After almost two years of design development, visitors at the National Gallery of Ireland can now gaze at Magnus Modus, a freeform timber sculpture standing seven metres tall in the newly renovated Sculpture Courtyard. However, the delicately handcrafted work bears a secret – hidden engineering details allow the slender form to stand upright. Working closely with Irish designer maker, Joseph Walsh and his team at Joseph Walsh Studios (JWS), Arup provided structural engineering design advice for the structure.
As a key attraction and only permanent sculptural installation of the Sculpture Courtyard, Magnus Modus brings contemporary art to all ages. Responding to the artist’s key design criterion of the structure to be flexible, we developed a structural solution strong enough to let the sculpture move like a tree and light enough to minimise the use of material. Not visible to the bare eye, this innovative solution invites visitors to question and interact with the piece.
The piece was commissioned following a competition by the Office of Public Works and funded under the Per Cent for Art Scheme, an Irish government initiative that allocates parts of the costs of publicly funded projects to the commissioning of public art.
7m tall structure
2flexible wooden loops
16mmthick leading edge at the top of the piece
Known for his free-form sculptures inspired by the characteristics and behaviour of the material itself, Joseph was keen that Magnus Modus would be flexible, tree-like and react to the environment around it, moving as people interact with it.
Designing the sculpture
During the early phases of the project, numerous designs for a flexible fixing at the base of the piece were considered to give the piece an increased sense of movement. In its final form, the flexibility of the structure is achieved through the piece itself – strong and trunk-like at the base, thicker sections where structural analysis indicated high stresses and light branch-like sections at the top. The piece is fixed firmly to the floor of the gallery using a concealed fixing embedded within the layers of timber laminate.
Material efficiency and sustainability
The sculpture was created by layering laminates of olive ash wood and gluing them together to form the overall geometry. Sustainability was at the heart of the design, with the use of material minimised over the height of the piece, giving it the lightness and flexibility of form that Joseph wanted to achieve. The final carving and shaping was done almost exclusively using hand tools and traditional craftsmanship following European and Japanese methods.
The use of manmade materials has been limited to key locations required for the structural integrity of the piece – hidden pins have been used in high stress areas and an embedded steel plate is provided at the base to anchor the piece to the floor.
Parametric design enables creative structural solutions
The structural design and the scalability of the piece relied heavily on the use of parametric modelling and was supported with the use of empirical test data. Using a parametric workflow in Rhino and Grasshopper, Arup completed the structural analysis of the initial form using Oasys GSA.
Once the overall form was finalised, limited by the access route to the Sculpture Courtyard itself, Arup undertook detailed structural analyses to study the first- and second-order behaviour of the piece – including assessments of its tendency to buckle. This was key in pushing the slenderness of the piece. A series of prototype tests were undertaken at the studio to test the bending and torsional strength of the section, the material stiffness and the interaction between the timber and embedded steel plates where the piece is fixed to the floor.
Since installation in the gallery, the piece has been monitored by an ongoing series of laser scans. This information has been used to verify the long-term behaviour of the piece and confirm the results from the analysis model, in particular the creep deflection.
Joseph Walsh and Arup
Arup began collaborating with Joseph and his team in 2014 as he started to scale up his sculptures into what would become the Magnus series. Since then, Arup and JWS have worked together on the design of a series of installations in Ireland, Italy, the US, India and the UK. Current collaborations include the ‘Earth, Wind & Fire: Made in Cork Contemporary’ exhibition at the Crawford Art Gallery in Cork, which has been sponsored by Arup and exhibits some of Joseph Walsh’s expansive sculptural works.