The easiest way to to this is to hold the plywood vertically with its long edge on the ground. First, plot your arc onto a piece of 3/4" plywood. Now it's getting interesting! This is where you build a half-circle shaped wooden insert that will support your bridge's stones as you build it. Then reverse the process and you have 2 solid footings! If you don't have a dry season, you will have to divert the flow of the water to one side while you pour the footing on the other. Our stream has a flow season and a dry season, so we poured the footing during the dry season. NOTE: Digging below the level of the stream bed can make water pool up in the foundation footing.
FEATHERS AND WEDGES HARBOR FREIGHT HOW TO
If you are a novice to pouring concrete, just look up a youtube video on how to do it! It's very simple, and there is a ton of content on youtube that will help with this. You will probably use at least 2 cubic yards of concrete, so hiring a company to bring it will probably save you a ton of time and money. I recommend just having a concrete truck come out and pour it for you. Pour the concrete at least 8" thick, reinforcing with 1/2" rebar placed in a grid at intervals of 12". Make it a minimum of18" below the level of the stream bed and 6 inches wider than the base of your bridge on all sides.
Now pour a solid concrete footing on which will rest each side of the bridge. If they are not firmly grounded on a good foundation, these bottom stones will slide over time, flattening the bridge and causing collapse. One arch bridge is thought to be about 3,300 years old! Fig 3 shows also how the compression load of the bridge will try to "flatten out" the arc of the bridge by pressing the stones apart. As they settle they just become more and more locked together in compression, thus providing greater strength to the bridge. Because of this compression with the arch of stone, these bridges age extremely well. This is crucial because as load is applied to the top of the bridge, these stones are compressed into each other horizontally, locking them together and supporting the load of the bridge. This bridge will collapse because it has only the shear resistance of the blocks keeping it up over the arch.įigure 2 shows a bridge that is supported by an arch of stones, each of which is parallel to the radius of the imaginary circle that is an extension of your arc. 1 and fig 2:įigure 1 shows a bridge that is basically just a block wall that someone cut a hole out of. The way we do that is by creating an arch of squared off rocks that all run parallel to the radius of your arch.
Stone has poor tensile and shear force resistance, but excellent compressive resistance: Like 28,000 pounds/sq. Stone bridges all have arches supporting them. and you'll need a bunch, depending on your project size.)ġ0) Basic concrete tools: a trowel $5, a shovel$12, and if you want, a grouting bag $5ġ1) Concrete for the bridge foundation ($100-$150 a ton if delivered by a truck) They are your bread and butter.) ($10 for a pack )ĩ) Mortar ($5/ bag. This will be the most expensive, but you will save a ton of time cutting stone.)Ģ) Household Tools: A hammer (preferably 2 or 3 pound in weight with a beveled end), a shovel, a drill, a circular saw, screws.)ģ) Masonry chisels: (at least one 3" wide and one 1.5" wide) ($10/ea)Ĥ) A rotary hammer drill with 9/16 bit (for drilling holes used to split stone I got mine at Harbor Freight for $80)ħ) 3/4" Plywood, 1/4" plywood, 2圆 boards ($100-$150)Ĩ) Plug and feathers (also called wedge and feather: by far the most specialty item, but available online. A third option is to buy pre-cut landscaping stone from a landscaping supply company. Shot rock, purchased at your local quarry will take more time to cut, but will also work great. Preferably, use whatever stone you have on the property! It will look great and give you immense satisfaction to see your project built out of stone native to your land.
The bridge I built spans roughly 10 ft and I probably used 5 tons of stone, harvested from the stream and the surrounding hillside. Assuming you have the household tools already, you're looking at $400-$800 in suppliesġ) Tons of stone (Like seriously, TONS. Much of this stuff is common household tools/supplies, but if you don't already have it, all can be purchased at your local hardware store (possible exception would be plug and feather which can be purchased on.
0 kommentar(er)
