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.
When generating shear walls and deep beams, you can assign not only surfaces and cells, but also members.
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".
Using the "Beam Panel" thickness type, you can model timber panel elements in 3D space. You just specify the surface geometry and the timber panel elements are generated using an internal member-surface construct, including the simulation of the connection flexibility.
The building model is calculated in two phases:
- Global 3D calculation of the global model, where the slabs are modeled as a rigid plane (diaphragm) or as a bending plate
- Local 2D calculation of the individual floors
After the calculation, the results of the columns and walls from the 3D calculation and the results of the slabs from the 2D calculation are combined in a single model. This means that there is no need to switch between the 3D model and the individual 2D models of the slabs. The user only works with one model, saves valuable time, and avoids possible errors in the manual data exchange between the 3D model and the individual 2D ceiling models.
The vertical surfaces in the model can be divided into shear walls and opening lintels. The program automatically generates internal result members from these wall objects, so they can be designed as members according to any standard in the Concrete Design add-on.