Walt + Galmarini – Structural art

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WaltGalmarini

As engineers we interpret the architects’ ideas and support them in creating meaningful spaces, characterized by aesthetic structures and details that follow the path of the loads. In the sense of the term “structural art” we intend holistic efficiency through an integral interpretation of the scope of the project, as well as economic efficiency through optimization of the structural systems, material combinations and construction methods. Thereby we responsibly emphasize the constructive design of the details according to the project.
In the four projects shown in the exhibition, we could participate within the interdisciplinary dialogue in creating the competition project and thereby contributed to the design of the room spaces. Within the same interdisciplinary dialogue we refined the structure, the materialization and the strategic details during the following project phases, until execution.
For the Elefantenhaus we constructed the free-form threedimensional roof-shell over the inner compound, with a light-weight construction system. The wooden shell fulfills the aesthetic, static, climatic, building-physical, ecologic and usage related requirements.
The rough alpine climate at 2653 metres above sea level with large wind peaks and up to 6m snowfalls, as well as the site logistics influenced the structural concept and the materialization of the summit restaurant on the Aroser Weisshorn. The competition concept foresaw precisely prefabricated building components designed to fit the local transport possibilities. These components had to be installed and to screwed quickly during the particularly short building season.
For the poorly accessible and up to 50 m high walls of the Energiezentrale (power plant) in Bern, we looked for smooth surfaces that would remain as dust-free as possible. The giant machine halls required a removable building envelope, so that machine parts can be replaced. Prefabricated, up to 34m long panel columns fulfill this requirement and give the facade a light expression. Thereby, the amount of required material and weight could be significantly optimized.
In the university building ETH LEE we were able to reduce over 25% of the slabmass through prefabrication, and at the same time gain space for the installations within the room occupied by the structure. The use of concrete ribs leads to a durable and ecologic structure with separate primary and secondary structural members, that also defines the arrangement of the partition walls and interior fittings.

Elefantenhaus
Zürich CH 2014
Architect: Markus Schietsch

It has become a trend to house wild animals inside buildings characterized by extraordinary architecture. With the construction of the elephant park with its spectacular wooden roof made out of over 30.000 pieces and with a clear span of over 85m, the Zürich Zoo consolidates this trend. The roof crouches over the landscape as a flat, free-form wooden shell, so that its considerable size remains almost unnoticed. It dissolves into a network-like transparent structure, blending with its organic design, into the surrounding forest. Only from inside the roof unfolds its full impact. The light filters through the filigree roof-structure like through a canopy of leaves, letting the rays of light wander during the course of the day.
Wood, as an anisotropic and inhomogeneous building material, is not an obvious choice for a real shell structure with 271 skylights of random geometry. In the form of multi-layered panels it becomes a material that is easy to process and that can be adapted into the desired form on the construction site. Then why don’t we let the formwork, that would be needed anyway for a concrete shell, support the loads itself?

Gipfelrestaurant
Arosa CH 2013
Architect: Tilla Theus

The restaurant presents itself as a generous hall spanning up to 10m, which is unusual for this location. The facade pillars lean against the massive ground-floor and cantilever from the intermediate floor to the roof to support the large snow loads. Since no bracing elements were wanted in the circunferencial façade windows, these pillars resist the horizontal loads according to the “brush effect”, or like a “comb”. As panels, the roof above the inclined inner pillars and the intermediate floor carry the wind loads to the concrete core.
Not only in exposed locations it makes sense to combine the different building materials in hybrid structures according to their advantages:
- Concrete for foundations and ground slabs in contact with humidity and for building elements containing many installations.
- Steel, where large loads should be carried by columns, which need to be as slender as possible, or for beams requiring a minimum cross-section.
- Wood for extensive, visible and insulating box-elements in the building envelope and for a special !room ambiance.

Energiezentrale
Bern CH 2013
Architects: Graber Pulver

The whole power plant can be described as a large filigree folded plate structure, composed of the structures: bunker, processing building, power plant with chimney, operations building and walkway.
It is characterized by the combination of walls and slabs to folded plates, and by the folded free- standing high walls and wide-spanning ceilings, the so-called ripping.
The 52m-high bunker stocks wood chips and garbage until their burning. The bunker is a honeycomb and folded plate structure. The floor and roof slabs of the loading hall, the basement of the processing building and the intermediate floor-slabs and compartment walls of the bunker brace the long and high walls of the garbage-bunker. At the same time the garbage-bunker walls support floor-slabs and the roof of the loading hall, reducing their span.
The processing building, where the burning of garbage, wood and gas takes place, only consists of in-situ concrete, from the floor slab up to a height of 14m. The demontable building envelope, made of up to 34m high panel columns and up to 18m spanning roof beams, was mounted on top of the in-situ cast base.

ETH LEE
Zürich CH 2014
Architect: Fawad Kazi

Prefabricated ribbed slabs carry the vertical loads to the facades and cores. Perimetrical beams along the facades and beams spanning between the pillars and core walls carry the loads from ribbed slabs to the columns and core walls, which lead to the foundations. This results in flexible, clearly structured 8.4 m spanning spaces, free of columns. The rhythm of the supporting structure determines, consequently, the location of the windows and partitions. Through the use of ribbed slabs the amount of material needed for the slabs is minimized.
The mural character of the building is achieved by the large, structured prefabricated concrete façade elements. These protect the building from wind and weather. The large self-weight of the façade elements is the decisive load case. Due to the chosen structural system of a self-supporting façade, these heavy loads are carried vertically, from element to element, into the foundations. Wind and earthquake loads are directly transmitted to the load-bearing structure by specially designed facade anchors.

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