bridges - trestle

[ltressaud]

I would like to know what maximum deflection of steel trestle with concrete pile cap supporting concrete bridge.What kind of bearings do you have to use (neoprene, roller...)?

 

[bridgebuster]

It depends on what code you're following and if your client has any specific requirements. Codes such as AASHTO only discuss maximum live load deflections. It doesn't matter if you call the structure a trestle, a bridge, a viaduct, etc.

 

[Qshake]

Bridgebuster, I think the person is referring to a "bent" as in railroad trestle.

The deflection tolerable or otherwise I would believe to be governed by the foundation capacity and as such I can't really give you an answer. But if you're driving the pile our battered members of the trestle to bedrock then I would like to believe that the deflection is negligible. Low Profile bearings are used mainly today although if this is for a railroad I hesitate to say neoprene unless it has a pretty high durometer.

If this is for a highway or road then the bent is just called a "pile bent" or "pile cap bent" and 60 or 70 durometer neoprene pads are typically used. Again, the deflection is likely to be based on the soil-pile interaction and would need to be evaluated by COM-624 or equal. But if driven to refusal - nothing need to be evaluated.