Effect of Bracing on Deflection of Beam

[aluminum123]

Does bracing has any effect on deflection of beams? I am presently working on an alumunium mullion design which is laterally bracedd by transoms (horizontal members) in a curtain walls. So, whether I should use the span length for deflection calculation from bracket to bracket (which is fixed at the slab at both ends), or whether I should use longest span length between two transoms.

The Height of the mullion is 3.65 meters with bracing provides at 0.7m from the ends.

The connection between the mullion and transom is held by a two screws.

So, should I use the full span length neglecting the bracing as like a simply supported which would render conservative results or whether I can assume the pin support at mullion and transom connection and find deflection by inditerminate beam methods.

Can bracing be consideredd as a support point in the beam?

 

[MiketheEngineer]

How much can the bracing possibly add? You give no dimensions on that. If it is less than 10% help - I might just move on UNLESS you need every little bit you can garner!!

 

[aluminum123]

Actually the transom which is horizonally intersecting the mullion is of the same section as the mullion. Both of these sections are like tubes. The length of the transom is 1.08 meters.

My main issue still remains is that if I take the full length of the mullion without considering the effect of transom in between it gives comparatively large deflection.

MiketheEngineer I want to know that the unbraced length should be 2.25m (3.65-1.4) or it is 3.65meters in order to use in the deflection calculation.

 

[tngolfer]

What's supporting the transoms? How would they "support" the mullion? I think the mullion span is 3.65 m.

 

[aluminum123]

Transoms are connected with the vertical mullions only so does this mean these are the mullions who support the transoms? I have also found a software from an aluminum mullion and transom profile manufacturer they have also neglected the effect of the horizontal transoms.
I am also thinking that I should use 3.65m for deflection calculation but further elaboration whould be helpful.

 

[BAretired]

A sketch is always better that trying to explain it in writing.

BA

 

[paddingtongreen]

If you are speaking of in-plane loads, the bracing does nothing for deflection. If you are speaking of in-plane loads, as in a shear wall, the transom converts two independent drunks into two mutually supported drunks, it does nothing unless further connected to a reaction point.

Never mind asking us, can you find a mechanism where it would have any effect? It is disturbing that you even ask.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[charliealphabravo]

If the transoms are only lateral braces and are not continuous across the span then I'm not sure how you would assign any beam behavior to them. This means that the primary span (mullion) is forced to act alone in terms of out-of-plane deflection.

Now if the mullions and transoms can both act like beams then I would do a deflection compatibility calculation if I really wanted to determine how the transoms assist the mullion.

 

[hokie66]

aluminum123,
Asking such a simple and uninformed question indicates that you are not a structural engineer. This site is for sharing of information between engineering professionals. Please seek advice from an engineer in your area.

 

[aluminum123]

Yeah I also think it like that the the transom is not connected so much properly with the mullions to consider it as a reaction point but it may act as bracing which has nothing to do with the deflection. Thanks guys for your help.

BAretired here is a sketch

hookie66 Yes I am not a Professional Engineer yet.