Look into floor trusses. Be prepared for bouncy floors though no matter what you use. Have them design in a high ratio like L/600 or more if you want to avoid excessive deflection.
ahhhh, EVERYTHING:laughing::laughing: Imagine if you could you had your shop/garage and 15' into it all the way across was a row of posts...how practical for opening truck doors would it be, how practical for building something inside would it be? Not at all, unless you were going to rent the space out for go-kart slamon courses:laughing:What are you doing in the shop that will not tolerate a row of posts down the center?
Gantry? This river don't go to Gantry.I'd look into steel on 15' centers for carriers and either 2x10 or 2x12 joists, depending on your intentions for the upper level. I believe you may save money over using I-joists and you can use the steel I beams as gantrys to offload material and shift it side to side.
Steel is always a good choice but more blocking will be needed. Stay away from 12 ga as it usually costs quite a bit more than 14 ga. So if you can get 14 ga 14" should work well for you.Light gauge steel joists, 12" or 14" deep by 14 or 12 ga, will get you the span without intermediate supports on 12 or 16" centers. Price in the $2.5-3.5 /lf range.
Dietrich & Marinoware are two that come to mind. There are many others. check with a drywall supplier as an alternative. They can special order form the same guys who form CTL studs.