Arup is recognised as one of the world’s leading consulting engineers working on many prestigious projects around the globe, including 30 St Mary Axe (“The Gherkin”), the Sydney Opera House and Beijing’s Olympic Stadium. One of their latest landmark projects, The Pinnacle, will become the tallest building in the City of London when it is completed in 2013. Arup’s role in the project includes structural and geotechnical engineering, wind, fire, acoustic and transport consultancy. As part of the structural package, they delivered a Tekla Structures model of the building’s superstructure, enabling the transfer of model information to the steel fabricators and improving the downstream process.

The Pinnacle – an icon of future London

Pinnacle structural design
The Pinnacle will be a 63 storey landmark building in London and will join the Gherkin, Tower 42 and Heron Tower to form a distinctive cluster of tall buildings in the City. The tower will be 288m high from street level, this equates to nearly 305m above ordnance datum. The building will provide 131,511 m2 of usable floor area, with a construction value of £700million. The base geometry was planned in order to facilitate various layout issues such as site and office space utilisation. This was organised as a set of geometric concepts constructed parametrically to develop the overall shape of the building.

There will be 20 heavy H-section fabricated plate columns spaced around the perimeter of the main tower.  They will be linked together structurally by a set of braces to form a braced perimeter tube stability system. This system will create a stiff and efficient structure, and will carry the lion’s share of the stability forces on the building. 625mm deep fabricated plate girders will span from column to column at each floor level.

There will also be a jump formed reinforced concrete core. The core will act as temporary bracing for the partially completed steel frame during erection. It will provide safe vertical access for operatives via jump lifts installed in the shaft.  It will provide a location and a laterally stable connection point for two of the project’s four tower cranes and will reduce the steelwork piece count, increasing the speed of erection.

The space at ground level will mainly be given over to the public domain with retail and pavement cafes as well as the main entrance to the tower. The Pinnacle’s restaurant and the uppermost viewing gallery will become the highest of their kind in Europe. The building is topped with a glazed spire, which rises an additional 42m. The viewing gallery will be accessed by a high-speed “street-to -sky” lift, taking visitors from the ground floor entrance to the gallery levels in just over 30 seconds.

The building will be triple glazed. The external ‘snakeskin’ glazing is permanently partially open, which will moderate conditions outside the internal double glazed units and greatly extend the season in which natural ventilation is possible. The snakeskin glazing uses one size of glass pane, the varying geometry of which will be accommodated by altering the amount by which the individual panels overlap each other.

Pinnacle structural design
Pinnacle structural design

Making the Move to Tekla BIM

Arup purchased their first Tekla licences in 1998 but their use of Tekla’s BIM software really took off after taking the decision to upgrade their existing 3D+ software to Tekla Structures Engineering licences following Tekla’s buyout of 3D+ in 2009. Arup quickly realised that Tekla offered a more intuitive and comprehensive engineering solution and would provide greater downstream benefits to the project by engaging the steel fabricators at an early stage. In addition, having the ability to archive existing 3D+ projects by converting them to a native Tekla model provides long term benefits for consultants and clients alike.

Pinnacle structural design
According to Arup’s Building Engineering London Group 4, the engineering team quickly took to Tekla Structures and started to see the benefits almost immediately. “One of the most satisfying aspects of Tekla Structures is the usability and the speed with which our technicians go from basic understanding to proficient user within a couple of weeks. Within months they are excelling with the software and really starting to push the boundaries of what we thought was possible with BIM solutions. We are also working closely with Tekla to develop bespoke learning modules to further enhance the training offering.” The structural engineers are using Tekla’s Viewer and Project Manager Licence configurations for checking, reviewing and approving models for the upstream and downstream deliverables.

Engaging the Supply Chain

As part of Arup’s continuous drive to improve downstream processes and add value for their clients, the firm have started to involve the manufacturing supply chain much earlier in the design phase with a view to creating constructible models that can be passed on to the steelwork contractor. Arup believe that there are major benefits to be had in engaging specialist subcontractors as early as possible in the process to identify potential fabrication and constructability issues, saving valuable time and money downstream.

