Reinforced concrete building design step-by-step 10

[fa2070]

Hello,

What book(s) would you recommend for learning the design process (emphasis on "design") of low-rise/mid-rise reinforced concrete buildings?

For example, after the architect hands me the typical plan view of, say, a 6-story building and asks me to design the structure [small](see picture for illustration purposes, not from a real project)[/small] ... where do I begin?

In other words, what is the thought process that seasoned/senior structural engineers apply to arrive at the most satisfactory structural design?

How do they perform load analysis to begin with? How conservative is this process? How many combinations are tested? e.g. for a 3-span beam: LOADED-LOADED-LOADED -or- LOADED-LOADED-UNLOADED -or LOADED-UNLOADED-UNLOADED etc. etc.
Secondly, how do they choose the locations, dimensions and thicknesses of all the elements that comprise the structure, namely footings, internal columns, edge columns, beams and slabs?
Thirdly, what are the criteria for the design and inclusion (or not) of:
[ul square]
[li]Bracing: Why/where/when and how ?[/li]
[li]Shearwalls: Where and how many of them? When does wind start to be a concern? Lateral forces... how do designers deal with wind/drift/vibrations?[/li]
[/ul]
Fourthly, what is the common practice with regards to continuity in concrete elements? What's the relevance of workmanship in this decision? Do they design the concrete skeleton as a framed structure or as a myriad of column-supported continuous beams with neglegible to null moment transmission at edge columns? What consideration is given to foundations settlement and the impact (read: cracking) on neighboring buildings?
Fifthly, how do they do the detailing? Manually? Or is it computer-assisted? If so, what software do they use for detailing?
How do they choose A_s/A_c for the concrete members? What's the tipping point that makes A_s/A_c non-viable (read: anti-economic) and signals the designer to increase A_c?
And last but not least, what are the things to watch out in a structural design? What can go wrong? What are the pitfalls to avoid?

This is what I don't want.
I don't want math-bloated volumes aimed at teaching structural analysis. I also don't want books that dissect the latest and greatest construction codes.
I want a book (or books) targeted at the practicing engineer, written with a "from mentor to mentoree" spirit, aimed at teaching the timeless and code-immune^{[red](*)[/red]} craft that is the structural design of reinforced concrete buildings. The content should be straightforward and practical, preferably with worked and commented end-to-end examples.

Can anyone give me a pointer or two?

Thanks.

^{[red](*)[/red]} Except for Live Load selection.

 

[civilperson]

Design from the top down. Make a list of loadings applicable to this structure. Design roof, roof beams, top floor columns, top floor, top floor beams, etc. to the foundation. Get approval from the architect and go back to detail all connections and the bracing systems. check original load assumptions with the now firm dead load calcs to see if you need to redo anything.

 

[hokie66]

I don't know that such a book exists. University courses and textbooks deal with the technical issues, analysis, etc., but not how to be a structural engineer. I had to learn by working under experienced engineers, attending technical workshops, and reading whatever seemed applicable. Always keep an open mind and don't accept advice that at first seems incorrect without thoughtful consideration.

Good luck, and if you do find a book such as you described, let us all know.

 

[JAE]

hokie66 is right. The reason engineering is a [red]profession[/red] and not a [blue]job[/blue] is that you just don't read it in a book and then do it.

Apprenticeship is necessary.

That said, the steps I've done, in general, for concrete structures would be something like this:

1. As with any structure, conceptually determine the type of concrete system that best meets the layout, size, budget, fire-protection, loading,and expected durability.
2. With a framing concept in hand, do some preliminary sizing calculations to set structure depths and verify that the concept will adequately support the loads and meet serviceability criteria.
3. Draw out the framing for each level.
4. Identify joist or beam "runs" as I call them. These are individual lines of continuous joists or beams that share common spans and loadings.
5. For joists and beams, I usually do a continuous beam analysis using alternating live loads (Live on Even Spans, LL on Odd Spans, LL on adjacent spans - three types, and LL on all spans.)
6. Design the reinforcing for these beam runs.
7. For columns that are not part of the lateral force resisting system, do the design and detail them.
8. Identify which beams might participate in lateral resistance (for moment frames) and create models to analyze the overall building for wind and seismic.
9. Design the reinforcing for the lateral system beams and columns.
10. Design any shearwalls that are used.
11. For beams acting as collectors, re-design with added tension or compression forces and supplement the reinforcement accordingly.
12. For unique situations, floor openings, special concentrated loads, floor drops, ramps and stairs, provide design efforts on these special areas and adjust supporting beams and columns as necessary.
12. Design the footings.

I'm sure I left out some steps but this is a snapshot of what I've done. Also, there may be times when you must iterate the design due to changing conditions, too-shallow depths, etc.

