Moments? Beam to Column connection

[BauTomTom]

Hi Struct.Engs.

I have a problem with a ansymetric column.

Don't know if I get Fixing Moments by a Column-Beam connection
and if I get, with wich lever arm?

It is actually a typical detail but how to handel it?

BauTomTom

 

[BauTomTom]

See attached sketch

 

[csd72]

Why would they not be fixed?

This worries me as it is so fundamental. You really need a good mentor to guide you on this one rather than relying on a forum.

 

[e104909]

BauTomTom,

I would suggest you look into detailing so you could familiarize yourself with the connection and rebars. The assumption at every joint is very important thing. There are code requirements also which could help you to satisfy such fixity needed.

Say your beam sits in a corbel or nibs or depends on the function of the beam which you may want to detail it as fixed connection or pin connection.

However, with the connection you have shown seems to be a fixed end.

Assuming you are analysing a building. sometimes if you look into the big picture you might not consider little eccentricity or offsets and you may just assume it is on the center line. say you want to model in a 3d model software. you might not want to model your beam A eccentric to column. and you just need some engineering judgement in the end to justify your design that does not exceed the limits. forces can be extracted and you may want to manually design or use software.

For beam B, the lever arm which you may want to use at the center of the column. this is because the center of your beam B coincides with the center of the column. if in case it is eccentric, as what i have told you, some minor offsets can be neglected and you may just see the safety factor of your design.

remember that engineering judgement is important thing...

why? because we cannot go into such "exact detailed design"...

your card relies on safety factors, loadings and your decision..

and as a designer..you "MUST" always have the

GOOD FEELING....before you do any design.

I hope this helps.

Regards,
E104909

 

[ishvaaag]

If you cast the beams monolithic to the column, you get fixity moments, that are determined by analysis. Certainly I don't get well with not having such knowledge when dealing with the safety of gents, as csd72 implies even more politely. So I endear you to rework anything you have previously studied about structural analysis and get the sooner the better further training on the matter ... in fact you will gain much of so doing. Furthermore you will get properly self-reliant on what you have added to your knowledge

 

[ishvaaag]

Just to not discourage, showing more rebuke than help, let's add that even isostatic support at the sides will provoke some bending moment, it being the product of the reaction at the end of the beam multiplied for the eccentricity respect the orthogonal plane to the beam holding the column axis.

 

[BauTomTom]

-- to csd72 ---
How you mean fixed? Of course they will be fixed to the column but the question is. Which eccentricity will I get from the beam on the column?
Of course I would like that the beam “B” would give his load in the center axis of the column, but how?


-- to e104909 —-
By a corbel would it be easy to calculate the moment since the leaver arm is quite obvious there.

Yes it is a fixed end, because I have no other way. I would like to have a pined one but how? I don’t want to give the edge column to many moments and the beam is designed with a pinned support.

But don’t I get through the beam deformation (exaggerate) a uneven load distribution?
Let me rather show it on a sketch, what I actually mean. Please see attachment

I like your idea or you principal of the GOOD FEELING and that a struct.eng actually can’t calculate into such an detail. So why am so happy that I can ask you all here and that I get every time very good tips.

-- to ishvaaag -—
You actually wont cast it together. As I show on the sketch the first concreting level will be below the beam, the reinforcement of the beam will then be placed on top and the beam will be cast. I assume, it will be done this way or?

You see we don’t have this cases in the assignments. There usually you have a column and the eccentricity or the moment is given already and then you design the reinforcement. It is a big problem actually, that the real systems on the site maid be very different to your exams at the university

BauTomTom

 

[leisure17]

are all these big words suppose to confuse non structural guys?

 

[csd72]

leisure17,

2 things:

Firstly these terms have specific meanings for which there are no simple english terms to replace them.

Secondly, if you are not a structural guy then what are you doing on the structural forum?

 

[e104909]

Leisure17,

Actually it should not confuse anybody who have taken basic mechanics..maybe for some engineering courses it would be a bit confusing but i doubt if you are an engineer...

Yet, even the profession itself is a bit confusing if you haven't experience it though there are many ideas and engineering solutions..every professional has its own unique way to solve a problem.

It is once quoted during elementary days..math without english is useless..so if you cannot understand the basic thought and you are considered as engineer then i would say you have to read all over again.

Cheers!

Regards,
E104909

 

[csd72]

I think they are referring to terms like isostatic, orthogonal, and eccentricity.

 

[msquared48]

I have cross-posted in Mechanical and other forums a few times, and find some humor in many of the terms with which I am not familiar. However, this does not prevent me from learning what they really mean. It only helps with communication between disciplines. Twisting reality for a laugh doesn't hurt either as long as no one is offended by it.

If we cannot laugh at ourselves, we need not laugh at anyone.

Mike McCann
MMC Engineering

 

[RFreund]

Ok now this is getting out of control someone is trying to cover up this deleting post conspiracy.

EIT

 

[e104909]

Csd72,

I agree.

Anyway...seems the problem is solved and some solutions were deleted...we can now move on





Regards,
E104909