Birmingham REP & Library

United Kingdom

Client

Morrisroe / Architect: Mecanoo, NL

Structural Engineer

Walsh Associates

Acoustic Consultant

Buro Happold

Main Contractor

Carillion / Steelwork: Fisher Engineering

Key Facts

55 Laminated Bearings supplied to the Studio Theatre (delivered just before Christmas 2011)

396m² Isomat Floating Floors

1100 Isomat Floating Floor Isolators

142 Larger Isomat Floating Floor Isolators to support blockwork walls

The Challenge

This project was part of a £193 million development scheme designed to combine the new library and the repertory theatre (REP) in Birmingham city centre, thereby creating a unique centre for knowledge, learning and culture. Scheduled to open at the end of 2013, the main library building is a nine-storey structure. Floor to floor heights vary and are up to eight metres in the archive areas with the highest loaded floors high up the structure. Within the library building is a studio theatre, which is a steel framed structure, acoustically isolated from the rest of the building.

As well as being close to the Monument Lane railway tunnel, the site is also located adjacent to the International Convention Centre (ICC) and a number of residential buildings meaning that there were several acoustic challenges to overcome. In addition some areas of the development would be shared between the Library and the REP (e.g. a new studio theatre, restaurant, shops, foyer, rehearsal rooms and workshops). The REP theatre and the Library will be joined together and will share a number of facilities including a foyer, cafe restaurant, meeting rooms, rehearsal rooms and a new 350 seat auditorium to complement the theatre’s two existing auditoria.

To achieve this, a ‘box-in-box’ construction was designed in conjunction with the Architect and the Structural Engineer. This was geared around specific acoustic construction requirements for the floated concrete floors and the perimeter walls.

The Solution

In the first instance for the Studio Theatre Farrat supplied 55 Laminated Bearings to support an internal box-in-box
steel and concrete structure. There were a range of unfactored dead and live loads, all designed to achieve between 10 and 12Hz at dead load reducing to 8-10Hz under dead and live loads. Farrat provided installation instructions as well as guidance to the steelwork and concrete contractors. The floors for the new rehearsal studios in the REP theatre were not required until one year later. These studios also featured adjacent apartments for visiting performers.

The Isolators and concrete slabs were designed to provide a dynamic natural frequency under 16Hz with damping over 10% which was very important due to the nature of the building structure and the proximity of residential spaces right next to the rehearsal studios. Farrat designed their Isomat floating floor to accommodate a range of load cases. The floating concrete slabs were 130mm thick C40 concrete with A193 mesh reinforcement and 130 meters of perimeter formwork was required to form the concrete slabs.

The installation process was a complex one due to the logistics of craning in materials to the second floor 20 metres above ground level, the lack of a watertight structure and some extra works on the dry system such as forming around steel which was required to accommodate the external cladding.

AcouStruct successfully installed the ‘dry system’ before handing over to the client for them and providing guidance which enabled them to pour the floating concrete slabs.