Earthquake-proof shoring solution for new iconic structure in Athens

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The SNFCC will house the National Library of Greece as well as the Greek National Opera. The whole complex, which also features the Stavros Niarchos Park, covers an area of almost 21 hectares. Italian architect Renzo Piano was awarded the contract after an evaluation procedure lasting more than a year against competitors from around the world based on his "vision, intellectual curiosity and a historical and geographical understanding of the project's location and significance". The architectural design followed the highest environmental standards – among other things, through emission-neutrality and the appropriate choice of materials.

The highest possible architectural concrete quality as well as the temporary support of a 10,000 m² canopy at a height of around 40 m above the ground were the biggest challenges regarding formwork and scaffolding operations for the project.

Sophisticated architecture and architectural concrete requirements realized

The buildings of the National Library of Greece and the Greek National Opera are located behind a man-made hill whereby the sloped roofs of the buildings form, as it were, an extension of the incline. The best architectural concrete quality is required for the numerous walls and columns of the structures. All buildings are characterized by their distinctive geometries, including inclined slabs at heights of up to 31 m.

Before construction started, concreting operations were trialled on-site using the PERI VARIO Wall Formwork in order to determine the quality that could be produced under the actual boundary conditions found on the jobsite, to develop and ensure the technical procedures, as well as to provide training for the personnel. The surface quality which was defined in this process as the "reference surface" was agreed as the binding standard for the acceptance.

For the execution, VARIO elements with double formlining skins were selected. In order to avoid the presence of impressions of any kind, FinPly formlining sheets have been screwed on from the rear. The joint arrangement and position of the anchor points were planned by PERI engineers in accordance with the design specifications. In some areas, self-compacting concrete has also been used; here, the formlining joints have been additionally sealed with silicone and taped to ensure the best-possible joint formation.

For the higher walls, the wall formwork is positioned on CB Climbing Platforms and FB Folding Platforms whereby the brackets are lifted by crane to the next concreting section. Through the use of a special anchoring system, the construction team has achieved the required finish here. All the walls without special requirements for the visible surfaces have been quickly realized with the proven, large-sized TRIO Panel Formwork. For the up to 6 m high, circular columns, the SRS steel Column Formwork fulfils the requested surface quality.

Under the slabs, which in part are inclined and up to 30 m high, load-bearing scaffolding on the basis of PERI UP Modular Scaffolding and ST 100 Shoring Towers have been used depending on the loads involved. The specially planned shoring has made a very convincing case through simple, quick assembly and optimum adaptation to match the geometry and loads.

Earthquake-proof shoring solution for a suspended energy roof

The entire structure of the Greek National Opera is fitted with an additional 10,000 m² large canopy. This is suspended about 12 m above the actual roof and thus approx. 40 m above ground level – the architect compares it with a flying carpet. This additional roof is actually the central element in order to achieve the planned target of emission neutrality. The construction consists of a prefabricated ferrocement panel arrangement which is subsequently spliced together with a mortar fill. Solar modules supply the "green" energy to cover part of the electricity requirements of the complex. The shape of the canopy resembles a convex lens – the cross-section therefore tapers towards the edges. Thirty very slender steel columns support the construction and are arranged in a 15 m grid formation on a steel frame. Load transfer into the ground takes place via the building's supporting columns positioned below. Visually, the columns seem to merge into the supporting structure of the Greek National Opera.

A major challenge for this very extraordinary architecture and the special design of the roof was the realization of the required shoring solution during construction phase. In the process, the scaffolding has to assume a variety of functions. On the one hand, it serves as a support for the prefabricated ferrocement modules and simultaneously allows fine adjustment of these modules in their final positions. On the other, safe working areas with easy access for the required assembly work and concreting operations had to be created around 2 m under the roof surface. Last but not least, the temporary scaffolding construction had to be earthquake-proof.

