Supporting Frame Structure for Steeple Renovation in Kerpen, Germany

Customer Project

Structural Engineering Engineering Consultancy Klimpel
Bochum, Germany
www.ib-klimpel.de
Scaffolding Geistert Gerüstbaulogistik GmbH
Duisburg, Germany
www.geistert.de
Investor Katholische Kirchengemeinde St. Martinus
Kerpen, Germany

Length: 10 m | Width: 10 m | Height: 30 m | Weight: ~ 25 t
Nonlinear Effects: Tension and buckling elements, nonlinear member releases
Number of Nodes: 721 | Members: 2,600 | Materials: 1 | Cross-Sections: 6

To perform renovations for the steeple of the St. Martinus parish in Kerpen, Germany, a scaffold was required. It was a part of the construction project with an order volume of approximately € 850,000.

The designers in charge had to meet a special challenge because the frame construction had to be set up at the top of the spire without applying anchorages by pressure usually used in scaffolding.

Furthermore, a coating with covers had been the reason why the frame construction had to be designed without a reduction of wind loads.

The frame was built by means of modular scaffolding, type of polygon with 16 edges of approximately 40 to 60 m and another one with 8 edges of approximately 60 to 70 m.

Structural Analysis

RSTAB was used to design the spatial framework structure. The RSTAB add‑on modules RSBUCK, RSIMP and EL‑PL completed the calculation.

Generating the Structure
First, the structure was modeled in the design software AutoCAD. Then, the data was imported to RSTAB using the DXF interface and the relevant materials were assigned to the individual cross‑sections. The member releases were simulated by nonlinear RSTAB member releases according to building regulations.

Input of Loads
Wind loads were determined according to EC 1 and DIN 1054 T4. The analysis included the approach for a 16‑edge and an 8‑edge structure. Moreover, by way of comparison, the shape of a cylinder was tested.

The load group which was finally decisive resulted from a combination consisting of the self‑weight and the maximum wind load (in scaffolding the partial safety factor γF for load cases is always 1.5).

By using the specific RSTAB function for generating loads it was possible to perform with minimum effort an alternative analysis for different types of wind load applications.

Stability Analysis
The lowest buckling shape was determined with the help of the RSBUCK add‑on module. On the basis of this buckling shape, the RSIMP add‑on module generated automatically imperfections for RSTAB.

The load cases for self‑weight, wind and imperfections were combined together in a load combination which was calculated according to the second‑order analysis. Finally, the elastic‑plastic design was performed.

Programs Used for Structural Analysis

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