Kwiimeko ezahlukeneyo zesakhiwo, iinjineli zinokufuna ukuvavanya amandla eejoyinti ezenziwe zii-welds kunye nee-mechanical fasteners. Namhlanje, ii-mechanical fasteners zihlala ziyi-bolts, kodwa uyilo oludala lunokuba nee-rivets.
Oku kunokwenzeka ngexesha lokuphuculwa, ukuhlaziywa, okanye ukuphuculwa kweprojekthi. Uyilo olutsha lunokufuna ukuba iibholiti kunye nokuwelda zisebenze kunye kwindawo edibeneyo apho izinto eziza kuhlanganiswa ziqala zihlanganiswe kunye zize emva koko zifakwe i-weld ukuze zinike amandla apheleleyo kwindawo edibeneyo.
Nangona kunjalo, ukufumanisa umthamo womthwalo opheleleyo wejoyinti akulula njengokudibanisa isixa sezinto ngazinye (ii-welds, ii-bolts, kunye nee-rivets). Ukucinga okunjalo kunokukhokelela kwimiphumo emibi kakhulu.
Uqhagamshelo olunebholiti luchazwe kwi-American Institute of Steel Structures (AISC) Structural Joint Specification, esebenzisa iibholiti ze-ASTM A325 okanye ze-A490 njenge-tight mount, i-preload, okanye i-sliding key.
Qinisa uqhagamshelo oluqinisiweyo ngesixhobo sokutsala okanye isitshixo usebenzisa isixhobo sokutsala esiqhelekileyo esinamacala amabini ukuqinisekisa ukuba iileya ziqinile. Kwisixhobo sokutsala esixineneyo, iibholithi zifakelwa ukuze zithwalwe yimithwalo enzima yokutsala, kwaye iipleyiti zithwalwe yimithwalo yokucinezela.
1. Jika i-nut. Indlela yokujika i-nut ibandakanya ukuqinisa i-bolt uze ujike i-nut ngobuninzi obongezelelweyo, obuxhomekeke kububanzi nobude be-bolt.
2. Lungisa isitshixo. Indlela yesikrufu esilungisiweyo ilinganisa i-torque enxulumene noxinzelelo lwebholiti.
3. Ibholithi yokulungisa uxinezeleko lohlobo lweTorsion. Iibholithi zoxinzelelo ezijijekileyo zinezikhonkwane ezincinci ekupheleni kwebholithi ejongene nentloko. Xa i-torque efunekayo ifikelelwe, i-stud iyakhululwa.
4. Isalathisi sokutsala esithe tye. Izalathi zoxinzelelo oluthe tye zii-washers ezikhethekileyo ezineethebhu. Ubungakanani boxinzelelo kwi-lug lubonisa inqanaba loxinzelelo olusetyenziswa kwi-bolt.
Ngokwendlela eqhelekileyo, iibholiti zisebenza njengezikhonkwane kwiindawo eziqinileyo nezixineneyo, njengephini yobhedu ebambe inqwaba yephepha elineembobo kunye. Iindawo ezityibilikayo ezibalulekileyo zisebenza ngokungqubana: ukulayisha kwangaphambili kudala amandla okuthotywa, kwaye ukungqubana phakathi kwemiphezulu yoqhagamshelwano kusebenza kunye ukumelana nokutyibilika kwejoyinti. Kufana nebhinda ebamba inqwaba yamaphepha kunye, kungengenxa yokuba imingxunya ibhoboziwe ephepheni, kodwa ngenxa yokuba ibhinda icinezela amaphepha kunye kwaye ukungqubana kubamba inqwaba kunye.
Iibholiti ze-ASTM A325 zinamandla okutsalwa ubuncinane angama-150 ukuya kwi-120 kg ngesikwere intshi (KSI), kuxhomekeke kububanzi bebholiti, ngelixa iibholiti ze-A490 kufuneka zibe namandla okutsalwa angama-150 ukuya kwi-170-KSI. Iijoyinti ze-rivet zisebenza njengeejoyinti eziqinileyo, kodwa kule meko, iiphini zii-rivets ezihlala ziqinile kangangesiqingatha kunebholiti ye-A325.
