| Lessening the
lean gives leaning Tower of Pisa new lease on life Abstract The first period of construction began in 1173 and lasted five years. A century later, during an equally brief bout of construction activity, the tower started to lean to the south and masons began to build a backward curve into the stonework in an effort to keep it vertical. Another century passed before a final decade of construction completed the belfry in 1370, when the lean was approximately 3.5 degrees from the vertical. The 142-tonne Pisa tower itself was likely on the verge of collapse. The tower had a negligible factor of safety against toppling and was leaning more each year. Built on 5 m of silty soil over alternating layers of clay and sand, the tower would probably have collapsed during construction. Did they manage to arrest further leaning of the tower? CLICK THIS LINK for the full paper. April 2001 |