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Views: 222 Author: Hazel Publish Time: 2025-04-02 Origin: Site
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>> 1. What was the main challenge in constructing the Portuguese National Pavilion?
>> 2. How did lightweight concrete contribute to the pavilion's design?
>> 3. What role did Cecil Balmond play in the construction of the pavilion?
>> 4. Can you describe the architectural style of the Portuguese National Pavilion?
>> 5. What is the significance of the Portuguese National Pavilion?
The Portuguese National Pavilion is an iconic piece of architecture that demonstrates the possibilities of imaginative construction and engineering[1]. Designed by Álvaro Siza Vieira, with structural engineering by Cecil Balmond, the pavilion was the centerpiece of the 1998 Lisbon World Exposition, commemorating Portugal's maritime heritage with the theme "The Oceans: A Heritage for the Future"[5][7]. The pavilion is located at the mouth of the Tagus River in Lisbon[2][7]. Its most striking feature is the vast, undulating concrete canopy that appears to float weightlessly over the public plaza while framing the river[1][5].
Álvaro Siza Vieira, one of Portugal's most admired architects, designed the Portuguese National Pavilion as a link between Portugal's past and future, symbolizing its navigational legacy and modern identity[1][5]. Siza, who won the Pritzker Prize in 1992, was selected to design the Expo's entrance as a grand architectural landmark[2][4]. Siza aimed to create a grand entrance to the fairgrounds that was visually stunning and functionally effective, meeting the festival's programmatic needs and site-specific requirements[5][7].
Siza chose to divide the building into two parts: one portion designed to be adaptable for various uses, and the other an outdoor yard, where he would create a strong architectural gesture[2][5]. The architect covered the patio with a 70-metre-long concrete canopy that bends down in the middle and frames views of the Tagus River[2][5]. Siza experimented with a large gabled roof but found it too tall and ineffective against rain and wind[2]. He also considered a large slab supported by a "forest of pillars" but rejected it because the columns cluttered the space[2].
According to Siza, the result is interesting because it's a very special half and a very almost banal second building side-by-side[5]. Siza completed the project with fellow Portuguese architect, Eduardo Souto de Moura[2][5].
- Monumental Canopy: The pavilion's most significant feature is the vast, undulating canopy that forms the roof of the public plaza[1].
- Open Public Plaza: The focal point of the project is a large, open public plaza shaded by a suspended overhead canopy[7].
- Connection to the Tagus River: The architect emphasized the connection between the space and the view beyond, wanting to frame the vista of the river with an enclosed and column-free space[7].
- Two Monumental Porticoes: Two monumental piers support the roof[7]. The porches comprise nine columns that are covered in ceramic tiles and spaced apart to create shadowy nooks in between[2][5].
The construction of the Portuguese National Pavilion, which began in 1995 and ended in 1998, was a remarkable achievement in modern architecture and engineering[1]. The primary goal was to create a large, open public space shaded by what appeared to be a weightless concrete canopy[7]. The building covers an area of about 55 x 90 square meters, with an average height of 12 meters[4].
The canopy's structural ingenuity is now regarded as one of the most remarkable engineering achievements[1]. The canopy, made of a concrete layer only 20 centimeters thick, spans a total distance of 65 meters without any columns in between, giving the impression that the concave awning is floating weightlessly while perfectly framing the river[1][5].
The canopy is made of a catenary arc of steel cables draped between porticoes and then filled with pre-stressed concrete[1][2]. It uses suspension bridge technology and is designed as a stressed-ribbon structure, where loose cables are stiffened with concrete to prevent swaying and bouncing[1]. The painted concrete gives the canopy a sleek, clean texture and weighs it down to prevent strong drafts from moving or lifting it from below[1].
The small sag (3 meters against the 67.5 meters distance of supports) induces large horizontal thrust on the top of the fins[6].
Lightweight Leca® concrete was chosen as the material because of its low dead weight, which reduced horizontal stresses on the roof and supports while maintaining adequate strength and rigidity[1][8]. The use of lightweight Leca® concrete reduced the roof's total weight by around 430 tonnes[8]. The canopy structure is a 20 cm thick parabolic membrane Leca® lightweight concrete slab hung on prestressed tendons anchored along the two short sides in slabs[8].
The canopy's arresting feature is made possible by suspension cables that connect the roof to two porticoes[1]. The architects intentionally left a glimpse of these suspension cables visible where they connect with the support—a small but defining detail that highlights the structural integrity of the architecture[1]. This meticulous construction combines elements of tension and balance[1].
More than 3,900 square meters of falsework were used during the concrete pouring operation[1]. The pouring began with a 2.5-meter central strip, followed by neighboring strips poured simultaneously using four pumps and two construction teams[1]. The concrete construction took ten hours and was completed in one operation[1].
Álvaro Siza worked with engineer Cecil Balmond to develop the unusual, scooped structure, which comprises white-painted concrete supported on steel cables[2]. Balmond ran Arup's Advanced Geometry Unit, a design group that collaborated with internationally renowned architects[3].