But I'd agree there is no book out there that will do you justice. The best "book" is one with skin, a pocket protector, and an old HP calculator that can teach you the concepts, teach you the pitfalls, and teach you how to respond to special extraordinary challenges....i.e. a good mentor.

 

[hokie66]

JAE's list is good, but somewhere along the way, when you are confident that your system will work, share it with the architect. Don't take the chance of doing all the work and having to start over for some reason. Projects normally evolve: schematic design, preliminary design, final design.

 

[JAE]

Oh yes...good point.

 

[fa2070]

Thanks everybody for sharing insights.

I understand the value of good mentorship. Unfortunately that has been elusive in my case. And like me, many many others.
It's somehow unfair that the professional growth for an (aspiring) structural engineer is so dependant on the availability of a resource that he cannot control: mentorship.

Other professions put personal development mostly in the hands of the individual, not so much on third parties.

 

[rapt]

And last of all, especially for someone in your position, pay someone else who really does know what he is doing to check your work.

 

[hokie66]

fa2070,

I share your concerns deeply about the availability of mentoring. Many firms do a good job of leading young engineers through their apprenticeship, but unfortunately it is not universal. Some posts on this forum seem almost in despair for help.

In your case, it may be a struggle, but you will prevail. The reason for my confidence is that you have the ability, as evidenced in this discussion, of formulating a systematic approach to a problem. Solving the problem is the easy part.

 

[asixth]

I agree with mentoring, good mentoring is not universal and I would say that my assigned "mentors" didn't care about my career development (or their own professional development). I have the mindset to make sure when it becomes my turn to mentor, I am going to do a damn good job at it.

Always consider patterned loading, I see too many guys not considering patterned loading in there designs.

Actually do some design during the schematic and preliminary design phase. I had the task of completing a detailed design for a job where the senior engineer had a "gut" feel of what the sizes should be and they were way off.

Set out the column grids and span lengths based on punching shear and deflection calculations during the preliminary design. If you consider these two aspects early, the design should go together smoothly.

If there is a bible of engineering out there with all the answers in it, then I haven't found it yet (pardon the Christian reference). You need to accumulate a library of texts, papers, design aids, other technical info, notes from workshops, user manuals and professional relationships for your design expertise.

I think when you encounter one specific problem, you should throw the question up on eng-tips, someone will help you out.

 

[ARLORD]

fa2070 I feel your pain.
I agree there are no books describing the building engineering design & detailing process. I didn't get a lot of help coming out of school. I also looked for books, found some but nothing like you are looking for. I found that getting a complete set of drawings (Str&Arch) from a completed job that someone you trust in you firm has done in the recent past. I would take them home and study them to make sure you understood where EVERY line & word on EVERY plan & detail came from. Feel free to ask questions from the original designer. Also once you understand the complete set, see how you would approach the design. Also try to see if you can improve any aspects of the design, there is no perfect job. I did this several times my first five years as a design engineer. It worked for me.

 

[ash060]

One thing that might help when it comes to what you need for your design, is to check other engineer's drawings. By looking at old drawings of similar buildings you will notice elements common among them all.

For example, beam and column schedules, framing notes, typical details, etc. These things should be on any concrete job. Looking at the drawings may help you get a feel for how the engineer designed the building.

Remember we are engineers and have alot of equations and techniques for designing and personal preferences and opinions about how things should be done, but in the end we (for the most part) we produce a unique product, we produce drawings. You can be the best engineer in the world and know everything there is to know about concrete, but if you don't produce a good set of drawings no one will know that.

So when thinking about how to go about your design remember to keep in mind the product you are going to produce just as much as the engineering you used to get there.

 

[McQSE]

I agree with all the great advice that has been given. Here are some of my thoughts.

If you are not a member of ACI, I would strongly recommend you join. They have an outstanding web site with a lot of resources for the structural engineer. This includes a couple of building design examples. They are not full examples (at some point they will say “beam design - analyzed using software”), but they do give the process.

I recommend getting the ACI 318 code if you don’t already have it. Also get “Notes on ACI 318 Building Code Requirements for Structural Design.” This will give you some examples on how to use the code.

I have 8 different concrete text books. All of these are the current additions that have been published within the past two years. None of them have complete building design examples. They have chapters on a specific design procedure but never put it all together.

For your third question, a good general structural design book sounds like what you need. The overall design methodology is the same for steel, concrete, wood, etc. Lateral loads and gravity loads must always be resisted regardless of material. One of the critical first steps in the design process is figuring the correct loads to apply to the structure.

You really would need several books to cover everything and they all would not be concrete books. As previously mentioned in the other posts, this still is not sufficient. A structural engineer needs some assistance besides text books and codes. A good mentor is the best place to learn; however, mentors can come in several forms these days. You can learn just about anything on the internet. This site is a great place to learn. This site allows you access to numerous engineers to ask questions, and therefore you should get a good answer to your question.

