Step 4: When the caisson is in place the sealing system is activated and the inner volume of the caisson can be emptied. The concrete foundations are then built in a dry environment. Inside the caisson the three dimensional steel structures required to transfer the loads of the tower legs to the seabed are erected, thus achieving continuity of the two structures. Within each of the three caissons, various facilities and parking areas can be a ccomodated on several levels between the transfer structures, since the total height available will be50 meters or more.
Thereafter, the construction work above sea level is carried out in a more conventional manner, although the site is located several hundred meters offshore.
DESIGN CRITERIA
This conceptual design already takes into account the stability design criteria that such structure shall meet.
It is of course essential that the implementation of the various design criteria be carefully coordinated as it is always the case for major civil engineering projects.
Taken individually the three main criteria are:
Wind effect
Mr. Jerzy Wianecki(3), Chief Engineer of the CEBTP, when advising on the design of the Louis II stadium canopy made suggestions regarding the aerodynamic of such major structures.
Taking these suggestions into account we will in parallel, calculate the wind load applied to the overall caissons and superstructure system and perform aerodynamic model tests in wind tunnel. In accordance with the French norms, the building must be designed for a wind speed of 200 kin! hour. This generates, at the foot of the tower, a shear load in the order of 7,000tonnes and a tilting moment of 1,000,000tonnes.meter at sea level. This wind load is to be combined with wave loads.
Wave effect
On this matter, we obtained the advise of Mr.Bouchet(2),Technical Adviser to Monaco’s government, who has carried out, for many years, studies related to Monaco offshore projects such as the new dike of the Hercule Harbour and the Fontvieille II scheme.
For a water depth in the order of 70 meters and for a heavy structure, we have to account for the full wave loading over the caissons. The criteria is the maximum wave increased by 10 per cent for a return period of 100 years.
The wave height is B meters and the resulting load is 10tonnes per m between -10 m and sea level
The combined wind and wave loads are:
-total shear load : 36,000tonnes
-combined tilting moment : 3,3 million tonnes/meter applied at seabed level
