Long Term Deflection for Concrete:

Long term deformation (or deflection), Δ, is found by multiplying an amplification factor (λ) by the initial deflection (Δi).

The long term deflection is found by using the following equation:

Δ = λ Δi

where:

Δi = the initial deflection? of the concrete beam
λ = amplification factor = i\over {1+50ρ'}
i = 1.0 (for 3 months), 1.2 (for 6 months), 1.4 (for 1 year), 2.0 (for 5+ years)
p' = the compression steel ratio = A'_s\over bd
b = the width of the concrete beam
d = the depth of the concrete beam (note: that this is not the same as the height of the beam)

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