I'm thinking about what it would take to upgrade the bridge coming in my driveway. This Bridge served us well all these years with 80,000 pound semi's driving over it daily. Feed deliveries, and a daily milk tanker 7 days a week x 30 years.
The Footings are concrete, and probably 80-100 years old. They are part of the creek channel with 10-12 feet width between them and the bridge beams are 8 feet from the bottom of the creek channel. They cross the driveway at an angle so it is a straight shot down the driveway. Over time some tree roots grew behind one of the footings and created some concern it would possibly tip that footing . We removed the tree in question, but it makes me think perhaps it would be wise to move the bridge footings back from the edge of the creek. Perhaps set some precast concrete in the existing roadbed perpendicular to the road.
The deckspan is 2 -12 inch I-beams topped with 4x6 and 4x8 pressure treated lumber that runs parallel to the creek, (angled, not perpendicular) to the driveway)topped with 4 2x12 treads along the wheeltracks . the I beams are under the middle of each tread.
The beams are roughly 17 feet long on their existing footings. I'm wondering if moving the footings back to be perpendicular with the driveway might be a good upgrade. That would make the span 22-25 feet . If I used 2- 12 inch I beams under each tread, that should make up for the reduced capacity of the longer span. This would have the added benefit of raising the bridge, since the creek will flood occasionally and flow over the existing bridge for a couple of hours. I'd make the Deck 10 feet wide inside the railing.. it currently is only 9' 5" between the bumper rails. which can be an issue for pulling a trailer.
I'm no engineer, and neither was my great grandfather who built this one. What am I not taking into account?
I looked up I beam capacities on this web page: https://www.engineeringtoolbox.com/w-steel-beam-uniform-load-d_1722.html
The Footings are concrete, and probably 80-100 years old. They are part of the creek channel with 10-12 feet width between them and the bridge beams are 8 feet from the bottom of the creek channel. They cross the driveway at an angle so it is a straight shot down the driveway. Over time some tree roots grew behind one of the footings and created some concern it would possibly tip that footing . We removed the tree in question, but it makes me think perhaps it would be wise to move the bridge footings back from the edge of the creek. Perhaps set some precast concrete in the existing roadbed perpendicular to the road.
The deckspan is 2 -12 inch I-beams topped with 4x6 and 4x8 pressure treated lumber that runs parallel to the creek, (angled, not perpendicular) to the driveway)topped with 4 2x12 treads along the wheeltracks . the I beams are under the middle of each tread.
The beams are roughly 17 feet long on their existing footings. I'm wondering if moving the footings back to be perpendicular with the driveway might be a good upgrade. That would make the span 22-25 feet . If I used 2- 12 inch I beams under each tread, that should make up for the reduced capacity of the longer span. This would have the added benefit of raising the bridge, since the creek will flood occasionally and flow over the existing bridge for a couple of hours. I'd make the Deck 10 feet wide inside the railing.. it currently is only 9' 5" between the bumper rails. which can be an issue for pulling a trailer.
I'm no engineer, and neither was my great grandfather who built this one. What am I not taking into account?
I looked up I beam capacities on this web page: https://www.engineeringtoolbox.com/w-steel-beam-uniform-load-d_1722.html
