Steel Bracing Hello everyone! I 1

[ahmi786]

Steel Bracing
Hello everyone!
I want to ask a question that when we use steel bracing as the corner of building and then apply same bracing on same building but at some other location ( not at corners), we get different base shear, time period, frequency and roof displacement. Why this happens? why changing position changes the results.

 

[Agent666]

If you move some bracing, in the simplest sense you're changing the dynamic response of the structure (period may be different, if period is different the base shear will potentially be different depending on where you are located on your code design spectrum).

For example the structures stiffness may be affected, so your period and base shear will differ, therefore your deflections may be different.

Similarly, moving bracing to be closer to the centre of mass might make your structure more sensitive to torsional effects, again potentially leading to more deflection out on the building perimeter due to the twisting in plan

 

[ahmi786]

Agent 666 thanks for your reply. I need some urgent more help. Below is description:

WHAT I DID:
I made two building models of the same specification (plan,sections,load, bracing type etc.) On one I applied bracing at corners and on the other I applied same amount of bracing at its central outer portion.

I have received more good results w.r.t internal forces (storey displacement, time period, frequency, base shear) when I placed my bracing at Outer central portion of building as compared to bracing at corner.

BUT,

When I checked the structural members, I found that when bracing is at central outer portion many structural members (i.e., beams and some columns) get fails but no member failure found when bracing is at corner.


I found that from internal forces point of view the bracing is good to be at central outer portion but from ULS and SLS point of view it is not good.

NOW MY QUESTION IS:

Are there any differences in bracing system behavior if it is placed at the central or corner position?

 

[Agent666]

Post some screenshots or sketches of the two configurations. Start putting some numbers to your results. For example the term 'more good results' has no context and is open to all sorts of interpretations, is it 20% or 209% different for example.

Reread my first reply. Obviously if you're changing the configuration, you're changing the period to some degree, then you're changing the seismic loads, so of course you're then possibly changing the member loads, and possibly making some failures occur for the same member sizes.

There is no generic rule to say one location for bracing is better or that the response or loads will be better. Each structure is going to be unique, storey height, beam lengths, bracing demands will all typically differ for example as will the seismicity of the site compared to another site.

Sorry for the late reply.