Peer Review 1

[twheng]

We are designing a small pedestrian bridge in Calif. that needs AASHTO design. Can someone help with guidance and/or peer review.?

 

[bridgebuster]

Do you need to follow CalTrans standards? Most likely, you have to follow AASHTO LRFD Guide to Pedestrian Bridges, which supplements the LRD Bridge Design Spec. There's no mystery to ped bridge design, however, you need to consider vibrations as a service limit state.It's all spelled out in the AASHTO guide spec.

 

[twheng]

Thank you for the reply. The County is going to have Caltrans take over the maintaince so they(Caltrans) wants it to their specs. We have never done AASHTO but the bridge is simple so we decided to give it a go. We appreciate this heads up and we will look into it. If there is other heads up we would appreciate it. We are not designing the walkway and guardrail which is going to be designed at a later date. This is just to get the utilities over a creek then the final design will come later. Also, do you know of any resources for Corten steel lifespan? Thanks

 

[bridgebuster]

Take a look at this, regarding weathering steel

http://www.fhwa.dot.gov/bridge/t514022.cfm

 

[twheng]

Thanks we already have that doc. (I think i found it from one of your earlier replies to someone else) Is there any information on the "lifespan" of this stuff?

 

[bridgebuster]

Off the top of my head I don't know, but lifespan is based on many factors (just like human beings). To put things in perspective, we generally assume that a bridge has a useful life of at least 75 years.

Brooklyn Bridge wasn't built from weathering steel but it's still going strong.

 

[TomDOT]

I've had a good look at the Pennybacker Bridge pretty recently - weathering steel in a mild environment installed in 1982

http://en.wikipedia.org/wiki/Pennybacker_Bridge

There is no appreciable degradation or pitting in the weathering steel. I expect the weathering steel to last well over a hundred years (absent extreme external factors, like a gasoline truck impact and fire) and would not be surprised if it lasted much longer