Traffic engineer wants to switch to structural 3

[dassouki]

Hey All, I've been doing traffic and transportation engineering for the last 6 years. I love it and all, but I'm finding more and more that my passion and interests are with structural.

I'm not a total ignoramus in structural but at the same time, I'm no guru either. If it matters I live in Canada.

I used to work as a building designer (Architecturally) for a few years and still do it part time but was never involved with the structure.

This is a building I designed a few years ago (again just building layout and NOT structurally), that I'm trying to design the structures for it as a learning experience. For now, I'll be ignoring seismic loads until I get a better handle of the other analysis. It's a 6 story building, with a main and typical 5 on top. I'll be ignoring the sloped roof for this analysis as well. I divided the structural grid into a grid as shown in the drawings. Building Plans and one Elevation

http://97.107.136.148/building.pdf

Going through the code, here is what I calculated or found:

Roof live load: 1.0 kPa
Living space live load: 2.4 kPa
Balconies and Cantilevers: 4.8 kPa
Exists and main lobby: 4.8 kPa

Where tributary areas are greater than 20 m2, the live load becomes LL = LL * (0.3 + sqrt(9.8/b)) where b is the tributary area

For dead Loads, I'm using the self weight of the material as 25 Kn/m2, which is then evenly distributed over the columns below. For initial calculations i'm assuming 200 mm concrete exterior walls and balconies, and 150mm slab. I'm also assuming studded interior walls (wood + gypsum)All columns except for the F3, are 600 x 200 mm, Column F3 is 300 x 300 mm.

I'm adding a lateral load of 0.5 kPa on the sheer walls which I assume will be the elevator and stair cases.

For snow Load, I have calculated it to be about 3.8 kPa

For the windloads, I have found that on the corner : -2.4 kPA, the edge -1.9 kPa, and the field (-1.3 kPa)

As I said previously, my first go at it, I'm ignoring Seismic Loads.

Using Ultimate states, I will have 5 load-combination cases as outlined by the code. For now, I’ll assume 1.25 Dead Load + 1.5 Live Load as a principal load with a 0.5 Snow load or 0.4 Wind load as a companion load.


Questions:
-----------

1. Loads: Now that I have my loadings, what is the proper way to distribute them across the structure? Also, from recalling structures and concrete class from 8 years ago, it seems that i probably am missing some more lateral loads. With loads, I'm also struggling to find out which ones of my nodes are fixed or roller based.

2. Frame analysis: Currently, I'm trying to understand which frames to analyze first. Should I analyze the X/Y frames first or Y/Z frames?
Here is the X/Y Frame section at E.

http://97.107.136.148/section_at_e.pdf

. Is this an accurate representation at that plane? Drawing the BMD for that section, i'm assuming that I would have a vertical uniform going across every member consisting of the load combination, and a point load where the walls are. The lateral loads would be the wind loads applied to all exterior nodes of the building. Also after the BMD, I should calculate the Reactions, R and V, and moments and the distance at shear for every member.

3. Moving on: If with your help I get an answer for 1 and 2, I'm assuming here is the following procedure that I need to do:
3.1 Design for flexure: Design all beams for flexure
3.2 if applicable design for development and splices
3.3 Design for shear and tortion
3.4 Design of slabs
3.5 Design for deflection
3.6 Design of foundation.

4. Feel free to critique and help me with this exercise. As I said before, I've been involved with traffic for so many years, that my memory on a lot of the structural stuff is a bit vague. I would like to learn and get back into structural, bu


Note, I'm sorry if this has been a long winded post, but I'd like to learn and get back into structural for a personal level for now, and perhaps if a job posting comes up for a structural I would at least have some knowledge and information to be able to apply to it with some beginner degree of confidence.

 

[dassouki]

For now, I'd like to do the calcs by hand and Excel, I know I could use a software for it, but I fear doing so will hinder my learning experience

 

[e104909]

dassouki,

You might want to check the FAQ under this forum. To check some introductory tips.

Also, you might want to study some concrete books available at the bookstore. This would help you understand the load path, load assumptions, factors, materials, guides etc.

books by Arthur H. Nilson, David Darwin, Charles W. Dolan, Park R and T pauley and many more should help you.

However, I would suggest for you to use software. Though, you were after the in-depth learning..but I don't think software would hinder your growth as you will have the chance to understand how structure behaves and how do you want your structure respond to the way you expect. Its good to learn software as you can see it 3d. But you "must" identify parameters the way you know that it should be. The most important thing as ive mentioned is "KNOW THE BASICS"

Doing it manually will actually lead you to a very long process though and might give you confusion..but getting back to the basics will give you an edge.

After you determine the type of framing you have in the X or in the Z direction (Ordinary moment frames, braced frames, shearwalls..etc.) then you can divide your frames into sub-frames which you think is critical. The apply loadings and you can now check elements (beams and columns). Doing this is like you were analysing 2d for each frames which "you" as engineer should identify which frame you must consider as critical. All of these you can learn from available books.

Try to find this "The Design Process of Concrete Structures by J.W Wallace". I cannot attach as the file is quite big. Go to 4shared.com

Applying your load manually by using load combinations to achieve the ultimate design values. Then design as per distribution and load path.

Example ie. load from slab, will go to beam then will go to column..Gravity case

As I have said this would take a very long time..and you should understand structural analysis and proper distribution.

Take time to read first..it might be critical to presume everything.

As a good start, try to re-read structural analysis books, for you to understand level by level.

Best of the best..take masteral degree..to refresh everything.

Good luck

Regards,
E104909

 

[ron9876]

I recommend using hand calculations. If you have software available you might use it to check your answers.

If you make a change in discipline you will likely have to accept a reduction in compensation. But if you want to make a change I recommend that you make it sooner rather than later.

