專業(yè)英語建筑

Unit9第九單元

CrackingLoadandUltimateMoment

開裂荷載和極限彎矩教學(xué)目標(biāo)了解預(yù)應(yīng)力梁在開裂荷載下的反應(yīng)了解有（無）粘結(jié)力的預(yù)應(yīng)力構(gòu)件的極限彎矩能力熟悉預(yù)應(yīng)力構(gòu)件中的專業(yè)詞匯熟悉科技類文獻(xiàn)中的常用句型熟悉criterion(criteria)、modulus(moduli)、index(indices)的單復(fù)數(shù)區(qū)別；offset、counteract、against的含義；significant、yield的不同含義；conformto、compliancewith的含義；besubjectto、besubjectedto的不同含義；predict、anticipate的用法；lightly、slightly、highly的不同含義。 Ithasbeenshownthatavariationintheexternalloadactingonaprestressedbeam

resultsin

achangeinthe

locationofthe

pressureline（壓力線）forbeamsinthe

elasticrange.Thisisafundamental

principle（規(guī)律）ofprestressedconstruction.Inanormalprestressedbeam,this

shift（移動(dòng)）inthelocationofthepressurelinecontinuesat

arelativelyuniform

rate（速度）,

as（隨著）theexternal

loadisincreased,

to

thepointwherecracksdevelopinthe

tensionfiber.Afterthecrackingloadhasbeenexceeded,the

rateofmovementinthepressurelinedecreases

asadditionalloadisapplied,anda

significant（顯著）increaseinthe

stressinthe

prestressingtendon（預(yù)應(yīng)力鋼筋束）andthe

resultantconcreteforcebeginstotakeplace.ActionUnderOverload-CrackingLoad超載（-開裂荷載）下的反應(yīng) Thischangeintheactionoftheinternalmomentcontinuesuntilallmovementofthepressureline

ceases（停止）.Themomentcausedbyloadsthatare

appliedthereafter（其后）is

offset（抵消）entirely

byacorrespondingandproportionalchangeintheinternalforces,justasinreinforced-concreteconstruction.Thisfact,thattheloadintheelasticrangeandtheplasticrangeiscarriedbyactionsthatarefundamentallydifferent,isvery

significant（重要的）and

renders（使..變得）strengthcomputations

essentialforalldesignsinordertoensurethatadequatesafetyfactorsexist.Thisistrueeventhoughthestressesintheelasticrangemay

conformto（符合）a

recognized（公認(rèn)的）elasticdesigncriterion. 已經(jīng)顯示作用在一根預(yù)應(yīng)力梁上的外部荷載的變化會導(dǎo)致梁在彈性階段時(shí)其壓力線位置的變化。這是預(yù)應(yīng)力結(jié)構(gòu)的基本規(guī)律。在一根普通的預(yù)應(yīng)力梁中，隨著外力的增加，其壓力線位置以一個(gè)相對均勻的速度不斷移動(dòng)直至受拉纖維形成開裂的位置。在已經(jīng)超過開裂荷載后，隨著附加荷載的施加，壓力線移動(dòng)的速度便會降低，且使預(yù)應(yīng)力鋼筋束中的應(yīng)力和合成的混凝土力開始發(fā)生顯著的增加。內(nèi)部彎矩的作用不斷變化直到所有壓力線的移動(dòng)都停止。其后施加的荷載引起的彎矩完全通過相應(yīng)的、且按比例的內(nèi)力變化來抵消，正如在鋼筋混凝土的結(jié)構(gòu)中。這個(gè)事實(shí)，即彈性階段和塑性階段的力由基本不同的作用來傳送是非常重要的，且使強(qiáng)度計(jì)算變得對所有的設(shè)計(jì)都是必要的，以確保存在足夠的安全系數(shù)。這是正確的，即使彈性階段的應(yīng)力可能符合公認(rèn)的彈性設(shè)計(jì)準(zhǔn)則。 Itshouldbenotedthattheloaddeflectioncurve

iscloseto（接近于）astraightline

upto

thecrackingload

andthatthecurvebecomes

progressively（逐漸）more

curved

as

theloadisincreasedabovethecrackingload.

