RR Bridge Stiffeners

[TypeIV]

I am designing a Through Girder RR Bridge for BNSF and I need help with the intermediate stiffener.

I am bolting a WT stiffener to the web for the intermediate stiffeners, but I can't find anything in the AREMA code to give me a criteria for designing the bolted connection. (AISC had equation 1.10-4 to give a shear flow for the connection.)

I also wondered if I had to stagger the bolt pattern or can I provide a uniform pattern of two parallel rows of bolts?

I would appreciate any help offfered.

 

[MichSt]

Wow! I was thinking of posting a simlar question. I’m working on thru girder bridges for CN RR and CSX RR.

CN does not allow welding of the intermediate stiffeners, except at the top for connection of the stiffener to the top flange of the thru girder. CN has some standard drawings for the bolted connection, but not much detail. All their drawing says in regard to the connection is to use a 4” max bolt spacing vertically.

 

[civilperson]

Uniform bolt pattern can be equal in theory and superior in constructibility for drilling and aligning plates/girders.

 

[MichSt]

Type IV – I talked to a senior engineer in my office. We could not find anything in AREMA that covers this. He recommended using an equation in the AASHTO Standard Specs (I don’t have the number right now as I’m at home) which is used to size the area of intermediate stiffeners and is based on a critical load caused by the tension field action. I’m going to use this load to check the connection design. I am almost certain though that the 4” minimum spacing required by CN RR is going to govern by far.

By the way, I’m using a welded “T” section with one line of bolts on either side of the stiffener.

 

[TypeIV]

Thanks MICHST. I appreciate your looking into it. I am checking with another source too and I will post anything I learn.

Keep up the good work!