Now you are using your head.
That 4,000 Lbs, is that the total Gross load or the Live load, tractor, you and a 6 pack? What about the safety factor, how much over weight to make it break?Bridge#2
- Thread starter buggyman1
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Now you are using your head.
That 4,000 Lbs, is that the total Gross load or the Live load, tractor, you and a 6 pack? What about the safety factor, how much over weight to make it break?Be very, very careful where you put holes. A hole in the wrong place will %$#@&& the steel and down you go. Welding would be a better choice.
Something to think about. The bottom flange is in tension and the top is in compression. Where the Web meets the flange is in sheer, the two trying to slide past each other. You may drill a hole up to 1/3 the distance up/down from the center of the web. Again, safer to weld.
OP
buggyman1
Platinum Member
Now you are using your head.
Thats 4,000 lbs each, gross, plus the supports in the middle will make it stronger yet.
OP
buggyman1
Platinum Member
I have to disagree with you on the welding. I am a welder, and have the means to weld it (mig, stick, or tig... i have all three). It would have been so much easier to weld it vs. drilling 3/4" holes (bunches of them). I talked with professional iron-workers, as well as engineers at work, and my steel supplier, and all three told me the same (which was what I thought) that properly welding them, the heat would weaken the beams more than drilling and bolting them. I personaly think welding them would have been fine (as did they) but bolting them was..is stronger. Tractor, me, and a 12 pack are more worried about running off the side. I'm not saying you're wrong, and I like your input, you keep me on my toes.
OP
buggyman1
Platinum Member
Sorry...but i really don't mind a critic. They, he... has good ideas, and if just one thing i've overlooked, someone catches it, its better for all of us. I think we all know my little tractor will be fine on this bridge, but if anyone's input can make someones project better, stronger, easier....let them speak.
When you drill a hole in a member and load that component, say in tension the force per unit area on the average doesn't change all that much. However close to that hole the force per unit area increases dramatically and may excide the strength of that metal and start a crack. Over time that crack will grow. The size, location and number of holes matters, it's a big deal subject in any civil engineering training course, as is metal fatigue. Better to be safe than sorry.
foggy1111
Elite Member
I sold aluminum to semi trailer companies for years. A riveted trailer is a much better trailer than a welded trailer IMHO. Both can work (with good planning and engineering) but a riveted (or bolted) assembly is better in my book. Most of the old bridges you see were riveted together to provide a stress free joint. Welds can crack due to stress loads.
Having said that.....I would not hesitate to weld a bridge....just check it every now and again. My .02 cents.
Having said that.....I would not hesitate to weld a bridge....just check it every now and again.
My .02 cents.