Small Bridge Framing Issues

[willijamie]

I am working on a small bridge replacement project. The span length is approximately 42'. The problem is the structure is located in an intersection with a horizontal curve. The length of Abut.1 is a 37'-4" and Abut. 2 is 50'-4". We have proposed using steel beams with a splayed layout (Abut 1 spacing = 7'-7"; Abut 2 spacing = 10'-10"). The client wants use to use 5 beams with equal spacing of 7'-7" and use a "kicker" beam to make up the space due to the curvature of the bridge deck. My questions to anyone is:

1. Which alternate is better fabricated and erected? Why?

2. Stay-in-place deck forms are required and based on this information, would the splayed framing plan increase this cost due to differing girder spacing along the span instead of having uniform spacing between the beams?

The distance between the "kicker" beam and the outside girder at Abut. 2 is 12'-0". Current design is using W18x109 but with the use of the "kicker" beam, the beam depth might have to be increased.

Thank you for your help and input!

 

[bridgebuster]

Go with the kicker beam; it'll make the framing easier.

 

[TTK]

"kicker beam" can have different meanings to different people.

By "kicker" do you mean one splayed girder that frames into the adjacent girder on the short side and sits on the abutment seat at the long end?

If this interpretation is correct, then I would agree that is the best way to go for such a short span.

 

[71corvette]

One definite plus to using a kick beam is that the remaining girders will be similar (crossframe locations & lengths similar). With splayed girders each girder would need to be different. This increases fabrication and erection costs.

I've completed designs for splayed girder bridges and the

 

[Qshake]

I agree with bridgebuster, use the kicker beam or stub beam or whatever you want to call it. The framing will be easier and this is a detail that has been tried and tested over many years.

Do keep in mind when using an open seat abutment type there may be a possibility to have uplift on the kick/stub beam. And you don't want your bearing to walk out from underneath the short beam.

Regards,
Qshake

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