The

curvature（彎曲）oftheload-deflectioncurvefor

loadsoverthecrackingloadis

dueto（由于..所造成的）thechangeinthebasicinternalresistingmomentaction

thatcounteracts（抵消）theappliedloads,asdescribed

above,

aswellas

toplasticstrainsthatbegintotakeplace

inthesteelandtheconcretewhen

stressedtohighlevels（受到很大壓力）. 應(yīng)該注意到荷載撓度曲線在開裂荷載以內(nèi)是接近直線的，且在超過開裂荷載后，該曲線隨著荷載的增加逐漸變得更彎曲。正如上面所描述的，當(dāng)超過開裂荷載時(shí)，其荷載-撓度曲線的彎曲是由于抵消施加荷載的基本內(nèi)部抵抗彎矩作用的變化以及當(dāng)受到很大壓力時(shí)鋼筋和混凝土中開始發(fā)生的塑性應(yīng)變所造成的。

Insomestructuresitmaybeessentialthatthe

flexuralmembers

remaincrackfree（保持構(gòu)件不開裂）evenunder

significant（明顯的）overloads.Thismay

beduetothestructures’beingexposedto

exceptionally

corrosive（特別腐蝕）atmospheresduringtheir

usefullife（有效壽命）.Indesigningprestressedmembersto

beusedinspecialstructuresofthistype,itmaybenecessarytocomputetheloadthatcausescrackingofthe

tensile

flange（受拉翼緣）,inordertoensurethat

adequatesafety

against

crackingisprovidedbythe

design.Thecomputationofthemomentthatwillcause

crackingisalsonecessarytoensure

compliancewith（符合）somedesign

criteria（criterion的復(fù)數(shù)形式，標(biāo)準(zhǔn)）. 在一些結(jié)構(gòu)中，保持受彎構(gòu)件不開裂可能是必要的，甚至在明顯的超載下。這可能是由于結(jié)構(gòu)在它們的有效壽命期間被暴露在特別腐蝕的空氣中的原因。當(dāng)設(shè)計(jì)預(yù)應(yīng)力構(gòu)件用于這種類型的特殊結(jié)構(gòu)時(shí)，可能有必要計(jì)算引起受拉翼緣開裂的荷載，以確保該設(shè)計(jì)提供足夠抵抗開裂的安全性。也有必要計(jì)算會導(dǎo)致開裂的彎矩，以確保符合一些設(shè)計(jì)標(biāo)準(zhǔn)。 Manytestshave

demonstrated（證明）thattheload-deflectioncurvesofprestressedbeamsare

approximatelylinear（近似直線的）upto

andslightlyinexcessof（稍微超過）theloadthatcausesthefirstcracksinthetensileflange.(The

linearity（直線性）isafunctionoftherateatwhichtheloadisapplied.)Forthisreason,normalelastic-designrelationships（關(guān)系式）canbeusedincomputingthecrackingloadbysimplydeterminingtheloadthat

