MEMORIAL TO THE SHAKY ISLES: A DESIGN PROPOSAL FOR A 'NATIONAL MUSEUM' EXPLORING CONCRETE AS CHIEF TECTONIC AND EVOCATIVE MATERIAL

BEN ALLNATT

School of Architecture, Victoria University of ,

SUMMARY

New Zealand, the dislocated and shaky isles of the pacific, continues to be devastated by . Most recently, crumbled under the ravaging shakes of the earth. In the wake of these events, the brief for a National Earthquake Museum on the Wellington waterfront was proposed. This brief required an elegant yet powerful response, and enabled a research-by-design project that could exploit the properties of concrete.

INTRODUCTION

The proposed brief for a National Earthquake Museum provided the appropriate programmatic vehicle to employ concrete as a primary structural and evocative material in a major civic project, one embedded with incredible gravitas.

Thematically, the architectural concept was to simultaneously capture and evocate the colossal turmoil caused by a large-scale earthquake, as well as man’s communal ability to regain order and clarity post-disaster. Concrete applications were explored in order to enrich and convey these themes at a tectonic level, and to clearly express them to visitors of the museum.

THE ARCHITECTURAL CONCEPT

When conveying the concept, it was clear that the architectural language needed to set up a dialogue of spatial elements that could begin to symbolise the dichotomy of order and chaos inherent in a major natural disaster. Looking towards our built environment, it is clear to see man’s invention and often-strict adherence to the straight line and grid. We constantly strive for visual and systematic urban order in an attempt to control complex interrelations and maintain legibility. However, under the unpredictable and frenzied force of an earthquake, this semblance of order is warped, fractured and broken. A precedent artwork was used as the distilled visual representation of this notion (figure. 1).

Orthogonal grids were extrapolated from two main axis of the site. These grids informed an structured and intelligible Figure 1. Nicholas Kennedy Sitton's 'Twisted' Series spatial environment with a strong sense of the perspectival plane and 3-dimensional delineation and symmetry. Visitors enter through this ordered environment, as building elements are introduced singularly, initially as a forest of columns until finally walls and roof are added to become a gridded environment in 3-dimensions (Figures 2 & 3).

Figure 2. Museum Entrance

Figure 3. Museum Entrance Hall The architectural narrative continues for the visitor when they approach the axial intersection of the building. The perceived spatial order is confronted by a monolithic upheaval where a fractured mass surges and writhes towards the sky (Figure 4). This major portion of the building becomes emblematic of the earthquake itself, distorting the previously established grid, folding and creasing like lines of pressure close to fracture. This central mass juxtaposes the orthogonality that both precedes and succeeds it, creating a complex dialogue of spatial situations, which resonate both inside and out.

In this faceted volume lies the vertical circulation and major exhibitions of the museum. Four floors of exhibition space are arranged around the stairs, the latter forming an architectural centerpiece, where the floor openings are supported by pairs of angled columns to match the faceture of the shear walls at the perimeter (Figure 5). Adjoining this exhibition space is an auditorium and classroom wing designed to enable the education of visitors, thus becoming a space dedicated to future preparedness (Figure 6).

Figure 4. Longitudinal Section of museum showing juxtaposition of linear elements with the fractured mass that rises skywards.

Figure 5. Exhibition Space and Vertical Circulation Figure 6. ‘Preparedness’ Lecture Theatre

The architectural journey for the visitor continues out onto the large trussed cantilever on the third storey. Order via architectural orthogonality is reinstated, but no longer in the same way; rather a shift has occurred and a new direction taken. Exiting the building, the visitor arrives in the memorial, a pontoon on the water where the previous structure slowly dissolves to leave solitary posts extending into the water and dragging the eye into the distance, and though a memorialisation of the lives lost it prompts a regenerative gesture towards the future (Figure 7). Figure 7. Conclusion of museum narrative at the Memorial Pontoon STRUCTURAL DESIGN

