工程造价外文及翻译

TheCostofBuildingStructureIntroductionTheartofarchitecturaldesignwascharacterizedasoneofdealingcomprehensivelywithacomplexsetofphysicalandnonphysicaldesigndeterminants.Structuralconsiderationswerecastasimportantphysicaldeterminantsthatshouldbedealtwithinahierarchicalfashioniftheyaretohaveasignificantimpactonspatialorganizationandenvironmentalcontroldesignthinking.Theeconomicalaspectofbuildingrepresentsanonphysicalstructuralconsiderationthat,infinalanalysis,mustalsobeconsideredimportant.Costconsiderationsareincertainwaysaconstrainttocreativedesign.Butthisneednotbeso.Ifsomethingisknownoftherelationshipbetweenstructuralandconstructivedesignoptionsandtheircostofimplementation,itisreasonabletobelievethatcreativitycanbeenhanced.Thishasbeenconfirmedbytheauthors'observationthatmostenhanced.Thishasbeenconfirmedbytheauthors'observationthatmostcreativedesigninnovationssucceedundercompetitivebiddingandnotbecauseofunusualowneraffluenceasthefewpublicizedcasesofextravagancemightleadonetobelieve.Onecouldevensaythatadesignerwhoistrulycreativewillproducearchitecturalexcellencewithintheconstraintsofeconomy.Especiallytoday,wefindthatthereisaneedtorecognizethateleganceandeconomycanbecomesynonymousconcepts.Therefore,inthischapterwewillsetforthabriefexplanationoftheparametersofcostanalysisandthemeansbywhichdesignersmayevaluatetheoveralleconomicimplicationsoftheirstructuralandarchitecturaldesignthinking.Thecostofstructurealonecanbemeasuredrelativetothetotalcostofbuildingconstruction.Or,sincethetotalconstructioncostisbutapartofatotalprojectcost,onecouldincludeadditionalconsiderationforland(10〜20percent),financeandinterest(100〜200percent),taxesandmaintenancecosts(ontheorderof20percent).Butadiscussionoftheseso-calledarchitecturalcostsisbeyondthescopeofthisbook,andwewillfocusonthecostofconstructiononly.文档资料WordOntheaverage,purelystructuralcostsaccountforabout25percentoftotalconstructioncosts,Thisissobecauseithasbeentraditionaltodiscriminatebetweenpurelystructuralandotherso-calledarchitecturalcostsofconstruction.Thus,intraditionwefindthatarchitecturalcostshavebeentakentobethosethatarenotnecessaryforthestructuralstrengthandphysicalintegrityofabuildingdesign.“Essentialservices”formsathirdconstructioncostcategoryandreferstotheprovisionofmechanicalandelectricalequipmentandotherservicesystems.Ontheaverage,theseservicecostsaccountforsome15to30percentofthetotalconstructioncost,dependingonthetypeofbuilding.Mechanicalandelectricalreferstothecostofprovidingforair-conditioningequipmentandhemeansonairdistributionaswellasotherservices,suchasplumbing,communications,andelectricallightandpower.Thesalientpointisthatthisbreakdownofcostssuggeststhat,uptonow,anaverageofabout45to60percentofthetotalcostofconstructingatypicaldesignsolutioncouldbeconsideredasarchitectural.Butthispictureisrapidlychanging.Withhighinterestcostsandascarcityofcapital,clientgroupsaredemandingleanerdesigns.Therefore,onemayconcludethattherearetwoapproachesthedesignermaytaketowardsinfluencingtheconstructioncostofbuilding.Thefirstapproachtocostefficiencyistoconsiderthatwhereverarchitecturalandstructuralsolutionscanbeachievedsimultaneously,apotentialforeconomyisevident.Sincecurrenttrendsindicateareluctancetoallocatelargeportionsofaconstructionbudgettopurelyarchitecturalcosts,thisapproachseemsalogicalnecessity.But,evenwheremoneyisavailable,anyuseofstructuretoplayabasicarchitecturalrolewillallowthenonstructuralbudgettobeappliedtofulfillotherarchitecturalneedsthatmightnormallyhavetobeappliedtofulfillotherarchitecturalneedsthatmightnormallyhavetobecutback.Thesecondapproachachieveseconomythroughanintegrationofserviceandstructuralsubsystemstoroundoutone'sefforttoproduceatotalarchitecturalsolutiontoabuildingdesignproblem.Thefinalpricingofaprojectbytheconstructororcontractorusually文档资料Wordtakesadifferentform.Thecostsarebrokendowninto(1)costofmaterialsbroughttothesite,(2)costoflaborinvolvedineveryphaseoftheconstructionprocess,(3)costofequipmentpurchasedorrentedfortheproject,(4)costofmanagementandoverhead,and(5)profit.Thearchitectorengineerseldomfollowssuchanaccuratepathbutshouldperhapskeepinmindhowtheactualcostofastructureisfinallypricedandmadeup.Thus,thepercentaveragesstatedaboveareobviouslycrude,buttheycansufficetointroducethenatureofthecostpicture.Thefollowingsectionswilldiscusstherangeoftheseaveragesandthenproceedtoadiscussionofsquarefootagecostsandvolume-basedestimatesforuseinroughapproximationofthecostofbuildingastructuralsystem.PercentageEstimatesThetypeofbuildingprojectmayindicatetherangeofpercentagesthatcanbeallocatedtostructuralandothercosts.Asmightbeexpected,highlydecorativeorsymbolicbuildingswouldnormallydemandthelowestpercentageofstructuralcostsascomparedtototalconstructioncost.Inthiscasethestructuralcostsmightdropto10〜15percentofthetotalbuildingcostbecausemoremoneyisallocatedtotheso-calledarchitecturalcosts.Onceagainthisimpliesthatthesymboliccomponentsareconceivedindependentofbasicstructuralrequirements.However,wherestructureandsymbolismaremore-or-lesssynthesized,aswithachurchorCathedral,thestructuralsystemcostcanbeexpectedtobesomewhathigher,say,15and20percent(ormore).Attheotherendofthecostscalearetheverysimpleandnonsymbolicindustrialbuildings,suchaswarehousesandgarages.Inthesecases,thenonstructuralsystems,suchasinteriorpartitionwallsandceilings,aswillasmechanicalsystems,arenormallyminimal,asisdecoration,andthereforethestructuralcostscanaccountfor60to70percent,even80percentofthetotalcostofconstruction.Buildingssuchasmedium-riseofficeandapartmentbuildings(5〜10stories)occupythemedianpositiononacostscaleatabout25percentforstructure.Lowandshort-spanbuildingsforcommerceandhousing,say,ofthreeorfourstoriesandwithspansofsome20or30ftandsimple文档资料Worderectionrequirements,willyieldstructuralcostsof15〜20percentoftotalbuildingcost.Special-performancebuildings,suchaslaboratoriesandhospitals,representanothercategory.Theycanrequirelongspansandamorethanaverageportionofthetotalcostswillbeallocatedtoservices(i.e.,30〜50percent),withabout20percentgoingforthepurelystructuralcosts.Tallofficebuilding(15storiesormore)and/orlong-spanbuildings(say,50to60ft)canrequireahigherpercentageforstructuralcosts(about30to35percentofthetotalconstructioncosts),withabout30to40percentallocatedtoservices.Inmycase,thesepercentagesaretypicalandcanbeconsideredasameasureofaverageefficiencyindesignofbuildings.Forexample,ifalow,short-spanandnonmonumentalbuildingweretobebidat30percentforthestructurealone,onecouldassumethatthestructuraldesignmaybecomparativelyuneconomical.Ontheotherhand,thearchitectshouldbeawareoftheconfusingfactthateconomicalbidsdependonthepracticalabilityofboththedesignerandthecontractortointerpretthedesignandconstructionrequirementssothatalowbidwillensue.Progressinstructuraldesignisoftenlimitedmorebythedesigner'sorcontractor'slackofexperience,imagination,andabsenceofcommunicationthanbytheideaofthedesign.Ifacontractorisuncertain,hewilladdcoststohedgetheriskhewillbetaking.Itisforthisreasonthatboththearchitectandtheengineershouldbewell-versedintheareaofconstructionpotentialsifinnovativedesignsatetobecompetitivelybid.Attheleastthearchitectmustbecapableofworkingcloselywithimaginativestructuralengineers,contractorsandevenfabricatorswhereverpossibleevenifthearchitectureisveryordinary.Efficiencyalwaysrequiresknowledgeandaboveallimagination,andtheseareessentialwhendesignsareunfamiliar.Theforegoingpercentagescanbehelpfulinapproximatingtotalconstructioncostsiftheassumptionismadethatstructuraldesignisatleastofaverage(oftypical)efficiency.Forexample,ifatotalofficebuildingconstructioncostbudgetis$5,000,000,and25percentisthe“standard”tobeusedforstructure,aprojectedstructuralsystem文档资料Wordshouldcostnomorethan$1,250,000.Ifaveryefficientdesignwererealized,say,at80percentofwhatwouldbegivenbythea”“average”efficientdesignestimatestatedabovethesavings,(20percent),wouldthenbe$250,000or5percentoftotalconstructioncosts$5,000,000.Ifthe$5,000,000figureiscommitted,thenthesavingsof$250,000couldbeappliedtoexpandthebudgetfor“other”costs.Allthissuggeststhatcreativeintegrationofstructural(andmechanicalandelectrical)designwiththetotalarchitecturaldesignconceptcanresultineitherareductioninpurelyconstructiondesignconceptcanresultineitherareductioninpurelyconstructioncostsormorearchitectureforthesamecost.Thus,thedegreeofsuccesspossibledependsonknowledge,cleverness,andinsightfulcollaborationofthedesignersandcontractors.Theabovediscussionisonlymeanttogivethereaderanoverallperspectiveontotalconstructioncosts.Thefollowingsectionswillnowfurnishthemeansforestimatingthecostofstructurealone.Twoalternativemeanswillbeprovidedformakinganapproximatestructuralcostestimate:oneonasquarefootofbuildingbasis,andanotheronvolumesofstructuralmaterialsused.Suchcostscanthenbeusedtogetaroughideaoftotalcostbyreferringtothe“standards”forefficientdesigngivenabove.Atbest,thiswillbeacrudemeasure,butitishopedthatthereaderwillfindthatitmakeshimsomewhatfamiliarwiththetypeofrealeconomicproblemsthatresponsibledesignersmustdealwith.Attheleast,thiscapabilitywillbeusefulincomparingalternativesystemsforthepurposeofdeterminingtheirrelativecostefficiency.Square-footEstimatingAsbefore,itispossibletoempiricallydeterminea“