Structura layout and sizing: Wood ASD Method

Wood structure layout: Draw the plan of a simple one story building made with the

dimensions: $60$ x $30.$ The roof is flat, made of wood sheathing on wood joists,

supported by wood beams. No beam can span further than $40,$ no joist can span

further than $20.$ Indicate columns, beams, joists and load direction on the sheathing.

Draw on grid paper, scale $1/4=1.$ There is a $20$ wide opening at one of the short

ends of the building. Consider this when layout your joists and beams.

Loads DL $=20$ psf LL $=20$ psf

$*$note: load allowance includes weight of the structure. Do NOT add the weight of the

sheathing, joists or beams, the allowance already includes an estimate to account for

them.

Find the following $4$ structural elements, using $$short$-$cut$$ tables whenever possible.

The wood grades have been specifically chosen to allow the use of tables and graphs

provided in the textbook.

$1.$ Select Plywood Roof deck $($assume $2$ spans and strength axis parallel to supports$)$

Select the thinnest wood decking $($Table $5\mathrm{.}13)$

$2.$ Design Joist $($assume Doug$-$Fir Larch, No $1,$ Dimensional lumber$)$

Calculate actual bending moment.

Select Fb and appropriate modifiers.

Calculate required section modulus.

Select smallest area $2$x $($Table A$\mathrm{.}8)$

Apply CF to Fb and verify the resulting section modulus is still what can be

provided by selected $2$x$.$

Investigate selected $2$x for Shear.

Investigate selected $2$x for deflection, the deflection limit L$/240$ for LL only

and the deflection limit L$/180$ for TL$.$

Investigate the selected $2$x for bearing, assuming $2$ of bearing length is

provided by a joist hanger.

$3.$ Design Beam B$-2($assume Doug$-$Fir Larch, No $1)$

Calculate actual bending moment.

Select Fb and appropriate modifiers $$ run parallel analysis for $$Dimensional

Lumber$$ and $$Timbers$$

Calculate required section modulus for each size group.

Select smallest cross section area $($Table A$\mathrm{.}8),$ for each set, continue with the

smallest of the two.

Apply CF to Fb and verify the resulting section modulus is still what can be

provided by selected beam.

Investigate selected cross$-$section for Shear.

Investigate selected cross$-$section for deflection, the deflection limit L$/240$

for LL only and the Doug$-$Fir Larch, No $1)$

Investigate the selected beam for bearing, assuming $3$ of bearing length is

provided by a hanger.

$4.$ Design Column C$-4($assume Doug$-$Fir Larch, No $1)$

Calculate the total axial load on the column.

Select smallest area, square column $($Table $6\mathrm{.}1)$

Use un$-$braced height of $18$

Draw $2$ scaled, detail drawings at a section that includes the top of the column, the

joists, beam and the sheathing.