The museum’s structure relies on shear walls, roof and floor diaphragms and gravity- only columns (Figure 8). The ground floor has a shear sheer wall running the left length of the building in the Y-direction. It also has two 5 m long shear walls at each end of the building in the X-direction. The roof of the double height space is a 300mm deep waffle slab with grid squares measuring 1 m x 1 m. This only needs to support self-weight. 600 x 600 reinforced concrete columns in a 5 m x 5 m grid support this diaphragm. These are to be post- tensioned, with steel plates at top and bottom. At the axial intersection of the design, the 21 m x 21 m floor slabs rise up, with a 15-degree rotation at each level. These comprise 150 mm deep hollow-core slabs that span 7 m from the perimeter to the circulation void in the centre. Primary beams of 400 mm width and 600 mm depth support these. There are also secondary tie beams running perpendicular, which are 400 mm x 400 mm. These beams are supported by 600 mm x 600 mm concrete reinforced, gravity-only columns, which are positioned at the four corners of the central void. At the other end, these beams are supported by 250 mm thick folded shear walls, which line the entire perimeter of the volume, with minor openings for circulation. These walls have corbels along the fold lines to support the floor diaphragms. At the third floor there is a cantilevered floor that extends out of the volume in both directions. This comprises 15 m floor slabs spanning two supportive reinforced concrete trusses that run parallel along the length of the floor. The western end cantilevers 8 m beyond the shear walls. The eastern end extends 24 m beyond the shear walls. Two angled CHS concrete-filled steel members with 600 mm diameters support this volume. These are rigidly joined to a 1 m deep reinforced concrete beam that connects and supports the trusses from above.

Figure 8. Salient structural features throughout the museum design Concentrating on the intersecting portion of the design, the twisting shear wall structure resists torsion in the following ways. Due to the symmetry of the plan at levels 1, 2 and 4, the Centre of Mass and Centre of Resistance are coincident and there will be negligible torsion. However at level 3, as the cantilever floors are tied back into the primary structure, the centre of mass is off set. The four shear walls at the centre still offer the bulk of the torsional resistance, but the floor diaphragm will experience rotation. This rotation will affect the angled columns located farthest away from the Centre of Resistance most severely. They will be subject to large horizontal deflections, and the thickness, connections and foundation detailing would need to be considered carefully. When defining adequate structural values, all estimations were based on Resist Software and engineer recommendations, resulting in a physical structural model based on these values at 1:200 (Figure 9).

Figure 9. Demonstrative structural model at 1:200 scale

Figure 10. Four floor plan levels of the museum design showing interplay of orthogonal sections and the rotating volume at their intersection

CONCLUSION

The instigation of orthogonal grids within the museum’s architecture was used to inform ordered and intelligible spatial environments. This is then contrasted with a moment of monolithic upheaval, evocated by a hulking concrete volume that surges from below ground and deforms and transforms beyond its original orthogonality. The heavy post-tensioned concrete columns from within extend into the landscape and act as structural remnants that memorialise the lives that were lost during this chaos. The museum’s architecture becomes an austere yet elegant embodiment of the complex dialogue of man’s power to manipulate his landscape at the same time as nature’s latent power over man.

Concrete allowed a plethora of structural opportunities, including the large trussed cantilever. This torsional arm seems a rebellion against gravity, extending itself above the water, allowing the public to engage with the slender reinforced concrete angled columns that support such a remarkable mass. Perhaps most notably, a twisting volume comprising angular and faceted shear walls create a distinct language for the project. Technologies such as self-consolidating concrete were investigated as a means to achieve the previously impossible complex and striking folded forms. With careful formwork detailing, superior material finishes could be achieved while still enabling a complex form and adequate structural capacity for a major civic building in a city notorious for seismic activity. Concrete was hence used as both integral structure and primary expressive material.

The project aim was to imbibe a strong concept and aesthetic into a realizable project. The design investigates unique concrete applications while simultaneously exploring the relevance of evocative structures in museums and memorials.

Figure 11. Final rendered perspective of Museum in its intended position on the Wellington Waterfront