Enye yezinto ezimbini inokwenzeka xa ijoyinti ebotshelelwe ngoomatshini iphantsi kwamandla okucheba (xa into enye ithambekele ekutyibilikeni kwenye ngenxa yamandla asetyenzisiweyo). Iibholiti okanye iiriveti zinokuba macala emingxunya, nto leyo ebangela ukuba iibholiti okanye iiriveti zichebe ngaxeshanye. Okwesibini okunokwenzeka kukuba ukungqubana okubangelwa ngamandla okubamba ezi zibophelelo ezibekwe phambili kunokumelana nemithwalo yokucheba. Akukho kutyibilika okulindelweyo kolu qhagamshelo, kodwa kunokwenzeka.
Uqhagamshelo oluqinileyo luyamkeleka kwiindlela ezininzi, njengoko ukutyibilika okuncinci kungenakuzichaphazela kakubi iimpawu zoqhagamshelo. Umzekelo, cinga ngesisele esenzelwe ukugcina izinto ezinamaqhekeza. Kunokubakho ukutyibilika okuncinci xa ulayisha okokuqala. Nje ukuba ukutyibilika kwenzeke, akuyi kuphinda kwenzeke, kuba yonke imithwalo elandelayo ifana.
Ukuguqulwa komthwalo kusetyenziswa kwezinye iinkqubo, njengaxa izinto ezijikelezayo ziphantsi kwemithwalo yokuxinana kunye neyokuxinzelela. Omnye umzekelo yinto egobileyo ephantsi kwemithwalo ejijekileyo ngokupheleleyo. Xa kukho utshintsho olukhulu kwicala lomthwalo, uqhagamshelo olulayishiwe kwangaphambili lunokufuneka ukuze kupheliswe ukutyibilika okujikelezayo. Oku kutyibilika ekugqibeleni kukhokelela ekutyibilikeni okungakumbi kwimingxuma emide.
Amanye amalungu afumana imijikelo emininzi yomthwalo enokubangela ukudinwa. Oku kuquka ucinezelo, inkxaso yekreyini kunye noqhagamshelwano kwiibhulorho. Unxibelelwano olubalulekileyo olutyibilikayo luyafuneka xa unxibelelwano luphantsi kwemithwalo yokudinwa kwicala elichaseneyo. Kwezi ntlobo zeemeko, kubaluleke kakhulu ukuba ilungu lingatyibiliki, ngoko ke amalungu abalulekileyo atyibilikayo ayafuneka.
Uqhagamshelo olukhoyo olunebholiti lunokuyilwa kwaye lwenziwe ngokwemigangatho yale. Uqhagamshelo lwerivet luthathwa njengoluqinileyo.
Iijoyinti ezidityanisiweyo ziqinile. Iijoyinti ezidityanisiweyo zinzima. Ngokungafaniyo neejoyinti ezidityanisiweyo, ezinokutyibilika phantsi komthwalo, iijoyinti akufuneki zolule kwaye zisasaze umthwalo osetyenzisiweyo kakhulu. Kwiimeko ezininzi, izibophelelo zoomatshini ezidityanisiweyo kunye nezohlobo lwebhere aziguquguquki ngendlela efanayo.
Xa kusetyenziswa ii-welds kunye nee-fasteners zoomatshini, umthwalo udluliselwa kwinxalenye eqinileyo, ukuze i-weld ikwazi ukuthwala phantse wonke umthwalo, kwaye kuncinci kakhulu okwabelwana ngayo ne-bolt. Yiyo loo nto kufuneka kuthathelwe ingqalelo xa kudityaniswa ii-fasteners zoomatshini kunye nee-welds. Ingcaciso 1:2000 yokudibanisa isakhiwo - intsimbi. Isiqendu 2.6.3 sithi kwii-rivets okanye ii-bolts ezisetyenziswa kwiindawo zokudibanisa (oko kukuthi apho i-bolt okanye i-rivet isebenza njengephini), ii-fasteners zoomatshini akufuneki zithathwe njengezinokwabelana ngomthwalo kunye ne-weld. Ukuba kusetyenziswa i-welding, kufuneka zinikezelwe ukuthwala umthwalo opheleleyo kwi-joint. Nangona kunjalo, uqhagamshelo oludibeneyo kwi-element enye kunye ne-riveted okanye i-bolt kwenye into luvumelekile.
