Four-Story Timber Structure in St. Georgen, Germany
The EGT Group’s new St. Georgen location was to have a future-oriented design, taking into consideration 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
No concrete core was even used in the project, for structural stability. The structure’s stiffness comes exclusively from its 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 underground reinforced concrete floor. A total of 45 bored piles with a maximum length of 59 ft further support the foundation.
The underground floor area is approximately 102 ft x 82 ft while the aboveground 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 the most realistic 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 the ground-floor cross-laminated timber end walls. The walls are welded adjacently with steel anchors.
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In this article, the adequacy of a 2x4 dimension lumber subject to combined bi-axial bending and axial compression is verified using RF-/TIMBER AWC add-on module. The beam-column properties and loading are based on example E1.8 of AWC Structural Wood Design Examples 2015/2018.
RFEM/RSTAB add-on module RF-/TIMBER AWC | Design of members made of timber according to ANSI/AWC NDS-2015 (US standard)
RFEM/RSTAB add-on module RF-/JOINTS Timber-Timber to Timber | Design of direct timber connections according to Eurocode 5
RFEM/RSTAB add-on module RF-/TIMBER SANS | Design of members made of timber according to SANS 10163 (South African standard)
RFEM/RSTAB add-on module RF-/TIMBER CSA | Design of members made of timber according to CSA 086 (Canadian standard)
- 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
- Can I use RFEM to calculate a log house three-dimensionally?
- How do I display some results of all load cases in the printout report, but other results of the selected load cases only?
- I would like to carry out the flexural buckling design for timber components with imperfections and internal forces according to the second-order analysis. Is it sufficient to activate this in Details of the RF‑/TIMBER Pro add-on module or is it necessary to make additional settings?
- Can I design laminated veneer lumber with RFEM/RSTAB?
- How can I calculate a timber-concrete composite floor with cross-laminated timber?
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- Is it possible to save the structures of the manufacturer-specific cross-laminated timber plates in the RF‑LAMINATE add-on module?
- How is it possible to display the main support direction graphically in RF‑LAMINATE?
- Is it possible to create a second design case in RF‑LAMINATE?
- I have a model of a timber building, which I have transferred from Scia Engineer and adapted it into the RFEM program. The models should be the same; however, it can only be calculated in Scia Engineer while RFEM reports singularity. How do I edit the model to analyze it in RFEM?
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