Structural design scope

[bausk]

Please confirm or elaborate: For the redlined elements, only the section size is subject to design, i.e. shape types, steel grades, timber types are not to be altered?

[theoryshaw]

referred to redlines for reference: https://github.com/OpeningDesign/Lake_Kegonsa_Home/tree/master/Out/20141021%20-%20structural%20screencapture

• shape types -
  • The only beam depths that i'm conscience to keep a certain size, are wrapped in casework category. Please let me know if your calculated sizes push outside these bounds.
  • columns can vary, would like incase them in the 2x stud wall they are located in.
• steel grades - no, you can assign.
• timber types - no, you can assign--would only say that LVLs are more cost effective than glulams, for example, but please share you thoughts if you have a different approach.

Please let me know if you think any of the members would work better with steel or wood.

[bausk]

Ok, good.

Another input data related question: are the roof structure and material properties present in the model good as an input for analysing loads? Or are they tentative/preliminary? Maybe any manufacturer info on weight per sq.ft? I'm okay to go with ASCE minimum values, so I'm maybe being ultra facetious, just checking.

[theoryshaw]

yes, they all the roof materials are accurate.

Speaking of, these three I sized myself, please let me know if their size is calibrated correctly.

[bausk]

Please clarify what exactly you want to check with the roof size? As far as I see there are no details about rafters for the gable roof. Overall shape/sloping looks okay.

[theoryshaw]

• The rafters for these two flat roofs are 2x6s on 16" centers
• The rafters for this roof are 2x8s on 16" centers.

[theoryshaw]

i did not model the 2x8s, they are just part of the roof object.

[bausk]

Okay, rafters, I get it now, I'll check them. Also since there are no additional details, I'll assume category C for exposure and II Occupancy categoty, just for reference.

[theoryshaw]

It might be category D (as i understand it)...

"Wind exposure category D is comprised of flat, unobstructed areas exposed to wind flowing over open water for a distance of at least 1 mile. This exposure applies only to those buildings and other structures exposed to the wind coming from over the water."

cited from

Lake Kegonsa is to the north of the house.

Not sure, where you got 'II' from, but it would be a 'Residential Group (R)' occupancy. Thanks.

[bausk]

Yep, this sort of location warrants cetegory D.

"II" is Risk Category according to ASCE 7-10 table 1.5-1, since this is not a public building.

[bausk]

Ryan, Regarding the roof sizing,

for gable roof over garage storage: Grade examples that satisfy code include Spruce-Pine-Fir No.2 Southern Pine No.2

for the two porches, according to the code the timber grade should be for example Mixed Southern Pine No.1 if we want to keep the 6inch depth. I am concerned about snow drift on the flat porch roof. I'm going to calculate the drift value rather than use span tables.

[theoryshaw]

Sounds good, let me know. Perhaps we can switch to 12" centers, if you're concerned about the snow drift.

Thx.

[bausk]

Ryan, as an example, Spruce-Pine-Fir No.2 @ 12" will do fine for the two flat roofs. I will commit the analysis for rafters today and will move on to the beams. We can revisit the wood grades later if you want to check against a specific kind of timber.