The detailed planning developed by the PERI engineers on the basis of the PERI UP Modular Scaffold fulfils all requirements, and the system can make full use of its numerous advantages. Through its consistent metric grid dimensions, PERI UP is extremely flexible in all three dimensions and can be optimally adapted to suit both the complex forms as well as accommodating the varying loads – in the system, each leg is positioned to exactly match the geometry and loads to be transferred. A further advantage for the construction operations: due to the high rigidity of the ledger connections, large units can be moved by crane. The up to 40 m high PERI UP Stair Towers integrated in the load-bearing system provide quick access to the working areas at great heights.

The required working areas for the assembly operations under the canopy could be realized with UDI steel decks which provide a gap-free surface throughout. Then, the principle of perfectly matching ledgers and decking with lengths from 25 cm allows a change in direction when installing the decks. In all areas, end-to-end toe boards, guardrails and integrated access provide maximum safety and thus efficient working activities.

For the fine adjustment of the prefabricated roof module positions, PERI developed a special component with which the panels can be moved quickly and accurately in transverse and longitudinal directions by up to 5 cm.

Due to the high risk of earthquakes in Athens, earthquake resistance also has to be ensured during the entire construction phase. Consequently, the PERI UP Shoring is positioned on specially-designed floating supports that minimize the movement of the scaffold construction in case of an earthquake.

Logistical challenge

The size of the project and the tight construction schedule created a very special logistic challenge regarding the implementation. For forming the immense wall surfaces within the whole complex, large amounts of system formwork are in use on the construction site at the same time – the same applies to the huge quantities of shoring. An important aspect for successful cooperation therefore is the constant matching of requirements and the respective delivery quantities. A PERI project manager has ensured here the necessary communication and coordination as he supports the site management in helping to maintain the strict construction schedule.

The architect: Renzo Piano

Renzo Piano is today an internationally recognized architect. In the 1970s, he achieved world fame with the Centre Georges Pompidou in Paris. Since then, he has earned critical acclaim with his modern buildings all around the world which has included redesigning the old port of Genoa, redevelopment of the Potsdamer Platz in Berlin, and the Kansai International Airport Terminal in Osaka. In 1998, Renzo Piano was awarded the Pritzker Prize, the highest international distinction for architecture. Piano is considered a master of construction engineering. In all his projects, technology serves to stimulate the light, respect the environment, and to facilitate integration with nature. The selection of the architect for the design of the SNFCC was the result of a thorough evaluation of several candidates which was carried out by the Stavros Niarchos Foundation and its advisers as part of a closed, international architectural competition.

The Stavros Niarchos Foundation

The Stavros Niarchos Foundation (www.SNF.org) is one of the world's leading private international philanthropic organizations, making grants in the areas of arts and culture, education, health and sports, and social welfare. The Foundation funds organizations and projects that are expected to achieve a broad, lasting and positive impact for society at large, focusing on vulnerable groups such as children and the elderly, and also exhibit strong leadership and sound management. The Foundation also seeks actively to support projects that facilitate the formation of public-private partnerships as an effective means for serving public welfare.

From 1996 until today, the Stavros Niarchos Foundation has made grant commitments of $ 1.79 billion (€ 1.50 billion), through 3,252 grants to non-profit organizations in 111 nations around the world.

In June of 2015, the Foundation announced a new grant initiative of € 100 mil ($ 112 mil), in addition to its standard grant-making activities, to help address the deepening crisis in Greece by providing immediate relief support to the most vulnerable members of Greek society. The new initiative follows on the heels of two earlier initiatives in 2012 and 2013 of € 100 mil ($ 130 mil) each. While the initiative in 2012, which has been completed, aimed as well to provide immediate relief against the adverse effects of the socio-economic crisis, the one announced in 2013 aims to address the high percentage of youth unemployment, seeking to create better employment prospects and new opportunities for the young.

The Foundation's largest single gift is the Stavros Niarchos Foundation Cultural Center (SNFCC) in Athens, to be completed in 2016. The project's total budget of $ 831 mil (€ 596 mil) includes two grants of $ 6 mil (€ 5 mil) each to the National Library of Greece and the Greek National Opera respectively, aiming to support the organizations' transition to their new facilities. The SNFCC is a testament and a commitment to the country's future. It is also an engine of short- to mid-term economic stimulus.