How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask StructuralEng Your Own Question

StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6747
Experience:  Structural Engineer
59685895
Type Your Structural Engineering Question Here...
StructuralEng is online now
A new question is answered every 9 seconds

I am going to build a bridge with a 26 foot clear span it

Customer Question

I am going to build a bridge with a 26 foot clear span it will be 14 feet wide and will have corrigated steel deck with 2 inch asphalt wearing surface
I am planing on use of 5 beams 12" x 6" wide on concrete abutments I will have to splice the beams as they are only 24' now , so I will make them 29' . I will put the splices every other direction and was planing one set of diaphragms midd span .
I will butt the beams and penetrate weld all around then weld a plate 12" long center on both flanges.
Do you see a problem with this plan?
Thanks
Brian
Submitted: 5 months ago.
Category: Structural Engineering
Expert:  StructuralEng replied 5 months ago.

HELLO

Expert:  StructuralEng replied 5 months ago.

How thick will the concrete deck be below the 2" asphalt wearing surface?

Is this a bridge on private property?

Do you have a desired load rating?

Expert:  StructuralEng replied 5 months ago.

Is your question about the beam size or the method of splicing the beams?

Customer: replied 5 months ago.
No concrete just galv corigated steel deck with 1.5-2" asphaltThe bridge is on private propertyLoad for dump truck say 20 tonThe county has one built near me but this span is 3' longer but my beam spa will be a lot closer with the same beams and they have close to 3" of asphalt on thiers
Expert:  StructuralEng replied 5 months ago.

You can't drive a dump truck over corrugated metal deck without concrete fill.

Customer: replied 5 months ago.
There are two bridges within 1/4 mile of us over 20 years old that only have d deck and asphalt the one bridge they did not pave for two years built in speed bumps. That bridge was private the other is a township bridge, it was paved right away due to speed of the traveling public. There are still some decks with 2x4s on edge and tar chip as wearing course water proofing combo.
Customer: replied 5 months ago.
Go to contec website or big-R for this type of deck , my deck will be 27"between the edges of web with 1.5 ' overhang on each side.
Expert:  StructuralEng replied 5 months ago.

Is your question about the beam size or the method of splicing the beams?

Customer: replied 5 months ago.
Both
Expert:  StructuralEng replied 5 months ago.

I will check the beam size, but not the deck. I will comment qualitatively only on the beam splice. Is that reasonable?

Expert:  StructuralEng replied 5 months ago.

Assuming your beams are W12x26 and each tire load is equally shared between two beams...

Expert:  StructuralEng replied 5 months ago.

It almost works for strength, but deflection is about 1.5". That is too high.

Expert:  StructuralEng replied 5 months ago.

The method of splicing you describe is reasonable, but the weld from the plate to the beam and the connection between the two end plates must be properly designed.

Customer: replied 5 months ago.
Would the diaphragms help with the deflection
Expert:  StructuralEng replied 5 months ago.

The metal deck diaphragm?

Customer: replied 5 months ago.
No I want to put x bracing or say 10"" beams maybe mid span perpendicular to the beam line to stop any possible flop, and I also was figuring it would help spread the load to the adjacent beams. You have me concered with your 1.5" deflection. What would happen if I double stack 2 beam lines to make 24" beams in the wheel tracks?
Expert:  StructuralEng replied 5 months ago.

Those beams would be brace beams, not a diaphragm. They will not help with deflection.

Customer: replied 5 months ago.
I think I will have to go to a 14 "or 16 " tall beam. Correct
Expert:  StructuralEng replied 5 months ago.
That will be the most efficient beam to use. You can use a 12" beam, but they'll be heavier and more expensive.
Expert:  StructuralEng replied 5 months ago.
W16x36 is the best beam for you to use. 16" deep and 36 pounds per foot

Related Structural Engineering Questions