Underground car park in Nice Côte d’Azur

INGEROP – France

Underground car park in Nice Côte d’Azur

Building use

Other

Country/Region

France

Overview

The building is an underground parking garage with 5 floors below ground level and 482 parking lots.

Basic information (construction date, number of stories, gross floor area, adopted design code, engineer(s), Contractor(s), etc.)

Construction date: 2013
Number of stories: -5
Gross floor area: 15,000m2
Adopted design code: –
Engineer(s): Ingerop, architect Jean-Paul Gomis and 3A Architectes
Contractor(s): Impresa Pizzarotti, CCI Côte d’Azur

Issue and/or innovation

The need to operate with a top-down construction system: a conventional construction method would have created a very large hole in the plaza. Connected to this, the need to avoid provisional structures and build the final structural elements straight from the beginning of the construction.

Reason for composite solution

The use of the pre-fabricated composite beam – patented product by the company Tecnostrutture – allows the creation of underground spaces with a top-down construction method. The use of the specific solution allowed the construction of floor beams without the need to use temporary supporting elements for the props as this would have excluded the possibility to work on the levels below.

Specific solution/technical details

First, poured in place concrete diaphragm walls have been excavated along the perimeter of the underground garage to be created. Pre-fab composite beams have been installed at level 0, to lock the retaining walls in position and avoid any displacement of their upper level that would have caused troubles to the foundations of the buildings nearby. Then, excavation started to reach level -1 where the second set of beams have been installed to limit the deflection of the retaining walls and allow the excavation of the further level below. The sequence was then repeated until level -5 was reached. All the steel elements of the beams provided have been sandblasted and covered with polyurea to protect them from the aggressive marine environment (as the underground garage is only a few meters away from the banks on the Mediterranean sea. The beams have a native fire resistance of 90 minutes that did not require any further fireproofing.

Impact or effectiveness

The use of pre-fab beams allowed a faster construction schedule with the top-down method. This created the possibility to cover up the building site giving partial access of the construction site as a public square while construction continued underneath. The specific solution has been adopted also considering the need to reduce as much as possible the floor-to-floor height (it is 3 meters) without limiting the internal free height for vehicle circulation.