This case-study focuses on the new Irish National Stadium being constructed on the site of the historic Lansdowne Road stadium in Dublin, Ireland.  Due to the requirement to provide a 50,000 seat stadium in a highly constrained urban setting, a parametric approach has been adopted.  Although occasionally used in isolation by part of the design team as a tool for experimentation during concept stage, parametric modelling techniques have historically not been thought of as mature or reliable enough to be used on live projects.  However, with parametric modellers now being included in mainstream CAD packages, this is belief is changing.  In this case-study, a free-form architectural solution was developed that responded to a wide range of issues such as limited sight boundaries, natural light to ensure quality pitch-growth and strict planning requirements.  Early collaboration between the architects (HOK Sport Architecture) and structural engineers (Buro Happold) ensured that the single parametric model was capable of providing the flexibility to develop both the complex geometric form and the innovative structural solution.

The envelope was defined using a series of similar sections on a radial grid, constructed from tangential arcs and straight lines to give a smooth surface.  Sectional variation was controlled by a set of law-curves which capture the complex nature of the site constraints.  These sections are positioned on plan according to a building footprint also defined parametrically in anticipation of design development.  The resulting surface is intersected with planes on the seating bowl grid to automate the extraction and production of plans and sections.

Once the surface model has been defined by the architectural team, it is issued to the structural engineers in the form of a parametric CAD model with integrated Excel parameter data sheets.  The engineers then build on this, and by using normal offsets, intersections and sub-divisions a centre-line model of the supporting steel-truss structure is produced.  By taking a parametric approach, design considerations such as sight-lines, structural optimality and construction details have been embedded within the process to ensure a practical and efficient design.  A post-processing data translator has been written to automatically generate a finite element analysis model, whereby member sizes, restraint conditions and full loading information are calculated and applied.

Structure to support the cladding system is defined by introducing further sub-bays.  Planar panels of fixed width and varied length are set out along this sub-structure to define the position of the polycarbonate louvre-type cladding system.  An Excel datasheet calculates the degree of openness required for each louvre, based on the requirements of views from hospitality suites and ventilation.

This project has showcased a novel scenario, where a parametric approach has been used on a live project and a single adaptive model has been shared between architects and engineers in order to produce an integrated solution.  Despite a number of technical issues relating to the complexity of the model and the prototype nature of the software used, the project is regarded as a success, and the design team have benefited from sharing a single parametric model.
