Hauv ntau yam xwm txheej ntawm kev tsim kho, cov kws ua vaj tse yuav tsum tau soj ntsuam qhov muaj zog ntawm cov pob qij txha uas ua los ntawm kev vuam thiab cov khoom siv kho tshuab. Niaj hnub no, cov khoom siv kho tshuab feem ntau yog cov ntsia hlau, tab sis cov qauv qub yuav muaj cov rivets.
Qhov no tuaj yeem tshwm sim thaum lub sijhawm txhim kho, kho dua tshiab, lossis txhim kho ib qho project. Ib qho kev tsim tshiab yuav xav tau kev siv bolting thiab welding kom ua haujlwm ua ke hauv qhov sib koom ua ke uas cov khoom siv yuav tsum tau koom ua ke yuav tsum tau bolted ua ntej thiab tom qab ntawd welded kom muab lub zog tag nrho rau qhov sib koom ua ke.
Txawm li cas los xij, kev txiav txim siab tag nrho lub peev xwm thauj khoom ntawm ib qho pob qij txha tsis yooj yim li kev suav cov khoom sib xyaw ua ke (welds, bolts, thiab rivets). Kev xav zoo li no tuaj yeem ua rau muaj kev puas tsuaj loj heev.
Cov kev sib txuas bolted tau piav qhia nyob rau hauv American Institute of Steel Structures (AISC) Structural Joint Specification, uas siv ASTM A325 lossis A490 bolts ua qhov nruj nreem mount, preload, lossis sliding key.
Siv lub cuab yeej cuam tshuam los yog tus kws xauv xauv siv lub cuab yeej ob sab los ua kom cov txheej sib txuas nruj nreem. Hauv kev sib txuas ua ntej, cov ntsia hlau raug teeb tsa kom lawv raug rau cov khoom hnyav tensile, thiab cov phaj raug rau cov khoom hnyav compressive.
1. Tig lub txiv ntoo. Txoj kev tig lub txiv ntoo yog ua kom lub hau ntswj nruj thiab tom qab ntawd tig lub txiv ntoo ntxiv, uas nyob ntawm lub taub hau thiab qhov ntev ntawm lub hau ntswj.
2. Kho tus yuam sij. Txoj kev kho lub wrench ntsuas qhov torque uas cuam tshuam nrog lub zog ntawm lub bolt.
3. Cov ntsia hlau uas kho qhov nruj uas siv hom Torsion. Cov ntsia hlau uas ntswj tau muaj cov ntsia hlau me me rau ntawm qhov kawg ntawm cov ntsia hlau uas nyob rau sab nraud ntawm lub taub hau. Thaum lub zog torque uas xav tau raug ncav cuag, lub ntsia hlau yuav raug tshem tawm.
4. Cov ntsuas rub ncaj. Cov ntsuas kev nruj ncaj qha yog cov ntxhua khaub ncaws tshwj xeeb nrog cov tabs. Qhov ntau ntawm kev nias ntawm lub lug qhia txog qib kev nruj siv rau lub bolt.
Hauv cov lus yooj yim, cov ntsia hlau ua haujlwm zoo li cov koob ntsaws rau hauv cov pob qij txha nruj thiab ua ntej, zoo li tus pin tooj dag tuav ib pawg ntawv perforated ua ke. Cov pob qij txha swb tseem ceeb ua haujlwm los ntawm kev sib txhuam: preload tsim downforce, thiab kev sib txhuam ntawm cov chaw sib cuag ua haujlwm ua ke los tiv thaiv kev plam ntawm qhov sib koom ua ke. Nws zoo li lub binder uas tuav ib pawg ntawv ua ke, tsis yog vim muaj qhov raug punched hauv daim ntawv, tab sis vim tias lub binder nias cov ntawv ua ke thiab kev sib txhuam tuav pawg ua ke.
ASTM A325 bolts muaj lub zog tensile tsawg kawg nkaus ntawm 150 txog 120 kg ib square inch (KSI), nyob ntawm seb lub bolt diameter li cas, thaum A490 bolts yuav tsum muaj lub zog tensile ntawm 150 txog 170-KSI. Cov pob qij txha rivet ua zoo li cov pob qij txha nruj, tab sis hauv qhov no, cov pins yog rivets uas feem ntau muaj zog li ib nrab ntawm A325 bolt.
Ib qho ntawm ob yam yuav tshwm sim thaum ib qho sib txuas uas tau khi ua ke raug lub zog txiav (thaum ib qho feem ntau swb hla lwm qhov vim yog lub zog siv). Cov ntsia hlau lossis cov rivets tuaj yeem nyob ntawm ob sab ntawm cov qhov, ua rau cov ntsia hlau lossis cov rivets txiav tawm tib lub sijhawm. Qhov ua tau thib ob yog tias qhov kev sib txhuam los ntawm lub zog clamping ntawm cov fasteners pretensioned tuaj yeem tiv taus cov khoom hnyav shear. Tsis muaj kev poob qis rau qhov kev sib txuas no, tab sis nws ua tau.
