Intelligent Roof Truss Digitalization of the building Process
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Modellbyggare
Tidskriftstitel
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Volymtitel
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Sammanfattning
Sweden has a big market for different wood and timber products, but the raw material
usage still can be improved and optimized to its full strength and potential. The modern
building and construction industry uses wood according to its specified property values
in the different strength classes. However, it is well known that wood has a considerable
natural variability in its properties. In the grading process, the fifth percentile value,
also called the characteristic value, is used to declare and specify the properties in the
respective class of the structural wood member. This means that in a batch of wood
members from a strength class, 95% of all the members have a strength value above the
specified characteristic value. This aspect and uncertainty of the actual strength of an
individual timber member is considered in the calibration of safety factors in the design
standards, which aim at a certain target reliability. In this thesis the potential of using
the knowledge of the updated and actual material properties of the individual wood
members in the design and assembly process of structures in order to increase safety
and enhance resource efficiency is studied. So far truss builders don't use the results
and knowledge from the grading process they determined for each single piece of wood.
Instead, they only use the characteristic values from the strength class. Instead, in the
design and assembly process of structures, the members can be allocated in the structure
according to their actual properties, which can be used to increase the safety. In places
with more demands in terms of strength the wood members with the highest actual
strength values can be used, and in places with lower demands wood with lower actual
strength is used. In this thesis, this process is simulated in models in the software
MATLAB and RFEM and the probability of failure is determined. The results show
that the probability of failure can be reduced by using the updated knowledge of the
individual property values of each wood member instead of the characteristic value
only. The raw material saving potential for a more recourse efficient construction is
evaluated.
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Key words: Fink timber truss, grading of timber, characteristics value, structural reliability, probability of failure