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Can someone please explain the differences, and similarities, between a steel deck concrete roof/floor, and a composite slab/roof? I googled each of those examples, and they look very similar, only that the composite slab/roof (composite decking?) has steel stud that lock the steel deck to the...

Thank you so much for all your replies. It is a form deck, and not a composite slab. The building is old enough that the original specifications for the form deck is not available anymore, although the profile is clearly visible from below (at about 20 feet high), and the concrete on top of the...

I need to calculate the vertical load capacity of a 5"-thk. reinforced concrete roof placed on a metal deck that spans 7' between beams. Concrete is the normalweight 3000 psi. I have steel deck manufacturers' catalogs that provide load tables for the allowable vertical load capacity for their...

I would like to hear from practising structurals, and others, out there of quick and reasonably accurate ways to estimate beam sizes and weights when, for e.g., the AISC 9th Edition (Green Book) or 13th Edition (Black Book) are not easily available, when you are out on a job-site, when you just...

I have got a question about the analysis and design of tapered-section columns, either in a pre-engineered building, or in a steel structure. What is the best way to approach this? What is the theory behind it? Now, I have done some design for columns for purely axial loads, and for...

I've got a question about when to design torsion in structural members, say steel, but maybe reinforced concrete as well. A colleague of mine was designing structural steel members for bending and axial loads, but not for torsion and was put on the "hot seat" when his calcs were checked by the...

I have got a question about shear reinforcement(a.k.a. stirrups, ties or links) for the bottom of column bars that are embedded in deep slabs or footings, esp. for deep footings (>= 36"). Do we need to provide stirrups in this part of the column? Please see Sketches #1 abnd #2 below. Should...

While I await responses from my previously posed questions, I have got another questin about determining the area required, A for a bracing member. Say, I have a tension-only bracing member with an axial load of T. Allowable stress is 0.6Fy. Now the area required for the bracing member will...

Thanks for the quick responses, JAE and SHBH. Now, if I may expand my question a little bit. There is also the case of compression-only bracing, or struts. These are apparently very common in steel structures. Under what conditions do we specify these compression-only bracing, and is it...

I've got a question about the theory of bracing for steel structures, primarily vertical bracing but it applies to horizontal bracing also. Bracing primarily provides a load path for the lateral loads to be transferred to the foundation by being able to take tension and compression, right? It...

Thanks for the quick responses, DaveAtkins, dgkhan and JLNJ, and please keep it up. Can anyone elaborate on the thickness of base calculation with the lambda and OMEGA terms, please? dgkhan, I went back to the AISC Steel Design Guide 1, and it appears that OMEGA equal to 2.5 might not...

I am trying to determine all the possibilities for the hickness of a column base plate, t (ASD Method) for axial loads only without any substantial moments. The AISC Manual 9th Ed on Pg. 3-106 provides that t be the larger of or {2m or 2n} * SQRT(fp/Fy). My CERM 8th Ed also states that this is...

Thanks for helping out, people. The discussion and feedback was very useful and I hope, useful, to others, as well. My oversight, as I see it, is to use A, instead of Af, in my calcs. The other parts of the formulas were ok, but discussing and going to and fro about it reinforces the...

Thank you so much for your responses, people; RoadTech, Bagman2524, et. al. and esp. jike for giving the reference in the "green book" as Page 2-30. The formulas on that page for Lu are exactly the same ones that I put in my original question, i.e. Lu as the larger of 20000*Cb/((d/Af)Fy) or...

Thanks for the prompt response, 3doorsdwn. No, I am looking for the formula for Lu, which is the maximum unbraced length of compression flange for which Fb=0.60Fy. Lc is the maximum lengthn of compression flange for which Fb=0.66Fy. Does anyone know of an accurate formula for Lu, please? I...

Does anyone know the formula for Lu, please? Lu is the maximum unbraced length of compression flange at which the allowable bending stress may be taken as 0.60 Fy. My Civil Engineering Reference Manual, 8th Ed. on Page 59-3 provides Lu as the larger of 20000*Cb/((d/Af)Fy) or...

Thanks for all the responses, people. YoungTurk, were you talking more about radius of gyration in general? For JAE, when you said to include the 1/3 of the portion of the web that is above the neutral axis of the member, did you mean only 1/3 of the top half of the web. The N/A is gnerally...

I am trying to find out how to calculate the term "r subscript T". rT is used in the determination of Lu, which is the maximum unbraced length of compression flange for which Fb=0.60 Fy. In PPI's Civil Engineering Reference Manual 8th Ed on Page 59-3, rT is defined as the radius of gyration of...

jike and shin25, thank you very much for your quick responses. You basically confirmed what I had in mind, but you provided verification of what had been done before and the numbers certainly helped and gave me a feel of what I need to do. csd72, you brought up a very interesting and important...

I am designing shear lugs for my base plates on my mat foundation. The base plate is sitting on top of the mat foundation and the shear lug and shear lug pocket where they do occur (around vertical bracing areas, primarily) will interfere with the top reinforcement of my mat. To get a feel of...