Interview help - post tension design using hand calculations 5

[sparta7963]

Hi, I am a attending an interview with a company which does Post tension work. The job position is 'Structural Engineer - Post Tension Design'. I was told by the recruitment agency that the company will do a technical round interview where i have to use hand calculation in post tension design. I have about 5 years experience as a structural engineer but never done post tension design. Can you please tell me the some question that I might be asked in 'Post tension design' and what sort of hand calculations i have to do. I am in UK, so please provide me some study materials based of BS/EURO code. Thank you.

 

[KootK]

I find it interesting to consider this in terms of "balancing moment" as rapt suggested. With the extreme tendon position a given, the peak of that moment diagram is unaffected by the tendon disposition elsewhere.

What is affected by the tendon disposition elsewhere is the total area under the moment diagram and, by extension, the total area under the curvature diagram and, ultimately, deflection. Since a level tendon profile msximizes the area under the moment diagram, it makes sense that arrangement would maximize deflection.

So, if one were to design a cantilever with the singular goal of inducing upwards tip deflection, the best strategy would be to:

1) Raise the end anchorage as much as possible.

2) Use a concave down parabola to get from the end anchorage elevation to the support tendon elevation.

Both of these things because they "fatten" the moment diagram. But, then, we typically do neither of these things in conventional design for a number of practical reasons.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[cliff234]

There is no way that you will be able to teach yourself p.t. design sufficiently make this prospective employer think you know p.t. - and ethically speaking, you should not try to pass yourself off as being proficient at something you have no experience with. A better solution would be to make the case that you are an intelligent engineer who is eager to learn new things and is self-motivated. (Your message speaks to your eagerness to learn p.t. design.) I think the things most employers look for when hiring new engineers are things that cannot be taught - and eagerness to learn, a willingness and ability to communicate, a good work ethic, a genuine passion for structural engineering and an intelligence and curiosity about the way things work. Teaching p.t. someone how to design p.t. is easy - those other things are not.

 

[rapt]

Kootk,

Yes, the best for deflection. But when pushed too far you start causing transfer stress problems!

If he was alive today, poor old TY Lin would not like our conclusions regarding Load Balancing vs Moment Balancing, but Leonhardt and Guyon surely would.