Uplift at abutments of continuous plate girder 1

[OSUCivlEng]

I am working on the design of a 3 span continuous plate girder. The ratio of the span lengths are not ideal, the length of the end spans are half the center span. The span lengths are a function of an environmental problem or else they would be more balanced.

Of course the the minimum unfactored live load reaction is negative. However the total unfactored dead load reaction (DC1+DC2, not including DW) offsets the minimum unfactored live load + impact reaction by about 1 kip. So it would seem that the girder will never actually go into uplift. I have not checked the slab pouring sequence yet, but I will.

1 kip doesn't make me feel too secure, so my plan is to increase the end spans a bit more to make the dead load reaction offset the live load reaction. I just don't want to lengthen the bridge any more than I have to. I was wondering if anyone else had run into this problem before.

 

[edward1]

I would use integral girder back wall abutments to add the additional dead load concrete weight.

 

[BridgeEI]

In locations where this has been a problem we have had added keepers around the bottom flange to prevent uplift if it did occur.

 

[OSUCivlEng]

I am going with the integral abutment option.