resultsin

anet（凈）tensilestressinthetensileflange

(prestressminustheeffectsoftheappliedloads)that

isequalto

thetensilestrengthoftheconcrete.Itiscustomary

toassumethattheflexuraltensilestrengthoftheconcrete

isequaltothe

modulusofrupture（斷裂模量）ofthe

concretewhencomputingthecrackingload. 很多試驗(yàn)證明，在引起受拉翼緣最初開裂的荷載以內(nèi)或稍微超過時(shí)，預(yù)應(yīng)力梁的荷載-撓度曲線是近似直線的。（直線性是荷載施加速度的函數(shù)。）因此，通過簡單地確定導(dǎo)致受拉翼緣中產(chǎn)生一個(gè)凈的受拉應(yīng)力的荷載（預(yù)應(yīng)力減去施加荷載的效應(yīng)），普通的彈性設(shè)計(jì)關(guān)系式能用來計(jì)算開裂荷載，其值等于混凝土的抗拉強(qiáng)度。當(dāng)計(jì)算開裂荷載時(shí)，習(xí)慣上假定混凝土的受彎抗拉強(qiáng)度等于混凝土的斷裂模量。Inshouldberecognizedthattheperformance（性能）ofbonded（有粘結(jié)的）prestressedmemberisactuallyafunctionofthetransformedsection（換算截面）ratherthanthegross（毛）concretesection.Ifitisdesirable（想要）tomakeapreciseestimateofthecrackingload,suchasisrequiredinsomeresearchwork,thiseffect（影響）shouldbeconsidered.應(yīng)該承認(rèn)有粘結(jié)結(jié)的預(yù)應(yīng)力構(gòu)件件的性能實(shí)際上上是一個(gè)換算截截面的函數(shù)，不不是混凝土毛截截面的函數(shù)。如如果想要對開裂裂荷載作一精確確估計(jì)，例如在在一些研究工作作中需要的，該該影響應(yīng)該被考考慮。PrinciplesofUltimateMomentsCapacityforBondedmembers有粘結(jié)的構(gòu)件極極限彎矩能力的的規(guī)則Whenprestressedflexuralmembersthatarestrongerinshearandbondthaninbendingareloadedtofailure,theyfailinoneofthefollowingmodes（方式）:當(dāng)剪切和粘結(jié)比比彎曲強(qiáng)的預(yù)應(yīng)應(yīng)力受彎構(gòu)件受受荷失效時(shí)，它它們會以下列方方式中的一種失失效：（1）FailureatcrackingloadInverylightlyprestressedmembers,thecrackingmomentmaybegreaterthanthemomentthemembercanwithstandinthecrackedconditionand,hence,thecrackingmomentistheultimatemoment.Thisconditionisrare（很少的）andismostlikelytooccurinmembersthatareprestressedconcentricallywithsmallamountsofsteel.Itcanalsooccurinholloworsolid（實(shí)心）prestressedconcretemembersthathaverelativelylowlevelsofreinforcing.Determinationofthepossibilityofthistypeoffailureisaccomplishedbycomparingtheestimatedmomentthatwouldcausecrackingtotheestimatedultimatemoment,computedasdescribedbelow.Whentheestimatedcrackingloadislargerthanthecomputedultimateload,thistypeoffailurewouldtakeplaceifthememberweresubjectedtotherequiredloads.Becausethistypeoffailureisbrittlefailure,itoccurswithoutwarning–designsthatwouldyield（產(chǎn)生）thismodeoffailureshouldbeavoided.（1）開裂荷載下的失失效在施加非常少量量預(yù)應(yīng)力的構(gòu)件件中，其開裂彎彎矩可能大于構(gòu)構(gòu)件在開裂狀態(tài)態(tài)下能承受的彎彎矩，因此，開開裂彎矩為極限限彎矩。這種情情況是很少的，，且在構(gòu)件中最最可能發(fā)生用少少量鋼筋同心地地施加預(yù)應(yīng)力。。在空心或?qū)嵭男牡念A(yù)應(yīng)力混凝凝土構(gòu)件中也會會出現(xiàn)相對低等等級的鋼筋。通通過比較引起起開裂的彎矩估估計(jì)值與按下面面描述（的方法法）計(jì)算的極限限彎矩估計(jì)值來來確定這種失效效的可能性。當(dāng)當(dāng)估計(jì)的開裂荷荷載大于計(jì)算的的極限荷載，則則如果構(gòu)件承受受要求的荷載，，這種失效將會會發(fā)生。由于這這種失效是脆性性失效，因此其其發(fā)生時(shí)沒有警警告-產(chǎn)生這種種失效方式的設(shè)設(shè)計(jì)應(yīng)該被避免免。