Concrete Encased Vierendeel Truss Girder

[STrctPono]

I am working on a project where another Engineer has designed a bridge girder (140ft span) as a structural steel vierendeel truss. Top and bottom chord are W12x252's. 5'-0" deep truss. The vertical webs are intermittently spaced lighter W12 members. The whole girder is then encased in concrete. 6ft deep by 2ft wide rectangle. There are no shear studs of any type so it's uncertain what kind of composite action their getting, if any out of the design. IMO the design is terrible and I have a whole list of items of why but what I need is third party documentation of why it's bad. I want to say it's an antiquated design but I'm not really sure if concrete encased structural steel was ever a thing in bridge or building design. It's just a really weird and inefficient design that is going to be a maintenance nightmare. I can't find anything in AASHTO that addresses this type of design which is an indicator that no one does this. Have you guys heard of anything like this? Any articles, documents, publications that would cover anything like this? I'll take anything at all. Even if it covers just concrete encased wide flange beam flexural elements.

 

[OSUCivlEng]

Maintenance will be problematic, but it sounds like a major PITA to build as well. Building formwork around all those truss members so they can be encased in concrete? That's gonna cost the owner a bunch of money.

How can you inspect the truss connections?

Not to mention the cost of fabricating and erecting a truss. A 140 foot span isn't that big. Plate girders or bulb tees would would work much better.

Is there an architect involved in this project?

 

[TrussBridgeboy]

It sounds like a fun experimental project for an engineer to me. If it's for a paying customer I wouldn't touch it with a 10' pole. Unless you know where it's been done before successfully, then who knows what will happen, as many posters have speculated. Five feet is very shallow (inefficient) especially for a vierendeel (more inefficient) 140' span so deflections will be significant. I would be doing some serious analysis to prove shear connectors aren't warranted. If it's pedestrian, it might work. (Might also means might not). If there's highway loads, I can envision the concrete popping right off, but who knows?