Wood I-Joist Desgination?

[jim57]

Looking at a structure I believe was built in the 1980s. The floor beams are wood I-joists with the designation " WI 33-9 1/2. I'm guessing they are an older Georgia-Pacific product. Does anyone have load tables? or do you recognize eh manufacturer. Thanks

 

[charliealphabravo]

They look like legacy GP Wood I (WI) joists. Hopefully someone will post with the load table. I don't see anything smaller than the WI 40.

 

[BridgeSmith]

If getting the capacity/allowable span of the joists is the goal, will the original load tables even get you there now? You should be able to calculate a capacity based on the dimensions, species/type, and condition of the components. Don't know if I'd trust numbers from a 30 something year old load table for thirty-something year old joists.

 

[dik]

HR: you may not know what the flexural or shear strength of the material is if it is proprietary.

Dik

 

[BridgeSmith]

If the flanges are laminated veneers, that could be true, dik. However, if the flanges are 2x lumber and the web is OSB, as most of those were, the species of the lumber can usually be determined by a visual inspection. 90% chance the flanges are Douglas Fir, and the strength of OSB hasn't changed much, and neither has the strength of plywood. charliealphabravo had some info on the WI40, which should utilize the same materials, just in a larger size.

 

[dik]

HR: The material may be stress graded (MSR)... so, don't really know.

Dik

 

[BridgeSmith]

True, Dik. Assuming properties for visually graded lumber could be conservative. I didn't mean to disagree that having the specs for the joists would be preferable. In lieu of that, however, an assessment of their capacity can still be made. Even with the original load tables or properties, the current condition of the joists should be taken into account in assessing their adequacy for the current or proposed loading.