Appropriate Design loads for Monorail System
Appropriate Design loads for Monorail System
(OP)
We are designing columns, headers & footers for a free-standing, 30 ton capacity monorail system, 32' tall. We are somewhat deadlocked on the debate as to what LATERAL load should be applied to the structure (by the lifted load).
AISC (9th edition) page 5-29 notes that 20% of lifted load & trolley shall be used for lateral load and 10% of the sum of wheel loads is used for longitudinal load.
The problem is that this paragraph applies to bridge crane runways (3 axis movment) - not monorail systems (2 axis movement); With monorails, there is theoreticly Zero lateral load.
I believe that 5% is more in order unless there is certainty that the user will be lifting off center (at which point the 30 tons will violently swing towards center)
I would appreciate your opinions on this subject
copy of dwg attached if needed
AISC (9th edition) page 5-29 notes that 20% of lifted load & trolley shall be used for lateral load and 10% of the sum of wheel loads is used for longitudinal load.
The problem is that this paragraph applies to bridge crane runways (3 axis movment) - not monorail systems (2 axis movement); With monorails, there is theoreticly Zero lateral load.
I believe that 5% is more in order unless there is certainty that the user will be lifting off center (at which point the 30 tons will violently swing towards center)
I would appreciate your opinions on this subject
copy of dwg attached if needed






RE: Appropriate Design loads for Monorail System
Page 57 of "Whiting Crane Handbook, 3rd Edition" (free .pdf download from this page of my website http://www.slideruleera.net/miscellaneous.html ) has the following statement about lateral forces that are assumed when designing bridge crane girders: Of course this has to do with fact that the girders themselves, along with the lifted load, can be accelerated down the length of the runway. My point is that the assumed 5% is apparently adequate for "ALL" lateral forces on the girders. With that being the case, I see no reason to assume lateral forces any higher that 5%, for your application. At the same time, going any lower than 5% is probably not a good idea, because of the off center load lift, that you mentioned.
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RE: Appropriate Design loads for Monorail System
That may a much bigger concern depending on where this is going
RE: Appropriate Design loads for Monorail System
If the duty cycle is high I strongly recommend a patented rail in lieu of an I beam.
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RE: Appropriate Design loads for Monorail System
To MiketheEngineer - The project is located in Florida where seismic loads are not considered. Wind loads are being considered. Thanks for the reminder.
RE: Appropriate Design loads for Monorail System
To MiketheEngineer - The project is located in Florida where seismic loads are not considered. Wind loads are being considered. Thanks for the reminder.
RE: Appropriate Design loads for Monorail System
RE: Appropriate Design loads for Monorail System
I hope you have a RC controler.
An uncontrolled lift with two carriages is even worse. We have two single carriage monorails that we only allow around a 5 degree, measured at the carriage, off center load. We are going to a bridge crane to replace one of the monorails due to the possibility of having to pick an off center load.
RE: Appropriate Design loads for Monorail System
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RE: Appropriate Design loads for Monorail System
The trolley-hosits will in fact be radio controlled. Duty cycle fairly light. 5 to 8 lifts per day @ 50% to 85% capacity.
Why would we permit uncontrolled lifts? - I've been in this business long enough to know it's expected rather than dis-regarded. The 5% value presented represents an 18" off center pick. To clarify, load is first picked off of a flat-bed truck (which can/should be centered(???)) and then is transferred to a large water-filled tank for testing. Load is then picked out of tank (self centering) and then put back on truck.
Bare in mind we are trying to come up with a practical design load being transmitted into the "flagpole" columns and subsiquiently the footers. The design of the monorail beam itself is much less complicated.