Diaphragm action in modern medium-rise timber/hybrid structures A finite element parametric study of diaphragm response in modern timber/hybrid structures
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Structural engineering and building technology (MPSEB), MSc
Publicerad
2023
Författare
Thornadtsson, Emil
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
In the design of the structural system of a structure, the knowledge of how the
diaphragm distributes the horizontal actions is of essential importance. A diaphragm
can be classified as, rigid, semi-rigid, or flexural, where the classification is
governed by the structural response of the diaphragm. Furthermore, a rigid diaphragm
is characterized by a stiffness distribution of horizontal actions to the later load-
resisting structures, a flexible diaphragm is characterized by the horizontal actions
distributed by tributary area to the later load-resisting structures, and the semi-
rigid classification is characterized by the diaphragm response is a combination of
the rigid and flexural response.
The classification of the diaphragm, however, is not intuitive in timber structures as
there is a variety of variables that influence the response of a timber diaphragm, e.g,
of timber products, timber connections, etc., and the guidance provided by today’s
building regulations is insufficient. Furthermore, guidance in literature is often in
unquantified terms such as - the diaphragm can be considered rigid if the diaphragm
is a lot stiffer than the shear walls, and vice versa for a flexural response.
Hence, this project’s aim is to determine stiffness relation boundaries for a variety of
commonly used timber/TCC diaphragm types, where the influence of stiffness
variations of the structural joints of adjoining element/panels are taken into respect, and
the LLRS, that quantifies if the diaphragm response is flexible, semi-rigid or rigid.
To obtain the aim was a finite element parametric study executed, examining the
diaphragm response under extensive stiffness variations of the later load-resisting
structures. The parametric study was performed in the software FEM-Design, by a
coded C-sharp script that looped analysis with stiffness increment of the LLRS or
the structural joint o a diaphragm.
Obtained results from the parametric study showed that the stiffness of structural
joints in timber diaphragm has a great impact on the overall response and cannot
be neglected in diaphragm analysis. Stiffness relations of the diaphragms and LLRS
to classify the diaphragm response were obtained for the structural floor plan of
Object 1, however, for the structural floor plan of Object 2 were no correlations of
stiffness relations found. Finally, the obtained stiffness relations of the structural
floor plan of Object 1 need further studies to be confirmed.
Beskrivning
Ämne/nyckelord
diaphragm, diaphragm action, in-plane stiffness, parametric stiffness study, stabilization, horizontal load distribution.