Field splice of girder with different web thicknesses 5

[OSUCivlEng]

I am reviewing some shop drawings of a plate girder with a field splice with different web thicknesses. One web is 3/4" and the other web is 13/16". I think this is rather odd, but I'm not the EOR.

There is no filler plate called out in the construction drawings or shop drawings. There will be a 1/32" gap between the 3/4" web and the web splice plate assuming the webs are centered on each side of the splice. The filler plate would be 22 gauge thickness.

Personally, I would have used the same web thickness for both sides of the splice. I am struggling to find any reference in regards to this small of a difference in thicknesses of plates joined in a field splice and a requirement for a filler plate. It would appear to me that this splice doesn't meet the requirements for a slip critical connection in the AASHTO LRFD Bridge design specs.

 

[Settingsun]

Rod, what's the tolerance on pretensioned concrete girders in your area?

 

[BridgeSmith]

The tolerance on prestressed girders varies, depending on the situation. We try to come up with a range of camber that is reasonable for the type of girder and the span, and accommodate that range in the finishing of the driving surface. We don't do many prestressed girders, and the ones we do are typically small, low-speed county road bridges. We've found the long-term camber is difficult to predict accurately, so we choose where we use prestressed accordingly.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[pikku14]

In my part of the world we cater for variation in prestressed girder hogs by estimating and documenting at various time intervals (transfer, 30, 60, 90 days typically). The surveyors and site team then can compare what's actually achieved in the precast yard and prior to erection and adjust bearing pedestal levels as required. Deck thickness will typically vary from the nominal/minimum at mid-span and increase over piers/abutments.

 

[BridgeSmith]

The 'final' camber (increasing camber slows, but never stops) of prestressed girders can be controlled much better by extending the time from casting to transfer, but it's not very popular with the precasters around here.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[OSUCivlEng]

Where I work we have standard haunch thicknesses for each size of prestress beam. The longer the span the thicker the haunch. We don't worry about camber and I have never heard of a problem with negative haunch or deck thicknesses less than 8". Prestressed concrete is commonly used for spans from 40' to 130'.

 

[BridgeSmith]

Nearly all of our prestressed girders are either decked bulb tees or trideck sections. It we're going to use a CIP deck, we pretty much always opt for steel girders, as the more economical option in this area.

Rod Smith, P.E., The artist formerly known as HotRod10