Long-term composite beam deflections due creep/shrinkage?
Long-term composite beam deflections due creep/shrinkage?
(OP)
I have a couple questions about long-term composite steel beam deflections due to creep/shrinkage:
When is it necessary to consider them? Is there is a certain DL/LL ratio where it should be calculated?
Also, how do you account for the creep/shrinkage when you think it is necessary? I have read about people only considering half of the concrete modulus in deflection calculations.
When is it necessary to consider them? Is there is a certain DL/LL ratio where it should be calculated?
Also, how do you account for the creep/shrinkage when you think it is necessary? I have read about people only considering half of the concrete modulus in deflection calculations.






RE: Long-term composite beam deflections due creep/shrinkage?
"Structural Steelwork Eurocodes Development of A Trans-national Approach"
See images in the attached zip. The last formula in the 3d image points to 67% effective stiffness of concrete (respect full effective section considered).
Effective width can be taken 100% when for slabs under uniform loads.
More complete engineering judgement tips can be extolled from the reference.
RE: Long-term composite beam deflections due creep/shrinkage?
"In practical floor construction, these requirements are met (although not explicitly
stated in EC4) if the span:depth ratio of the composite section is less than the
following:
• for simply supported beams: 15 to 18 for main beams, 18 to 20 for
secondary beams (joists);
• for continuous beams: 18 to 22 for main beams, 22 to 25 for secondary
beams (joists)."