As mentioned, I would get someone to check your projects until you are confident in your design ability. Also, always keep the architect in the loop. You will find that some of them change their minds on an hourly basis without concern for your design.

 

[JackTrades]

While I've never used it, the PCA has a book entitled, "Simplified Design of Reinforced Concrete Buildings of Moderate Size and Height," that may be of some help.

Also, ACI has one called, "Essential Requirments for Reinforced Concrete Buildings (for Buildings of Limited Size and Height, based on ACI 318-02)," which I found helpful.

 

[fa2070]

Thanks everybody for the replies.

In your case, it may be a struggle, but you will prevail.

Thanks for your encouragement hokie66. It will take me an inordinate amount of time to "get there", measured in years... long long years.

I've compiled a list of books that show some potential.
The focus is primarily on concrete buildings.
Maybe there are other hidden gems that I didn't find. Anyways, here is my list:

[ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Tall Building Structures: Analysis and Design[/li]
[li]Author(s): Bryan Stafford Smith, Alex Coull[/li]
[li]Pages: 537[/li]
[li]Publication Year: 1991[/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Understanding Structures[/li]
[li]Author(s): Fuller Moore[/li]
[li]Pages: 304[/li]
[li]Publication Year: 1998[/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Examples of the Design of Reinforced Concrete Buildings to BS 8110[/li]
[li]Author(s): C.E. Reynolds, J.C. Steedman[/li]
[li]Pages: 320[/li]
[li]Publication Year: 1992[/li]
[li][blue]Though it targets an older version of the British code, the Table of Contents looks very promising.[/blue][/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Reinforced Concrete Design to BS 8110 - Simply explained[/li]
[li]Author(s): A.H.Allen[/li]
[li]Pages: 256[/li]
[li]Publication Year: 1998[/li]
[li][blue]A bit dated but at barely 256 pages it sounds interesting.[/blue][/li]
[/ol]
[li][tab][tab][/li]
[ol square]
[li]Title: Essential Requirements for Reinforced Concrete Buildings[/li]
[li]Author(s): Icontec / AIS / ACI[/li]
[li]Pages: 248[/li]
[li]Publication Year: 2002[/li]
[/ol]
[li][tab][tab][/li]
[ol square]
[li]Title: SP-66(04): ACI Detailing Manual-2004[/li]
[li]Author(s): ACI[/li]
[li]Pages: 212[/li]
[li]Publication Year: 2004[/li]
[/ol]
[li][tab][tab][/li]
[ol square]
[li]Title: SP-17: Design Handbook: Beams, One-Way Slabs, Brackets, Footings, Pile Caps, Columns, Two-Way Slabs, and Seismic Design[/li]
[li]Author(s): ACI[/li]
[li]Pages: 482[/li]
[li]Publication Year: 1997[/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Simplified Design: Reinforced Concrete Buildings of Moderate Size and Height[/li]
[li]Author(s): Portland Cement Association[/li]
[li]Pages: 300[/li]
[li]Publication Year: 2004[/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Why Buildings Stand Up: The Strength of Architecture[/li]
[li]Author(s): Mario Salvadori[/li]
[li]Pages: 328[/li]
[li]Publication Year: 2002[/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Why Buildings Fall Down: How Structures Fail[/li]
[li]Author(s): Matthys Levy, Mario Salvadori, Kevin Woest[/li]
[li]Pages: 336[/li]
[li]Publication Year: 2002[/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: The Art of Construction: Projects and Principles for Beginning Engineers & Architects[/li]
[li]Author(s): Mario Salvadori[/li]
[li]Pages: 160[/li]
[li]Publication Year: 2000[/li]
[li]Reading Level: Ages 9-12 [/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Building Structures[/li]
[li]Author(s): Malcolm Millais[/li]
[li]Pages: 355[/li]
[li]Publication Year: 1997[/li]
[li][red]Generic and conceptual, like Salvadori's books.[/red][/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Structures: Or Why Things Don't Fall Down[/li]
[li]Author(s): J.e. Gordon[/li]
[li]Pages: 424[/li]
[li]Publication Year: 2003[/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Simplified Design of Concrete Structures (Parker/Ambrose Series of Simplified Design Guides)[/li]
[li]Author(s): James Ambrose, Patrick Tripeny[/li]
[li]Pages: 448[/li]
[li]Publication Year: 2007[/li]
[/ol]
[li]
[tab][tab]

[/li][ol square]
[li]Title: Concrete Structures[/li]
[li]Author(s): Mehdi Setareh, Robert M. Darvas[/li]
[li]Pages: 576[/li]
[li]Publication Year: 2006[/li]
[/ol]
[/ol]

 

[GalileoG]

I really recommend the first book on that list.

 

[McQSE]

I have No. 15 on your list. It is a good text book. It has a lot of design flow charts.

I also recommend No. 8 on your list. I use it a lot as a design reference.