ABBEY MILL HOUSE
Reading, United Kingdom
A 16-storey 90-metres tall high-specification fully glazed steel construction office building and 9-storey reinforced concrete residential block. The building superstructure consists of highly efficient 13.5m long span composite steel floors made up of cellular steel beams with integrated services with a composite slab on metal deck completing a highly efficient floor structure.
The first floor was designed to hang off the second floor due to the architectural requirement of an inset façade at the first floor level. The same situation reoccurs at the 13th floor, which also thus performs the function of a transfer floor. The 14th floor was designed for a heavy plant floor.
Other building features include a 30m-high steel pinnacle spire and truss, a 90m-high steel feature staircase, steel mega columns, RC flat slabs, RC stability cores and RC bored piling in chalk.
Unique features of the project involved the design of a 30m-high cladded spire at the top of the building projecting out of the building footprint. The design of this 20 tonne spire and its supporting truss together with their associated cast-in connections into the RC stability core required detailed thought and verification. The design was consistently refined following numerous discussions with the main, concrete, steelwork, cladding and cleaning access subcontractors to find the most optimum solution to satisfy both design and construction practicality and sequencing considerations.
Beneath the spire, a feature steel staircase rising 14 storeys stands. More importantly, the connection design of the various elements of the staircase required the close coordination with the steelwork contractor for a practical and efficient design and construction. The stairs were spliced at appropriate 3 storey levels. Connections were designed such that the stair may be lifted into place on site without the exposition of bolts or welds. In other words, all connections were hidden to achieve the architectural appearance of a seamless continuous staircase. The staircase then stood upon a deep tapered 1500mm cantilever pile cap due to the fact that an existing sewer ran beneath.
The main office floors consist of long 13.5m clear span composite steel floors. The first floor was designed to hang off the second floor due to the architectural requirement of an inset façade at the first floor level. The same situation reoccurs at the 13th floor, which also thus performs the function of a transfer floor. The 14th floor was designed for a heavy plant floor.
Stability is designed to be provided solely by the two reinforced concrete cores. The coordination of builders work in connection for service penetration within these cores for this high-specification office proved to be very challenging as the structural efficiency of the cores were consistently compromised, thus requiring numerous design revisits and re-evaluation.
Note project is a previous principal work experience at whitbybird.
Client: PMB Holdings
Consultancy Scope: Full Structural Engineering
Project Cost: £32mil.
Project Status: Completed in 2009
COMPOSITE CELLULAR STEEL BEAM FLOOR WITH INTEGRATED SERVICES
As part of a value engineering exercise, we converted standard composite steel plated girders to composite cellular steel beams of optimum sizes. In doing so, savings of almost 20% of the total steelwork tonnage was obtained, i.e. from about 940 tonnes to 760 tonnes of steelwork.
The steelwork tonnage savings were obtained due to the following reasons: –
the cellular beam manufacturing process allows for the optimisation of steel material due to the fact that cellular holes are created within the webs
the cellular beam manufacturing process allows for the optimisation of steel material due to the fact that universal beams (UBs) can be chosen for the top half of the beam section and universal columns (UCs) can be chosen for the bottom half of the beam section
the redesign was done at a very advanced stage of the project allowing for the employment of accurate final loadings and bespoke designs