upper floors design above a transfer beam
Hi all,
My question is about transfer systems and regarding the floors which have one or more of their vertical support being transfered using a transfer beam in the lower stories.
These columns (which are planted in the below stories) will have some vertical deformation due to the fact that the transfer beam is deflecting. the differential deflection between the columns in one story will result in additional moment and shear in the slabs (above the transfer beam ) due to this joint displacement that has been occured.
To take this into account in the design, should we :
- Assign the long term deflection of the transfer beam as a joint displacement in the columns being transfered (when modeling the upper floors) which will result in the inversion of the bending diagrams at support and the middle of span (at support, some bottom reinforcement will be required depending on the deflection of the column).
- Or should we model the column being transfered by a spring instead of a fixed support ?
_Or finally (and the most easy and practical solution), we limit the long term deflection of the beam to some stringent allowable deflection (L/500) and we assume that, when modeling the upper floors slabs, taking the columns as a fixed support can be assumed even though, in the real life of the structure, this may not totally true.
How do you treat this problem ?
Thank you
My question is about transfer systems and regarding the floors which have one or more of their vertical support being transfered using a transfer beam in the lower stories.
These columns (which are planted in the below stories) will have some vertical deformation due to the fact that the transfer beam is deflecting. the differential deflection between the columns in one story will result in additional moment and shear in the slabs (above the transfer beam ) due to this joint displacement that has been occured.
To take this into account in the design, should we :
- Assign the long term deflection of the transfer beam as a joint displacement in the columns being transfered (when modeling the upper floors) which will result in the inversion of the bending diagrams at support and the middle of span (at support, some bottom reinforcement will be required depending on the deflection of the column).
- Or should we model the column being transfered by a spring instead of a fixed support ?
_Or finally (and the most easy and practical solution), we limit the long term deflection of the beam to some stringent allowable deflection (L/500) and we assume that, when modeling the upper floors slabs, taking the columns as a fixed support can be assumed even though, in the real life of the structure, this may not totally true.
How do you treat this problem ?
Thank you
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