【英语翻译Formsshouldbedesignedbyconventionalengineeringpracticestoresisttheforcesresultingfromtheknownloads.Ifdesignedbyexperienceorguesswork,theformsmightbetoolightandsubjecttoanexpensivefailure.Ontheotherhand,】

　　英语翻译

　　Formsshouldbedesignedbyconventionalengineeringpracticestoresisttheforcesresultingfromtheknownloads.Ifdesignedbyexperienceorguesswork,theformsmightbetoolightandsubjecttoanexpensivefailure.Ontheotherhand,theformscouldbestrongerthannecessaryandcosttoomuch.

　　Whenformsaretobeusedmanytimes,thatpartoftheformincontactwiththeconcretemustbeofagoodgradeofmaterial,whichwillhaveahighfirstcostbutwillbeeconomicalduetomorethanoneuse.Ifthefinishsurfaceoftheconcretemustbesmoothandfreeofblemishes,theuseofaveryhighgradeofmaterialwillminimizeexpensivefinishing.

　　Toattainmaximumeconomyinformwork,thehighestpracticalunitstressesfortheformmaterialshouldbeused.Whentheconcreteisjustcast,itismoreorlessfluidandexertsconsiderablesidepressureontheforms.Inseveralhourstimeaftertheconcretehassetup,thesidepressurewillceaseandthebeamwithitsreinforcementwillcarryitsowndeadplusthesuperimposedliveloads;andstressesintheformworkwillbepracticallynothing.Thustheformswillbesubjectedtomaximumstressesforaveryshortperiodoftime.Woodiscapableofabsorbinglargeoverloadsifthestressesareonshortduration,andbecauseofthistheallowablestressesbasedonconstantloadsoflongdurationmaybeincreasedby,sayonethird,aslongastheforms,whicharetobereused,areprotectedfromabuseandexcessiveexposuretoweather.However,itmustbenotedthattheallowabledeflectionsinformworkwillmanytimesgovernthedesignforthereasonthatiftheweightofthefreshconcretedeflectsthemembrertoomuch,eitherhorizontallyorvertically,thefinishedconcretewillsetupinthedeflectedshape.

　　Somewaysbywhichthecostofformworkmaybekeptataminimumarethefollowing:

　　1.Havethestructuralandarchitecturaldesignerspreparetheirplansatthesametimesothattheymaybothbecompatiblewithaneconomicalsystemofformwork.

　　2.Keepthestructuralsystemuncomplicatedsothattheformworkmaybesimpleandeconomicallyerectederectedandremoved.

　　3.Usethesamesizeofcolumnsoverawholebuilding,ifpossible,oratleastoverseveralfloors.Thiswillpermitthereuseofbeamandcolumnformswith