Analys of Geometrical Imperfections in Structural Columns
Translated title
Analyse af Geometrisk Imperfektioner i Søjler
Authors
Christensen, Martin ; Roug, Peter
Term
4. term
Education
Publication year
2014
Submitted on
2014-06-10
Pages
63
Abstract
Dette speciale undersøger, hvor meget last slanke IPE160-stålsøjler kan bære, før de bliver ustabile og knækker (global instabilitet). Det kombinerer analytiske beregninger efter den gældende standard DS/EN 1993-1-1:2007 (Eurocode 3) og numeriske simuleringer i softwareprogrammet Abaqus. Undersøgelsen er afgrænset til leddelt understøttede søjler i enakset tryk og omfatter forskellige imperfektioner, dvs. små afvigelser fra den ideelle geometri og belastning. De beregnede bæreevner sammenlignes med publicerede forsøgsdata, og usikkerheder i modellerne kvantificeres. Resultaterne bruges til at bestemme pålidelighedsindeks (et mål for sikkerhedsniveauet) og udlede partialkoefficienter (sikkerhedsfaktorer i normerne) ved hjælp af First-Order Reliability Method (FORM), som verificeres med Monte Carlo-simulering. De foreslåede partialkoefficienter diskuteres og kalibreres, og søjlers opførsel belyses løbende sammen med en historisk og state-of-the-art gennemgang for at vurdere betydningen for gældende normer.
This thesis examines how much load slender IPE160 steel columns can carry before they become unstable and buckle (global instability). It combines analytical calculations in accordance with the current DS/EN 1993-1-1:2007 (Eurocode 3) standard and numerical simulations in the commercial software Abaqus. The study is limited to simply supported columns under uniaxial compression and considers a range of imperfections, meaning small deviations from the ideal geometry and loading. The predicted load capacities are compared with experimental data reported in the literature, and the associated model uncertainties are quantified. These results are then used to compute a reliability index (a measure of safety level) and to derive partial safety factors (code factors used to ensure safety) using the First-Order Reliability Method (FORM), which are verified through Monte Carlo simulation. The proposed partial safety factors are discussed and calibrated, and column behavior is reviewed alongside a brief history and state-of-the-art overview to assess implications for current standards.
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