Pinnacle structural design

Customising the drawing output to Arup’s existing CAD standards was critical to the successful implementation of Tekla Structures in order to ensure that their corporate image was retained. Whilst there was initially a certain amount of time and effort involved in creating our drawing output requirements, the final results are now exactly in line with our standards and all of our deliverable 2D output remains live within the 3D model environment. This is already creating significant efficiencies in our design process as we start to deliver more and more projects in Tekla Structures.

Pinnacle structural design
Whilst it was important to ensure that existing deliverable standards were maintained, Arup also work closely with their MEP engineers to coordinate their designs, exporting models from Tekla Structures via 3D DWG format to append to their MEP modelling software. One major benefit of this process is that designers are able to spatially coordinate the models and eradicate potential clashes that would have a costly impact later in the project life cycle.

Arup are heavily involved in facilitating the downstream processes by working to ensure that their Tekla models are deliverable to the steel fabricators. “One of our goals is to develop an agreed process for passing Tekla Structures models between consultants and fabricators in an effort to improve efficiency and quality of work as well as reduce costs and programme timescales. Tekla are currently working closely with us to develop a ‘Good Practice Guide’ which will hopefully one day be published as a White Paper on BIM processes from an engineering standpoint.”

Arup are also developing processes where the expertise and experience of the steel work contractors can be utilised at an earlier stage in design. This is being used on two projects within our group, using independent steelwork designers and detailers to assist in model creation and improving the downstream deliverables.

A bi-directional link is currently being developed between Tekla Structures and Oasys GSA, Arup’s in-house structural analysis software. The goal is for the engineers to design within the 3D model environment and deliver a fully engineered, analytical structural model. This represents a great opportunity for Arup to improve our internal efficiency and the quality of their service to the client.

The Tekla Advantage

Pinnacle structural design
“Whilst Tekla Structures excels in all structural steelwork projects, the concrete modelling has improved tremendously and we are currently looking at expanding our use of the software in this area. Interoperability is also vital in enabling an integrated process and the open nature of Tekla Structures means that Arup can pass models to other project parties with ease. The relatively small file size of Tekla models is integral to this process, especially with the geometrically complex projects with which Arup are consistently involved. The magnitude of these large complicated projects means that Arup would find it very difficult to cope up without Tekla Structures’ multi-user functionality.” Several of Arup’s Building Engineering London Group 4’s projects are currently being undertaken in a multi-user environment, with up to six structural technicians at any one time working live within the model environment, which also brings great productivity benefits.

Although Arup are currently monitoring the benefits that Tekla is bringing in terms of productivity to determine more accurate statistics on their efficiency improvements, the companies are already beginning to get a feel for impact of Tekla on their processes, “Arup estimate that since they started using Tekla Structures they have managed to save 10% in internal efficiency savings working together with the structural engineers. This includes model review and checking, drawing output and RFI queries. For example, it now takes less than an hour for an engineer to review the model using the clip planes, save views and red line mark up whereas with our previous processes it would have taken significantly longer.” Given that within Building Engineering London, Arup’s CAD related turnover is approximately £11million and that BEL Group 4’s structural CAD turnover is around £1.5million, this represents a significant return on investment.

Pinnacle structural design

As a result of these short term achievements, Tekla Structures is now being widely used within three Arup Groups across the UK, and, as Arup comments, the expectation is to increase this usage: “The further investment in Tekla software by Arup shows how popular its BIM solution has become with our staff, especially for large and complex structures where it really does stand on its own. It’s important for Arup to look outside our regular scope of work, and we feel that the Tekla solution really allows us to do that. Coupled with the fantastic level of support we receive from Tekla, this creates a strong partnership between the two companies, and we look forward to developing our joint offerings and being able to support a complete BIM workflow from design through to manufacturing and beyond throughout the Arup business both in the UK and globally.”

NBMCW December 2010