New Construction for a Bus Station in Aarau, Switzerland
A unique structure which roofs the main bus station in the Swiss town of Aarau was built at the end of 2013. The canopy has a cloud-like shape and contains the largest single-chamber cushion in the world. It has a volume of 63,920 ft3 and a roofed area of 11,517 ft2.
Structural engineering, workshop planning steel, foil, cables, construction management + quality control
formTL Ingenieure für Tragwerk und Leichtbau GmbH, Radolfzell
Project Planning and Solid Construction
suisseplan Ingenieure AG
Arge Foliendach mit Ruch AG
Vector Foiltec GmbH, Bremen, Germany
Vehovar & Jauslin AG
City of Aarau, Switzerland
The external dimensions of the roof are l x w = ~ 138 ft x ~ 128 ft. The eave height is 23 ft. There is an organically-shaped opening in the center of the canopy. The air cushion is inflated and reaches a height between 4.3 ft and 10.5 ft. Furthermore, a clear and blue‑dyed foil with a finely balanced print was used.
The cushion is enveloped and spanned by an irregular mesh of stainless steel cables that are fixed to the curved pipes on the edge. The edge beams are supported by a load-bearing system consisting of steel girders lying within the cushion.
The entire technical infrastructure for water, air, electronics, and sensor technology has been integrated into the inner steel structure.
The roof is supported by a total of 11 filigree columns made of round pipes with a diameter of d = 11 3/4 in that are slightly inclined in an axis. The "cloud" seems to float. The ETFE cushion has such an airtight and energy‑saving design that only 15% of the forecast air power needed to sustain the structure is required.
Immediately after the bus station was put into service, it became an exhibit in the "architektur 0.13" Swiss architectural trade show in Zürich.
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The calculation of complex structures by means of finite element analysis software is generally performed on the entire model. However, the construction of such structures is a process carried out in multiple stages where the final state of the building is achieved by combining the separate structural parts. To avoid errors in the calculation of overall models, the influence of the construction process must be considered. In RFEM 6, this is possible by using the Construction Stages Analysis (CSA) add-on.
Compared to the RF-/STEEL EC3 add-on module (RFEM 5/RSTAB 8), the following new features have been added to the Steel Design add-on for RFEM 6 / RSTAB 9:
- In addition to Eurocode 3, other international standards are integrated (e.g. AISC 360, CSA S16, GB 50017, SP 16.13330)
- Consideration of hot-dip galvanizing (DASt guideline 027) in the fire protection design according to EN 1993-1-2
- Input option for transverse stiffeners that can be taken into account in the shear buckling analysis
- Lateral-torsional buckling can also be checked for hollow sections (e.g. relevant for slender, high rectangular hollow sections)
- Automatic detection of members or member sets valid for the design (e.g. automatic deactivation of members with invalid material or members already contained in a set of members)
- Design settings can be adjusted individually for each member
- Graphical display of the results in the gross section or the effective section
- Output of the used design check formulas (including a reference to the used equation from the standard)
- How do I perform stability analysis to determine the critical load factor in RFEM 6?
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- Why do the results in a modal analysis differ between the initial prestress and the surface load?
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- Is it also possible to use RF‑/TOWER Loading without the other TOWER add-on modules?
- Although I have modeled two identical structural systems, I obtain a different shape. Why?
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- I have a roof structure resting on a steel column that runs to the foundations. The column runs through a perimeter wall that supports the false ceiling. A considerable part of the load from the roof is transferred to the wall. I want the steel column to carry all the vertical loads from the roof. How can I do it?
- Are the models and presentations from Info Day 2018 freely available, and can you send them to me?
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