Client/Developer: Landsec
Architect/Designer: Bryden Wood
Construction Manager: Sir Robert McAlpine Mace JV
Steel and concrete installer: J Coffey Construction
Steelwork fabricator: DAM Structures (part of Severfield)
Tata Steel products: ComFlor® Beam
Year: 2021
A new office development in Southwark, south London is being heralded as a transformational scheme that will enable the construction industry to become leaner and greener.
Located behind the Tate Modern, the project comprises two nine-storey office blocks, that will together offer close to 13,000m2 of floor space.
Known as The Forge, as the site was once occupied by a foundry, the two office blocks have been named Bronze and Phosphor.
The development is aiming to be the UK’s first net zero carbon commercial building, both constructed and operated in line with the UK’s Green Building Council’s (UKGBC) framework definition of net zero carbon buildings.
The scheme is also a pioneering innovation project and the first major commercial building to be built using a platform approach to design for manufacture and assembly (P-DfMA). The project has been awarded funding from Innovate UK for its innovative design and ground-breaking construction techniques, which has the potential to act as a catalyst for change in the construction sector.
P-DfMA uses standardised components assembled using a ‘kit of parts’ methodology, whereby most elements are fabricated offsite in repeatable sections. By utilising this ground-breaking construction method, the job is expected to be completed 40% faster than a similar sized commercial scheme using more traditional construction techniques.
“The Forge is setting new industry standards for sustainable and cost effective construction. The use of an innovative P-DfMA structure and ‘kit of parts’ approach is a world-first for a commercial office project,” says Landsec Head of Design Innovation and Property Solutions Neil Pennell.
“By developing a platform structure with a repeatable format and one that interfaces easily with services and cladding, we improve delivery, reduce the amount of materials needed and lessen the project’s carbon footprint.”
The P-DfMA method uses a hybrid steel and concrete framing solution to construct the buildings. Steelwork was chosen for the primary structure due to its speed of delivery and because the beams and columns can be fabricated offsite, in line with the project’s industrialised construction based philosophy. The secondary framing uses novel beam assemblies to effectively create a ribbed concrete slab adding the benefits of structural mass and a pleasing aesthetic to the exposed structural solution.
Tata Steel’s ComFlor® Beam is used as a vital component in this innovative approach and was chosen after the project team contacted Tata Steel about the availability of a suitable product that would meet their needs.
A standardised grid of vertical hollow section columns, spaced at 9m centres, are linked together horizontally by ComFlor® Beam composite deck elements. The product has been designed specifically for this project with the addition of steel reinforcement members to create a completely new type of structural beam assembly. The ComFlor® Beam elements are in fact used as a secondary steel frame, spaced at 3m intervals within the main frame. Once installed, they are filled, floor-by-floor, with in-situ self-compacting concrete. The structure is completed using reusable mobile formwork to support the casting of a concrete slab between the primary and secondary frame, which is moved up the building as work progresses.
Props, which are necessary to support the ComFlor® Beams until the concrete is cured, are fastened with pins, and moved up the building along with the formwork. The props are fixed diagonally back to the main steelwork columns and a series of ‘faux columns’ transferring the load directly into the primary structure allowing easier open access to the floor which would not be possible with a traditionally propped solution. The team has also sought to minimise installation times through the use of automated construction techniques and digital technologies.
Prior to The Forge development, Landsec working closely with designers Bryden Wood and prototyping specialists Easi-space had previously pioneered the P-DfMA structure and automated construction methods with a test-run in 2019, whereby a full-scale offsite prototype was constructed.
During the planning stage the initial design of the building structure was based around a traditional steel frame design. Landsec however were keen to explore the opportunity to use modern methods of construction to build faster, better and greener, and following the success of the prototype the decision was taken to adopt the innovative P-DfMA ‘kit of parts’ led approach on the project.
Following a detailed technical review and consultations between Landsec, Bryden Wood and Tata Steel, it was decided that ComFlor® Beam, repurposed as a secondary beam, offered a proven, cost effective and off the shelf solution which could be used an essential component of the ‘kit of parts’.
The ComFlor® Beam profile has provided the scheme with a number of benefits including better floor-to-ceiling heights. The trapezoidal shape forms a shallow beam which when combined with an integrated services solution minimises the resulting combined structure and services zone maximising the clear height and apparent volume of the space.
Bryden Wood Associate Director Bernat Csuka says:
“The detailing of reinforcement proved to be easier with ComFlor® Beam as well as achieving continuity at supports, especially around columns. ComFlor sections are also readily available, cut to length with high fabrication tolerances. This is beneficial in achieving high accuracy on the structural frame. The ComFlor profile also provides corrosion protection to the downstand beam in the permanent condition and its shape and width enables the use of large diameter reinforcing bars.”
For Tata Steel this intriguing development opens up a great opportunity to provide a key component in an optimised platform structural solution which could be widely used across the commercial building sector.
EN-Construction-Contact-BSUK - Structural
Building Systems UK technical team - Structural
Tata Steel
Shotton Works
Deeside Flintshire CH5 2NH
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