Office building in Paris la Defense

Office building in Paris la Defense

Building use

Office building

Country/Region

France

Overview

The project consists in the deep renovation of a pre-existent office building originally built in 1986. Parts of the previous building were demolished to profoundly change its shape and the relation to the city, and about 24,500 square meters of new flooring structure have been built, using a mixed steel-timber structure.

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

Construction date: Original building: 1986; restoration and extension: 2019
Number of stories: 14
Gross floor area: 37,000m2
Adopted design code: Eurocode
Engineer(s): Khephren Ingénierie, Cro&Co Architecture (Design architect)
Contractor(s): Eiffage Construction Grands Projects

Issue and/or innovation

The newly built part of the building consists in a vertical extension, providing new office space and a loggia that wraps the building all arounds its perimeter. To provide this unobstructed circulation element, the volume above had to be cantilevered using a truss element formed by a composite column and steel tie rods and props.

Reason for composite solution

Composite was used both for fireproofing reasons and to give higher rigidity at the element

Specific solution/technical details

The composite element is composed of a steel square section made with welded plates of steel S355JR-J0. The element is 450×260 mm when supporting only one diagonal post, and 475×475 when it is on a corner and thus supporting 3 posts. The steel tube is filled with concrete C30/37. The diagonal posts are made of a steel profile with a variable section made of welded tubes.