Kev sib txuas nruj me ntsis yog qhov siv tau rau ntau yam kev siv, vim tias qhov sib txhuam me ntsis tsis tuaj yeem cuam tshuam tsis zoo rau cov yam ntxwv ntawm kev sib txuas. Piv txwv li, xav txog lub silo uas tsim los khaws cov khoom siv granular. Tej zaum yuav muaj qhov sib txhuam me ntsis thaum thauj khoom thawj zaug. Thaum muaj kev sib txhuam, nws yuav tsis tshwm sim dua, vim tias txhua qhov kev thauj khoom tom qab ntawd yog tib yam.
Kev siv qhov kev thim rov qab ntawm lub nra hnyav yog siv rau hauv qee qhov kev siv, xws li thaum cov khoom tig tau raug kev hloov pauv ntawm cov nra hnyav tensile thiab compressive. Lwm qhov piv txwv yog ib qho khoom khoov uas raug kev hloov pauv tag nrho. Thaum muaj kev hloov pauv tseem ceeb hauv kev coj ntawm lub nra hnyav, kev sib txuas ua ntej yuav tsum tau ua kom tshem tawm qhov kev sib txhuam ntawm lub voj voog. Qhov kev sib txhuam no thaum kawg ua rau muaj kev sib txhuam ntau dua hauv cov qhov ntev.
Qee cov pob qij txha muaj ntau lub voj voog thauj khoom uas tuaj yeem ua rau qaug zog. Cov no suav nrog cov nias, cov crane txhawb nqa thiab cov kev sib txuas hauv cov choj. Cov kev sib txuas tseem ceeb uas swb yog qhov yuav tsum tau muaj thaum qhov kev sib txuas raug kev txom nyem los ntawm kev qaug zog hauv qhov kev coj rov qab. Rau cov xwm txheej zoo li no, nws yog ib qho tseem ceeb heev uas qhov sib txuas tsis txhob plam, yog li cov pob qij txha uas plam tseem ceeb yog qhov xav tau.
Cov kev sib txuas uas twb muaj lawm tuaj yeem tsim thiab tsim khoom raws li cov qauv no. Cov kev sib txuas rivet raug suav hais tias nruj.
Cov pob qij txha uas vuam yog cov khoom tawv. Cov pob qij txha vuam yog cov khoom nyuaj. Tsis zoo li cov pob qij txha uas nruj nreem, uas tuaj yeem plam thaum muaj kev thauj khoom, cov vuam tsis tas yuav ncab thiab faib cov khoom siv rau ntau qhov. Feem ntau, cov khoom siv sib txuas uas vuam thiab cov khoom siv bearing tsis deform tib yam.
Thaum siv cov welds nrog cov khoom siv kho tshuab, lub nra hnyav raug xa mus rau qhov nyuaj dua, yog li qhov vuam tuaj yeem nqa yuav luag tag nrho cov nra hnyav, nrog rau me ntsis sib koom nrog lub bolt. Yog vim li cas yuav tsum tau ceev faj thaum vuam, bolting thiab riveting. Cov Lus Qhia Tshwj Xeeb. AWS D1 daws qhov teeb meem ntawm kev sib xyaw cov khoom siv kho tshuab thiab welds. Cov Lus Qhia Tshwj Xeeb 1: 2000 rau kev vuam qauv - hlau. Nqe 2.6.3 hais tias rau rivets lossis bolts siv rau hauv cov pob qij txha hom kabmob (piv txwv li qhov twg lub bolt lossis rivet ua haujlwm ua tus pin), cov khoom siv kho tshuab yuav tsum tsis txhob xav tias yuav sib koom cov nra hnyav nrog lub weld. Yog tias siv welding, lawv yuav tsum tau muab los nqa tag nrho cov nra hnyav hauv qhov sib koom ua ke. Txawm li cas los xij, kev sib txuas welded rau ib qho khoom thiab riveted lossis bolted rau lwm qhov khoom raug tso cai.
Thaum siv cov khoom siv kho tshuab uas muaj cov kabmob thiab ntxiv cov vuam, lub peev xwm ntawm lub bolt feem ntau tsis quav ntsej. Raws li txoj cai no, qhov vuam yuav tsum tau tsim los hloov txhua yam khoom thauj.
Qhov no yeej zoo ib yam li AISC LRFD-1999, kab lus J1.9. Txawm li cas los xij, tus qauv Canadian CAN/CSA-S16.1-M94 kuj tso cai rau kev siv sawv ntsug thaum lub zog ntawm lub tshuab txuas lossis ntsia hlau siab dua li ntawm kev vuam.
