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Timber beam deflection

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Roy,

When you remove the load after the sag has increased to 0.50 inches, with 
0.25 inches initially, the residual sag should be in the neighborhood of 0.25 
inches.  (The elastic deflection is 0.25 inches, the creep is 0.25 inches, 
and only the elastic deflection can be recovered.)

The last part of your post is harder, because I never really thought about 
it, but I would guess that the initial (elastic) deflection will once again 
be 0.25 inches, and that eventually, another 0.25 inches of creep will occur, 
with a final deflection of 0.75 inches.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Roy Levy wrote:

. > Can someone advise on this hypothetical timber beam deflection problem?
. > 
. > 1 .A  beam is loaded. The immediate sag is 0.25 ins. The load remains and 
. > in time the sag creeps to 0.50 ins.
. > 
. > 2. After that, the load is removed.  What is the sag now?
. > 
. > 3.  The load is reapplied. What is the sag now and in the long term?
. >