Janusz Murzewski, Kraków, Poland
NEW RULES FOR DESIGN OF GUYED MASTS
10th Nordic Steel Construction ConferenceCopenhagen, 7-9 June 20041
NONLINEAR FIRST ORDER THEORY
• Streletski, Moscow,1961
• Petersen, Berlin 1970
• etc.• Old Polish Standard
PN-79/B-03204
SIMPLE SECOND-ORDER THEORY
• Eurocode 3 Steel design. General rules prEN:1997
• Polish Steel Design Standard PN-90/B-03200
ADVANCED SECOND-ORDER THEORY
• European Prestandard prEN 1993-3-1:1997 Towers and masts
• New Polish Standard PN-B-03204:2002
NO-WIND SITUATION
2-nd order parabola 4-th order parabola
false slope
g [kN/m] = const
true slope
G [kN] = const
WINDWARD GUY at ULS2-nd order parabola nearly straight line
W(lo,o) = const W(l,) – non-conservative
LEEWARD GUY at ULS2-nd order parabola Non- analytical curve
SBa - inclined SBa - horizontal
THE ELASTIC SHAFTcontinuous beam free beam-column
() – buckling factor yM(z)+yN(z) - amplification
UNCERTAIN INNOVATIONS prENV 1993-3-1:1997(who?) PN-B-3204:2002 (A.Cz.)
Wind patch loading
MW=Mm+Mp -global effect
Geometrical imperfections
yi=li/250 - to be amplified
CONCLUSIONS I
• Out-of-plumb is the main reason of non-linear behaviour
• Normal-to-the-shaft component of gravity loads G sin
• Moment of external forces at the bottom hinge M0 = 0
CONCLUSIONS II
• Non-linear behaviour of the windward guy – not important
• Deformation of leeward guy needs not to be analysed
• The mast at the ULS is statically determined
CONCLUSIONS III
• If there are degrees of freedom of the analysis, initial tensions of guys may be optimised
• The mass of guys remains constant during deformation
• Patch load procedure and geometrical imperfections shall be verified
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