The team was led by British engineering expert John Burland. A study found that 'the bell tower is stable but tending to straighten' and that it had moved a further 2. The structure is expected to straighten another couple of millimetres and then start to lean again — but at a much slower rate. The tower was closed to the public in for engineers to come up with a way to stop the tower collapsing.
The team hit on a solution that would reduce the tower's inclination by about half degree - reducing stress on the building's masonry and stabilising its foundations.
The method — known as soil extraction — saw engineers dig a series of tunnels on the north side of the tower and remove small amounts of earth. The tower leans to the south. Steel cables helped pull it back into its original position. The project team also found that the tower tilted more in winter as the north side water table was higher than the south when it rained.
This lifted the north side even more. The tower straightened itself by 38cm after the work was done and has continued to straighten since.
It reopened to the public in The people of Pisa are delighted that the tower has been restored but not that it has been straightened. There are other buildings that lean more than the tower of Pisa. It has an 18 degree slope — 5 times more than Pisa — although it was deliberately constructed to slant. Pisa is not even the most accidentally lopsided building in the world.
Medieval towers in the German towns of Bad Frankenhausen and Suurhusen both lean more than the Italian structure. Meanwhile, Pisa got involved into a long was with the nearby city-state of Genova and the works for the Tower were halted for about years. It took years to complete this incredible piece of art and engineering.
In works resumed with the objective to compensate the lean and to build the Tower up to the 7th tier. It was a challenging operation since the Tower was now tilted on one side.
At the time, no one ever attempted a similar operation. The engineer Giovanni de Simone took up this massive challenge. Fortunately this gave time for the underlying soil to settle, otherwise the tower would almost have certainly toppled. In , for example, under the architect Di Simone, engineers built upper floors with one side taller than the other, and it is because of this that the tower is curved.
Eventually the bell tower was added in , with the largest of the seven bells installed in The length of the project, caused by a mixture of construction failures, war and differing architects and designers makes the completion of the Leaning Tower even more impressive. Its struggles can be seen in the fact that it still leans, whilst its combination of Gothic and Romanesque style demonstrate its centuries worth of production.
Interestingly despite its unstable structure the tower is still with us today, surviving wars and natural disasters. Engineers have concluded that this is a result of the dynamic soil-structure interaction which enables the Tower to withstand tremors. Through a combination of the buildings height and stiffness and its soft foundations, the Tower does not resonate with earthquake ground motion, making its greatest vulnerability its cause of survival.
It kept leaning more and more. The next stories were built slightly taller on the short side of the tower in an attempt to compensate for the lean. However, the weight of the extra floors caused the edifice to sink further and lean more. See more Leaning Tower of Pisa facts.
Pisa Tower was eventually completed in the mids. WHY was the leaning Tower of Pisa built?
0コメント