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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6819
Experience:  Structural Engineer
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A 14 foot bridge with stringers 9 in deep and 7 in wide,

Customer Question

A 14 foot long bridge with stringers 9 in deep and 7 in wide, spaced 10 feet wide with one each at perimeter, then 16 in centers to the next towards the middle, then 4 more stringers (7x9) on 11 in centers, with a then 10 in to center-line of bridge width, and repeated from the opposite side, being a total of 10 stringers. These sit on 12 x 9 timbers 10 feet long across each end, which then sit on concrete pillars 2 ft long by 11 ft wide x 9 ft deep (approx 4 ft of that below grade). This is decked with slightly spaced 10in x 3 in x 10 ft timber decking.. I do not know the type of timbers used, but the builder(deceased) was a retired bridge builder for the railroad. what is the approximate load rating for such a structure?
Submitted: 12 months ago.
Category: Structural Engineering
Expert:  StructuralEng replied 12 months ago.

Hello

Expert:  StructuralEng replied 12 months ago.

I can help. Can I get back to you in a few hours?

Customer: replied 12 months ago.
Sure
Expert:  StructuralEng replied 12 months ago.

can you post a sketch of how this framing is laid out? The description is not very clear.

Customer: replied 12 months ago.
does this help?
Customer: replied 12 months ago.
I have not gotten a response from you as of yet...did you receive my makeshift drawing?
Expert:  StructuralEng replied 12 months ago.

I did. I'm looking at it now. Do you know the soecies and grade of the lumber? Are they full 9x7 or nominal?

Customer: replied 12 months ago.
I do not know the species or grade...very tight, sturdy, non cracked wood...like I said, he worked for the rairoad building brideges if that is any help in direction of type of timber. They are true 9 by 7. Will a road plate enhance or detract from whatever the load rating could be?
Expert:  StructuralEng replied 12 months ago.

A plate will not increase the capacity of the beams.

Customer: replied 12 months ago.
But in my line of thinking, a 10 ft wide 16 ft long section of 1 inch steel plate laid atop a 14 ft long span of bridge, sitting on concrete piers allows for a heavier load than the initial rating of said plate or bridge...but my main question of the approx rating of said bridge is what please?
Expert:  StructuralEng replied 12 months ago.

6,000 pounds

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