© Aldo Amoretti

The Timber Roof of the TUM Campus in Munich

With a roof area of 22,000 m2 and built with 5200 m3 of construction timber, the TUM Campus is one of Europe's biggest timber structures. Its trademark is the 150 m wide roof with a cantilever of nearly 19 m and consisting of 40 prefabricated hollow box girders.

The TUM Campus is the greatest construction project developed in Munich's Olympiapark since the 1972 Olympics. The overall concept of the building and the sports facilities spanning 20 ha was developed by the landscape planners Balliana-Schubert and the architects Helmut Dietrich und Much Untertrifaller (MU). Konrad Merz, Gordian Kley (GK) and Bertram Käppeler (BK) of merz kley partner were responsible for the structural engineering.

This article was published in DETAIL Magazin, 05 2023.

© David Matthiessen

Bright, airy and generous

(MU) The task defined by the architectural competition for the new structure aimed at replacing the halls of the University Sports Center facility dating from 1972 in connection with the desire for integrating all spaces of the Department of Sport and Health Sciences on the Olympiapark Campus was both challenging and thrilling. All new halls were supposed to be built on the site while operations were in full swing. Later – after demolition of the existing structures – the remaining functional program was supposed to be amended in a way leading to a coherent whole that functions in an optimal way by offering logical correlations of spaces while maintaining short distances.
We considered ourselves well prepared in terms of the task at hand, thanks to realising the ETH Zurich Hönggerberg Campus for University Sports only a few years earlier.

The following question was decisive to us: How can we respond to the renowned, high profile historic landmarks in the Olympiapark? This includes the elegant and extensive free form structures created by Behnisch & Partner in collaboration with Frei Otto, as well as the amazing landscape park by Günter Grzimek. With the highest degree of respect for the context, but also a great amount of joy, we accepted this task and the related responsibility. In our view, we developed an adequate solution capable of fostering a sense of identity on this particular site. Most of all, the objective was to create a place of exchange, for the joy of physical activity and learning, of wellbeing and inspiration for its users.

Connected to a bridge along the embankment created by Grzimek, a horizontally anchored building volume of extensive dimensions seemingly floats in the air within the 20 ha landscape. Self-confidently, it embraces the expansive open air sports facility with its deeply cantilevered canopy. The eave height is continuously low all around the building and, thus, supports the self-evident integration of the structure into the surrounding topography. All taller volumes within the facility exceed this clear delineation in height. With its many skylight openings, the structure constitutes a vivid and green roof landscape – an important consideration, given views from above­ originate in the Olympic Tower and parts of the Olympic Village. An intense dialogue between interiors and exteriors is omnipresent along all sides of the building.

Two important pathways arranged perpendicular to each other intersect the entire complex as well as the entire site. A “Rue Intérieure” or internal access divides both floors along an east-west axis.

© Aldo Amoretti

« Die Rue Intérieure läuft als 180 m langer Kommunikationsbereich vom Eingang bis zur Mensa und der großen Terrasse. »
Much Untertrifaller

© David Matthiessen

Open, yet fireproof

(GK) The load bearing roof structure of the 150 m long Rue Intérieure is only partially visible. In combination with the clear building grid measuring 2.50 m, it allowed utilising an economically highly advantageous type of timber roof construction: Glued laminated timber primary beams arranged in five m intervals with secondary beams consisting of solid timber placed between them. The roof surface was created by mounting OSB panels that also establish the stiff ceiling slab. In connection with the warm roof construction assembled from above the result is a simple and highly robust overall roof construction. It is also a response to the occasional need for building a timber structure during adverse weather conditions.

The Rue Intérieure functions as a central access corridor, as well as a central means of emergency egress. As such, it is subject to extensive fireproofing regulations and, in this case, required an F90 “fire-­ resistant” classification of the entire structure, up to the bottom of the roof construction. In connection with the irregular pattern of point supports for the ceiling slab and the high degree of building services installations, the solution here was a conventional reinforced concrete structure for the floor slabs and the interior walls. This was also the case for five different longitudinal volumes comprising building services for the sports halls, the perimeter walls of the tall auditorium, the basement spaces and, of course, all foundation engineering. In sum and despite the predominance of the timber structure, a significant quantity of about 10,000 m3 of concrete and roughly 900 t of steel reinforcement was used for the building.

Exchange and communication

(MU) The upper arrival area borders the row of alternatingly arranged, adjacent auditoriums and sports halls, allowing mutual views. The generous dimensions of the Rue Intérieure support permanent interaction between theory and practice. The result is an inclusive place for the community of all users, exceptionally suitable for all kinds of communication, learning and relaxation. It terminates at the library and the cafeteria, offering westward views to the outdoor facilities and the cityscape beyond. The lower level features centrally placed locker rooms with consistently separated areas for hygiene and exercise, interlinking all sports spaces.

