A Post and Beam Shop

This is a rough sketch of a shop building I had been thinking about.
	Several days later I was sawing up a large white pine log and it made a nice timber. The shop I'd been doodling on was underway. I needed more accurate plans to dimension the timbers. Google's free Sketchup program proved to be quite accurate and easy to use. I drew a base model and used it to work from, adding components and modifying as I changed each bent. This is an early shot of the first bent. When I checked dimensions and calculated the stresses, the web braces were unneccesary.
To give an idea of what Sketchup is capable of, this shot is from inside the bottom chord timber looking down it at a steel connecting plate I was considering using at one point. Early on I zoomed in and got lost inside a peg hole one night.
	I notched and rough fit the first truss at the outfeed end of the sawmill.
This is a shot of the top of the kingpost with the top chords of the truss coming in. There is a tennon on the end of the top chords that slips into a mortise in the kingpost top.
	This is the heeljoint of the first bent. This joint on most trusses, this one included, is the point of greatest stress. The joint must resist crushing as well as avoiding being sheared off. It also cannot allow a strong wind to lift the joint apart. There is a hidden threaded rod through the joint holding the top chord to the bottom chord to prevent uplift.
I decided to tip up the truss bents one at a time as they were finally fitted together. To accomplish that I needed a hinged foot at the bottom of each post. This is one fitted and ready to tip up. An 8" section of 8" I beam was reinforced in its web area with a piece of channel welded on each side. A section of pipe forms the hinge and is welded to a plate that has been cast into the concrete piers. Once the post is tipped up, the I beam is fully welded to the plate. The I beam will be covered when the slab is poured.
	This shows how the pipe was welded to the post base, the center was cut out and welded to the plate in the pier. A piece of 5/8 rod was used as the hinge pin.
We tipped up the first bent using about 200' of cable hooked to the tractor which was on the terrace above the shop. The 3x3x20' pieces of angle iron are well strapped to the frame and to a 6x6 across the bottom chord/kingpost splice to hold everything in place for the lift. This is probably the greatest stress the frame will ever see. Even after jacking and cribbing the first few degrees of tilt the tractor didn't have enough traction. We finally had the 4wd truck hooked to the tractor to stand it up. Getting that coordinated didn't give the best control of the lift. I started thinking about another way. We got it up, 25' wide, 20' to the peak, it weighs about a ton.
	This picture of a medieval barn raising with a pair of gin poles and windlasses might help explain what is to follow
Bent 1 was timber framed, that is it has timber joinery and is connected with wooden pegs. Bent 2 is post and beam, steel connections. The splice at the kingpost is covered by 2x10 fish plates that are bolted through on each side of the kingpost with 3 one inch diameter bolts. The heeljoint thrust is restrained by an angle let into and lagged to the top of the botton chord. An angle is welded across the heel of the top chord and a plate then goes over the top to prevent uplift. The contraption here is our "lifting engine", or gin. The blue racking is shelving from an old building supply. I've set up two rows, loaded the bottom shelf with well over a ton of rocks and cabled it diagonally for safety. There is a cable from a windlass at the right side of the assembly, a pulley on a beam at the top, down to the gin pole to assist in getting the lift angle correct and finally to the bent. The stump just beyond the excavation would be the donor of the least travelled timbers in the project.
	This shot is standing behind the windlass looking at the gin pole and the bent. The red pipe is a 6" diameter casing through which a 2" diameter pipe has been set up as an axle. The axle is attached to each row of shelving. The orange handles are welded to the red pipe. The handles are leverage to turn the pipe and wind in the cable. The horizontal steel behind the upper handle is our brake. We can lower it behind a handle to stop the lift at any point and rest or check things.
Halfway up and parked for the moment taking a break. For scale, Michelle is walking around the right side.
	Bent 2 up and temporarily braced. The cribbing in the foreground was used to support the timbers level as they were assembled.
The 6x6 purlins were then attached across the rafters and board sheathing was nailed over them. The bents are 10' apart.
	The purlins were set between 6x6 blocks attached to the rafters to avoid notching into those top chords and weakening them.
The kneebraces in each bent resist racking across the bents. This X bracing between bents resists racking front to rear. There is a panel like this on each sidewall of the shop.