（2）FailureduetoruptureofsteelInlightlyreinforced（少量加筋）memberssubjectedtoultimateload,theultimatestrengthofthesteelmaybeattainedbeforetheconcretehasreachedahighlyplasticstate（高度塑性狀態(tài)））.Thistypeoffailureisoccasionallyencounteredinthedesignofstructureswithverylargecompressionflangesincomparisonto（與..相比）theamountofprestressingsteel,suchasacomposite（復(fù)合）bridgestringer（縱梁）.Computationoftheultimatemomentofamembersubjecttothistypeoffailurecanbedonewithahighprecision.Themethodofcomputation,aswellasthedeterminationofwhichmembersaresubjecttothismodeoffailure,isdescribedbelow.（2）鋼筋斷裂引起的的失效在少量加筋并承承受極限荷載的的構(gòu)件中，鋼筋筋的極限強(qiáng)度可可能在混凝土達(dá)達(dá)到高度塑性狀狀態(tài)之前就達(dá)到到。這種失效在在與預(yù)應(yīng)力筋的的數(shù)量相比有很很大受壓翼緣的的結(jié)構(gòu)設(shè)計(jì)中會會偶然遇到，如如一個(gè)復(fù)合的橋橋梁縱梁?？梢砸愿呔鹊赜?jì)算算易遭受這種失失效的構(gòu)件的極極限彎矩。這種種計(jì)算方法以及及確定哪根桿件件易遭受這種失失效方式將在下下面描述。（3）FailureduetostrainTheusualunderreinforced（配筋不足）,prestressedstructurethatareencounteredinpracticeareofsuchproportions（尺寸）that,ifloadedtoultimate,thesteelwouldbestressedwellinto（早已進(jìn)入）theplasticrangeandthememberwouldevidence（顯示）largedeflection.Failureofthememberwilloccurwhentheconcreteattainsthemaximumstrainthatitiscapableofwithstanding.Itisimportanttounderstandthatresearchinto（..的調(diào)查）theultimatebendingstrengthofreinforcedandprestressedconcretehasledmostinvestigatorstotheconclusionthatconcrete,ofthequality（特性）normally（通常）encounteredinprestressedwork（工程）failswhenthelimitingstrainof0.003isattainedintheconcrete.Sincetheultimatebendingcapacityislimitedbystrainratherthanstressintheconcrete,itisafunctionoftheelasticmoduli（modulus的復(fù)數(shù)形式,模模量）oftheconcreteandsteel.Themagnitudeoftheultimatemomentformembersofthiscategorycanalsobepredicted（預(yù)測）,asarule,withinthenormaltolerance（正常的允許誤差差）expectedinstructuraldesign.Theultimatemomentofunderreinforcedsectionscannotbepredictedwiththesameprecisionasthelightlyreinforcedmembersdescribedabove,sincetheultimatemomentsofunderreinforcedmembersareafunctionoftheelasticpropertiesofthesteelandtheeffectivestressesintheprestressingsteel,whereastheultimatemomentcapacitiesoflightlyreinforcedmembersarenot.（3）應(yīng)變引起的失效效在實(shí)踐中遇到通通常配筋不足的的預(yù)應(yīng)力結(jié)構(gòu)具具有這樣的尺寸寸，以至于如果果加荷至極限，，鋼筋的應(yīng)力早早已進(jìn)入塑性范范圍，而該構(gòu)件件將顯示出很大大的撓度。當(dāng)混混凝土達(dá)到其能能承受的最大應(yīng)應(yīng)變時(shí)，該構(gòu)件件將發(fā)生失效。。明白對預(yù)應(yīng)力力鋼筋混凝土的的極限抗彎強(qiáng)度度的調(diào)查已經(jīng)導(dǎo)導(dǎo)致多數(shù)調(diào)查者者得到了結(jié)論，，即當(dāng)混凝土達(dá)達(dá)到0.003的極限應(yīng)變變時(shí)，具有在預(yù)預(yù)應(yīng)力工程中常常遇性能的混凝凝土?xí)?，這這點(diǎn)很重要。由由于極限抗彎能能力受到混凝土土中的應(yīng)變而不不是應(yīng)力的限制制，因此，它是是混凝土和鋼筋筋彈性模量的函函數(shù)。作為一個(gè)個(gè)規(guī)律，這類構(gòu)構(gòu)件極限彎矩的的大小也能被預(yù)預(yù)測在結(jié)構(gòu)設(shè)計(jì)計(jì)所預(yù)期的正常常的允許誤差范范圍內(nèi)。配筋筋不足截面的極極限彎矩不能以以與上面描述的的少量配筋的構(gòu)構(gòu)件相同的精度度來預(yù)測，因?yàn)闉榕浣畈蛔愕臉?gòu)構(gòu)件的極限彎矩矩是鋼筋彈性性性能和預(yù)應(yīng)力鋼鋼筋中的有效應(yīng)應(yīng)力的函數(shù)，而而少量配筋構(gòu)件件的極限彎矩能能力則不是。