Building my bridge crane

[SPYDERLK]

Yeah I'm going to disagree with you on that! Have you run FEA on both design to look at stress concentrations?

Also bolting is a more controlled solution to splice two beams together. Done all the time in I-beam structures. Multiple bolt holes distribute stress loads and friction force holds everything together.

The beauty of bolting is that its something anyone can do. No special tools or skills required. IOW, very little control needed for a serviceable job ... except maybe tighten the bolts again after initial [fast] tensile creep.

 

[Shield Arc]

What do you do to keep the cable tight?

You could use turn buckles.


I'm just another Stalker in the background watching this project

I think I have a turn buckle at each end, for sure one end. In 14-years I havn't tightened it once.

 

[Shield Arc]

The engineer that helped me with my bridge crane, never once mentioned bolts for splicing my span beam right in the center.

When it comes to engineering, well I can't even spell engineer! But I'll side with dragoneggs, I
know what he does for a living!

 

[LD1]

got the beam set and welded to trucks. still gotta do the bracing, but it rolls real nice:thumbsup:

Gee LD, the last I remember, you were sorting through a load of lumber looking for straight purlins. Got to give you a huge attaboy on your awesome shop!

Once we got through the sopping wet spring, it went up pretty quickly.

But I like my work schedule for that. Work 4 12hr days and get 4 off. Can get alot done in 4 full days:thumbsup:

 

[Streetcar]

The engineer that helped me with my bridge crane, never once mentioned bolts for splicing my span beam right in the center.

When it comes to engineering, well I can't even spell engineer! But I'll side with dragoneggs, I
know what he does for a living!

It is hard to roll a wheel over a bolted splice. Welds work better for that.

 

[ProjectKing]

WRONG! ... The tapered ends act to blend the stiffness from the beam into the stiffer area of the patch. Also the taper away from the edges of the flange inhibit a tear/crack beginning at the edge of the flange.

,,, Bolting is a bad idea in comparison to a good weld. Many stress riser sharp edges are inherent in drilling holes, and are difficult to blend out to alleviate cracking. ... Also you lose the strength of the material removed from the holes.
larry

First of all take this info for what you paid for it. Which was nothing. In other words its for discussion only.

Attached you will find FEA of OPs spliced beam... using tapered and square scab plates. Note hot spots at points of scab plate. With that being said, highest stress is at butt welds between two beams and not at scab plates.

Also I've included approx safety factor at 10,000 lbs with indicated loading... around 1.1. OP should inspect rail at butt weld joint for possible fractures. Proceed at your own risk. Not sure what you are gonna rate this crane at but be careful. Cranes are serious business.

Good day.

 

[Shield Arc]

Cranes are serious business.

They sure are! I use to get to play with them on the water.

 

[CNC Dan]

First of all take this info for what you paid for it. Which was nothing.

Attached you will find FEA of OPs spliced beam... using tapered and square scab plates. Note hot spots at points of scab plate. With that being said, highest stress is at butt welds between two beams and not at scab plates.

Good day.

<img src="http://www.tractorbynet.com/forums/files/build-yourself/448277-building-my-bridge-crane-1-jpg"/><img src="http://www.tractorbynet.com/forums/files/build-yourself/448278-building-my-bridge-crane-2-jpg"/><img src="http://www.tractorbynet.com/forums/files/build-yourself/448279-building-my-bridge-crane-3-jpg"/><img src="http://www.tractorbynet.com/forums/files/build-yourself/448280-building-my-bridge-crane-4-jpg"/><img src="http://www.tractorbynet.com/forums/files/build-yourself/448281-building-my-bridge-crane-5-jpg"/>

Looks like the supports at the end of the beams are restrained supports, not simple supports. Is that the right kind of support for the OP's situation?

 

[dragoneggs]

Looks like the supports at the end of the beams are restrained supports, not simple supports. Is that the right kind of support for the OP's situation?

My question too. Might be somewhere between fixed and pinned. For mid beam I would assume pinned to be conservative. Always nice to have FEA tools and thanks for sharing. The devil is in the details as they say...

 

[jwmorris]

I spliced an I beam together in my shop when I removed a wall after I welded it, I used square scabs but plug welded them and welded just the top and bottom.

A little different than the OP's bridge crane though because the top of the beam is attached to the rafters preventing deflection side to side, making it much less likely to fail.