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Rehabilitation of the 26th floor of Pirelli skyscraper
18 12 2003On the 22nd April 2002 a small airplane crashed into the Pirelli skyscraper in Milan, causing the death of 2 persons and huge damages to the higher floors of the building.
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Rehabilitation of the 26th floor of Pirelli skyscraper
published: 18 12 2003
On the 22nd April 2002 a small airplane crashed into the Pirelli skyscraper in Milan, causing the death of 2 persons and huge damages to the higher floors of the building.
On the 22nd April 2002 a small airplane crashed into the Pirelli skyscraper in Milan, causing the death of 2 persons and huge damages to the higher floors of the building.
Floors were damaged due to fire caused by airplane explosion and serviceability was seriously compromised. The 26th floor was the most damaged one, with a loss of stiffness and consequent increase of deflection in the middle of the slab.
The year after the State Administration of Lombardia, owner of the building, decided to start rehabilitation works, in order to repair all damages and bring higher floors to working conditions and give a strong sign of will for renewal.
In order to reduce deflections and bring floor back to correct position, it has been decided to introduce an external post-tensioning, placing cables on the bottom side of the slab.
Anchorages have been placed inside special designed steel boxes which have been fixed, through the use of post-tensioning inox steel bars, to both sides of beams running beneath the floor.
Moreover special designed steel deviators have been placed just in the middle of the span, where post-tensioning forces have been capable of lifting up the slab.
Tensacciai 7MTAIE external post-tensioning cables have been made with 7 strands type 15,7 mm, externally protected by an hdpe tube, itself protected by an outside inox steel tube giving both higher protection and aesthetic nice perspective.
The preliminary placing and fixing of steel boxes to beams have been made through the use of Tensacciai annular stressing jacks for bars.
Due to reduced working spaces beneath the slab, stressing of cables has been carried out with the use of monostrand jacks, giving forces to strand one by one and monitoring slab movement during load increase.
Grouting of cables have been finally performed to achieve the best corrosion protection conditions.
The post-tensioning system has been finally left in open space, visible to everyone who is interested in rehabilitation systems for concrete structures and will of overcome damages in structures.
Floors were damaged due to fire caused by airplane explosion and serviceability was seriously compromised. The 26th floor was the most damaged one, with a loss of stiffness and consequent increase of deflection in the middle of the slab.
The year after the State Administration of Lombardia, owner of the building, decided to start rehabilitation works, in order to repair all damages and bring higher floors to working conditions and give a strong sign of will for renewal.
In order to reduce deflections and bring floor back to correct position, it has been decided to introduce an external post-tensioning, placing cables on the bottom side of the slab.
Anchorages have been placed inside special designed steel boxes which have been fixed, through the use of post-tensioning inox steel bars, to both sides of beams running beneath the floor.
Moreover special designed steel deviators have been placed just in the middle of the span, where post-tensioning forces have been capable of lifting up the slab.
Tensacciai 7MTAIE external post-tensioning cables have been made with 7 strands type 15,7 mm, externally protected by an hdpe tube, itself protected by an outside inox steel tube giving both higher protection and aesthetic nice perspective.
The preliminary placing and fixing of steel boxes to beams have been made through the use of Tensacciai annular stressing jacks for bars.
Due to reduced working spaces beneath the slab, stressing of cables has been carried out with the use of monostrand jacks, giving forces to strand one by one and monitoring slab movement during load increase.
Grouting of cables have been finally performed to achieve the best corrosion protection conditions.
The post-tensioning system has been finally left in open space, visible to everyone who is interested in rehabilitation systems for concrete structures and will of overcome damages in structures.
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| Project | : | Rehabilitation of the 26th floor of Pirelli skyscraper |
| Location | : | Milan, Italy |
| Type | : | Building floors with external post-tensioning cables |
| Total length of cable | : | 17 m |
| Cable strand | : | 1,5 tons |
| No. of cable | : | 10 |
| Max no. of strands per cable | : | 7 |
| Main Client | : | State of Lombardia |
| Contractor | : | Grassi & Crespi |
| Designer | : | Prof. Eng. Antonio Migliacci |
| Period | : | Autumn 2003 |
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