Siza experimented with a large gabled roof but found it too tall and ineffective against rain and wind[2]. He also considered a large slab supported by a "forest of pillars" but rejected it because the columns cluttered the space[2].
The porticoes play an important structural role and are articulate architectural elements[5]. Each has nine massive columns arranged rhythmically but asymmetrically[5]. Deep cuts between the columns create dramatic contrasts of shadow and light, highlighting the clean lines of the columnar profiles[5]. A façade treatment of colorful ceramic tiles in the deep recesses, glazed in the national colors of green and red, adds a playful touch to the otherwise austere and monumental structures[5].
The Portuguese National Pavilion remains an iconic landmark in Lisbon, Portugal, years after Expo '98[1]. Its creative design and engineering continue to inspire architects and engineers worldwide[1]. The pavilion represents the possibilities of modern architecture by combining structural honesty with aesthetic elegance[1]. The structure and architectural form work in graceful harmony[7]. The interplay between moments of delicacy and monumentality is perhaps the most striking quality of the pavilion[7].
The Portuguese National Pavilion stands as a testament to innovative design and engineering[1]. Álvaro Siza Vieira, with the help of Cecil Balmond and Eduardo Souto de Moura, created a structure that not only met the requirements of Expo '98 but also left a lasting legacy in architectural history[2][5]. The pavilion's canopy, with its delicate balance and structural ingenuity, embodies the spirit of Portuguese discovery and innovation[1].
The main challenge was creating a vast, open public space shaded by a concrete canopy that appeared to float weightlessly[7]. This required innovative engineering solutions to ensure the structure's stability and aesthetic appeal[1].
Lightweight concrete, specifically Leca® lightweight concrete, was used to reduce the overall weight of the canopy[1][8]. This minimized the horizontal forces on the roof and supporting structures, ensuring structural integrity while maintaining the desired aesthetic[1][8].
Cecil Balmond was the structural engineer who collaborated with Álvaro Siza Vieira to develop the unusual, scooped structure of the canopy[2]. His expertise was crucial in bringing Siza's vision to life, ensuring the structural feasibility and safety of the design[1].
The pavilion's architecture emphasizes geometric shapes, celebrates industrial processes, and reveals structural elements as primary architectural features[1]. It combines elements of tension and balance, creating a space that is both monumental and delicate[1].
The Portuguese National Pavilion is significant because it showcases the possibilities of imaginative construction and engineering[1]. It represents a blend of structural honesty and aesthetic elegance, making it an iconic landmark and a source of inspiration for architects and engineers worldwide[1].
[1] https://www.ignant.com/2020/02/26/tension-and-balance-are-defining-features-of-alvaro-siza-vieiras-portuguese-national-pavilion/
[2] https://www.dezeen.com/2019/08/02/expo98-portuguese-national-pavilion-alvaro-siza-movie-interview/
[3] http://useofcement.cembureau.eu/2018/04/09/strength-and-beauty-how-cement-made-the-portuguese-pavilion-possible-2/
[4] https://koerstue.nl/media/KOersief/Online%20artikelen/2020-2021/Uit%20de%20oude%20doos%20KOersief%20artikelen/Expo%201998/Portuguese%20National%20Pavilion.pdf
[5] https://www.thisispaper.com/mag/portuguese-national-pavilion-alvaro-siza-vieira
[6] http://www.sta-eng.com/DOCUMENTOS/ARTIGOS/99.05%20USE%20LWC%20EXPO98_ERMCO.pdf
[7] https://www.yinjispace.com/article/Alvaro-Siza-Expo-98-Portuguese-National-Pavilion.html
[8] https://www.leca.co.uk/case-studies/National%20Pavilion-Lisbon-Portugal
[9] https://engexpor.com/en/project/pavilion-de-portugal/
[10] https://studystructural.wordpress.com/2012/05/24/the-flying-curve/comment-page-1/
[11] https://divisare.com/projects/397064-alvaro-siza-vieira-giovanni-nardi-portuguese-national-pavilion
[12] https://archjourney.org/projects/pavilion-of-portugal/
[13] https://en.wikipedia.org/wiki/Pavilh%C3%A3o_de_Portugal
[14] https://www.archdaily.com/583307/ad-classics-expo-98-portuguese-national-pavilion-alvaro-siza
[15] https://www.archdaily.com/583307/ad-classics-expo-98-portuguese-national-pavilion-alvaro-siza/543ca8b9c07a801fe70001cf-ad-classics-expo-98-portuguese-national-pavilion-alvaro-siza-image
[16] https://en.wikiarquitectura.com/building/portuguese-pavilion-expo-98/
[17] https://www.irbnet.de/daten/iconda/CIB4047.pdf
[18] https://archeyes.com/the-portuguese-pavilion-of-1998-by-alvaro-siza-a-modern-symbol-of-lisbons-expo-98/