Xa kusetyenziswa izibophelelo zoomatshini zohlobo lokuthwala kunye nokongeza ii-welds, amandla okuthwala umthwalo we-bolt awakhathalelwa kakhulu. Ngokwale migaqo, i-weld kufuneka yenzelwe ukuhambisa yonke imithwalo.
Oku kufana kakhulu ne-AISC LRFD-1999, isiqendu J1.9. Nangona kunjalo, i-CAN/CSA-S16.1-M94 esemgangathweni yaseKhanada ikwavumela ukusetyenziswa kwayo yodwa xa amandla e-fastener okanye i-bolt yomatshini ephezulu kuneyokuwelda.
Kule meko, iikhrayitheriya ezintathu ziyahambelana: amathuba okubopha ngoomatshini bohlobo lokuthwala kunye namathuba ee-welds awahlanganisi.
Icandelo 2.6.3 le-AWS D1.1 likwaxoxa ngeemeko apho iibholiti kunye nee-welds zinokudityaniswa kwijoyinti enamacandelo amabini, njengoko kubonisiwe kuMfanekiso 1. Ii-Welds ngasekhohlo, zibotshiwe ngasekunene. Amandla apheleleyo ee-welds kunye nee-bolts anokuqwalaselwa apha. Inxalenye nganye yonxibelelwano lonke isebenza ngokuzimeleyo. Ngoko ke, le khowudi ayihambelani nomgaqo okwinxalenye yokuqala ye-2.6.3.
Imithetho esandula ukuxutyushwa isebenza kwizakhiwo ezitsha. Kwizakhiwo ezikhoyo, icandelo 8.3.7 D1.1 lithi xa ubalo lwezakhiwo lubonisa ukuba i-rivet okanye i-bolt iya kugcwala ngumthwalo omtsha opheleleyo, ngumthwalo omileyo okhoyo kuphela omele unikwe yona.
Imithetho efanayo ifuna ukuba ukuba i-rivet okanye i-bolt igcwele kuphela yimithwalo engashukumiyo okanye iphantsi kwemithwalo ejikelezayo (yokudinwa), kufuneka kongezwe isinyithi esisisiseko kunye nee-welds ezaneleyo ukuxhasa umthwalo uwonke.
Ukusasazwa komthwalo phakathi kwezibophelelo zoomatshini kunye nee-welds kuyamkeleka ukuba isakhiwo silayishwe kwangaphambili, ngamanye amazwi, ukuba kuye kwenzeka ukutyibilika phakathi kwezinto ezidityanisiweyo. Kodwa kuphela imithwalo engashukumiyo enokubekwa kwii-fasteners zoomatshini. Imithwalo ephilayo enokubangela ukutyibilika okukhulu kufuneka ikhuselwe ngokusebenzisa ii-welds ezikwaziyo ukumelana nomthwalo wonke.
Ii-welds kufuneka zisetyenziswe ukumelana nayo yonke imithwalo esetyenziswayo okanye etshintshatshintshayo. Xa izibophelelo zoomatshini sele zigcwele kakhulu, ukwabelana ngomthwalo akuvumelekanga. Phantsi kokulayisha okujikelezayo, ukwabelana ngomthwalo akuvumelekanga, kuba umthwalo unokukhokelela ekutyibilikeni okungapheliyo kunye nokugqithisa kakhulu kwe-weld.
umzekeliso. Cinga ngejoyinti yelaphu eyayibotshelelwe ngokuqinileyo ekuqaleni (jonga uMfanekiso 2). Isakhiwo songeza amandla ongezelelweyo, kwaye uqhagamshelo kunye nezihlanganisi kufuneka zongezwe ukuze zinike amandla aphindwe kabini. Kumzobo 3 ubonisa isicwangciso esisisiseko sokuqinisa izinto. Uqhagamshelo kufuneka lwenziwe njani?
