Posts Tagged ‘true arch’
This arch one of the stronger arches. The keystone bears the weight of the stones pressing down from above. This pressure in turn pushes on the stones or bricks next to the keystone on both sides. This pressure is relayed from stone to stone, down both sides of the arch until it reaches the bottom blocks and then is carried down the piers to their foundations and into the ground. If the arch is too long, or if the piers at the ends are too light, the outward thrust will push the sides out and the top will cave in. If the arch is too light at the top, or too heavy at the sides, the sideward thrust of the arch walls will push the top up, and the sides will cave in.
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A semi- circular arch made with an odd number of bricks to accommodate the center keystone usually the simplest to build. Similar to the true arch.