Entered by Arup
The museum drew inspiration from the desert rose
The National Museum of Qatar, in Doha, is the flagship in an important series of cultural and educational projects being commissioned by the Qatari government. It is currently on site, having been in design since 2008.
The project architect, Ateliers Jean Nouvel, drew inspiration from the desert rose, a crystalline formation found below-ground in saline regions of the desert. When imagined as a building, the result is a four storey, 300m by 200m sculpture of intersecting disc shapes up to 80m in diameter.
The structural solution settled on radially and orthogonally-framed steel trusses, supporting fibre-reinforced concrete cladding panels to create the required aesthetic and performance of the building envelope.
The key challenges for the design resulted from the highly complex geometry of the disc interaction. No two discs are the same; no two discs intersect each other in precisely the same way. The galleries and other key spaces in the building are created by the interstices between the discs; any alteration to the architecture involves moving discs and thereby moving the structure within the discs.
This has led to an evolution of systems and processes required to handle, manipulate and develop geometric ideas from the architect, and establish engineering solutions, before communicating them in their most useful form to the wider community.
Therefore the structural modelling (both analysis and production) needed to address the requirement to:
- Position elements in the correct place in 3D space within the cladding envelope.
- Generate and model elements as efficiently and automatically as possible in order to keep up with iterations of architectural arrangement.
- Facilitate cross-discipline coordination, both with our own MEP design and 3D modelling team in London, plus the architectural team based in Geneva and Paris and a client in Qatar.
The structural team developed a parametric Generative Components script-based tool to automatically create wire-frame geometry in the correct position within the architectural Rhino envelope. The basic wire-frames were further populated with property and loading data using spreadsheet-based automation.
Custom-designed spreadsheet macros were further used to combine separate disc models into larger combined models for structural analysis. Element strength checking was also automated as far as possible, to make practicable the design of the 250,000 separate steel elements.
The analysis models were used as the basis of the production Tekla model, directly translating geometry, section data and also key annotation such as disc-to-disc interface nodes.
The Tekla model was issued to the contractor at tender stage for accurate pricing. The model has been kept up to date and reissued as the design has been completed, and contains the live drawing files needed to communicate information in 2D.
During the site phase, the contractor has adopted and developed this model to a fabrication level of detail. RFIs raised result in either a sub-model being issued, which is incorporated in the contractor's live model, or a proposal from the contractor incorporated back in the original design model. In the latter instance, the proposed model is exported and used directly to modify the analysis and design, to confirm acceptability. The design model makes use of Tekla phases and classes to keep track of issue status of recent updates.
Also at tender, the Tekla model was used to interrogate concrete volumes in order to produce accurate steel reinforcement figures.
Superstructure steelwork connections
The scheme for the building involves many intersecting steel framed discs and therefore results in numerous connections between discs with largely different geometries. Advice was taken from external steel fabricators and their design teams (who might ordinarily carry out the detailed design of such connections), to establish an effective normalised solution where possible. Though many bespoke connections could not be avoided, a significant number could be based around a connecting CHS which could tolerate a large range of incoming member arrangements and thus standardising the supporting steel arrangement. In order to communicate this to the contractor, a number of connections were designed, detailed and illustrated on drawings with 3D perspectives and 2D sections. The nature of the each connection was such that the geometry and therefore design could not properly be understood without interrogation of the intersecting members in three dimensions, for which Tekla was invaluable.
Within discs, families of connections were defined to cover typical arrangements such as the bracing connection to the chord of a truss. Although more simple than the connections between discs, it was also useful to understand these in 3D to investigate how the subtle changes in geometry between discs changed the nature of the connections. Typical internal connections were again represented by both 3D and 2D information on the drawings with tables of parameters such as plate thickness and number of bolts defined for a range of section sizes and incoming member angles.
- Architectural surface information was received in .igs format plus additional defining numerical data. Bentley Generative Components was used to process this data and produce a basic structural frame which could be read directly by GSA structural analysis software. Rhinoscript tools were developed to read the geometric data from GSA into Rhino, and compare to the architectural .igs surfaces. This allowed fast manipulation of the framework to make structural connections and trim the structure to suit the architectural layout. The resulting GSA models were imported directly to Tekla using a Tekla plug-in tool, which could then be used to define the required Tekla objects. Once modelled accurately, including all required tapers, trimming and allowance for connection details, dwg and ifc files were exported to a common 'live' directory, which automatically imported into Navisworks for MEP and further architectural coordination.
- 1600 piles, each individually designed with bespoke trim and toe levels, was carried out in Tekla using a macro script to read the required data from a suite of design spreadsheets.
- Drawing and labelling of interface connection tags in 3D space, was carried out using a combination of the GSA to Tekla plugin to create spherical objects at the required 'node' locations, and then using spreadsheet lookups to compare and update those object properties from the labelled connection nodes in the analysis model.
- Clash checking was carried out using the same .ifc exports as for MEP coordination, but in the Tekla BIMsight environment. Each steel disc and concrete entity was compared against every other, to ensure a minimum proximity tolerance was maintained to allow for differential movements expected. Clashes highlighted were then categorised using the Tekla BIMsight layer tools as either 'Connection – no action', or 'Clash – to be resolved'. Further comments on proposals for resolution were stored in the commenting facilities in BIMSight, which could be read by the design and CAD team.
- Verification of the drawn structure was made possible by visual checking of the Tekla model using the Tekla viewer, model reviewer and web viewers, but also using spreadsheet scripts to automatically compare geometry and sizing from Tekla and GSA text data outputs.
- Effective communication with off-site/remote CAD technicians around the world was possible using the Tekla comment tool plug-in. This captured comments and marked up screenshots, but could also be stored in a live 'cloud' type server account for sharing with the design team, without the need for downloading and updating new files every day.
Challenges solved using Tekla
- Tekla BIMsight was instrumental in identifying and resolving steel-to-steel and other clashes within the production model, focussing engineering input in the right places.
- The complex 3D structure was broken down into 2D 'component drawings' for each disc, in order to communicate the design clearly and succinctly to complement the client's contract hierarchy.
- The Tekla model was a key input into the team's Digital Projects BIM model to effect cross-discipline coordination.
- Connection design was carried out in collaboration with fabricators, identifying and modelling 'real' geometry examples to communicate connection design intent in 3D.
- Tekla's system of phase identification and colouring was essential in identifying and tracking change for the contractor.
Project owner: Qatar Museums Authority
General contractor: Hyundai
Architect: Ateliers Jean Nouvel
Structural design: Arup
Mechanical engineering: Arup
Steel detailing: Arup and Eversendai
CIP/reinforcement detailing: Arup
Other structural detailing: Arup
HVAC/MEP detailing: Hyundai
Steel fabrication: Eversendai