Author
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Dalel Daleyev
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University
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Vienna University of Technology, Austria
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I-Joists in Timber - Discussion of Current Design Practice and Implementation in Structural Analysis Software
Finnjoists or I-joists are optimized composite beams with an I-section made of timber materials, where the flanges are made of laminated veneer lumber (LVL) and the web of OSB. The cross-section elements are glued together. The components can be used as a beam or a column. In this bachelor thesis, the simplified design practice of the European Technical Approval ETA 02/0026, based on the limit internal forces, is compared with the more general design practice according to ÖNORM B 1995‑1‑1:2019, based on the limit stresses, and checked for consistency of the results.
![FE Model of Steel Connection](/en/webimage/052000/4028239/1.png?mw=512&hash=9d7f6c198b6d4ae6ee8f2fa8bca75f85579e14c9)
![Timber Panel Wall Stiffnesses](/en/webimage/049956/3893282/49956.png?mw=512&hash=8dfc2b6d0af6ade74073e21655c6a73a34a77751)
![KB 001875 | AISC 341-22 Moment Frame Member Design in RFEM 6](/en/webimage/047794/3736755/im01.jpg?mw=512&hash=33697d419a0e8a96b738e8e2e97fae057743a108)
![Feature 002870 | Charring Diagram](/en/webimage/052232/4048985/Abbrand.png?mw=512&hash=0333d7e95677edbc27ef88041e376cbb561c1140)
For the fire resistance design of timber surfaces, you can display a charring diagram depending on the time of fire exposure.
It is also possible to print this charring diagram into the printout report.
![Feature 002825 | Shear Walls and Deep Beams Consisting of Members](/en/webimage/050709/3925056/50709.png?mw=512&hash=8e57b70946dcc367584aee1ee2d82b3efafa652f)
When generating shear walls and deep beams, you can assign not only surfaces and cells, but also members.
![Feature 002824 | OSB Material for USA and Canada](/en/webimage/050460/3955503/2024-06-28_10-42-39.png?mw=512&hash=5ec86ff7955d8c9a50e53301df3f21fceda009a5)
In RFEM, the oriented strand board (OSB) material is available for the USA and Canada. The material parameters are taken from the "Panel Design Specification manual".
![Feature 002792 | Timber Panel Element](/en/webimage/048109/3767848/2024-03-14_13-56-20.png?mw=512&hash=c2c60498cb42f6ae62fb1ccfea4928bacda0d865)
Using the "Beam Panel" thickness type, you can model timber panel elements in 3D space. Simply specify the surface geometry and the timber panel elements are automatically generated using an internal member-surface construct, including the element connection stiffness. The Beam Panel thickness type is defined using the Multilayer Surfaces add-on.
A "beam panel" provides you with the following advantages:
- Single-sided or double-sided sheathing
- Automatic calculation of a semi-rigid coupling between studs and sheathing
- Nailed sheathing connection
- Stapled sheathing connection
- User-defined sheathing connection
- Representation as a complete geometric 3D object (frame, studs, surface, etc.), including eccentricity and automatically calculated stiffness between elements
- Consider openings via surface cells
- Design of the individual structural elements utilizing the Timber Design add-on (full shear wall design planned for a future release)
- Other material options available (e.g., particle board, gypsum, or fiberboard sheathing with cold-formed steel sections)