Semi intergral end screen wall
Semi intergral end screen wall
(OP)
Hi,
I am designing a semi integral bridge in the UK. It is a 2 span bridge (both spans approx 30m), with fixed bearings at the central pier and free bearings at the abutments to allow for expansion.
The deck is continuous steel plate girder with a RC deck slab. At the ends of the bridge the deck continues round the ends of the girders to form an end screen wall (i.e. the ends of the girders are protected by a continuation of the deck, perpendicular to the carriageway surface above.)
This end screen wall projects about 2-2.5m into the embankment, so it will retain some earth and will therefoe be subjected to associated earth pressures. I'm also concerned about the forces on the wall from thermal expansion of the plate girders.
Does anyone have experiance designing a similar detail?
I am designing a semi integral bridge in the UK. It is a 2 span bridge (both spans approx 30m), with fixed bearings at the central pier and free bearings at the abutments to allow for expansion.
The deck is continuous steel plate girder with a RC deck slab. At the ends of the bridge the deck continues round the ends of the girders to form an end screen wall (i.e. the ends of the girders are protected by a continuation of the deck, perpendicular to the carriageway surface above.)
This end screen wall projects about 2-2.5m into the embankment, so it will retain some earth and will therefoe be subjected to associated earth pressures. I'm also concerned about the forces on the wall from thermal expansion of the plate girders.
Does anyone have experiance designing a similar detail?





RE: Semi intergral end screen wall
A few years ago I worked on a similar type bridge - the "end screen", or as we called it the "end diaphragm" or "end block", was 2 meters deep. We took a simple design approach: Case 1 - earth pressure loads; Case 2 - wheel load + self weight. Minimum reinforcement controlled. We didn't bother to include a thermal force in the end block.
RE: Semi intergral end screen wall
Most of examples I've seen have a vertical plate welded accross the ends of the girders, with shear studs on the other side going into the end block. I'm not sure if this is just a 'good practice' detail or if there are any design calculations behind it. Did you include a similar detail on your design or were your girders actually cast into the end block?
RE: Semi intergral end screen wall
As such I don't such a plate is really necessary for the final arrangement but if I were to place such a plate I can see the point of making sure it is composite with the end diaphragm (screen wall).
Regards,
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RE: Semi intergral end screen wall
For thermal expansion, you’re girders will push the ‘end screen’ in to your fill. This may or may not mobilize full passive pressure from the soil, but typically you will just be conservative and design the concrete for full passive pressure. That will take into account the thermal forces in your concrete design.
As for details, here’s one detail that I have seen used:
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Also, the reinforcement in the ‘end screen’ is typically continued through drilled holes in the girders. If you have a skew, make sure the holes are oversized enough to fit the skewed rebar.
RE: Semi intergral end screen wall