Lateral torsional stability of timber beams
Transcript of Lateral torsional stability of timber beams
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Baláž Ivan & Koleková Yvona
Faculty of Civil Engineering
Slovak University of Technology in Bratislava
Slovak Republic, EU
Lateral torsional stability of
timber beams
M2D2015, Ponta Delgada, Azores, 26-30 July 2015
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Lateral Torsional Buckling
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Die Espe Die Birke
ASPEN BIRCH
OSIKA BRZOZA
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LTB of member will occur even if it is
loaded in the plane of minor stiffness
when point of load application is too
high over shear center
This phenomenon is called „mosquito wings“ effect
.
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Structure magazine, February 2008
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Elastic critical moment Mcr
„fork“ boundary conditions, uniform bending moment M,
uniform nonwarping cross-section: warping stiffness EIw= 0 kNm4
L
GIEIM
tz
cr
EIz bending stiffness
GIt torsional stiffness
L span
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Taking into account all influences
L
GIEIM
tz
cr
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C1, C2, C3 are coefficients depending on
type of loading and boundary conditions
For symmetric cross-section to axis y-y is zj = 0
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ENV 1993-1-1, ENV 1999-1-1
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ENV 1993-1-1, ENV 1999-1-1
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Cantilever
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EN 1999-1-1 EN 1995-1-1
steel + alumunium timber
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X =
X =
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F at the free end of the cantilver
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CONCLUSION
Harmonization and unification of rules
of metal (steel, aluminium) and timber
Eurocodes, if it is reasonable,
will be good for everybody
especially for designers in practice.
Shortening of Eurocodes is desirable.
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Thank for agreeing with us