Our house's foundations serve two purposes. One is to spread the weight of the house over the soil. The other is to resist lateral (sideways) motion. Our foundations are unusual, because they must remain above ground on the National Mall. Generally footings are underground, and in no danger of sliding. Tests were required to determine the footings' coefficient of friction. In combination with the weight of the house, this coefficient allows us to analyze whether an extremely strong wind could push the house sideways on its foundations.
The team tested the footings both on the parking lot surface of the construction site and on a grassy surface simulating the National Mall site. Loads of known weight were placed on the test footing. Lateral force (also known as a "push") was applied with the forklift. The team used engineering instruments to determine how much force was required to move the footing under a range of loads.
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