Allowable Stress Increase?
Allowable Stress Increase?
(OP)
I am currently using IBC 2000 that references ASCE 7-98 for wind loads. ASCE 7 has eliminated using the 1/3 increase for the D+W load case. Does this mean when designing Simpson holdowns for wood framing subject to uplift or shear walls that we cannot use the values listed in the Simpson catalog as 1.33 or 1.6 times the allowables?






RE: Allowable Stress Increase?
RE: Allowable Stress Increase?
DaveAtkins
RE: Allowable Stress Increase?
Thanks for your input! Could you reference a code section in ASCE 7 that states that?
RE: Allowable Stress Increase?
DaveAtkins
RE: Allowable Stress Increase?
This overstress factor is not allowed for connectors in wood construction, because the connectors are not made from wood. (I suppose if the connections were mortise and tenon, you may be able to make the argument.)
Unfortunately, it appears that IBC 2000 has done away with the probably 100 year old practice of 4/3 allowable overstress when wind is a major factor.
RE: Allowable Stress Increase?
in 1977 called "The Mysterious 1/3rd Stress Increase" on the AISC e-pubs website. Free to read if your a member. It tries to explain the history of its origin and use from 1896.Good Luck.
RE: Allowable Stress Increase?
RE: Allowable Stress Increase?
RE: Allowable Stress Increase?
DaveAtkins
RE: Allowable Stress Increase?
I tried to call Simpson today to discuss this, but they are off for President's Day. I will try to talk to them tomorrow.
RE: Allowable Stress Increase?
DaveAtkins
RE: Allowable Stress Increase?
The old stress increase of 1.33 for wind or seismic increased to 1.6. Simpson reflects this. The capacity of the Simpson connectors is limited by the engineered preperties of wood, not the bolts or the steel that make the connectors. That's why the design values are peculiar in their catalogs for species and load duration.