Deflection Limits for concrete transfer beam supporting columns

Question

Deflection Limits for concrete transfer beam supporting columns

CLARENCEQ (Structural)

(OP)

31 May 22 15:23

Hello All,

I am searching the information about deflection limits for concrete transfer beam.
The situation is that I am designing a concrete beam to support 4 stories high concrete column(load is about 100 kips ASD).
For the deflection limits, should I use L/480 with considering concrete long term deflection? Or Using L/240 is acceptable?
My colleague recommends to use L/600 with long term deflection(3 times short term deflection as estimation) as engineer judgement. But it seems too strict.
Any idea about what deflection limits should be used?

Thank you so much!

jayrod12 (Structural) · Answer 1 · 2022-05-31 15:33:36

I'm with your colleague. I don't have anything code specific to back it up, just that deflection in that one beam affects more than just one floor, so I'd be careful.

Obinna1992 (Civil/Environmental) · Answer 2 · 2022-06-05 14:18:32

Transfer structures are critical structural elements because their failure can be catastrophic. In the Eurocodes, the method of checking deflections using 'deemed to satisfy rules' is also applicable to reinforced concrete transfer beams.

Since most transfer beams can be treated as deep beams, their deflection is rarely a problem. There is an example of a design of transfer beams below;

Analysis and Design of Transfer Structures

le99 (Civil/Environmental) · Answer 3 · 2022-06-08 15:02:52

I think the decision shall be based on how sensitive is the upper structure to the subjected deflections.

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Deflection Limits for concrete transfer beam supporting columns