Ekubeni intsimbi entsha kwakufuneka idityaniswe nentsimbi endala ngee-fillet welds, injineli yagqiba ekubeni yongeze ezinye ii-fillet welds kwindawo edibeneyo. Ekubeni ii-bolts zazisekhona, ingcamango yokuqala yayikukongeza kuphela ii-welds ezifunekayo ukuze kudluliselwe amandla ongezelelweyo kwintsimbi entsha, belindele ukuba i-50% yomthwalo idlule kwii-bolts kwaye i-50% yomthwalo idlule kwii-welds ezintsha. Ngaba kuyamkeleka?
Masiqale sicinge ukuba akukho mithwalo imileyo esetyenziswayo okwangoku kuqhagamshelo. Kule meko, kuyasebenza umhlathi 2.6.3 we-AWS D1.1.
Kule joint yohlobo lwebheri, i-weld kunye ne-bolt azinakucingelwa ukuba zabelana ngomthwalo, ngoko ke ubungakanani be-weld obuchaziweyo kufuneka bube bukhulu ngokwaneleyo ukuxhasa wonke umthwalo ongaguqukiyo noguquguqukayo. Umthamo we-bearing wee-bolts kulo mzekelo awunakuthathelwa ingqalelo, kuba ngaphandle komthwalo ongaguqukiyo, uqhagamshelo luya kuba kwimeko yokungakhathali. I-weld (eyenzelwe ukuthwala isiqingatha somthwalo) iqala ukuqhekeka xa umthwalo ugcwele. Emva koko i-bolt, nayo eyenzelwe ukudlulisa isiqingatha somthwalo, izama ukudlulisa umthwalo ize iqhekeke.
Ngaphezulu cinga ukuba kusetyenziswa umthwalo ongashukumiyo. Ukongeza, kucingelwa ukuba uqhagamshelo olukhoyo lwanele ukuthwala umthwalo osisigxina okhoyo. Kule meko, kuyasebenza umhlathi 8.3.7 D1.1. Ii-welds ezintsha zifuna kuphela ukumelana nemithwalo eyongezelelekileyo engashukumiyo nephilayo ngokubanzi. Imithwalo efileyo ekhoyo inokwabelwa kwizixhobo zokubopha ezikhoyo.
Xa ilayishwa rhoqo, uqhagamshelo alugobi. Endaweni yoko, iibholithi sele zithwele umthwalo wazo. Kubekho ukutyibilika koqhagamshelo. Ke ngoko, ii-welds zingasetyenziswa kwaye zinokudlulisela imithwalo enamandla.
Impendulo yombuzo othi “Ingaba oku kuyamkeleka?” ixhomekeke kwiimeko zomthwalo. Kwimeko yokuqala, xa kungekho mthwalo ungashukumiyo, impendulo iya kuba negative. Phantsi kweemeko ezithile zemeko yesibini, impendulo nguewe.
Ngenxa yokuba kusetyenziswa umthwalo ongashukumiyo, akunakwenzeka rhoqo ukufikelela kwisigqibo. Inqanaba lemithwalo engashukumiyo, ukwanela konxibelelwano olukhoyo lwe-mechanical, kunye nohlobo lwemithwalo yokugqibela—nokuba yi-static okanye yi-cyclic—inokutshintsha impendulo.
UDuane K. Miller, MD, PE, 22801 Saint Clair Ave., eCleveland, OH 44117-1199, Umphathi weZiko leTekhnoloji yokuWelda, iLincoln Electric Company, www.lincolnelectric.com. ILincoln Electric yenza izixhobo zokuwelda kunye nezinto ezisetyenziswayo zokuwelda kwihlabathi liphela. Iinjineli kunye neengcali zeZiko leTekhnoloji yokuWelda zinceda abathengi ukusombulula iingxaki zokuwelda.
I-American Welding Society, 550 NW LeJeune Road, eMiami, FL 33126-5671, umnxeba ku-305-443-9353, ifeksi ku-305-443-7559, iwebhusayithi www.aws.org.
I-ASTM Intl., 100 Barr Harbor Drive, eWest Conshohocken, PA 19428-2959, umnxeba ku-610-832-9585, ifeksi ku-610-832-9555, iwebhusayithi www.astm.org.
I-American Steel Structures Association, One E. Wacker Drive, Suite 3100, Chicago, IL 60601-2001, umnxeba ku-312-670-2400, ifeksi ku-312-670-5403, iwebhusayithi www.aisc.org.
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