Library of Birmingham

Birmingham
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Story

The Library of Birmingham replaced the existing Central Library with a state-of-the-art destination for learning and culture. Located adjacent to Centenary Square in the City Centre, the new library was integrated with the existing and adjoining Birmingham Repertory Theatre.

This was a flagship project for Birmingham City Council and part of their 20 year ‘Big City’ Regeneration Plan. The Library was designed by world renowned architects Mecanoo to capture imaginations and incorporated a number of unique design features, such as the ‘Harry Potter’ central light well rotunda and a ‘Willy Wonka’ glass lift.

Value Engineering

The original structural design concept was for a steel frame with significant trusses at various levels. We proposed an alternative design involving post-tensioned concrete floor slabs and post-tensioned concrete transfer walls and arches, which offered substantial improvements to the design (allowing for larger horizontal spans across the public spaces providing better light distribution and additional floor space), as well as programme benefits and commercial savings over the original steel proposal.

We were appointed to construct the superstructure which consisted of two slip formed RC cores with typical storey heights of 5m, and nine post tensioned slabs each with central voids to allow additional light to penetrate the various floors of the building from the glass roof.

The structure’s unusual features presented a range of technical challenges which our engineers highlighted below.

35,000m² library
300 seat auditorium
Single storey basement
21,000m3 concrete
3000 tonnes of rebar
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highlights

Cantilevered floors

The first and second floors consisted of 10m cantilever sections over the Centenary Square. The cantilevered spans were suspended from the storey height post tensioned concrete arches on level 2 with a 14.4m backspan.

Several of the arches were connected to the slip-formed core structures with connections capable of transferring working loads up to 2500kN (250 tonnes). Each of these connections required up to 36 40mm diameter coupled steel dowels to be accurately cast-in to the core walls during slip-forming operations.

Central rotunda

The striking central atrium through the full height of the building and internally overlapping rotundas (up to 21 metres in diameter) was achieved by using post-tensioned floor slabs cantilevered up to seven metres in places and utilising the three storey high ‘book-wall’ on the 2nd, 3rd and 4th floors as an integral part of the structure.

High level hanging structure

Storey height post-tensioned transfer walls on level 7 were used to accommodate the high-level hanging structure. These supported loads from the hanging floor slabs as well as loads from the 5 floor slabs above the hanging structure. Significant temporary works were used to support the slabs whilst building up to level 7 and bespoke temporary steel props and hydraulic jacks were used to allow a smooth transition of loads from the temporary to the permanent condition.

Archive facilities on the 2nd, 5th and 6th floors

Archive storage located on the 2nd, 5th and 6th floors shifted the loading on the structure to the floors further up the building. Heavily loaded floors with live loads of up to 17.5kN/m² (1.75 tonnes/m²) were achieved with 275mm thick post-tensioned concrete floor slabs, spanning 7.2 metres and 450mm deep post-tensioned concrete band beams spanning 9 metres. Structural loads were concentrated on relatively few columns and cores, and we were able to achieve very slender column design for working loads up to 23000kN (2300 tonnes) by using composite high strength reinforced concrete combined with heavy structural steel UC sections.

Project
Library of Birmingham
Architect
Mecanoo
Engineer
Buro Happold and Walsh
Contractor
Carillion
Sectors
Public
Special Projects
Services
Preconstruction
Superstructures
Design
Location
Birmingham
Status
Completed
Project summary
Project summary
Project
Library of Birmingham
Architect
Mecanoo
Engineer
Buro Happold and Walsh
Contractor
Carillion
Sectors
Public
Special Projects
Services
Preconstruction
Superstructures
Design
Location
Birmingham
Status
Completed