Abdul Malik Memon

Column Placing/Positioning

7 posts in this topic

Asalam-o-alaikum,

I'm working on a Ground +3 residential bungalow. The column position  assigned by architect seems quite vague to me and i think that number of columns can be reduced but as I'm an beginner need seniors advice. The attached file is an architect plan.

Furthermore, are there any standards for column placing/positioning? if yes, then what are those?

  After designing a structure what check must be performed before handing over the design results?

And any literature about pick-up beams?

Thank you, hope I haven't flooded the post with question. 

arch jawad drawing.dwg

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On 6/19/2016 at 6:08 AM, Abdul Malik Memon said:

Furthermore, are there any standards for column placing/positioning? if yes, then what are those?

Nothing specific. There is nothing wrong with having this many columns. These columns are more like confined masonry columns rather than structural columns.

On 6/19/2016 at 6:08 AM, Abdul Malik Memon said:

After designing a structure what check must be performed before handing over the design results?

Sanity checks. Your results should make sense and load path should be complete.

On 6/19/2016 at 6:08 AM, Abdul Malik Memon said:

And any literature about pick-up beams?

Pick-up beams?

 

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First you must be clear about requirements (arch, mep etc). Have a clear understanding of dwgs, are the cols masonary, non load bearing? Have you prepared 2, 3 different struc schemes? If you think you can value engineer and reduce cols, check with client req if they too want it.

Then you make sure the scheme is working, deflections, load paths, foundations, framing, cost.

Reducing cols mean, bigger beam and slab spans and so more deflections. Have you checked that? Also more local load on foundations if cols are far, and more sway in wind/eq bcz less bending stiffness of vertical elements (if you are not increasing col/wall sizes to compensate that).

If above is okay, you can eliminate cols that are not required. As a struc engr you have to be proactive, pitchin and promote the "most efficient" scheme that is "simple" and "necessary".

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i have heard about pick-up columns but not beams. i think they are not structural columns but just for architectural purpose or so. If any of the seniors could explain about these two, it would be great.

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Pickup columns or planted columns are structural cols supported on transfer slabs or beams (which you are referring as pickup beams i think).

For seismic design you have to overdesign collector elements like transfer beams or slabs by omega factor.

Issues with pickup cols is loads in them depend on stiffness of slabs/beams supporting them. If supports are flexible they are literally just hanging threads from slabs above carrying little or no load at all, you cannot just manually transfer loads to them by distributary area. Another thing is to check deflection at upper and below slabs as well as punching on both slabs.

Make sure the transfer slab has sufficient shear strength.

Another issue might be consteuction sequence and long term deflections due to these columns.

Also make sure you check for irregularity clauses of seismic code.

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On 6/21/2016 at 3:11 AM, Ayesha said:

Pick-up beams?

 

 

On 6/23/2016 at 3:41 PM, Hira Malik said:

i have heard about pick-up columns but not beams. i think they are not structural columns but just for architectural purpose or so. If any of the seniors could explain about these two, it would be great.

sorry means, heavy beams beneath the pick up columns.

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These columns are like 9"x18" or 9"x21" . at places these are coming into the doors  which should not be actually. if these are to confine masonry then you do not need that much larger sections just 9x12 or 9x9 columns  are enough. if you are proposing a combined frame and masonary or frame only then increased columns sections will be used. make different design proposals and discuss personally some senior near you. 

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