Unique and extraordinary architectural identity has always been in the roots of Zaragoza, Spain, whether we talk about churches of Islam and Romanesque style, stripped classical arcades, or Fin de siècle’s huge avenues.
Location: Zaragoza, Spain
Total floor area: 6415 m2
Maximum height: 30m
Foundational Depth: 68m
Client: Expoagua Zaragoza 2008
Constructed by: ARUP associates
Design by: Zaha Hadid Architects
Steel structure and steel cladding by: URSSA(Spain)
Glass-reinforced concrete(GRC) was supplied and installed by: Rieder(Austria) and Eurogramco(Spain)
Electrical and Mechanical services: Cymi(Spain) and Lac(Spain)
Architectural metalwork by: Inoxbier(Spain)
A similar uniqueness for connecting two places by combining engineering infrastructure and architectural elements is in Zaragoza Bridge Pavilion. A design by the Queen of the curve, London architect Zaha Hadid, the 280m-span structure acts as a bridge and pavilion above the Ebro River. “The first completed bridge project” by the ZHA welcomed visitors to Zaragoza’s EXPO in June 2008 and attempted to connect the river with the city.
Concept, site & surroundings
Zaha Hadid’s curvaceous-complex structure placed diagonally over the site took three decades for intricate research, examination, and testing. The gateway for the Delicia’s International station and EXPO on opposite sides was interestingly designed to handle the Tramontana wind blowing along the river Ebro and Zaragoza’s sun path. According to the EXPO’s theme of ‘Water and Sustainability (Fluvio)’, the structure had a similar story with its organic flow of the paths and lines. Moreover, the envelope of the bridge pavilion with a very carefully carved body looks quite powerful through its engineering techniques, relation with the environment in surroundings, and the atmospheric variations.
Other than Zaragoza Bridge Pavilion’s outermost shell, the detailed research and development of the diamond-shaped section offer the programming and structural properties as the core. The extrusion of this section along the different curved paths leads to the formation of four separated objects or “pods”. While interlocking and stacking each other, the Quartet trusses (pods) maximize structural load distribution while providing a natural difference for interiors leading to specific exhibition spaces. Zaha Hadid blended the pavilion with each riverbank through the smooth inclined terrain. Except for one pod, which was 1.5 meters above the main level and intersected with the others, each pod was at the same altitude. Furthermore, all but one have an upper floor suspended from the diamond section construction and provide views of the bottom level.
A fascinating design always has eye-catching principles that intrigue the community, and the similarity was noticed in these ‘Pods’. Zaha Hadid incorporated the factors of a Traditional bridge through the dominance of steel structure as a visual element while being open to the environment and an Exhibition pavilion with controlled light and climate permeability. The interiors with complex spaces had a combination of large, tall halls and tiny transition or buffer zones with the provision of strong-visual connections to the Ebro River and the EXPO. The interlocking of pods provided a better engagement between the visitors, incorporating: –
- The Zig-zag movement, formed by ramps, galleries, and different levels
- Proper readability within the pods and performing it as a three-dimensional orientation device
- Huge naturally ventilated areas and the play of the light-dark concept
Skins: Internal and External
Zaha Hadid and the team investigated the Bridge Pavilion’s outer material to know its natural surface while introducing the external façade of an array of beautiful optical patterns. The skin was divided longitudinally into two elements: a structural metal plate bottom deck and a dry-wall covering of GRC (Glass Reinforced Concrete) panels in various shades of grey on the upper deck. A free-flowing geometry was introduced on the lower deck, acclimating into an enclosed structure with huge openings, optically linked with the river and EXPO. On the other hand, the upper-level cladding by a single layer included 26,500 rectangular panels of equal size. These panels followed a triangular pattern limiting the variation to 10 inscriptions when combined with the chromatic variation to the GRC panels, creating the array of optical-patterns visible on the Bridge Pavilion’s façade.
The triangular pieces or Shark scales used in the panels are economical, functional, and visually appealing. Furthermore, its pattern can wrap over any form of complex-curved structures through a simple system of rectilinear ridges. The internal skin has a smooth semi gloss surface of plasterboard finish, with several layers of polished polyurethane resin.
The complex, unusual, and interesting construction method was chosen according to the deadline, and the launch of such a method was even challenging for Zaha Hadid Architects, which were used to complex types of techniques. Through the working of the pavilion on both the sites of the riverbank, the northern site was used to build more on a common method, whereas the southern site introduced the main span or the rest of the structure.
The 280m long structure was conceptually divided into two spans; 125m and 155m, supported by two-span girders with variable cross-sections in which the continuous upper chord passed through the pods and the non-continuous ones in the lateral pods. A lower chord was formed by a box girder, just below the lowest platform, and lateral trusses between both chords, upper and lower, called “diagrid”, the latter showing some discontinuities to allow for windows. The structure is modulated lengthwise into 3.60 m equally spaced cross-sections, and at each of them and within the lower box girder, there exist transverse diaphragms from which “ribs” extend out, reaching for, and connecting to, the upper chords. Diagrid panels were installed between those ribs.
The Three-phase Construction
The Southern launching of the curved structure with variable height, width and symmetry was the most spectacular part of the construction of the Bridge. The teams started the process by determining the centre of gravity, as the permanent structures and auxiliary elements that were to be launched were sensitive to their central position. After that, the process was divided into three phases: –
Hydraulic jacks and two sliding railing paths helped the structure to move 44m longitudinally and 9m transversely towards the North direction.
With the same two previous skidding elements and the installation of “driving” stay cables on the Northern side, the structure was overpassed the river with a displacement of 79m while being cantilevered. To balance or control the process, retaining cables anchored to an ad hoc temporary cast-in-place counterweight were provided on the southern side.
The structure launched at 2.7m above the final level was lowered after getting the proper allowance for launching the auxiliary elements.
Zaha Hadid, most specialists and top contractors, completed the connection within two weeks; however, the planning, analyzing, and preparation to reach that vision took many months. The Zaragoza Bridge Pavilion can be considered one of the best examples with a fusion of Parametric Architecture and the best construction techniques.
- Zaha Hadid architects. Zaragoza Bridge Pavilion – Zaha Hadid Architects. (n.d.). Retrieved March 30, 2022, from https://www.zaha-hadid.com/design/zaragoza-bridge-pavilion/
- Fairs, M. (2008, June 16). Finalize details. Citation Machine, a Chegg service. Retrieved March 30, 2022, from https://www.citationmachine.net/apa/cite-a-website/new
- Heathcote, E., 2008. Zaragoza Bridge Pavilion/Zaha Hadid, Expo 2008, Zaragoza. ProQuest, [online] Available at: <https://www.proquest.com/docview/229197997?accountid=9838&forcedol=true&parentSessionId=ixU7xZduX09yd%2F6VdAXGLB6yx%2Fi8f7tLpTUWJxJ3yt8%3D&pq-origsite=primo> [Accessed 21 March 2022].
- 2022. Zaragoza Bridge Pavilion. [ebook] Available at: <http://file:///D:/Social%20Media/RTF%20(14.03.2022-%2020.06.2022)/27.03.2022-%202nd%20Article/Extras/zaragoza.pdf> [Accessed 30 March 2022].
- Vicente Perez Perez (Civil Eng.), Luis Peset Gonzalez (Civil Eng.), Hugo Corres Peireti (Dr., Prof.) & Felipe Tarquis Alfonso (Dr.) (2011) The Launching of the Pavilion Bridge, Zaragoza, Spain, Structural Engineering International, 21:4, 437-442, DOI: 10.2749/101686611X13131377725848