Underhung beam to beam direct bolt connection

[Ceelo124]

I am designing a monorail that is connected underneath to the bottom flanges of cross beams. The monorail has bolts going directly through its top flange connected to the bottom flange of the cross beam. Do I design for the full moment in the monorail at the connection locations? I designed the bolts using the moment arm between them to get the tension force required, but how do I check the flanges of each beam?

 

[human909]

(I'll preface this by saying I won't claim to be an expert here nor am I aware of what code you are working.)

I wouldn't be designing the connection for moment, though doing so would be conservative for the connection. The stiff monorail with low deflection and the normally very flexible bottom flange of a transverse beam would transfer very little moment.

 

[DaveAtkins]

What you are describing would normally be considered a pinned connection. Zero moment.

DaveAtkins

 

[human909]

And regarding the other part of your question. Checking the flanges. This shouldn't be different to your normal T-STUB checks in bolted flanges under tension:

https://www.finesoftware.eu/help/finec/en/end-plate-or-column-flange-in-bending-bolts-in-tension-01/

Though I must admit I normally haven't been rigorous here in my checks I normally put 4 bolts in and call it a day. The monorail beam and normally the supporting beams normally have quite thick flanges. The monorail wheels would put putting larger forces on the unstiffened flange than the bolted connection is doing. I DO very much check this aspect of the monorail design EVERYTIME. The AS code I use has a fairly convoluted empirical formula for the minimum flange thickness required.

 

[dhengr]

Ceelo124:
The beam moment passes right through that joint, in the crane rail beam, the stiffer element in that joint, and the most direct load path through that joint. The flg. bolts and the cross beam should be looked at to the extent that, based on their relative stiffness against a loading condition, or compatibility w.r.t. defection and rotation they will try to follow the crane beam in its deflection and curvature. A crane load coming from the left will try to twist the cross beam counter clockwise as it approaches the cross beam; the motion will be all vert. deflection when the crane load is centered under the cross beam; and then the cross beam will be deflected and rotated clockwise as the load continues to the right. It is akin to a two beam grillwork of beams which must remain compatible at their connection point. And, since the cross beam is not very stiff torsionally it goes along with the crane beam curvature, as a function of the flg. stiffness’ and bolted connection stiffness, but does not attract much moment in the process of twisting. The bolts should take something more than the crane load, which is basically the condition when the crane is right under the cross beam.