Hauv qhov teeb meem no, peb cov qauv yog sib xws: qhov ua tau ntawm kev sib txuas ntawm cov khoom siv kho tshuab ntawm hom kabmob thiab qhov ua tau ntawm kev vuam tsis sib ntxiv.
Tshooj 2.6.3 ntawm AWS D1.1 kuj tham txog cov xwm txheej uas cov bolts thiab welds tuaj yeem ua ke ua ob ntu sib koom ua ke, raws li pom hauv Daim Duab 1. Welds sab laug, bolted sab xis. Tag nrho lub zog ntawm welds thiab bolts tuaj yeem coj mus rau hauv tus account ntawm no. Txhua feem ntawm tag nrho kev sib txuas ua haujlwm ywj pheej. Yog li, cov lej no yog qhov zam rau lub hauv paus ntsiab lus muaj nyob rau hauv thawj ntu ntawm 2.6.3.
Cov cai uas nyuam qhuav tham txog siv rau cov tsev tshiab. Rau cov qauv uas twb muaj lawm, kab lus 8.3.7 D1.1 hais tias thaum kev xam cov qauv qhia tias lub rivet lossis bolt yuav raug thauj ntau dhau los ntawm tag nrho cov khoom thauj tshiab, tsuas yog lub nra hnyav uas twb muaj lawm yuav tsum tau muab rau nws.
Cov cai tib yam yuav tsum tau ua yog tias lub rivet lossis bolt tsuas yog overloaded nrog static loads lossis raug cyclic (qaug zog) loads, txaus base hlau thiab welds yuav tsum tau ntxiv los txhawb tag nrho cov load.
Qhov kev faib tawm ntawm cov khoom thauj ntawm cov khoom siv kho tshuab thiab cov vuam yog qhov txais tau yog tias cov qauv tau thauj khoom ua ntej, hais lwm yam lus, yog tias muaj kev sib txhuam ntawm cov khoom sib txuas. Tab sis tsuas yog cov khoom thauj static tuaj yeem tso rau ntawm cov khoom siv kho tshuab. Cov khoom thauj uas tuaj yeem ua rau muaj kev sib txhuam ntau dua yuav tsum tau tiv thaiv los ntawm kev siv cov vuam uas muaj peev xwm tiv taus tag nrho cov khoom thauj.
Yuav tsum siv cov vuam kom tiv taus txhua qhov kev thauj khoom siv lossis kev thauj khoom dynamic. Thaum cov khoom siv kho tshuab twb tau thauj khoom ntau dhau lawm, tsis pub sib koom thauj khoom. Nyob rau hauv kev thauj khoom cyclic, tsis pub sib koom thauj khoom, vim tias qhov thauj khoom tuaj yeem ua rau kev sib txhuam mus tas li thiab kev thauj khoom ntau dhau ntawm qhov vuam.
daim duab. Xav txog ib lub pob qij txha uas tau muab ntsia kom nruj (saib Daim Duab 2). Lub qauv ntxiv lub zog ntxiv, thiab cov kev sib txuas thiab cov khoom sib txuas yuav tsum tau ntxiv kom muab ob npaug ntawm lub zog. Hauv daim duab 3 qhia txog txoj kev npaj yooj yim rau kev txhawb zog cov ntsiab lus. Yuav tsum ua li cas thiaj txuas tau?
Vim tias cov hlau tshiab yuav tsum tau txuas nrog cov hlau qub los ntawm kev sib txuas fillet, tus kws ua choj txiav txim siab ntxiv qee qhov kev sib txuas fillet ntawm qhov sib koom ua ke. Vim tias cov bolts tseem nyob hauv qhov chaw, lub tswv yim thawj zaug yog ntxiv tsuas yog cov welds uas xav tau los hloov lub zog ntxiv rau cov hlau tshiab, xav tias 50% ntawm cov khoom thauj yuav hla dhau cov bolts thiab 50% ntawm cov khoom thauj yuav hla dhau cov welds tshiab. Nws puas siv tau?
Cia peb xav ua ntej tias tsis muaj cov khoom siv static tam sim no siv rau qhov kev sib txuas. Hauv qhov no, nqe 2.6.3 ntawm AWS D1.1 siv tau.