（4）FailureduetocrushingoftheconcreteFlexuralmembersthathaverelativelylargeamountsofprestressingsteelorrelativelysmallcompressiveflangesarereferredtoasbeingoverreinforced（超配筋的）.Overreinforcedmembers,whenloadedtodestruction,donotattainthelargedeflectionsassociatedwithunderreinforcedmembers––thesteelstressesdonotexceedtheyieldpointandfailureistheresultoftheconcretebeingcrushed.Computationoftheultimatemomentsofoverreinforcedmembersisdonebyatrialanderror（試算）procedure，involvingassumedstrainpatterns（模式）,aswellasbyempiricalrelationships（經(jīng)驗(yàn)關(guān)系式）.（4）混凝土壓壓碎引起的失效效有著相對大量預(yù)預(yù)應(yīng)力筋或相對對小的受壓翼緣緣的受彎構(gòu)件稱稱為是超配筋的的。當(dāng)受荷至破破壞的超配筋構(gòu)構(gòu)件沒有達(dá)到與與配筋不足構(gòu)件件有關(guān)聯(lián)的大撓撓度-鋼筋的應(yīng)應(yīng)力沒有超過屈屈服點(diǎn)，因而失失效是混凝土被被壓碎的結(jié)果。。通過試算過程程以及經(jīng)驗(yàn)關(guān)系系式來計(jì)算超配配筋構(gòu)件的極限限彎矩，包括假假定應(yīng)變模式。。Itmustbeemphasizedthatthereisnocleardistinction（明顯的區(qū)別）betweenthedifferentclassifications（類別）offailurelistedabove.Forconvenienceofdesign,certainparameters,whichareafunctionofthepercentageofsteel,areusedbydifferentauthorities（權(quán)威）todistinguishbetweenthedifferenttypesoffailurethatwouldbeanticipated（預(yù)測）.必須強(qiáng)調(diào)在上面面列出的不同的的失效類別之間間沒有明顯的區(qū)區(qū)別。為了便于于設(shè)計(jì)，通過不不同的權(quán)威采用用某些參數(shù)（這這些參數(shù)是鋼筋筋百分率的函數(shù)數(shù)）來區(qū)別被預(yù)預(yù)測的不同類型型的失效。Inordertosimplifytheexplanationofthetheoryrelatedtothecomputationoftheultimatemoments,arectangularsectionwillbeassumedthroughout（在整個(gè)..的過過程中）thederivation,inordertoeliminate（消除）thevariable（變化因素）offlangewidthwhichisfrequentlyencounteredwithIorTsections.Inaddition,thefollowingassumptions,someofwhichdifferslightlyfromthosecontainedinACI-318,aremade:為了簡化與極限限彎矩計(jì)算有關(guān)關(guān)的理論的解釋釋，在整個(gè)推導(dǎo)導(dǎo)的過程中將假假定一個(gè)矩形截截面，以消除翼翼緣寬度的變化化因素，其常常常被遇到是I或T形截面。而且，，作以下假定，，其中一些稍許許不同于ACI-318中包括的假定：：Planesectionsareassumedtoremainplane.Thestress-strainproperties（特點(diǎn)）ofthesteelaresmoothcurveswithoutadefinite（確定的）yieldpoint.Thelimitingstrainoftheconcreteisequalto0.0034,regardlessofthestrengthoftheconcrete.Thesteelandconcretearecompletelybonded.假定平截面依然然是平面的；鋼筋的應(yīng)力-應(yīng)應(yīng)變特點(diǎn)是光滑滑的曲線，上面面沒有確定的屈屈服點(diǎn)；混凝土的極限應(yīng)應(yīng)變等于0.0034，不考考慮混凝土的強(qiáng)強(qiáng)度；鋼筋與混凝土是是完全粘結(jié)的；；Thestressdiagramoftheconcreteatfailureissuchthattheaverageconcretestressis0.80f’candtheresultantofthestressintheconcreteactsatadistancefromtheextremefiberequalto0.42ofthedepthofthecompressionblock.Thestraininthetopfiberunderprestressalone（僅僅）isequaltozero.Thesectionissubjecttopurebending.Theanalysisisfortheconditionofstaticloadsofshortduration（持續(xù)時(shí)間）.在混凝土失效時(shí)時(shí)的應(yīng)力圖中，，平均的混凝土土應(yīng)力為0.80f’c，而混凝土中的應(yīng)應(yīng)力合力則作用用在離端部纖維維的距離為0.42倍的受壓壓區(qū)深度處；僅在預(yù)應(yīng)力作用用下頂部纖維的的應(yīng)變等于零；；截面易遭受純彎彎；分析是針對靜力力荷載在短的持持續(xù)時(shí)間下的情情況。