need for zone 5 (or 3 for the roof). See Figure C30.3-2, ASCE7-22 and read the commentary, it is explains and summarizes it nicely. Same Figure in ASCE 7-16 too.
First question, you may refer to BS 6399-2 Wind British Standard (I added few screenshots).
Second question, the two cases are coming from enveloping wind tunnel results. ASCE 7 copy values from Australia/New Zealand wind code, British standard gives very close results. (Edit: remember those...
Beams could have a compression force (beam-column action) typically when it is part of diaphragm and acts as collector or chord for lateral loads (which typically will have the force as tension or compression depending on the direction of the applied lateral loads). In such case the beam...
Check if the difference is due to torsion. The beam will see torsional load as it sit on the edge (slab moment will act as torsion on the beam). You can see the torsion reinforcement separately from >> Concrete Design >> Beam design.
I think this is coming from the concrete crushing strain taken to be 0.003 by ACI. See the original presentation here (about 10 minutes from beginning, he didn’t go in detail though)
https://youtube.com/watch?v=x_P1EezPXGI&feature=youtu.be
It’s a good presentation.
Notice that there is an exemption from size factor for shallow foundation as there is no failure reported and they benefit from redistribution of soil pressure (based on FAQ from ACI or something similar they published before). The section 13.2.6.2 in ACI 318-19 reads:"For one-way shallow...
