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Olli Ilveskoski
METNET International workshopVilnius, LithuaniaWednesday 13th and Thursday 14th March
BRACING OF MULTIPLE STRUCTURES
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Olli Ilveskoski
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Olli Ilveskoski
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FASTNER STRENGHTSSTIFFENESS VALUES ?
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FastenersSelf-drilling:• for hot-rolled structure (walls' thickness – 3-12 mm),• for cold-bent structure (thickness – 1.5-5 mm).Note: fasteners are available in galvanized or lacquered -white versions. On special demand it is possible to providehoods or fasteners in external facing colour of a sandwichpanel.
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BEAM BUCKLING FLOW CHART
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COLUMN BUCKLING FLOW CHART
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BUCKLING RESTRAINT FORCE FLOW CHART
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SECTION CLASS
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RESISTANCES
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RESISTANCES
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BUCKLING RESISTANCE
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RESTRAINT SEGMENTS
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(3)B At each plastic hinge location, the connection (e.g. bolts) of the compression flange to the resisting element at that point (e.g. purlin), and any intermediate element (e.g. diagonal brace) should be designed to resist a local force equal to 2,5% of Nf,Ed (defined in 6.3.5.2(5)B) transmitted by the flange in its plane and perpendicular to the web plane, without any combination with other loads.
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NO RESTRAINT CONNECTION STIFFNESS REQUIREMENT IN EUROCODE ?
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CHENG & JURA / AISC: RESTRAINT STIFFNESS REQUIREMENT
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CONCLUSION: BEAM BUCKLING RESULTS
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COLUMN BUCKLING RESISTANCES
Nrdy = 709 kN stronger direction
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COLUMN BUCKLING RESISTANCES
Nbrdz = 453 kN weaker direction, Buckling restraint segment 2m, ifno restraints Nbrdz = 155 kN < Ned
BUCKLING TAKES PLACE !
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INTERACTION FORMULAS
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COLUMN’S BRACING CONNECTION FORCES AND CONNECTION STIFFENESS REQUIREMENTS ?
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COLUMN DESIGN RESULTS CONNECTION FORCES AND CONNECTION STIFFENESS REQUIREMENTS ?SANDWHICH PANEL BRACING ?
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CONNECTION STIFFENESS REQUIREMENT
CONNECTION STIFFENESS VALUE
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CONNECTION STIFFNESS REQUIREMENT / NODAL RESTRAINTKortesmaa / VTT
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FOR N EQUALLY SPACED BRACES RECOMMENDED STIFFNESSCheng & Jura
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CONNECTION STIFFNESS REQUIREMENT / CONTINUOS RESTRAINTCheng & Jura
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CONCLUSIONS:
BRACING DESIGN REQUIRES A TOTAL APPROACH
BEAM / COLUMN BRACING RESTRAINT FORCES AND STIFFENESS VALUES MISS COMMON PRACTISE ?
CONNECTION STIFFNESS PLAYS A ROLE ?
BRACING WITH SANDWHICH – PANELS ?
FASTNER’S STIFFNESS PROPERTIES ?
AVERAGE DESIGNER NEEDS MORE CLEAR TOOLS