One bridge(twin girder), 2 cranes. What design hoist load?
One bridge(twin girder), 2 cranes. What design hoist load?
(OP)
Pals
I have the standard twin-girder bridge that will have two cranes(ie two cabs) running on it, one lifting for the half span, the other for the other half span.
Any literature or specs for what design load the bridge girder be designed for?
respects
ijr
I have the standard twin-girder bridge that will have two cranes(ie two cabs) running on it, one lifting for the half span, the other for the other half span.
Any literature or specs for what design load the bridge girder be designed for?
respects
ijr






RE: One bridge(twin girder), 2 cranes. What design hoist load?
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: One bridge(twin girder), 2 cranes. What design hoist load?
respects
ijr
RE: One bridge(twin girder), 2 cranes. What design hoist load?
RE: One bridge(twin girder), 2 cranes. What design hoist load?
OK, but then they can not both be found at midspan given such a heavy load.
My assumption is they would be say at a third points.
respects
ijr
RE: One bridge(twin girder), 2 cranes. What design hoist load?
RE: One bridge(twin girder), 2 cranes. What design hoist load?
Remember to check buckling.
RE: One bridge(twin girder), 2 cranes. What design hoist load?
If so, I think you must assume the hoisted loads are as close to one end of the bridge crane span as possible, not at the third points. The manufacturer should be giving you the maximum wheel load.
DaveAtkins
RE: One bridge(twin girder), 2 cranes. What design hoist load?
I am designing the crane bridge(the two parallel running girders that carry the crane), not the runway girders(the ones over which the bridge moves )
the case is special: two cranes on the same bridge
respects
ijr
RE: One bridge(twin girder), 2 cranes. What design hoist load?
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: One bridge(twin girder), 2 cranes. What design hoist load?
Please ignore my above comment as it is based on a misunderstanding.
As paddingtongreen has stated, the design should be based on the worst load positions for shear, bending, deflection and lateral loading. You need to find out what the minimum distance is between the two cranes as well as the closest possible distance to the ends and base it on that.
Shear would obviously be both cranes as close as posssible to one end, e.t.c.
Look up the SCI guide on cranes.
RE: One bridge(twin girder), 2 cranes. What design hoist load?
If you don't now know the hoist geometry and the crab dimensions, it would be conservative to assume that both hooks can and will be at the span center for bending purposes.
Mike Halloran
Pembroke Pines, FL, USA
RE: One bridge(twin girder), 2 cranes. What design hoist load?
As previously stated, the max shear for either of the two girders would be for both 20 Kip loads:
1. as close as possible to one end of the girder, and
2. each hoist as close as possible to one girder.
The maximum moment would be for both 20 Kip loads:
1 with each hoist as close as possible to the center of the girder span, equally spaced from the center line, and
2. with each hoist as close as possible to one girder.
Remember that the hoists carriages travel along the length of the girders, but the hoists themse3lves, depending on the model, can travel transverse to the girders too for better piock and placement capability.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: One bridge(twin girder), 2 cranes. What design hoist load?
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: One bridge(twin girder), 2 cranes. What design hoist load?
RE: One bridge(twin girder), 2 cranes. What design hoist load?
hokie66, the owner will not want the bumper, and he is the one who specifies.
So I will go ahead and consider both cranes working. It will be a very conservative design.
respects
ijr
RE: One bridge(twin girder), 2 cranes. What design hoist load?