1. The Cracking of St. Peter’s Dome Location: Vatican City, Italy Completion Date: 1626 Diameter: 42.3 metres Type: Ribbed Purpose: Religious Materials: Concrete Architect: Donato Bramante, Michelangelo

2. The Cracking of St. Peter’s Dome St. Peter’s Basilica is situated in the Vatican City. St. Peter’s Basilica is situated in the Vatican City. The Dome of St. Peter’s Basilica was commissioned in 1506. The Dome of St. Peter’s Basilica was commissioned in 1506. The principal designer of the dome was Michelangelo. The principal designer of the dome was Michelangelo.

3. Design of the Dome The original plan was for a single shelled dome. The original plan was for a single shelled dome. However, this was proved unfeasible. However, this was proved unfeasible. Michelangelo’s design was a double shell dome made of heavy masonry. Michelangelo’s design was a double shell dome made of heavy masonry.

4. Design of the Dome The dome would be 42.3 metres in diameter and would rise 120 metres above floor level. The dome would be 42.3 metres in diameter and would rise 120 metres above floor level. Iron tension rings were built into base of dome to contain outward force.

5. Dome Diameters St Peter’s Dome 138’

6. Problems Arise Early 18 th Century. Dome began cracking. When a dome is too heavy, the sides push outward, and cracks appear throughout the bottom portion of the structure.

7. Solution Vatican engineers tied several tension rings around the structure. These acted like hoops on a barrel. This proved successful.

8. Present Day The hoop design of the Vatican engineers has stood the test of time. Outward forces have caused no further damage to the dome.

9. Group 21 Thank you