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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 4791
Experience:  Structural Engineer
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I need to build a bridge over a creek on my property. The span

Customer Question

I need to build a bridge over a creek on my property. The span will be 85 feet, and the bridge needs to carry the weight of a full concrete truck (~80,000 lbs).
What size, and how many steel I-beams are required?
Submitted: 2 years ago.
Category: Structural Engineering
Expert:  StructuralEng replied 2 years ago.

Customer:

Hi, I can help with this.

Customer:

Give me a minute to run some numbers.

Customer:

You're not going to like this answer.

Customer:

You need four W40x593's just to keep deflection to L/600, which is really too high for a bridge. A better option is custom built-up plate girders.

Customer:
Customer :

I've had a bridge builder out to look at the site. He proposes to use a railroad flat car, 89 ft long X 10.5 ft wide. Says it will carry a 140,000 lb load. Total installed cost of ~$53,000 to $58,000. Does that seem reasonable, considering this is such a wide span and high load requirement?

Customer :

That includes drilled footings to ~25 ft and concrete structures to set the rail car on. Covered with massive timbers.

Customer :

When I tried to ACCEPT, the site said it would end the session. I wanted to see if you had an opinion on what the bridge builder said first.

Customer:

Give me a minute to think about this

Customer:

The price seems reasonable for the construction, but I would strongly recommend having an engineer review the footings and support details. These spans and that load are nothing to mess with.

Customer:

Additionally, a railroad flat car could work, but it would need to be designed to meet strength and deflection criteria. There is not just one size railroad flat car out there, just like there isn't only one steel beam out there.

Customer:
Customer :

Thanks. You've been very helpful. I'm about to ACCEPT. How do I leave feedback (it's my first time to use the site)?

StructuralEng, Consultant
Satisfied Customers: 4791
Experience: Structural Engineer
StructuralEng and other Structural Engineering Specialists are ready to help you
Expert:  StructuralEng replied 2 years ago.
When you click on the "accept" button, you should be prompted to leave feedback.

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