Everything under one roof

(BK) The halls offer room for 14 sports fields and a climbing facility. It was therefore necessary to develop a structure capable of covering 7000 m2 of roof surface that allowed assembly based on prefabrication to the highest possible degree while remaining completely visually exposed. In connection with the aim of maintaining economic efficiency, the result is a structure as simple as it is functional. It is also similar to the roof structure of the Rue Intérieure: Roof trusses with pitched top chords and straight bottom chord were arranged parallel to each other at 2.50 m intervals.
Purlins with smaller cross sections, acoustic (light-weight wood wool) panels and a stiffening layer of OSB panels were placed orthogonally on top of the structure. The skylights are a special feature and dis- tribute light into the halls through conical protrusions consisting of three-layer panels. The warm roof construction corresponds to the previously mentioned roof construction of the Rue Intérieure: A bituminous sealant layer consisting of rigid mineral wool insulation and a bituminous vapour barrier are arranged beneath the green roof. The walls of the sports halls were prefabricated as timber wall framing elements that permit the integration of roof columns. All of these walls were­ prefabricated as large scale frame elements. This allowed reducing the time required for assembly to the highest possible degree and, thus, minimising the risk of exposure to critical weather conditions­ during assembly.

Access as spatial experience

(MU) The Rue Extérieure traverses the entire site from Moosacher Strasse in the north to Mittlerer Ring in the south. It branches beneath the cantilevering canopy, either leading upwards to the cafeteria terrace and downwards again across a large inclined surface serving for bicycle parking, or along the laboratories facing the running track. Here, the covered area allows sports medicine related examinations in the open. On the building exterior, the Rue Extérieure serves as the main circulation space for the extensive outdoor sports facilities.

« Beim Vordach war eine flächige Holzkonstruktion gefragt, die ohne Unterzüge punktgestützt auf den schlanken Stützen aufliegt. »
Gordian Kley

In the open, yet protected

(GK) The roughly 150 m wide roof cantilevers nearly 19 m beyond the glazed facade. The circumferential roof edge of the building is continued within the canopy and maintains a minimal structural depth of 1.60 m without necessary coping for sealant layers and cladding. In combination with the desire for a visibly exposed timber ceiling underside, a timber structure was required that relied on point supports consisting of slender steel columns for the glazed facade while remaining free of downstand beams. The solution was to develop a hollow box girder structure. It features altogether 40 roof elements measuring 28 × 3.75 × 1.60 m that only require four point supports and allow cantilevering by nearly 19 m.
The hollow boxes include all required building services installations. Drainage piping remains accessible behind the reveal panels of the skylights. In addition, the hollow box elements enable permanent control through revision openings along their underside.
Adhesive bonding of panels and ribs leads to a hollow box cross section with high load bearing capacity. To create the deep cantilever, it possesses the minimum stiffness required in order to keep deformations along the roof edge within acceptable limits. The hollow boxes feature a structural camber of 20 cm at the tip of the cantilever. When the scaffolding required for assembly was removed, the planners were delighted to see that the structural camber declined precisely according to their calculations. The decisive aspect for the construction of such hollow boxes with integrated cross beams is paying attention to adequate element sizes, as well as addressing questions on available panel­ formats and how to assemble them into an element. Panels in the areas where webs are interrupted by cross beams bear tensile and compressive loads originating in the bending moment at their support and, thus, are continuous according to the required maximum length. This results in the need for large panel sizes, in this case of up to 20 m. The connections between the lateral webs and the cross beams, different than the previously described extensive adhesive bonding, employ mechanical fasteners (bolts and grooved nails in combination with steel components). Mechanical fasteners also enable the transmission of large tributary loads into steel columns along limited areas via steel plates and long fully threaded bolts that reinforce transverse compression.

© Aldo Amoretti

Space and construction

(MU + GK) Drawing on our shared and long-standing passion for wood as a material with its outstanding technical and atmospheric properties, we designed one of the largest timber buildings in Europe - even during the competition. In addition to the various sports halls, special rooms and office wings, the design work focussed in particular on the mighty projecting canopy. Thanks to our many years of collaboration with many realised projects and the great mutual understanding and trust, it was possible to develop such a sophisticated concept in the short time available for the competition.

Text: Much Untertrifaller (MU), Gordian Kley (GK) und Bertram Käppeler (BK). Published in DETAIL Magazine, 05 2023

Wood in the City

The return of timber as a urban building material has by now been recognised at almost all levels. There are many arguments in favour of its use, enabling it to re-establish itself in the urban environment - also beyond high-rise buildings. In recent years, load-bearing structures made of wood have been built in cities around the world. The positive experiences made are encouraging. And also investors are increasingly focussing on this renewable building material.

further

We don't have the need to fail on climate crisis

Dominik Philipp is certain, we automatically act sustainably if we respond to our needs. Anja Koller spoke to him about the challenge of designing today’s architecture for tomorrow, about creating flexibility for construction and use and why no other material can keep up with wood in terms of precision.

A conversation about updating buildings, networking and the flexibility of wood.

This article first appeared on
competitionline.com on 22 February 2023. Dominik Philipp was interviewed by Anja Koller, Editor Sustainable Design and Construction.

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TUM School of Medicine and Health, Munich (DE)
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ETH Sport Centre, Zürich (CH)
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Unterdorf Elementary School, Höchst (AT)
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