Monorail Splice

[Ringoo]

Hi,
I am designing a monorail. The total span is 21m.The maximum lifted load is 9MT.The section used is S610. The monorail is simply supported from its top flange at 4 location i.e. each span is 7m and wheels are rolling for the bottom flange of S610.This monorail will be installed outside the building where the temperature difference is about 70 degree C. As per CMAA 74 the maximum gap that rail can have is 1/16".Based on temperature difference my rail will expand about 7.8mm.If I put this as a gap between two sections then I am not satisfying maximum gap restriction of 1/16" as per CMAA. So my questions are:-

1) Can I go for say 8mm gap between the two section and let the wheel to roll over this gap. This monorail will be used only one time in a year for the maintenance of draft tube gates.

2) Can I used slip critical bolts to connect the webs of the sections and maintain a gap of 1/16".If yes, then for what forces these bolts should be checked, other then the longitudinal thrust due lifted load. I will put slot holes in the top flange for the rail(S 610) to expand.

3)What is industry practice to splice the monorail for a temperature difference like this.

Let me know if I am clear.

Regards

Ringoo

 

[TehMightyEngineer]

Can you weld the monorail beams together and put slotted holes where the new monorails is attached to it's supports such that you release axial temperature stresses?

Maine EIT, Civil/Structural.

 

[hokie66]

Similar to TME's comment, I would make the beam in one piece. Brace it against longitudinal movement near the middle, and allow the ends to move. How you detail it to allow this movement depends on the method of support. The top flange must be braced laterally against buckling.

 

[GregLocock]

If you use shorter pieces of rail then each gap will be smaller. I can't help feeling that a single welded rail would rip the supports out of whatever they are attached to, unless you allow for slip betwixt rail and bracket. Is the rail straight?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[jayrod12]

Or provide unslotted holes for the two connections close to the splice, Locate these connections such that a 1/16" gap is present at the average temperature at time of annual use and that the gap can be "just" closed at the hottest possible temperature to prevent unintended axial stresses.

Provide slotted holes on the outer connections and let all the expansion happen away from the splice.

 

[Ringoo]

Thanks TME,

The reason I am not welding is because I haven't got confirmation from the fabricator/contractor that they can weld these two rails together and finally ship to the site, as the site being very remote. But thanks once again for your valuable comment.

Hokie66,

For lateral buckling I am satisfying the clause 3.5.6 of CMAA 74 i.e. computed compressive stress is less than the allowable.

Thanks