Four-Story Timber Structure in St. Georgen, Germany
The EGT Group’s new St. Georgen location was to be future-oriented designed considering both energy efficiency and sustainability. The new four-story oval building consists mainly of timber and was constructed in just four short weeks.
EGT Energy GmbH, Triberg, Germany
Ketterer Architects, Konigsfeld-Neuhausen, Germany
Isenmann Ingenieur GmbH, Haslach/VS-Villingen, Germany
Holzbau Bendler, Nordrach
A concrete core was not even used in the project for structure stability. The structure’s stiffness comes exclusively from the solid cross-laminated timber walls.
Isenmann Ingenieur GmbH located in Haslach performed the structural static and dynamic analysis of the timber building in RFEM.
Structure and Seismic Analysis
The four-story timber structure is built on an under-ground reinforced concrete floor. A total of 45 bored piles with a maximum length of 59 ft further support the foundation.
The below-ground floor area is approx. 102 ft x 82 ft while the above-ground floors are 82 ft x 69 ft. The maximum height of the timber structure is 49 ft 4 in.
The building is located in seismic zone 1. Preliminary calculations confirmed seismic forces governed for the lateral design. Therefore, a modal analysis was performed on the 3D model in RFEM. In the calculation model, the individual components’ stiffnesses were set to a realistic as possible value.
For earthquake analyses, timber construction behaves more favorably than reinforced concrete structures. The acceleration design value is lower while the decreased mass has a beneficial effect on the calculated seismic forces.
To counteract the tensile forces, welded plates were added to ground floor cross-laminated timber end walls. The walls are welded adjacently with steel anchors.
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- General stress analysis
- Graphical and numerical results of stresses and stress ratios fully integrated in RFEM
- Flexible design with different layer compositions
- High efficiency due to few entries required
- Flexibility due to detailed setting options for calculation basis and extent
- Based on the selected material model and the layers contained, a local overall stiffness matrix of the surface in RFEM is generated. The following material models are available:
- Hybrid (for combinations of material models)
- Option to save frequently used layer structures in a database
- Determination of basic, shear and equivalent stresses
- In addition to the basic stresses, the required stresses according to DIN EN 1995-1-1 and the interaction of those stresses are available as results.
- Stress analysis for structural parts of almost any shape
- Equivalent stresses calculated according to different approaches:
- Shape modification hypothesis (von Mises)
- Maximum shear stress criterion (Tresca)
- Maximum principal stress criterion (Rankine)
- Principal strain criterion (Bach)
- Calculation of transversal shear stresses according to Mindlin, Kirchhoff, or user-defined specifications
- Serviceability limit state design by checking surface displacements
- User-defined specifications of limit deflections
- Possibility to consider layer coupling
- Detailed results of individual stress components and ratios in tables and graphics
- Results of stresses for each layer in the model
- Parts list of designed surfaces
- Possible coupling of layers entirely without shear
- How can I create a curved or arched section?
- How are the signs for the release results of a line release and line hinges interpreted?
- After the design with RF‑/TIMBER Pro, I optimized a cross-section. Why is the utilization of the optimized cross-section exceeded now?
- Is it possible to design the support pressure or the compression perpendicular to the grain in RX‑TIMBER?
- Why are the stresses of the 90° orientation not displayed for a layer with the orthotropy direction 90° for σb,90 in RF‑LAMINATE?
- How can I get the member end forces to design the connections?
- I design timber components. The deformations of load combinations deviate from the manual calculation exactly by the factor of the material partial safety factor. Why?
- How can I run the RX‑TIMBER Frame plugin? I did not find it in the Add-on Modules menu nor in Project Navigator - Data.
- I have a question about the results of the serviceability limit state design: How is the increment of the dead load by the factor 1.8 and the imposed load by 1.48 explained in the result combinations for the SLS design?
- Where can I adjust the effective length lef according to Table 6.1 of Eurocode 5 in the TIMBER Pro add-on module?
Programs Used for Structural Analysis
Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements
Dynamic analysis of natural frequencies and mode shapes of member, surface, and solid models
Seismic and static load analysis using the multi-modal response spectrum analysis
Design of steel members according to Eurocode 3