This bell tower owes some of its unique beauty to nature. the unstable foundation resulted in the tilt that’s made the tower so famous.
Begun in 1173 and finally completed 200 years later, the tower in pisa, italy, has undergone many different restoration efforts to try to halt the lean and prevent the tower’s collapse, and in 2008, they seemed to have been successful.
The lean is currently at four degrees, with the top about 17 feet off the vertical from the base below, and it should hold that way for the next 200 years.
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| Leaning Tower of Pisa |
The height of the tower is 55.86 metres from the ground on the low side and 56.67 metres on the high side. the tower has 296 or 294 steps; the seventh floor has two fewer steps on the north-facing staircase.
At least four strong earthquakes hit the region since 1280, but the apparently vulnerable tower survived. the reason was not understood until a research group of 16 engineers investigated.
The researchers concluded that the tower was able to withstand the tremors because of dynamic soil-structure interaction. the height and stiffness of the tower, together with the softness of the foundation soil, influences the vibrational characteristics of the structure in such a way that the tower does not resonate with earthquake ground motion.
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