IRC 2009 Wall Bracing

[dchin]

I am working on a house project that has two full stories above grade over a basement. There is a third story that is under the roof and is constructed using attic trusses. I am looking at the bracing requirements for the first floor and I am trying to determine in Table R602.10.1.2(1) (90 mph) which diagram this first floor belongs with: a. the center diagram of the second grouping or b. the right most diagram of the third grouping. I attempted to upload a pdf to go along with my question but cannot make one under 50 KB.

Also, if for Method PFH as shown in Figure R602.10.4.1.1 there is a limit for the number of stories that can be over the portal frame? In Figure R602.10.3.3 it mentions different widths depending on whether it is a one or two story structure, but no mention in R602.10.4.1.1.

Thanks,

Donald

 

[Architect1281]

I would treat the attic frame truss as a roof ceiling and justify by TABLE R602.3(5) second diagram from left

as this introduces the requirements of bearing walls into the bracing

then while you are in 602.10.1.2(1) I would apply the center diagrams as two stories above the foundation

for a more comprehensive analysis take a look at where these concepts come from on the awc.org web site track down the WFCM workbook

that document is free to download and tracks a standard design through all load applications.

if i tracked it correct it should be here

http://www.awc.org/pdf/wfcm2001workbookandappendix.pdf

page two of general describes that design as Finished Attic which is what I belive you are describing

more information there than most need but not enough for those who engineer them

 

[dchin]

Thanks so much for your reply - great stuff.

Don

 

[Architect1281]

dchin

take a look for a course called

continuous load path wood frame structures

this course is offered free by Simpson Strong-tie

it is at least a full day course and will introduce the concepts of continuous load path

and is reference by code sections.

It is one of the better product oriented education offerings by a manufacturer.

http://training.strongtie.com/stc/sstpub/psciis.dll?CLASSMENU=sstpub&searchoption=FIELDS&fisDirectList=1&field0=XOWNER&value0=24

every code cycle or so I take or retake tis class myself and on occasion have made arrangements to have them offer it to

inspectors and officials in our area.

other more intense courses are for architects engineers and specifiers of are here

http://training.strongtie.com/stc/sstpub/psciis.dll?CLASSMENU=sstpub&searchoption=FIELDS&fisDirectList=1&field0=XOWNER&value0=24

i normally would not push a manufacturer but these courses are extremley informative