Aswestatedabove,therelationshipsthatweredevelopedareapplicabletorectangularsections.Theserelationshipsareequally（同樣得）accurateforflangedsections（帶翼緣的截面））,provided（假如）theneutralaxis（中性軸）ofthesectionatultimateiswithinthelimitsoftheflange.Iftheneutralaxisfallsoutsideoftheflangearea（區(qū)域）,thesamestrainsdistributionapplied（采用）asinthecaseofrectangularsections,butduetothevariablewidthofthesection,thedistancetotheresultantofthecompressiveblockmustbecalculated.Tofacilitate（方便）thecalculationofthelocationoftheresultant,thecompressionblockcanbeassumedtoberectangularratherthancurvedwithoutintroducingsignificanterror（導(dǎo)致重大錯(cuò)誤））.正如我們上面所所述，那些被提出的的關(guān)系式適用于于矩形截面。假假如在極限狀態(tài)態(tài)時(shí)截面的中性性軸落在翼緣的的邊界之內(nèi)，則則這些關(guān)系式對對有翼緣的截面面同樣得準(zhǔn)確。。如果中性軸落落在翼緣區(qū)域的的外面，則采用用與矩形情況中中相同的應(yīng)變分分布，但是由于于截面寬度的變變化，必須計(jì)算算（中性軸）至至壓力區(qū)合力的的距離。為了方方便計(jì)算合力的的位置，可以假假定受壓區(qū)是矩矩形的，而不是是彎曲的，這不不會導(dǎo)致重大的的錯(cuò)誤。Whensmallquantitiesofnon-prestressedreinforcementareusedincombinationwithsmallquantitiesofprestressedreinforcement,theadditionalultimatemomentduetothenon-prestressedreinforcementcanbecalculated.Forlargeramountsofnon-prestressedreinforcementorformemberswithhighsteelindices（index的復(fù)數(shù)形式，率率）,themomentshouldbedeterminedbytrialanderrorfromthebasicstrainpatterns.當(dāng)采用少量的非非預(yù)應(yīng)力鋼筋再再加上少量的預(yù)預(yù)應(yīng)力鋼筋，則則可以計(jì)算由于于非預(yù)應(yīng)力鋼筋筋引起的附加的的極限彎矩。對對較多數(shù)量的非非預(yù)應(yīng)力鋼筋或或具有高鋼筋率率的構(gòu)件，其彎彎矩應(yīng)該根據(jù)基基本的應(yīng)變模式式通過試算來確確定。Examination（研究）willshowthatsmallvariations（微小變化）intheeffectiveprestresshavenosignificanteffectontheultimatestrengthofprestressedmembers.Itisimportanttonotethateveniferrorsaremadeinestimatingthelossesofprestress,inestimatingthestressing（施加應(yīng)力）friction,orevenifthestressingisnotcarriedouttoahighprecisioninthefieldduetopoorworkmanship（低劣的手藝）,theeffectontheultimatemomentisgenerallysmallforflexuralmemberswithbondedtendons.研究顯示有效預(yù)預(yù)應(yīng)力的微小變變化對預(yù)應(yīng)力構(gòu)構(gòu)件的極限強(qiáng)度度沒有顯著的影影響。很重要地地注意到，即使使錯(cuò)誤地估計(jì)了了預(yù)應(yīng)力的損失失和施加應(yīng)力的的摩擦，或即使使在現(xiàn)場由于低低劣的手藝而沒沒有高精度地施施加應(yīng)力，對有有粘結(jié)鋼筋束的的受彎構(gòu)件極限限彎矩的影響通通常也是小的。。PrinciplesofUltimateMomentCapacityforUnbondedMembers無粘結(jié)的構(gòu)件極極限彎矩能力的的規(guī)則Becausetheprestressingtendonscanslip(withrespecttotheconcrete)duringloadingofanunbondedmember,therelationshipsforultimatemomentcapacitydonotapplyto（適用于）unbondedbeams.Becausethetendonscanslipwithrespecttotheconcrete,othervariables（另外的變量）affecttheultimatemomentcapacityofunbondedprestressedconcretemembers.由于在對無粘結(jié)的的構(gòu)件加荷期間，，施加預(yù)應(yīng)力的鋼鋼筋束會相對于混混凝土滑移，因此此極限彎矩能力的的關(guān)系式不適用于于無粘結(jié)的梁。由由于該鋼筋束會相相對于混凝土滑移移，因此另外的變變量影響了無粘結(jié)結(jié)的預(yù)應(yīng)力混凝土土構(gòu)件的極限彎矩矩能力。Variablesthataffe