Metropol Parasol, Plaza de la Encarnacin Adventures in Engineering

Jan-Peter KOPPITZ Associate Ove Arup & Partners San Francisco, CA, USA Jan-peter.koppitz@arup.com Jan-Peter Koppitz, born 1973, received his civil engineering degree from the Bran. Tech Univ. of Cottbus. He has worked for Arup for 14 years, in London, Madrid and San Francisco.

Jos de la PEA Director Ove Arup & Partners Madrid, Spain Jose.de-la-pena@arup.com Jose de la Pea, born 1962, received his civil engineering degree from the E.T. S. de Ing. de Caminos, Canales y Puertos, Univ. Politecnica de Madrid in 1986. He leads the structural department at Arup Spain.

Volker SCHMID Professor at the TU Berlin, Germany, Consultant for Arup, Berlin, Germany volker.schmid@tu-berlin.de Prof. Dr.-Ing. Volker Schmid is head of the chair for composite and hybrid structures at the TU-Berlin. Before he took up the professorship and became a consultant he was working for Arup in London and Berlin.

Summary

The Metropol Parasol is a unique hybrid structure near the center of the old quarter of Seville. This paper describes its structural design within the context of the overall architectural design and as part of the urban rejuvenation of the Plaza de la Encarnacin. The project includes a museum, a fresh produce market, retail space, an elevated plaza and a high-level cafe with panoramic walkways. The parasols, the most visible part of the public square, are a free-formed timber mega-structure, constructed with a combination of timber, polyurethane, epoxy and steel. The engineering design ensured the successful realization of the Metropol Parasol, which has become an integral part of the urban fabric in the heart of Seville.

This presentation will focus mainly on the design of the 28-meter-high and 150-by-100-meter timber mega-structure, from concept stage all the way through to construction. The six blended parasols resemble mushrooms and are manufactured from laminated veneer lumber (LVL) plates.

The design team selected elastic polyurethane coating sprayed onto the LVL planks to protect the structure against weathering. Based on an epoxy-adhesive for the bonded-in steel rods, this

innovative and well-researched and tested connection detail is post-cured in order to increase its heat resistance in Sevilles hot climate. This paper highlights the creative design process at the concept

stage, the use of various structural materials and the computational design tools necessary for the successful completion of the Metropol Parasol, Plaza de la Encarnacin.

Keywords: timber structure, free-formed geometry, urban regeneration, composite, hybrid

Fig. 1: Metropol Parasol, Plaza de la Encarnacin

1. Overall concept

Given the diverse architectural and functional requirements, Arup engineers defined different kinds of structures and materials for the different areas. The foundations are concrete piles, a long spanning steel-composite structure bridges the column free archaeological museum and the shops at ground floor level. Reinforced concrete is also used for two of the trunks, the platform for the restaurant itself is a steel-concrete composite structure and the Parasol structure itself is formed of timber, specifically Kerto-Q laminated veneer lumber planks. And finally, the walkways on top of the timber structure and the emergency staircases within the timber trunks are made from steel.

2. Timber structural concept

2.1 Concept Development

The starting point of the structural concept for the Parasols was the architects idea of an iconic, tree-like, free formed and amorphous form.

The choice of timber was based on many different reasons. Firstly, fabrication is simplified, as flat timber planks with no double curvature define a complex geometry. Also, due to limited foundation capacity and locations, the self-weight of the entire structure had to be kept to a minimum. Timber, with a very high strength/self-weight ratio was a perfect candidate. And finally, through the innovative protective PU coating (see below) maintenance is guaranteed and does not need upkeep as steel would need.

2.2 Structural Concept

The timber elements are arranged in a two directional grillage, and connected with moment-stiff connections, ensuring out-of-plane stiffness. Steel diagonals, most of them concentrated below the walkways to minimize the visual impact, brace the timber grid in its horizontal plane and make the structure work like a grid shell with a very high bending capacity (Fig 10).

2.3 Integrated design and fabrication

Throughout the project the precise shaping, sizing and optimizing of the structures components were the keys to the projects success. Fundamental for this process was a continuous flow of digital information amongst all design team members in form of a basic building information model (BIM) An iterative calculation was run as many times as necessary until convergence, which was run by a partially automated calculation routine between our FEM model and the structural checking spreadsheet.

3. Discussion and Conclusions

In summary, the Metropol Parasol project exemplifies how architects, engineers and specialists can collaborate to deliver transformational projects. There were many extremely challenging times too. But now the square is a changed place: the museum proudly exhibits the excavated Roman ruins, the market stalls have moved back to a central place, and bustle with activity every day, and the public plaza hosts a myriad of public events, from political meetings, to viewings of major sports events. Additionally, the neighborhood around the Parasols is experiencing a rejuvenation which ensures a fresh feeling of optimism amongst the local neighbors. All of this helps to give this new urban space a sense of meaning and purpose again.

3.1 Acknowledgements

Building owner: City of Seville; Concessionaire and General contractor: Sacyr SAU; Timber contractor: Merk Timber, Aichach, Germany; Architect: Jrgen Mayer H., Berlin; Engineering: Arup, Berlin, Madrid