高强度钢材轴心受压构件整体稳定性能与设计方法研究_班慧勇

中国钢材供求网高强度钢材轴心受压构件整体稳定性能与设计方法研究(申请清华大学工学博士学位论文)培养单位：土木工程系学科：土木工程研究生：班慧勇指导教师：石永久教授二○一二年五月ResearchontheOverallBucklingBehaviorandDesignMethodofHighStrengthSteelColumnsunderAxialCompressionDissertationSubmittedtoTsinghuaUniversityinpartialfulfillmentoftherequirementforthedegreeofDoctorofPhilosophyinCivilEngineeringbyBanHuiyongDissertationSupervisor:ProfessorShiYongjiuMay,2012摘要I摘要随着生产和加工工艺的不断提高，高强度钢材钢结构已经开始在国内外建筑和桥梁结构工程中得到应用，并取得了良好的效益。由于在材料力学性能、加工工艺、初始缺陷影响等方面的差别，高强度结构钢材构件的整体稳定性能与普通强度钢材有明显不同；相关的研究工作国外刚刚起步且数量很少，国内还未开展研究。我国现行钢结构设计规范允许使用最高强度等级为420MPa的结构钢材，相应设计条款均基于普通强度钢材的研究制定，这不利于高强度钢材钢结构优势的发挥。本文紧密结合我国目前钢结构设计规范的修订工作，通过大量的试验研究、数值计算和理论分析，全面、深入地研究了高强度钢材轴心受压构件的整体稳定性能，并提出了设计方法和计算公式；本文主要完成了以下几方面工作：（1）截面残余应力分布是研究构件整体稳定性能的最重要前提条件；本文采用分割法，测量了3种强度等级高强度钢材（420MPa、460MPa、960MPa）、3类截面（热轧等边角钢、焊接工字形和箱形截面）、共计35个试件的残余应力全截面分布；系统地研究了板件宽厚比、板件厚度、焊缝类型、人为测量误差、钢材强度、截面板件相关性等因素对残余应力分布的影响。（2）基于本文的试验研究，并结合国内外大量实测数据，提出了针对不同强度等级钢材和不同截面类型的完整的残余应力分布模型，准确考虑了截面尺寸对残余应力数值的影响，并提出了详细的计算公式，为构件稳定性研究奠定了基础。（3）进行了3种强度等级高强度钢材、3类截面、共计84个轴心受压构件的整体稳定性能静力加载试验，研究了其失稳破坏形态和稳定承载力。（4）建立了能够准确考虑几何初始缺陷和残余应力影响的有限元数值模型，中国钢材供求网并通过与本文及其他试验对比，验证了模型的可靠性和准确性；通过大量参数分析，研究了几何初始缺陷、残余应力、钢材材料力学性能等因素对高强度钢材轴压构件整体稳定性能的影响。（5）计算了不同强度等级共计930个钢柱的整体稳定系数，通过与国内外主要钢结构设计规范对比，建议了高强度钢材轴压构件柱子曲线类型的选取，并提出了新的柱子曲线，同时基于我国现行规范设计方法提出了能够反映钢材强度影响的修正系数计算公式；为工程应用及研究提供了合理、可靠的设计方法。关键词：高强度钢材；残余应力；轴压构件；整体稳定；设计方法AbstractIIAbstractWiththedevelopmentofthesteelproductionandmanufactureprocess,highstrengthsteelstructureshavebeenincreasinglyappliedtobuildingandbridgeconstructionsinrecentyears,duetotheiradvantagesinstructuralsafety,architecturalfunction,economicalbenefitandresourcesavingetc.Theoverallbucklingbehaviorofhighstrengthsteelcompressioncolumnsmaybecharacterizeddifferentlyfromthatofnormalstrengthsteel,becauseoftheirdifferentmaterialproperties,manufacturingprocessesandeffectsfrominitialimperfectionssuchasinitialgeometricdefectandsectionalresidualstresses.However,investigationsonhighstrengthsteelcolumnsinternationallyhavejuststarted,whileinChinathereisnorelevantresearchavailable.ThecurrentdesigncodeforsteelstructuresGB50017-2003inChinaallowstheuseof420MPahighstrengthsteels,andtheoverallbucklingdesignprovisionsforcolumnsinthisstandardaremainlybasedontherelevantresearchesofnormalstrengthsteelstructures,whichisinadequatetomobilisetheadvantageofhighstrengthsteelstructures.Consequently,thesolutiononhighstrengthsteelcolumnsisinurgentneed.AsonepartoftheresearchworkforimprovingcurrentChinesesteelstructuredesigncode,alargeamountofexperimentalandnumericalinvestigationswerecarriedouttostudytheoverallbucklingbehaviorofhighstrengthsteelmembersunderaxialcompressioninthisdissertation,andthedesignmethodandcalculationformulaewereproposed.Themainresearchworkscoveredinthisdissertationinclude:(1)Asoneofthemostimportantprerequisiteforunderstandingthecolumnbucklingbehavior,theresidualstressdistributionandmagnitudeof35differentsectionsweremeasuredbyusingthesectioningmethod,includingthreetypesofsteelgrades(i.e.420MPa,460MPaand960MPa)andthreetypesofsectionshapes(i.e.hot-rolledequallegangle,weldedI-shapeandboxsections).Theeffectsofthewidth-thicknessratio,platethickness,weldtype,humanoperatingerror,steelgrade,interactionamongsectionalcomponentplateswereclarified.(2)Accordingtotheexperimentalinvestigationconductedinthisdissertationaswellasmanyotherresearches,residualstressdistributionmodelsfordifferentsteelgrades(i.e.420MPa,460MPa)andvarioussectiontypes(i.e.hot-rolledequallegangles,AbstractIIIweldedI-shapeandboxsections)wereproposed.Inaddition,theunifiedmodelwhichcanbeappliedtotheabovesteelgradesweldedI-shapeandboxsectionswasalsosuggested.Thedetailedcalculationformulaeforcompressiveresidualstressmagnitudesweregiven,whichcanconsidertheeffectofsectionaldimensions(i.e.width-thickness中国钢材供求网)verywell.(3)Experimentalinvestigationswerecarriedouttoclarifytheoverallbucklingbehaviorof420MPasteelhot-rolledequalleganglecolumns,460MPaand960MPasteelweldedI-shapeandboxsectionmembers.Totally84columnsweretested.Initialimperfectionssuchastheresidualstress,initialbendingandloadingeccentricityweremeasured.Basedontestresultsthebucklingdeformationandcapacitywereinvestigated.(4)Thefiniteelementmodelwasestablished,whichconsideredthegeometricnonlinearproperty,initialgeometricimperfectionandresidualstress.Bycomparingthenumericalsimulationresultswithexperimentalresultsinbothpresentdissertationandotherresearches,thefiniteelementmodelwasvalidated.Alargeamountofparametricanalysiswerecarriedouttoinvestigatetheeffectsfrominitialgeometricimperfections,residualstressestosteelmaterialpropertiessuchastheyieldstrengthandyield-tensilestrengthratio.Itwasindicatedthateffectsofinitialimperfectionswerelesssevereforhighstrengthsteelcolumns,andthusthenondimensionalbucklingstrengthofsuchmembersbecomessignificantlyhigherthanthatofnormalstrengthsteelcolumns.(5)Alargenumberofcolumnswithvarioussectiondimensionsandslendernesswerecalculatedbyusingthefiniteelementmodel,includingthosefabricatedfr