standard”per-square-footcostfactorbasedontheaverageofcostsforsimilarconstructionatagivenplaceandtime.more-or-lessefficientdesignsarepossible,dependingontheabilityofthedesignerandcontractortousematerialsandlaborefficiently,andvaryfromtheaverage.Therangeofsquare-footcostsfor“normal”structuralsystemsis$10to$16psf.Forexample,typicalofficebuildingsaveragebetween$12and$16psf,andapartment-typestructuresrangefrom$10to$文档资料Word14.Ineachcase,thelowerpartoftherangereferstoshortspansandlowbuildings,whereastheupperportionreferstolongerspansandmoderatelytallbuildings.Ordinaryindustrialstructuresaresimpleandnormallyproducesquare-footcostsrangingfrom$10to$14,aswiththemoretypicalapartmentbuilding.Althoughthespansforindustrialstructuresaregenerallylongerthanthoseforapartmentbuildings,andtheloadsheavier,theycommonlyhavefewercomplexitiesaswellasfewerinteriorwalls,partitions,ceilingrequirements,andtheyarenottall.Inotherwords,simplicityofdesignanderectioncanoffsettheadditionalcostforlongerspanlengthsandheavierloadsinindustrialbuildings.Ofcoursethereareexceptionstotheseaverages.Thelimitsofvariationdependonasystem'scomplexity,spanlengthover“-1”“normal”andspecialloadingorfoundationconditions.Forexample,theCrownZellerbachhigh-risebankandofficebuildinginSanFranciscoisanexception,sinceitsstructuralcostswereunusuallyhigh.However,inthiscase,theuseof60ftsteelspansandfree-standingcolumnsatthebottom,whichcarrytheconsiderableearthquakeloading,aswellasthespecialfoundationassociatedwiththepoorSanFranciscosoilconditions,contributedtotheexceptionallyhighcosts.Thedesignwasalsounusualforitstimeandadecisionhadbeenmadetoallowhigherthannormalcostsforallaspectsofthebuildingtoachieveopenspacesandforbothfunctionandsymbolicreasons.Hencetheproportionofstructuraltototalcostprobablyremainedsimilartoordinarybuildings.Theeffectofspanslongerthannormalcanbefurtherillustrated.The“usual”floorspanrangeisasfollows:forapartmentbuildings,16to25ft;forofficebuildings,20to30ft;forindustrialbuildings,25to30ftloadedheavilyat200to300psf;andgarage-typestructuresspan,50to60ft,carryingrelativelylight(5CH75psf)loads(i.e.,similartothoseforapartmentandofficestructures).wherethesespansaredoubled,thestructuralcostscanbeexpectedtoriseabout20to30percent.Toincreasedloadinginthecaseofindustrialbuildingsoffersanotherinsightintothedependencyofcostestimateson“usual”standards.Iftheloadinginanindustrialbuildingweretobeincreasedto500psf(i.e.,文档资料Wordtwoorthreetimes),theadditionalstructuralcostwouldbeontheorderofanother20to30percent.Thereferenceintheabovecasesisforfloorsystems.Forroofsusingefficientorthotropic(flat)systems,contemporarylimitsforeconomicaldesignappeartobeontheorderof150ft,whetherofsteelorprestressedconcrete.Althoughspace-framesareoftenusedforsteelorprestressedconcrete.Althoughspace-framesareoftenusedforsteelspansover150ftthefabricationcostsbegintoraiseconsiderably.Atanyrate,itshouldberecognizedthatverylong-spansubsystemsarespecialcasesandcaninthemselveshaveagreatorsmalleffectonisadded,structuralcostsforspecialbuildingscanvarygreatlyfromdesigntodesign.Themorespecialtheform,themorethatdesignknowledgeandcreativity,aswellasconstructionskill,willdeterminethepotentialforachievingcostefficiency.Volume-BasedEstimatesWhenmoreaccuracyisdesired,estimatesofcostscanbebasedonthevolumeofmaterialsusedtodoajob.Atfirstglanceitmightseemthatthearchitectwouldbeillequippedtoestimatethevolumeofmaterialrequiredinconstructionwithanyaccuracy,andmuchlessspeed.Butitispossible,withamoderatelearningeffort,toachievesomecapabilityformakingsuchestimates.Volume-basedestimatesaregivenbyassigningin-placevaluetothepoundsortonsofsteel,orthecubicyardsofreinforcedorprestressedconcreterequiredtobuildastructuralsystem.Forsuchapreliminaryestimate,onedoesnotneedtoitemizedetailedcosts.Forexample,in-placeconcretecostsincludethecostofforming,falsework,reinforcingsteel,labor,andoverhead.Steelincludesfabricationanderectionofcomponents.Costsofstructuralsteelasmeasuredbyweightrangefrom$0.50to$0.70perpoundinplaceforbuildingconstruction.Forlow-risebuildings,onecanusestockwide-flangestructuralmembersthatrequireminimumfabrication,andthecostcouldbeasbowas$0.50perpound.Morecomplicatedsystemsrequiringmuchcuttingandwelding(suchasacomplicatedsteeltrussorspace-framedesign)cangoto$0.70perpound文档资料Wordandbeyond.Forstandardtallbuildingdesigns(say,exceeding20stories),therewouldtypicallybeabout20to30poundsofsteel/psf,whichoneshouldwishnottoexceed.Adesigncallingforunder20psfwouldrequireagreatdealofingenuityandthecarefulintegrationofstructuralandarchitecturalcomponentsandwouldbearealaccomplishment.Concretecostsarevolumetricandshouldrangefromanin-placelowof$150percuydforverysimplereinforcedconcreteworkto$300percuydforexpensivesmallquantityprecastandprestressedwork.Thislargerangeisduetothefactthatthecontributingvariablesaremorecomplicated,dependingupontheshapeoftheprecisecomponents,theerectionproblems,andthetotalquantityproduced.Formworkisgenerallythecontrollingfactorforanycast-in-placeconcretework.Therefore,toachieveacostof$150percuyd,onlythesimplestofsystemscanbeused,suchasflatslabsthatrequirelittlecuttingandmuchreuseofforms.Whereanybeamsareintroducedthatrequirespecialformsanddifficultyinplacementofconcreteandsteelbars,therangebeginsat$180percuydandgoesupto$300.Since,inadevelopedcountry,highlaborcostsaccountforhighformingcosts,thisresultsinpressuretousethesimplestandmostrepetitiveofsystemstokeepcostsdown.Itbecomerewardingtoconsiderthepossibilityofmass-producedprecastandprestressedcomponents,whichmaybringasavingincostsand\orconstructioncompletiontime.Thelatterresultsinsavingsduetolowerconstructionfinancingcostsforthecontractorplusquickerearningsfortheowner.Tosummarize,therangeofcostpercubicyardofstandardtypesofpoured-in-placeconcreteworkwillaveragefrom$150to$250,theminimumbeingforsimplereinforcedworkandthemaximumformoderatelycomplicatedposttensionedwork.Thisrangeislargeandanyestimatethatignorestheeffectofvariablesabovewillbecommensuratelyinaccurate.5.SummaryTheestimateandeconomicaldesignofstructurebuildingareimportantandessentialwork,whichshouldbevaluedbyallarchitectsandengineersandothers.Betteryoudoit,moreprofityouwillreceivefromit!