Library in Rouen

Building use

Other

Country/Region

All Regions

Overview

The development for the university of Rouen created a complex building with multiple functions including auditoriums for up to 600 people. Here, the floor assembly of the circular-shaped library is described. This space is characterized by very long spans up to 18 meters and severe loads up to 1t/m2.

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

Construction date: 2002
Number of stories: 4
Gross floor area: 28,000m2 for the whole university settlement
Adopted design code: Eurocode4
Engineer(s): Groupe Alto
Contractor(s): –

Issue and/or innovation

The design brief was calling for 28.000 square meters of new construction on a site of less than 1 hectare, and very stringent urbanistic rules that set a very low height for the whole development, thus pushing to the need of minimizing as much as possible the structural height of the floor structures, to enable a maximization of the free internal heights.

Reason for composite solution

After a comparative analysis the composite solution was adopted due to the reduced structural thickness of the structural elements of the floor assembly and the lighter structure overall.

Specific solution/technical details

On 18 meters of span, the best solution proved to be with HEA 400 S355 beams, with a prefabricated slab of 6cm and a 16 cm slab poured on top. Shear studs of 150 mm of length and 2.2 cm of diameter are disposed with variable distances between 20 and 60 cm.

Impact or effectiveness

The comparative study of the different possible floor systems confirmed a floor/beam footprint of 1.20 m thick for reinforced concrete, 80 cm for prestressed concrete, 75 cm for steel beams and 65 cm for the mixed solution connecting the concrete slab. Also, the composite solution chosen allows for 45cm of free height under the beam for MEP and lighting. The provisions of the Eurocode 4 had to be adapted to the non-parallel beams imposed by the radial shape dictated by the architectonic design of the library. The solution adopted allows to save 41kg/square meter over the second ideal solution (steel beam) as the composite behavior developed thanks to the studs allows to move the neutral axis of the beam closer to the concrete section. The self weight of the floor assembly produced a 50mm buckling of the beam that was compensated with a counter buckling of the same magnitude to attain a perfectly flat floor system.