Multi-rotational Bridge Bearings - AASHTO LRFD Specifications - FACTORED LOADS

[jrdynamic]

As of late, many Engineers of Record (EOR) have been providing only UNFACTORED LOADS for the producers of Multi-rotational Bridge Bearings and are requiring the Manufacturer to Factor the loads for their design of these bearings. This seems contrary to AASHTO LRFD Specifications and other AASHTO documents that clearly state that the Bridge Designer (not the Bearing Producer) should determine the Factored Loads. It seems inappropriate for the EOR to put this onto the Bearing Producer who is not really qualified to determine the correct factors.

Does anyone have any comments on this???

 

[bridgebuster]

That's why we have RFI's.

 

[jrdynamic]

We have sent out RFI's asking for the factored loads. The Engineers have refused to supply that information!!!

 

[bridgebuster]

Here's what you do, take the I factored loads from the plans, factor them, and send them to the EOR for approval. State in writing you can't start the shop drawings until the loads are approved.put the onus on him.

 

[jrdynamic]

Yes.....that is a very good idea - except I am unsure how to factor the loads. Could you please give me some pointers on how to do this or advise me of some literature I can get to help me factor the unfactored loads?

 

[bridgebuster]

Can it wait till Monday? I'll be back in my office then. I have a copy at home but won't be there till Friday night and we have friends staying for the weekend. I hate to see you spend $500 on an AASHTO if you're not going to use it regularly.

You can try this site, they have some LRFD publications that might be useful:

http://www.aisc.org/contentNSBA.aspx?id=20244

 

[jrdynamic]

Yes.....it can certainly wait until sometime next week. Any help or advice you could give me would be greatly appreciated.

Thank you.

 

[bridgebuster]

According to AASHTO LRFD bearings are designed for Service I, so the load factors are 1.0.

The connection of the fixed bearing to the superstructure is designed for Extreme I or II, which requires several loads in addition to DL & LL.