Various Types of Bearing in Bridge 1

[umrce]

I have a bridge rehab project where we are widening the bridge and adding beam lines. Typically on projects like this if the existing bridge is in good shape, the DOT requests we replace the deck and reuse the old I-beam superstructure making repairs as necessary. Our bearing assemblies for the new beams are a reinforced elastomeric pad. To save money, the DOT wants us to keep the old roller rocker type bearings in the adjacent, original, beam lines. Should I be worried about any differential vertical or horizontal displacement (due to creep, shrinkage, temperature forces, etc.) in the steel vs. elastomeric bearing assemblies? I don't want any longitudinal cracking in the deck.

 

[bridgebuster]

I completed plans for the rehab of a steel viaduct. We don't have too many bearings as most of the mile long structure consists of stringers framed to steel pier caps. Most of the fascia stringers are being replaced. At one abutment we were going to sit the new stringers on elastomeric bearings but DOT wanted us to match the existing bearings (low steel sliding plates including bronze sheeting), which are to remain.

From previous experience they observed performance issues between with mixing different bearings and were concerned with deck cracking. The stringers are straight, no skew.

 

[umrce]

Good to know, Thanks.

 

[Qshake]

In the past, I've used taller elastomeric bearing to better match the planned expansion of the old rocker bearings. I say "planned" as after 30-40 years of service (or longer) the old rocker bearings don't always behave as they did on the first day. Often times the expansion is severly limited in this old bearings.

Good Luck.

Regards,
Qshake

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