文档资料Word建筑结构的成本前言众所周知，建筑物的结构设计是一个相当复杂的过程，其中既包含处理很多物质因素，又考虑诸多非物质方面的因素。如果建筑物的结构形式对空间组织和美化环境的设计起这句举足轻重的影响，那么它就是一个相当重要的物理因素，就应当采用分阶段的设计方法。对建筑物的经济考虑是一个主要的非物质因素，在最终的设计中应予以重视。对一个具有创造性的设计而言，经济考虑从某方面来说往往是一种制约，但这也并非是绝对的。如果事先清楚结构设计及施工组织方案与实现他们的造价之间的关系，那么创造性是同样可以实现的。调查表明，大多具有创造性的设计是在有竞争性的投标中获得成功的，而不是因为业主非常富有。尽管后者被大肆炒作，却很少使人信服。因此也可以说，真正具有创造性的设计因该具有很强的经济性。特别是今天，人们应该逐渐认识到，高雅和经济其实是一个可以统一的概念。因此，本文列举一些造价分析参数的简单解释，以及设计人员在他们的结构设计中考虑经济因素是经常采用的一些设计中考虑经济因素是经常采用的一些设计手法。结构造价本身是通过其在建筑物总造价中所占的百分比来衡量的。或者说，由于工程只是一个项目总造价的一部分，因此还要考虑附加费用如地价（10%~20%）、筹资利息（100%~200%）、税金及维修费（20%左右）。不过上面这些因素都不在本文的讨论范围之内，文章将重点介绍工程造价。平均来说，单纯的结构造价大约占建筑物总造价25%。按照惯例，建筑无的结构造价和所谓的建筑造价是分开的。一般说来，所谓的建筑造价，往往是指那些与建筑的结构强度和物理完整性无关的因素。“基本服务设施费”组成了第三类工程费用，主要是指机械供给、电器设备以及其他一些服务体系等费用。一般说来，这部分费用大概占建筑物总费用的15%~30%，这主要取决于建筑无的类型。机械和电气费用，主要是指空调系统费用以及其他诸如管道系统、通讯、照明及动力设备等其他服务设施。在这一造价分类中非常显著的一点是，一个典型的建筑物设计方案的总体费用，应该有45%~60%分配给建筑因素。但现在这种状况正在迅速改变，因为高利率以及资金的缺乏，现在大多业主更倾向于节约型设计。因此，设计者应该考虑两条途径，他们可以直接影响建筑无的工程造价。第一个节约开支的途径可以这样来考虑，即凡是那些建筑问题和结构问题文档资料Word能够同时解决的地方往往有着很强的经济潜力。由于目前大多设计都不愿将建筑物费用一大部分用于纯粹建筑设计，这种方法就显得尤为重要，也会节省一部分非结构预算，这一经费可用于一些本会被削减掉的建筑需求。第二种节约开支的途径，则是设计人员在设计过程中综合考虑服务设施和结构体系，尽力提出一个能够解决房屋设计和施工难题的总建筑方案。承包商通常回用不同的方式做出工程项目的最终报价。他们往往将其分为场地材料费、每一个施工过程中的劳动力资源费、工程所需购买、租借的装备费、经营管理费以及利润。建筑师以及工程师很少考虑的像上面所述的那么精确，但是头脑中应该有一个清楚的概念，那就是一项结构工程的实际造价最终使用什么方法定价以及承包商又是怎样标价的。显然，上面讲到的百分比平均数有些粗略，但是它足以说明总体造价的组成情况了。下面的几部分将讨论这些平均数的范围，并进一步阐述在对建筑无的造价进行粗略、近似估计时用到的平方英尺以及单位体积造价。百分比估价建筑物的类型将决定结构费用以及其他费用所占的白分比范围。正如所希望的，装饰性或者标志性较强的建筑物的结构造价在总体造价中所占的比重相对较低。一般而言，结构造价所占的百分比可低至工程总造价的10%~15%，这是因为更多的钱被用到那些非结构费用上了。这又一次说明“装饰”部分是与基本的结构要求无关的。然而对于一些诸如教堂类的综合性标志建筑物，对其结构体系的造价相对较高，其百分比可达到15%~20%或者更高。与之相对的是一些诸如仓库或者车库之类简易的和非象征性的工业建筑物，对于这种建筑，由于内部隔墙、天花板、管道设备系统以及装修部分要求较低，其结构造价在工程总体造价中所占的比例往往能达到60%~70%，有时甚至可达80%。对于一些中等高度（5~10层）得多层办公楼或住宅楼，其结构造价在总体造价中所占的比例，大约维持在25%这一中间值；而对于一些低矮且跨据短的商业用房和住宅，大约3~4层高且跨度为20~30英尺以及简单的竖向要求，其结构造价将占总造价15%~20%。而一些特殊用途的建筑，如实验室和医院，则另当别论。他们需要较大的跨度以及不一般要求高的机械装备。这就导致总体造价得以大部分将被用于服务费用（大约30%~50%）,而单纯的结构造价约占20%。对于15层或者以上的高层办公楼以及大跨度（约50~60英尺）建筑物，其结构造价在总体造价中将占较高的百分比（约30%~35%），而服务费用约占30%~40%。在任何情况下这些百分比数据都是具有典型性的，并可作为衡量建筑物设计平均文档资料Word效益的尺度。例如，如果一个较低的小跨度且不具备纪念价值的建筑物，仅仅结构造价投标就为30%的话，那么可以肯定这个结构设计是相当不经济的。另一方面，建筑师应该注意到的一个容易混淆的事实就是，经济投标往往取决于设计者和承包人的理解设计及施工要求的实际能力，能力强就能提供一个较低的投标。创造性设计受限往往是因为设计者或承包商在经验、想象力际交流方面的匮乏。如果承包者没有把握，那么它就会加大投资，以防可能遇到的意外风险。因此要使有创造性的设计在投标时具有竞争力，作为一名建筑师它应能够洞察工程潜力所在。至少建筑是应该尽可能地与想象力丰富的结构工程师、承包商甚至制造商惊醒密切配合。相反，即使对于最为普通的建筑设计，如果仅仅靠设计手册，是很难取得经济效益的。效率离不开专业知识，而最为重要的是想象力，这一点在面对一个不太熟悉的项目是尤为重要。如果建筑物结构设计至少具有中等（或标准）的效益时，前面所提到的百分比就对建筑物总造价估算有着很大的帮助。例如，如果一座办公楼总体造价500万美元，其中有25%时结构造价的标准，那么这一工程结构体系造价就不能超过125万美元。若设计很合理，比如时按上述的中等效益设计估算造价的80%时，那么就有25万美元，也就是5%的总体建筑费用被省下来。如果这500万资金已经到位，那么节省下的25万美元就可用于其他的经济开支。上面所有阐述表明，结构设计和建筑整体设计（机械和电器）的创造性结合的概念，将有助于减少单纯的结构造价，或在相同造价下提供更多的建筑费用。这样，设计成功的程度将取决于设计者的专业知识、灵活性以及设计者和承包人之间有洞察力的合作，上面讨论仅仅是提供一种关于建筑总体造价的全面视图，下面的部分将提供对建筑的结构造价进行估价的方法。有两种可供选择的方法将用来进行结构造价的近似估价：其一是根据单位平方英尺建筑面积，另一种则是根据所用的结构材料体积进行估价。参考上面所提到的有效设计的结构造价标准，最后的结构估价有助于对建筑的总体造价惊醒大概的了解。当然，这样得到的只是一个粗略的估价，但却会使设计负责人员对实际设计中经常要面对的经济问题有所了解。至少，这些将有助于对可供选择的结构体系的相对成本效益进行对比。平方英尺估算如前所述，在一个特定的时期和地区，是可以根据相似工程的平均造价，来经验