The Leaning Tower of Pisa
Leaning precariously 5.5 degrees from the perpendicular, the Leaning Tower of Pisa is one of the most famous buildings today. The unique tower impresses every person who visits it. It is located in Italy in the city of Pisa and the structure sits in Cathedral Square (Piazza dei Miracoli). Tourists who are not aware of its history normally wonder why a massive construction reflects poor civil engineering. The tower stands near to 2 impressive buildings, the Duomo the Baptistry and the Camposanto. This is one of the monuments that stir the imagination of everyone, from the young to the old.
Its long history
The construction of the imposing mass was started in the year 1174 by Bonanno Pisano. The structure begun from the bell tower in the year1173 as the final building of the Cathedral complex and was intended to stand at 185 feet high constructed using white marble. The tower was not leaning when it was built in 1173 and it was standing straight like a pole. 3 of its 8 stories had been completed when the uneven settling of its foundations in the soft ground became evident. During that time, there was a war between the Italian city-states, and project was halted for nearly a century. This halt allowed the building’s foundation to settle and possibly prevented its early collapse.
Pisano, the engineer in charge when building resumed, tried to compensate for the tilt by making the new stories a little taller on the structure’s short side, but that extra masonry made the structure to sink further. The construction was plagued with pauses, as engineers looked for solutions to the tilting problem, but the building was finally topped out in the 14th century. Double spiral staircases lined the structure’s interior with 294 steps which led from the ground to the bell chamber (one staircase incorporated two extra steps to compensate for the structure’s lean). Over the next 4 centuries 7 bells were installed on the tower; the largest bell weighed more than 3,600 kg. However, the heavier bells were silenced by the early 20th century, since it was believed that the bells’ movement could possibly worsen the tower’s lean.
The engineers tried strengthening the foundations by injecting cement grout and various types of reinforcement and bracing, but in the late 20th century the tower was still tilting, at the rate of 0.05 inch per year, and was almost collapsing. In the 1960s the government presented plans that the building should have a structural aid to prevent it from falling. Some people argued that it was important that the monument remain leaning because it attracted many visitors who came to the area just to see the historical tower. A magnitude of historians, professional engineers and mathematicians come together to analyze the best techniques and methods to adopt in order to strengthen the tower and secure it for the future generations.
In the year1990 the building was closed and all the bells silenced as contractors undertook a major straightening task. They siphoned earth from underneath the foundations, and this decreased the lean by 17 inches to 13.5 feet, the project was completed in 2001, and the tower was reopened to tourists. The structure continued to straighten without any further excavation, until 2008 when sensors showed that the tilting had finally stopped, at a total improvement of around 19 inches. The engineers expected the structure to remain stable for at least two hundred years. The top of the tower can be reached by climbing the 294 steps which rise in the form of a spiral and are on the inner side of the building walls. This structure demonstrates the dynamics of various elements that caused it to lean on one side with the passage of time. Too much weight on various areas of the soil led to a continuous shift which still continues up to today.
This very great work is of Romanesque style, and as already mentioned dates back to the year 1174. Its shape is cylindrical and is supplied whit 6 open galleries. A cornice separates the galleries and each gallery presents a series of small arches which are fixed on the capitals of the lean columns. In its base there is a series of huge blind arcades with decorations which are geometrical. In the belfry there is a similar design of arcades to that found in the base, with the difference being, apart from the reduced size, the housings of the bells.
Although stately, this tower is not lacking in lightness and elegance due to the open galleries between the stories and also the arcades. Even though it is a real masterpiece of architecture, this tower is mostly famous for its unique inclination. With its inclination it can be safely said that it is certainly due to a sinking of the ground underneath right from the time of the construction.
This tower also had much history apart from the gauche structure. Through the years the monument has played many significant roles, one of which was during the time of Second World War in which the structure was used as a surveillance post and amazingly endured the whole ordeal. Allies during the World War II learnt about the Nazis using this tower as their observation post. A story of Galileo Galilei dropping 2 cannon balls of different masses trying to prove that the speed of descent was dependent on their masses was widespread, but this was later proven to be fictional. 1987, the Leaning Tower of Pisa was publicly declared as a part of the Piazza del Duomo UNESCO World Heritage Site alongside the cemetery, cathedral and baptistery.
Unfortunately, even today the mass continues to lean very slowly. It is a question of around 1 mm. yearly. Since no one can state with mathematical security that the sinking will go on in the future at its present yearly rate, without its stopping, remedies by means of proper measures, based on the projects and scientific studies, are under consideration. Meanwhile supervision with equipment of very high precision is constantly being carried out to monitor the progress of the tilt.