This...
No, we just want to rely on bearing instead of the connector for force transfer. After the wet service factor is applied, bearing just holds a lot more.
In DCA6, the knee bracing is just for added stiffness. It isn't the primary loadpath.
There also online calculators provided by the American Wood Council such as a connection calculator and a span calculator.
http://www.awc.org/calculators/index.php
First, why aren't you using the latest version of DCA6?
Second, DCA6 can help you size your beam too.
Are you having doubts about DCA6's answers? Or do you just not like them?
I don't think this is a ASD vs. LRFD issue but a visually graded lumber vs. milled piece issue. Yes, the value from the NDS is taken as a clear specimen for white oak, but then it is reduced to compensate for defects, grade, and general MOV including the 95% offset to get a design value.
The...
a2mfk brings up a good point about the tension/compression couples to the existing house. This is how it is prescriptively done in the IRC with 1500# hold downs. The house diaphragm's ability to resist that force isn't mentioned.
Regarding knee braces, has anyone run a calculation on how much...
a2mfk:
From the 2008 Special Design Provisions for Wind and Seismic (SDPWS), Table 4.3D gives the nominal values of horizontal lumber sheathed shear walls as 140 for resisting wind. Divided that by 2.0 per 4.3.3 to arrive at an ASD value of 70 plf. Diaphragms also have a nominal value of 140...
A few notes about this research.
1) The deck is extremely overloaded at 12 psf. Horizontally sheathed shear walls have an allowable shear value of 70 plf. This is at 144 plf. The research notes that the large deflections (7 in.) allowed the people to rock in motion together and create a larger...
Lateral load on decks is tricky since there is no codified loading provisions. Decking has little diaphragm capacity per SDPWS, but since there is nothing to compare it to, one doesn't know if it is overloaded. I know of no way to laterally engineer a deck without loads. That is why prescriptive...
The change actually happened first around the 95 SBC and ASCE 7 was the motivating factor. Around that time the wind loads jumped up and designers were understanding about roof problems, but they questioned why suddenly their shearwall and diaphragm designs no longer worked despite a lack of...
Note that you are applying a reduced capacity to all the wall segments, so this is a rather harsh penalty. Just by having one segment out of compliance means all compliant segments get penalized as well.
You should notice that Doug Fir-Larch, Hem-Fir, SPF, Redwood, Western Cedars, Ponderosa Pin, and Red Pine are all being thrown in together. That means that the design values for Doug Fir-Larch aren't being used, but the worst of that group is.
There is the issue of the assumed cantilever on...
