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