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walkereng
walkereng, Consultant
Category: Structural Engineering
Satisfied Customers: 2591
Experience:  Over 30 years of Structural Engineering experience.
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I'm building a foot bridge, 4' wide x 32' span. Pedestrian

Customer Question

I'm building a foot bridge, 4' wide x 32' span. Pedestrian traffic for a residence. Needs to have a 1200 lb capacity and will have about 1500 lb. of pressure treated lumber for the deck and railing distributed evenly across the bridge. It won't be covered , so it will have up to a 2' snow load on it at some point. Wanted to use [2] steel I beams for the span. What size would I need? Thanks
Submitted: 11 months ago.
Category: Structural Engineering
Expert:  walkereng replied 11 months ago.

I can help

Expert:  walkereng replied 11 months ago.

Before we get started I’d like to point out that a Professional Engineer’s standard of care typically includes a site visit to assess field conditions and get an overall understanding of the structure. This can obviously not be accomplished through the internet. The information provided here is meant for planning purposes only (general sizing and budgeting) and is based on the information provided by you. All loading cases considered are for vertical loads only, no lateral analysis has been completed. The information should be verified by a professional engineer who can visit the site to ensure that potentially important information has not been overlooked or omitted.

Expert:  walkereng replied 11 months ago.

Let me run some numbers for you, I will be back with you a little later this morning.

Expert:  walkereng replied 11 months ago.

Sorry for the delay.

For a 2 beam bridge, using a 32’ span for design and a 4’ width and assuming a 40 psf Live Load and a 10 psf Dead Load, you can use the following:

W8x24 (50 ksi) steel beams. This beam is 6.5” wide, 7.875” deep and weighs 24 pounds per linear foot. You will need to provide solid mechanical connections between the wood decking and the top flanges of the steel beams. I am using a 4’ wide deck, 2 beams with 3’ center to center spacing. You will need to provide solid cross bracing/blocking at each support and at 8’ spacing across the 32’ span.

Expert:  walkereng replied 11 months ago.

If you feel you have received a satisfactory answer to your question, click the Rating button that is appropriate. Experts are credited for each adequately Rated answer they provide. If you have additional questions, please let me know. Thanks

Expert:  walkereng replied 11 months ago.

Let me know if you have any more questions

Expert:  walkereng replied 11 months ago.

If you feel you have received a satisfactory answer to your question, click the Rating button that is appropriate. Experts are credited for each adequately Rated answer they provide. If you have additional questions, please let me know. Thanks

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