Lunar Dome, USA
The year 2019 marked the 50th anniversary of the first moon landing. For this occasion, a road show was planned in several cities throughout the United States of America. For this road show, a large temporary theater tent housing 1,600 seats was designed.
Matthew Churchill Production Ltd. and Nick Grace Management Ltd.
|Architectural Design||Teresa Hoskyns and Matthew Churchill|
|Membrane Structural Engineering and Workshop Drawings||
formTL ingenieure für tragwerk und leichtbau GmbHRadolfzell, Germany
|Membrane Contractor||Canobbio Textile Engineering|
Main Structure Model Parameters
Dlubal customer formTL provided the structural engineering for this project. The finite element software RFEM was utilized for the analysis and design.
The tent was created as a temporary structure, optimized for quick assembly and easy transport A main membrane, supported by four truss arches, an elastically supported projection dome and a large ETFE façade, form the interior open space for this structure. The flexible foundation includes adaptable footing elements, anchored with long dowels. Pasadena, California was the first stop for the traveling theater for the "Apollo 11 - the Immersive Live Show" in the summer of 2019.
The Apollo Theater’s main structure is formed by 4 arch trusses. Hanging from these elements is an approximate 52,743 ft² membrane made of PVC-coated polyester fabric type III. The two slightly inclined center trusses carry the primary load of the 240-foot-long tent structure. These main trusses have a span of 183 ft and a height of 89 ft. The 36-foot-high smaller lateral trusses in the foyer and backstage area are set at a higher inclination.
The interior includes a projection dome above a surrounding timber wall. This dome has a diameter of 151 ft and a height of 49 ft. It is suspended from the two main arches with elastic cables. This suspension stiffness is extremely low to allow the prestressing force to change only slightly if the outer shell is deformed (e.g. due to strong wind). The projection dome membrane consists of lightweight PVC-coated polyester fabric with micro-perforations, which absorbs about 65% of the sound.
Located under the foyer arch are 32-foot-long facade supports with an ETFE cushion covering. The columns resist pressure loads only from the foyer arch. In the case of uplift loads, elongated holes provide decoupling.
The foundation for the arches includes large steel plates with 2.36 x 78.74 in piles. The plates can be used to compensate for height differences up to 19.69 in. The piles were designed according to EN 13782 and verified in a pullout test.
Within one short year, the planning, production, and assembly of an unmatched temporary tent structure were completed.
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The effects due to snow load are described in the American standard ASCE/SEI 7-16 and in Eurocode 1, Parts 1 through 3. These standards are implemented in the new RFEM 6 program and the Snow Load Wizard, which serves to facilitate the application of snow loads. In addition to this, the most recent generation of the program allows the construction site to be specified on a digital map, thus allowing the snow load zone to be imported automatically. These data are, in turn, used by the Load Wizard to simulate the effects due to the snow load.
For the components of the joint, you can check whether stability failure is relevant (add-on structural stability for RFEM 6/RSTAB 9 required).
The critical load factor for all analyzed load combinations and the selected number of mode shapes is calculated for the connection model. The smallest critical load factor is compared with the limit value 15 from the standard EN 1993-1-1, clause 5. In addition, a user-defined adjustment of the limit value is possible. Furthermore, the corresponding mode shapes are displayed graphically as the result of the stability analysis.
For the stability analysis, an adapted surface model is used to specifically recognize the local buckling shapes. The model of the stability analysis, including the results, can also be saved and used as a separate model file.
- Is it possible to display the deformation analysis of a surface (limit 0.5‰)?
- 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?