4结构设计原理

1、结构设计四分之一高度构造设定修正的原理astructuralengineeringprojectcanbedividedintothreephases :规划、设计和构建。structuraldesigninvolvesdeterminingthemostsuitableproportionsofastructureanddimensioningthestructuralelementsanddetailsofwhich 确定结构最佳的比例尺寸，确定主要构件和细节的尺寸) thisisthemosthighlytechnicalandmathematicalphaseofastructural

2、engineeringproject。 butitcannotandcertainlyshouldnot-beconductedwithoutbeingfullycoordinatedwitheplanningandconstructionphasesoftheproject。 是项目工程中技术最高、数学严密性最强的阶段，但与修订和施工阶段完全协调，不能合作就不应该付诸实行)。 thesuccessfuldesignerisatalltimesfullyconsciousofthevariousconsiderationsthatwereinvolvedinthepreliminaryplan

3、ningforthestructu ofthevariousproblemsthatmaylaterbeencounteredinitsconstruction特别是， thestructuraldesignofanystructurefirstinvolvestheestablishmentoftheloadingandotherdesignconditionsthatmustberesistedbythestruc ndthereforemustbeconsideredinitsdesign.(结构设置修订需要首先确定结构所需的载荷和其他设置修订条件。 他们是结构设定修订的必要条件) th

4、encomestheanalysis (or computation ) oftheinternalgrossforces (thrust、shears、bending moments )。 失真实践、失真、选择、和重定向按加载、临时、链接、创建， or other design conditions.(然后分析在负荷、温度、收缩、徐变及其他设定修正条件下由结构产生的总内力(轴力、剪切力、玩具、扭矩)、应力强度、应变、变形及反作用力) finallycomesproportioningandselectionofmaterialsofthembersandconnectionssoastore

5、sistadequatelytheeffectsproducedbythedesignc 的尺寸，由于抵抗选择那个材料的设定修正条件的作用) thecriteriausedtojudgewhetherparticularproportionswillresultinthedesiredbehaviorreflectaccumulatedknowledge现场和模型测试， 与实践行为)，实践， and judgement直观判别的方法) formostcommoncivilengineeringstructuressuchasbridgesandbuildings， theusualpracti

6、ceinthepasthasbeentodesignonthebasisofacomparisonofallowablestressintensitieswithoseproducedbytheserviceload inn ditions.(在桥梁和房屋等最一般的土木工程构造中，将许用应力与使用负荷和其他的设定修正条件下产生的应力进行比较是过去最一般的，并且根据它进行设定修正)。 thistraditionalbasisfordesigniscalledelasticdesignbecausetheallowablestressintensitiesarechoseninaccordance

7、withtheconceptthatttthatt pondingtotheyieldpointofthematerialshouldnotbeededatthemosthighlystressedpointsofthestructure.(原因选择是， 此类传统设置修订基础被称为柔性设置修订) of course theselectionoftheallowablestressesmayalsobemod orbrittlefractureorbyconsiderationofthepermissibledeflectionsofthestructuredependingonthetypeo

8、fstructureandtheconditionsinvolved是指： thestressintensitiescomputedbintheanalyticalmodeloftheactualstructurefortheassumeddesignconditionsmayormaynotbeincloseagreemen esproducedinactualstructurebytheactualconditionstowhichitisexposed .按设想的设定修正条件修正的应力强度和实际的结构在实际的条件下产生的应力强度可能一致或不一致thedegreeofcorresponde

9、nceisnotimportant，providedthatthecomputedstressintensitiescanbeinterpretedintermsofpreviousexperience. theselectionoftheserviceconditionsandallowablestressintensitiesprovidesamarginofsafetyagainstfailure.theselectionofthemagnitu hedegreeofuncertaintyregardingloading、analysis、design、materials、andcons

10、tructionandontheconsequencesoffailure.(储备量值的选择为相关负荷取决于施工和失效结果不真实自我的程度) For example，ifanallowabletensilestressof 20000 pisselectedforstructuralsteelwithayieldstressof 33000 psi。 themarginofsafety (orfactorofsafety ) providedagainsttensileyieldingis 33000/20000，或or 1.65.(例如，在结构钢的情况下，屈服应力为330 )the allo

11、wable-stressapproachasanimportantdisadvantageinthatitdoesnotprovideauniformoverloadcapacityforallpartsandalltypesoos c As a result，thereistodayarapidlygrowingtendencytobasethedesignontheultimatestrengthandserviceability witholderallowable-stressapproachservingasanalternativebasisfordesign .由此，基于以往的容

12、许应力法的设定修正只是可选方案之一)。 thenewerapproachcurrentlygoesunderthenameofstrengthdesigninreinforced-concretedesignliteratureandplasticdesigninsteel -。 ture.(最新的设定修正方法在钢筋混凝土设定修正规范中称为强度设定修正，在铁元素骨设定修正规范中称为塑性设定修正) whenproportioningisdoneonthestrengthbasis， theanticipatedserviceloadingisfirstmultipliedbyasuitablel

13、oadfactor (greater than1)、themagnitudeofwhichdependsupontheuncertainty 可持续发展转换基础架构、与、加载组合、likelihood、frequency， anddurationoftheparticularcombination .结构服务期间发生变化的可能性和荷载组合中各负荷的相似性、出现频率及其特殊组合的持续时间) inthisapproachforreinforced-concrete design thetheoreticalcapacityofastructuralelementisreducedbyacapacity-reductionfactortoprovideforsmalladversevariationsinmaterial hs thestructureisthenproportts dependingonthegove