ForteWeb software

[JStructsteel]

Anyone know where to change or see what design values the program uses for the 'commodity and premium' lumber option? Im curious to the values they use
Thanks
Jim

 

[phamENG]

JStructsteel - unfortunately it has a bit of a black box characteristic here. According to this page, it indicates that the commodity lumber values for Glulam and sawn lumber are based on NDS Supplement values. There's no way to change them (it is a free program, after all).

 

[JStructsteel]

Thanks, I saw that. Perhaps I can email them for info, see what they say.

 

[ChorasDen]

JStruct, pham is correct, that program references the NDS supplement from whatever design code year selected. Should be pretty easy to confirm the design values by calculating it yourself from design equations in NDS, I've done so in the past.

 

[phamENG]

While we're on the subject of ForteWeb - if you use it for applying wind load to studs or headers be sure to ignore their guidance on selecting exposure C/D. It is out of date (by about 14 years) and doesn't follow the guidance from ASCE 7. I sent them a note and they said their engineers are reviewing it to see if a change should be made in the next release.

 

[JStructsteel]

@ ChorasDen, I could confirm it, but my intention is to use their software and products so I dont have to do a bunch of calcs. Not being able to see the values, causes me to spec something else. They have premium and commodity lumber available as an option, and that can be a wide range.

They do need to update their program, its a handy program to use.

 

[Celt83]

Keep a careful eye on the deflection calculations with the commodity lumber option, last time I used Forte it did not apply the creep coefficient to dead load deflections.

I'm making a thing:

http://www.thestructuraltoolbox.com

(It's no Kootware and it will probably break but it's alive!)

 

[phamENG]

JStructsteel - I'm confused on your hang up, then. Are you concerned about them using the correct values, or are you concerned about selecting the right grade? Within the settings you can select which species to display. For instance, I can select Southern Pine No.2 when I check Commodity Lumber. So while I agree it's annoying that they don't list the reference design values they're using, by selecting 'Commodity Lumber', '2x SP No.2', and 7.25" depth, I know what I'm getting.

 

[phamENG]

Celt - correct. It does not apply creep deflection.

There is a deflection analysis type called Creep Analysis that checks long term deflection beyond instantaneous deflections due to heavy loads acting on a member for long periods of time. Our software does not analyze this type of deflection because North American building codes do not require creep analysis. However for Parallam® Plus, an approximation of long term deflection (creep) is included in the total load deflection result.

I guess the interpret the relegation of creep in Chapter 16 to footnotes to mean it's optional? I don't know. I read it to mean you have to consider creep...

 

[Celt83]

Yeah I got the impression they felt creep was not required or a design concern for their engineered products which they built forteweb around and then when they added lumber as a design option rather than call it a calc limitation they came up with this CYA note.

I read NDS 3.5 to be pretty clear that creep deflection using the Kcr term needs to be considered.

I'm making a thing:

http://www.thestructuraltoolbox.com

(It's no Kootware and it will probably break but it's alive!)

 

[JStructsteel]

PhamENG, you are right, I just have to dig to get the values, and assume they are correct, or verify with a hand calc. Just surprising they dont put the values in the report, etc.

 

[phamENG]

My take is that they expect that program to be used by designers and contractors, not engineers. So they're a little careful of how much information they put out there in case it gets misused. Of course they plenty of CYA notes about the operator being responsible yada yada, but it's way too limited to be of significant use to an engineer. It's handy to run quick calcs and size normal beams, but it's far from an end all/be all for wood design (though I suppose nobody has managed that yet, have they?).

 

[Celt83]

at $425/yr Woodworks is a pretty solid choice

I'm putzing around with the new Load Takedown analysis in Robot.

ForteWeb is like Hilti Profis they did a cost/benefit analysis and determined by getting a free design tool in the engineer's hands, that calcs proprietary and commodity product, that some percentage of those engineers would spec their product and lead to direct material sales and offset the dev/upkeep cost.

I'm making a thing:

http://www.thestructuraltoolbox.com

(It's no Kootware and it will probably break but it's alive!)

 

[phamENG]

Yeah - for a free package it's hard to beat Forte. My favorite part about it is that, of all of the EWP's available in my area, Weyerhauser is the weakest and has the lowest E values. So by running it in Forte, I know whatever ends up on site will work. If I sized all LP products and somebody put up a Microlam, we could have problems.

I've spent enough on trying out software packages for now...I'll give Woodworks a try eventually. (I never have time to effectively test out a trial version.)

 

[ChorasDen]

I read NDS 3.5 to be pretty clear that creep deflection using the Kcr term needs to be considered

I read it differently, what I would typically see/recommend in wood design is to consider creep deflection if the sustained load is to exceed 50% of the controlling live load. This is reflected in the commentary section C3.5.2, which states "Where dead loads or sustained live loads represent a relatively high percentage of the total design load, creep may be a design consideration. In such situations, total deflection from long-term loading, deltaT, is estimated by increasing the immediate deflection, deltaLT, associated with the long-term load component by the time dependent deformation factor, Kcr"

I suppose it's up to us to determine what "relatively high percentage" entails, but I've generally used 50% in the past.