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From those tributary areas it looks like it might be better to use the ridge dimension at the purlin locations and the 6x12 at the ridge. If you look at the beam equation for a continuous beam across 3 supports, the center support takes 5/8 of the load, each end 3/16... the ridge taking that from a rafter on each side has a 3/8 load. Wood engineering stuff;There is a good publication of beam equations used in the code referenced NDS for wood construction at awc.org under the publications tab, it is called DA6- Beam EquationsThe NDS is there as well which is the engineering code ref for woodYou have an engineer, I'm not seeing all they did, never forget that we are 2 amateurs on the internet.For bracing if there is no load path, you have a steel post. I keep wanting to weld a steel blade extending out along each 90 degree beam axis for a few feet, weld a support plate flatways under that knife plate. Split the beam and set it over the plate, pin low and securely at each end of the plate to the wood beams, a long rigidly connected lever arm. It's the same as the simpson connector only heavy, long and welded and doing so out of both 90° sides of the post. In other words I'm seeing some awesome steel posts easily fabricated to something rigid and then these wimpy bent tin connectors.( apologies to Mr Simpson, but theres a honkin heavy post there begging for some hot arc connections)The light ridge support arch could be somewhat similar, make a flitch plate composite beam, a sammich of a center steel plate shaped and sized for the load with wood side plates checked for buckling. That can probably get you back in that open direction. In all of this beam work if lightness is a factor glulam has the appeal of heavy timber but carries around triple the allowable design loads. Shrinkage allowances around connections are much lower.
If you look at the beam equation for a continuous beam across 3 supports, the center support takes 5/8 of the load, each end 3/16... the ridge taking that from a rafter on each side has a 3/8 load.
yup indeed. i will let kevin respond too since he was interested in the calcs to see if he sees anything else worth questioning. i am thinking about what to suggest - whether i want to switch material like you suggested (even consider just steel?), or just add a king post below the ridge. that for sure changes the aesthetics. i still think the 2 suggestions i make are figure out this ridge support issue, and replace the simpson joist with a stronger connect to the steel column. here are the structural details, including how the steel column is attached to the pad and caged in pole footing.(Image hidden from quote, click to view.)
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