 

[Forensic74]

Structural is dead, stick with site civil or transpo.

 

[dassouki]

@MainMan10 the ideal situation would be to stick with transpo, but be able to do small structural jobs here and there, a small basement here, a 1 story structure there, if you know what I mean

 

[abusementpark]

Structural is dead, stick with site civil or transpo.

What makes you say that?

My firm has been quite busy the past couple of years.

 

[rowingengineer]

This is crazy, stop. This is not something you take on without a mentor or supervision. Just like transport there is lots of information to learn, experience to gain. To be a good structural engineer, I believe you have to do it for a minimum of years. Just doing a structure here or there is dangerous for me, you and the client. You would be better suited to find a good referral structural engineer and hope that they refer back to you. We have a few referral systems with engineers for ground water and transport ect and it works great, we form good teams on lots of projects. That team makes money due it working well.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[Forensic74]

What makes me say that it's an insult to read a licensed engineer posting on here asking me how to do elementary tributary widths so he can take work away from me. We dont need another eng-tips educated engineer out there undercutting and competing for our work. Maybe it doesn't affect the big firms, but the qualified small firms see this kind of "engineering" all the time. Some roadway engineer thinks he can design a small building and it results in a bunch of weird details and poor design. I think its admirable the amount of knowledge available on this site, but it's like shooting ourselves in the feet. I agree with Rowingengineer and I think this thread needs to be deleted and the OP look into mentoring of a different kind if the OP really wants to pursue this career.

 

[abusementpark]

What makes me say that it's an insult to read a licensed engineer posting on here asking me how to do elementary tributary widths so he can take work away from me. We dont need another eng-tips educated engineer out there undercutting and competing for our work. Maybe it doesn't affect the big firms, but the qualified small firms see this kind of "engineering" all the time. Some roadway engineer thinks he can design a small building and it results in a bunch of weird details and poor design. I think its admirable the amount of knowledge available on this site, but it's like shooting ourselves in the feet. I agree with Rowingengineer and I think this thread needs to be deleted and the OP look into mentoring of a different kind if the OP really wants to pursue this career.

OK, I didn't realize it was a tongue-in-cheek comment.

Anyone who tries do what you are describing never prospers. I've seen them try.

 

[dassouki]

1. I wasn't trying to take any jobs from you
2. I wasn't going to design a building to be built without being confident and competent at it. I wanted to learn it for my self. I like to understand how things work and how they are built. IF after a few years of mentoring through the association or employment, then I can venture off and do small odd jobs here and there. I think individuals on here assumed that I was gonna do one exercise and then go about designing buildings. No that's not the case and nor will it be.
3. My second purpose of learning as I mentioned in the first comment is to apply to job postings as a junior.
4. I think lots of individuals on this thread jumped to conclusions way to fast without asking me more questions rather they misunderstood and therefore misjudged.

 

[e104909]

We should not feel threatened

It is more insulting that you come here in this forum and got nothing even a piece of advice knowing the site was called "Eng-tips" yet you will feel rebuked by professionals.

If it is for you then it is.

No offense but I don't think people in this forum who feels that way could not contribute to this forum. Sarcasm might end up with giving false solutions and deceiving ideas.

Anyway, some might be correct which I also agree. It cannot be obtained fully in this forum..proper supervision and experience is a must. or else computers and shallow assumptions will ruin you and the people who will occupy. If I were you, try to get some jobs in a junior position then you'll make your way to start your career.

Structural Engineering requires deep appreciation of what you are doing and certainly requires years of dedication and passion.

Regards,
E104909

 

[rowingengineer]

e104909,
the question is to big to be handle by a few tips. I do not feel threatened, I was/am more concerned about public safety. sure I could have given dassouki a quick run down on fix vs pinned vs roller columns, but after about an hour of explaining that, I would not have enough time to explain the load impacts ie part vs total ect.

If we take a look at dassouki's past posts I see someone trying to take a short cut in the understanding of structures. This is not good situation for anyone working with dassouki. It is likely they could think that he knows the basics and probably skip this step in his learning (probably the most important).

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[e104909]

Very well said.

I apologize if you were referring to me.

I would agree for what you have said.

However what i am just against of, is the "taking of work away from" and discouraging to grow.



Regards,
E104909

 

[Forensic74]

Hard earned growth is fine, but that's not what I'm reading in the OP.

I hope you realize that for every dassouki there are many more who read and don't post. The easier we make it for people to enter the job market, the lower our salaries go. AMA seems to understand that, why don't we?

 

[Ron]

I agree with RE...good comments.

With any related discipline of engineering, we all have some basic competence. I look at the geometry of some of the spaghetti interchanges that I've driven and think "what kind of drugs was that transportation guy on when he did this design?" I look at a site design and think "I would have put that retention pond on this side and the parking lot over there".....but I wasn't involved in either of the projects so I don't know the decision structure, the costs, the clients or a zillion other details that influence such decisions. It all looks easy from the safety of our individual perspectives.

While I applaud your desire to learn more and change, it must be done in a manner that yields professional competence. That isn't done by dabbling. It requires immersion. In some respects it's like learning a foreign language. We can all get a phrase book and read snippets of things to perhaps get us by. But there is that lurking probability that you will, at the least, embarass yourself with an errant phrase, or at worse, get your nose re-arranged.

If you want to make the change, start by taking coursework in structural design. Some of it will be a refresher, but much will be new. It will help you to understand load definition and application, sequencing, and combinations. The make the change by getting hired in a multi-discipline firm that perhaps can use your transportation talents as you work a bit closer with the structural guys, with the intent of a department change at some point. You'll probably lose less money if you can pull that off. Otherwise, bite the bullet and get into a structural firm as a newbie.

Good luck and don't design anything until you have someone available to you to check it!