Hauv qhov sib koom ua ke no, qhov vuam thiab lub ntsia hlau tsis tuaj yeem suav tias yog sib koom qhov hnyav, yog li qhov loj ntawm qhov vuam uas tau teev tseg yuav tsum loj txaus los txhawb tag nrho cov khoom thauj static thiab dynamic. Lub peev xwm ntawm cov ntsia hlau hauv qhov piv txwv no tsis tuaj yeem coj mus rau hauv tus account, vim tias yog tsis muaj qhov hnyav static, qhov kev sib txuas yuav nyob rau hauv lub xeev slack. Qhov vuam (tsim los nqa ib nrab ntawm qhov hnyav) pib tawg thaum siv tag nrho cov khoom thauj. Tom qab ntawd lub ntsia hlau, kuj tsim los hloov ib nrab ntawm qhov hnyav, sim hloov qhov hnyav thiab tawg.
Xav ntxiv tias muaj lub nra hnyav zoo li qub. Tsis tas li ntawd xwb, xav tias qhov kev sib txuas uas twb muaj lawm txaus los nqa lub nra hnyav tas mus li uas twb muaj lawm. Hauv qhov no, nqe 8.3.7 D1.1 siv tau. Cov vuam tshiab tsuas yog yuav tsum tiv taus cov nra hnyav zoo li qub thiab cov nra hnyav dav dav xwb. Cov nra hnyav uas twb muaj lawm tuaj yeem muab faib rau cov khoom siv kho tshuab uas twb muaj lawm.
Nyob rau hauv qhov kev thauj khoom tas li, qhov kev sib txuas tsis sag. Hloov chaw, cov bolts twb dais lawv lub nra hnyav lawm. Muaj qee qhov kev poob qis hauv qhov kev sib txuas. Yog li ntawd, welds tuaj yeem siv thiab lawv tuaj yeem xa cov khoom thauj dynamic.
Cov lus teb rau lo lus nug "Qhov no puas txais tau?" nyob ntawm cov xwm txheej ntawm kev thauj khoom. Hauv thawj qhov xwm txheej, yog tias tsis muaj kev thauj khoom ruaj khov, cov lus teb yuav tsis zoo. Hauv qab cov xwm txheej tshwj xeeb ntawm qhov xwm txheej thib ob, cov lus teb yog yog.
Tsuas yog vim muaj kev siv lub nra hnyav static xwb, nws tsis yog ib txwm ua tau kom xaus lus. Qib ntawm cov nra hnyav static, qhov txaus ntawm cov kev sib txuas mechanical uas twb muaj lawm, thiab qhov xwm txheej ntawm cov nra hnyav kawg—txawm tias static lossis cyclic—tej zaum yuav hloov cov lus teb.
Duane K. Miller, MD, PE, 22801 Saint Clair Ave., Cleveland, OH 44117-1199, Tus Thawj Coj Chaw Siv Tshuab Vuam, Lincoln Electric Company, www.lincolnelectric.com. Lincoln Electric tsim cov khoom siv vuam thiab cov khoom siv vuam thoob ntiaj teb. Cov kws ua haujlwm thiab cov kws kho tshuab ntawm Chaw Siv Tshuab Vuam pab cov neeg siv khoom daws teeb meem vuam.
Lub Koom Haum American Welding, 550 NW LeJeune Road, Miami, FL 33126-5671, xov tooj 305-443-9353, fax 305-443-7559, lub vev xaib www.aws.org.
ASTM Intl., 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, xov tooj 610-832-9585, fax 610-832-9555, lub vev xaib www.astm.org.
Lub Koom Haum American Steel Structures Association, One E. Wacker Drive, Suite 3100, Chicago, IL 60601-2001, xov tooj 312-670-2400, fax 312-670-5403, lub vev xaib www.aisc.org.
FABRICATOR yog phau ntawv xov xwm tsim thiab tsim cov hlau ua lag luam hauv North America. Phau ntawv xov xwm no luam tawm xov xwm, cov ntawv tshaj tawm txog kev siv tshuab thiab cov dab neeg ua tiav uas ua rau cov chaw tsim khoom ua lawv txoj haujlwm tau zoo dua. FABRICATOR tau nyob hauv kev lag luam txij li xyoo 1970.
Tam sim no nrog kev nkag mus rau tag nrho cov ntawv digital ntawm The FABRICATOR, yooj yim nkag mus rau cov peev txheej muaj txiaj ntsig hauv kev lag luam.
Cov ntawv xov xwm digital ntawm The Tube & Pipe Journal tam sim no nkag tau tag nrho, muab kev nkag mus tau yooj yim rau cov peev txheej muaj txiaj ntsig hauv kev lag luam.
Tau txais kev nkag mus rau STAMPING Journal tag nrho, uas muaj cov thev naus laus zis tshiab, cov kev coj ua zoo tshaj plaws thiab xov xwm kev lag luam rau kev lag luam hlau stamping.
Tam sim no nrog kev nkag mus rau The Fabricator en Español tag nrho, koj muaj kev nkag mus rau cov peev txheej muaj txiaj ntsig zoo hauv kev lag luam.