Overhead Cranes

[MaxSE]

Hi,

Re overhead travelling cranes

Can anyone advise if lateral inertia loads due to longitudinal acceleration of a crane bridge apply concurrently with loads due to oblique travelling/skewing of crane bridge during normal operations?

Notes re various codes requirements:
AS1418.1 combine inertia loads due to crane bridge acceleration with oblique travelling loads.
EN1991-3:2006 does not combine acceleration of crane bridge with oblique travelling/skewing of crane bridge.

cheers

 

[DaveAtkins]

I have always designed for both loads simultaneously. Generally, the longitudinal force can be resisted by all of the columns in the direction of the longitudinal force, while the lateral force is resisted by one or two columns in the vicinity of the force.

DaveAtkins

 

[hokie66]

I think it is customary to design for lateral forces in two directions only, and not at the same time.

 

[DETstru]

Though I don't have any sources handy, most guides I've read do not require the loads to be applied simultaneously. Sorry for no source, I can't find my guide at the moment. I believe it was a CISC document.

 

[MaxSE]

Thanks all,

I was referring to acceleration loads PHB due to long-travel drives as shown below.

and oblique travelling loads (Y21) as shown below

cheers

 

[Agent666]

I've only used AS1418 series before, so I've always combined them using the load cases outlined in there which are quite comprehensive depending on your cranes configuration.

The only way I would ignore this combined loading would be if the crane couldn't physically traverse in both directions at the same time. But most cranes I've seen can traverse in both directions at the same time, so ignoring the effect is flawed even if it's not specifically covered by the code of your choosing.

 

[MaxSE]

PHB forces act when the crane accelerates / decelerates along the runway with the ladden hoist located elswhere than in the centre of mass. They (the forces) are not due to transvere acceleratio/deceleration of hoist.

Y forces are born when the crane travels along the runway in a skewed position and the wheel guides make contact/hit the rail. This contact "straighten" the crane along the runway.

These forces are associated with long travel only, that is crane/hoist travel in one direction at the time.

I wanted to get a feel for whether these forces act at the same time as most overseas codes say they do not or the probability of that happening is very low and not considered.
I combine them all right - I also use only AS1418 - but the 10mm maximum deflection for runway supporting structures required by AS1418.18 is very strict.

There is no such restriction in overseas codes which are more relaxed in terms of required maximum deflection of structures supporting runways and I ask myself WHY?