Arena Zagreb by UPI-2M


Arena Zagreb in Croatia by architects UPI-2M was awarded Structural Design of the Year at the World Architecture Festival in Barcelona last week.

The muitifuntional hall comprises a polycarbonate facade and steel roof, both suspended from 86 curved reinforced-concrete columns.

The building has a footprint of 9,0340 square metres and columns vary in height between 26.5 metres and 38.8 metres.

More winners from WAF:

Havaianas by Isay Weinfeld
Corian Super-Surfaces Showroom by Amanda Levete Architects
Mapungubwe Interpretation Centre by Peter Rich Architects
Category winners

Here's some more information from the festival:


Arena Zagreb is multifunctional indoor hall with the footprint of 90340 sq. m. It is located in the southwestern part of Zagreb, Croatia, at one of the main city entrances. Also it lies opposite of popular Zagreb recreation and sports center Jarun. Arena Zagreb became a new city emblem in one of its main axes, offering to the citizens a large palette of amusement events. The unique shape of this building is strongly inspired by its significance in the city context, but also by its mega-structural characteristics that predefine main bearing elements. The shell shape is following the structure logic – it partly covers the inner space with curved columns. Basic shape and structural element of this hall are prestressed prefabricated reinforced concrete curved columns with the height up to 39 m. Eighty-six large curved prestressed, pre-fabricated concrete columns are carrying the main façade, mutually connected by illuminant semi-translucent polycarbonate envelope that enables for various light effects. They also support stands and carry suspended steel roof structure. Columns’ height goes from 26,5m to 38,8m. Span of steel roof structure equals 104m.

The major parts of the hall are: suspended steel roof structure, pre-stressed, prefabricated, reinforced concrete columns, and monolithic reinforced concrete structure of the stands, pit and entrance plateau.

Under the stands and field of play there is a garage with surface of approximately 30 000 m2 (with capacity of 817 vehicles). The garage lies on joint-less foundation slab with work dilatations. Number of work dilatations depends on available concrete fabrication plant (up to1000m3 per day). Part of work dilatations is performed in a way that one stripe (with width of 1 m) is being left in the middle and concreted subsequently. Such concept ensures undisturbed process of creep and shrinkage in initial faze. Avoiding of dilatation provides more simple (with easier quality control) and faster hydro-insulation montage in conditions of relatively high underground water. Above the garage there is 5 floor monolithic reinforced concrete structure of arena. Statically, it represents spatial frame with beams (span up to 10 m) and columns. On height of +5,0 (point of main pedestrian entrances) there is a support for 86 reinforced concrete prefabricated columns. After monolithisation of columns on mentioned height as well as on contact with beams of upper floors, they make one unit with monolithic structure. Reinforced concrete structure is made out of concrete of quality C30/37.

Statics scheme (cantilever with length up to 15m), load (2000 kN on the top of cantilevered beam), shape (curved), cross section (oval), size (39 x 8,5m) weight (up to 220 t) - all these data are the reason of using the mentioned technology in production of columns.

Columns are being produced on the site, using the concrete C50/60, in horizontal position inside the specially designed formwork and partly prestressed, in order to provide the fastest possible extracting from the formwork (30% of force). After extraction out of formwork, columns are being put in a „stand“, 12 cables are fully pre-stressed (1200 kN per cable) and injected. At that moment, columns are ready for „verticalisation“ and transfer (using crane with capacity of 500 t – at the end of the arm outstretched 70 m, one will have necessary capacity) till planned location for embedding.

Columns are embedded on pre-built anchors (HALFEN, part of anchors on which column is stacked is embedded in column’s bottom) and temporarily stabilised (till monolithisation process is finished). Monolithisation with spatial frame structure of the hall will provide necessary horizontal stability of columns in high seismic conditions (calculated acceleration of the ground 0, 27 g). On the top of the column, there is a point for anchoring of cables predicted, which carry roof structure.

On full locked cable with diameter of 66 mm, calculated resistance of 2636 kN and range of 103, 7 m using vertical and diagonal hangers (full rod with diameter of 34 mm), roof structure is suspended. Suspended steel roof structure is made out of steel HEB 450 profiles in major and secondary direction. Wind influence is dominant with uplift action on the roof with (wo= 0,7kN / sq.m; additional safety factor 1,5; shape factor c=-0,62). The weight of structure and stabilization truss have favourable influence on dynamics of structure, provides load disposal in case of asymmetric combination and ensure cable replacement.

In order to fulfil main characteristic of the ARENA ZAGREB – multi-functionality, it is necessary to predict locations where the equipment (sound speakers, spot lights etc) will be installed (hanged). For this Arena, total weight of such equipment equals 100 t. Deflection of structure for design loading (which includes elastic deformation of hanging points on top of the column) equals 33 cm. Steel beams of major direction (their ends) are supported by elastomeric bearings embedded in stands structure. Elasticity of bearings provides for roof structure to „float“above the hall (uplift is blocked).

CategoryStructural Design - Spans (eg bridges, stadiums, big sheds)
LocationZagreb, Croatia

Posted on Friday November 13th 2009 at 4:00 pm by . Copyright policy | Comments policy

  • INawe

    where are the interior shots? maybe some plans and sections too?

  • G

    The night shot is spectacular. The day shots less so, but still a very nice project.

  • R

    Nice project. The use of the basic rectangular plint to present the more sculptural but very subtle stadium as an object on top works well, though I still believe there could have been some improvements on the scale of both.

  • dw

    so coooool! it seems like the arena is floating

  • TH

    wish to see the steel roof that is suspended. love the night view…

  • I like the reflections the building makes in the water at night more than the actual stadium itself. Id also like to see some Sections!

  • eb nyc

    Nice. Good solid design. Modern, refined. Has a rigor to it. And looks like it is a local firm, too. So all very positive I find. That’s what the world needs and deserves. Not eccentric, non-descript objects by global ego-stars.

    Yes, plinth is nice, like the stairs leading up to it, simple railings. Overall a very good appearance. Water shot of course the seller.

    Text of project way too detailed on structure, other stuff. Where are the basics? How many seats? What is it mainly for? I suppose especially for basketball, as bb is very popular in Croatia.

  • me

    And who is the structural engineer????
    Just crazy to know always who’s the architect and not the structural engineer, even for a structural award!

  • hello from croatia

    basketball is NOT popular here :)
    it was built for handball championship, but is mostly used for concerts (Beyonce!), and right now they are setting up a temporary pool for water polo! that will be funny, but cool
    inside shots are oridanary, nothing especially interesting
    a functional mistake is that the flight of stairs lead directly toward the street, so they have to stop traffic when people start going outside, but nothing to worry about
    the night photo is with extreme telephoto lens, there is a recreational lake about 1km away but the arena is very visible from there! in fact, the arena is on a lot of visual axis’s of th city, so a very good landmark

  • Me him and her

    so useless to present this without showing the roof!!
    this is how it works:

  • w

    The ribs around the building are only for decoration.
    The roof is flat, there is nothing to do with the rhythm of the ribs at all.


    Is their no interior?

  • BRian


  • I am intrigued about the cables that lead inside, from the exterior ribs. I am just wondering what they are supporting what what’s there more to see.