Here are a few recent post bases where traditional sill framing were not an option.

4 post clusters sitting on a core filled and reinforced block column (to match the main walls - this is in tornado country) with local limestone caps and facing. Steel T plate in the center bolts down to a cast in connection and keeps the posts off the masonry. Floor system is steel and concrete which also included tubing for radiant. The straps have yet to be applied but will look similar to the detail of the cross tie.

Examples #2 - A large project on the water (RI coast) with high wind loads - this section of the building is 42' x 80' +/-. Center bents are 40' +/- clear span. The frame was required to do all the lateral loading as we couldn't count on shear values for the wall with the amount of glass, etc.

The floor system is a commercial style steel framing and concrete pan deck (to hold cars and large assemblies of up to 300 people) that includes radiant tubing and will be covered in brick pavers - it also includes a full basement. Post base is a moment connection - the spacing off the floor is tall enough to include a slight reveal, mortar bed, and the brick. These were set on steel plates that were set into piers. The post base was welded to the steel plate after the frame was racked, pegged, plumb, and square. There is a gusset hidden inside the post - we cut an angled slot to slide these in.

Sweet!
I don't think I've ever seen that much scaffold

Regarding longitudinal shrinkage .001-.002 of the length is typical, so 1-2" in that 80' length. Juvenile or reaction wood can indeed shrink many many times that amount. I've had decking shrink right off the joist it was on, 3/4" in about 12', shearing the screws in the process. The entire bole is not going to be juvenile or reaction wood though. The top of the stem will contain enough juvenile wood to cause some problems if you work close enough to meristematic tissue..the growing tip. In both of these what is going on is not necessarily the grain you see but the grain that makes up the secondary wall, or lamella, of the invidual cells.. the microfibril angle, MFA. In young supple trees that need to be able to bend with the forces of nature the microfibers that make up the thickest portion of the cell wall, and thus determine shrinkage direction, are wound at an angle to the axis of the tree, up to a 45* angle. As the water that is bound to these microfibrils leaves the cell wall the individual elements move closer together.. shrinkage. If they are laid at an angle the timber shrinks lengthwise. As the tree matures the MFA straightens coming into line with the axis of the tree.

Reaction wood also has MFA's on the bias. Interestingly as well a softwood builds tissue on the underside of a lean and injects huge amounts of the tree form of concrete, lignin, into those tissues. Its' strategy is to address support from the compression face, supporting the lean on compression wood. Hardwoods grow a specialized layer of rubbery gelatinous tissue on the inside of the cells called the G layer. This tissue is above the neutral axis of the tree and acts as cables or rubber bands in tension, trying to right the lean from the topside and forming tension wood. When you try to sand tension wood and keep getting the "fuzzies" this is that G layer of rubbery tissue hanging out of the cell lumens. Bowmakers sought out tension wood for their bows long before "smart" folks came along .

Hi Don,

Now I know what I didn't know !

The thought that was going through my mind about spiral grain is that because the grain has deviated from being parallel to the axis of the tree then it would also follow that shrinkage rates would then also start to deviate from pure longitudinal to cross grain shrinkage rates and hence it might become necessary to start to take longitidinal shrinkage into account in design and construction.

I maybe made my point rather clumsily but in elm the juvenille wood does not tend to spiral for the first 15 years or so then as subsequent wood is laid down then it starts to misbehave and what's more it can and does change its mind every 6 inches or so along the length of the trunk going from clockwise to anti clockwise to form wavy spiral grain.

I see lots of spiral grain timbers in buildings and have oft pondered why the carpenters chose to use it. They must have realised the downsides to this problematic timber.

Thank you for that informative explanation. Seems that Prof Hoadley got it right after all though we are in now in danger of deviating "off topic".

Regards

Ken Hume

They shrink wrapped the whole building so they could warm it up and set stone and be comfy all winter with no lost days to weather. 60 foot trusses with sheathing on them about 10 feet above the TF peak, scaffolding all anchored and guyed out. They had a gent from a local marina, who is used to wrapping expensive and large boats come by... then they turned on the heat and went to town.

Now we are off topic, for sure... here is a shot from the week before last - they have ripped the seams and the building will see the light of day... our frame is in there, just beyond the porta-johns...

A five-John job? Speechless...

Add 3 job trailers and another 5 up the hill...

Man, my first photo-posting experience. Sure hope the process gets faster. Anyhow, here is how I've done the post-to-foundation connection on a couple of occations. The steel base in this case is 4" high only because it was discovered the posts were 3" too short after they had been cut to length, usually 2"x2"square tubing is used. I have welded re-bar to the base and set it in the wet concrete but it was just too damn stressful getting all of them lined up and level before the concrete set up. In this case I just drilled holes and used anchors and lags after the forms had been removed. Of course there is a short stub tenon on the post bottoms to prevent lateral movement.

Did it work this time?

My friend Don used granite plinths for his barn. I will ask him what the connection is.