Elementos singulares en el dique de Mónaco

Special features of the Monaco dock

5.1. The ball joint This steel device is the most unusual part of the dock, and is used to connect it to the land. It has a diameter of 2.60 m and weighs 854 tonnes. Besides the proper object, also worthy of mention are the connections to the concrete of the dock and the abutment. It allows for movement of up to 5º in any direction and had to be designed to last over 100 years. It can also be disassembled, as well as acting as a fuse in the event of an earthquake. 5.2 Installation of mooring lines The mooring system of the dock consists of ten lines, eight of which are located at the lighthouse end of the dock (the other two, at the ball joint end, are not required to be in service status). These eight lines must control the rotation and displacement not controlled by the ball joint and enable the port to be operational. Each of these anchorages consists of a chain connected at one end to a fixed steel part on the dock and at the other to a mechanical pile driven into the seabed. The process to install these items to their final stress points in readiness for service is described. 5.3. Control of successive weights and ballast Between being floated in Algeciras until its commissioning in Monaco the dock passed through intermediate ballast stages (solid and liquid) involving highly detailed studies of weights, their distribution and overall forces throughout the structure. In order to do this, a ballast and ballast-removal system was used, which is described in this chapter. The control of weights on the dock during the projectdesign and construction stages was key. 5.4. Special features of the reinforcement of the structure Given the complexity of the works and the conditioning factors involved the structure had to be sized very strictly, with no variations in slab or wall thickness. This led to quantities of active and passive reinforcement that were significantly higher than usual: 75 kg/m³ of pre-stressing steel and over 250 kg/m³ of reinforcing steel. The difficulties involved, particularly in the ball joint area, are analysed. 5.5. Watertight control We are dealing with a structure that must remain permanently afloat. It also has a large number of construction joints and cracking as a result of heat effects during setting. Consequently, pre-stressing had to be carried out gradually, in stages, with special hose and injection treatments for all the joints on the dock, with the option of further injections using highly flexible resins. 5.6. Cracking control The studies carried out and thermo-mechanic models used were analysed. Any cracking on any of the sections was carefully monitored. 5.7. Monitoring the dock To ensure that the structure was not damaged during transport, the following parameters were recorded: ? Movements ? Bending stresses ? Ballast levels ? Pressures on the top slab and walls ? Temperatures These actions were taken during the flotation stages, during the sea crossing and during coupling operations by recording, sending and checking data in real time.