long term deflection

huangyhg

long term deflection
what is the long term deflection limitation for the two way concrete slab? aci 9.5.2.5(aci 318-99) eq 9-10 is too confusing, is any quick way to get the allowable deflection limitation to compare the result we got from ram concept?
happyday,
the code clause is pretty clear.
if you cannot understand it how are you going to understand how to manipulate ram concept to give reliable values for deflection, because the values it gives using the default settings will not be realistic allowing for cracking and long term effects.
see table 9.5(b) under "deflection to be considered"
ted
happyday,
your long-term amplification factor per aci 9.5.2.5 is (2) for accounting for creep and shrinkage in slabs. however, a multiplier of 2 is typically not adequate to estimate deflections in conventionally reinforced two-way slabs. several studies have indicated that a value of 3-4 should be used to estimate long term losses, or a lower modulus of rupture strength of 4*f'c^1/2 to account for cracking due to shrinkage restraint at columns. i would suggest the paper "long term multipliers for estimating two-way slab deflections" by graham and scanlon, aci journal nov-dec 1986. it has some good information that may help you determine the multiplier to use in concept. in addition, aci 435rfff"> control of deflections in concrete structures has information regarding the same topic.
good luck,
auce98