Load Distribution Factors for a Non-Composite I Girder

[saadeh]

Hi all!

I'm a bridge engineer at a local company and my boss assigned me a task to check the design of one of our projects and I'm confused a little bit about the type of girders we have here.

The girder section is a non-standard Precast post tensioned girder which has a shape nearly as an I girder but with no top flange, and the deck system will be precast 1.9x1.75m panels spanning between the girders and a topping of CIP concrete of about 150mm thick. When I'm usually asked to check the design of a girder, I do it by hand calculations and a simple stress check excel worksheet I've found and modified long time ago, I do some simple distribution factor calculations based on the LRFD specifications for the type of super structure I have then calculate the loads and check the allowable stresses, the anchor system specifications and design,..... etc.

The thing here is that since the deck is non-composite with the girder, can I use the dist. factors listed in the LRFD specifications though these D.F are for I girders with monolithic decks ??

And is there a good and easy-to-use software to do these kind of checks ??

Regards.

 

[bridgebuster]

The distribution factors are still valid for a non-composite deck; unless there is some hidden provision in LRFD.

If you have bars coming up from your girder in to the deck you may have enough steel to consider composite action.

 

[saadeh]

Hi Bridgebuster:

I just checked the rest of the details of the submitted girder and I found what you talked about; there is a sufficient number of shear connectors coming out of the girder into the concrete topping and sufficient longitudinal bars coming of the precast panels to develop with the shear connectors as well, so as you said, I will consider the girder to have a monolithic topping and recheck it accordingly...


Thanks alot !!

 

[bridgebuster]

No problem