Allowable Stress Load Combination Factor
- Prior to the '97 UBC and the 1612.3.1 load combinations the UBC permitted
an allowable stress increase of 1/3 if the corresponding load case involves
either wind or seismic forces.
- In example: fb £ 1.33 Fb'
- Known here as the allowable stress increase factor.
- Recognizes that it is unlikely that all of the loads in the respective combinations will be at full value.
- Factor is only applicable when design is based upon allowable stress methodologies.
- This factor, currently can only be used with the alternative load combinations of '97 UBC 1612.3.2. We will not use these loads or this adjustment.
- There was confusion regarding the use of allowable stress increase factor with the load duration factor, CD,for wind and seismic that is unique to wood design. This confusion should disappear as designers adopt the new code and the revised load combinations.
