Studying ... cont.

 ... hopefully I can assuage the fears of some ... regarding the exam and this wood stuff.

Though it looks awful (my solutions to Assn 6 for example) ... it's really pretty straightforward.

In `design' (structural design) we simply check that the stresses developed under design loads [...] don't exceed the allowable stresses for the material being used.

So, when we load a joist, beam, rafter, etc. ... stresses develop.  We start with area loads (sigma), calculate line loads (w), and from them the max bending moment M, design shear V, and Reaction R.  And we also calculate deflection.  These M,V, and R are what we could call internal forces or internal loads.

Then we get the stresses that these loads cause ...

bending stress, f_b = M/S

shear stress, f_v = (3/2)(V/A)

bearing stress, f_c, perp = R/A

Oh, and deflection ... (5/384)(wL^4/EI) (for a uniformly loaded simple beam)

Then we make sure that these stresses don't exceed the Allowable stresses for the wood.

The Allowable stresses are the F's ...

THAT'S WHERE WOOD GETS NASTY ...

To get the Allowable stresses we need to get the Design Values (the Fs) ... from, say, the NDS Supplement, and then we need to Adjust them to our particular conditions ... with all those C's.

The C's are in the Supp and also in the lecture materials and handouts.

IT'S NASTY STUFF! ... but others have done it and survived, and so can you.

With that in mind - churn through my solutions to Assignment 6 ... and see if it all makes sense.

The thing Nick found is kind of helpful, though not without some flaws.  Its weakness is that it doesn't have start-to-finish examples.

The NDS has example problems ... though I don't know if they are downloadable or printable ... but it might be worth a google.

I am almost done writing the exam.

MAKE SURE YOU ARE CLEAR ON BOARD FOOT MEASURE.

Doc