Dab tsi yog Steel Box Girder?
Lub thawv steel girder yog kaw, duab plaub lossis trapezoidal hollow cov tswv cuab tsim los ntawm welded steel daim hlau. Nws tus ntoo khaub lig-section muaj ib lub flange sab saum toj, ib lub flange hauv qab thiab ob txoj kab ntsug los yog inclined webs, tsim lub cell kaw. Nyob rau hauv lub thawv, longitudinal stiffeners (kaw U-ribs los yog tiaj phaj tav) thiab transverse diaphragms tswj lub zos buckling ntawm nyias daim hlau thiab ua kom tus ntoo khaub lig-section geometry ruaj khov nyob rau hauv load.
Cov seem kaw muab lub thawv steel girder peb qhov zoo ntawm qhov qhib kuv-girders:
Torsional nruj.Nyob rau hauv eccentric nyob loads, shear flow tsim nyob ib ncig ntawm lub tag nrho kaw perimeter, muab ntau dua St. Venant torsional nruj thiab qis distortion tshaj ib qho qhib seem ntawm qhov hnyav zoo sib xws.
Lub zog - rau - qhov hnyav piv.Lub thawv steel girder yog qhov sib zog dua li lub thawv prestressed pob zeb girder ntawm tib lub sijhawm, uas txo cov neeg tuag lub cev yuav tsum nqa thiab txo qis hauv paus thiab seismic thov.
Aerodynamic kev ua tau zoo.Lub tiaj tus, streamlined profile txo tus cab thiab pab txhawb nqa qhov tseem ceeb cua ceev rau flutter piv nrog truss girders, uas tseem ceeb rau cov ntug hiav txwv dej thiab cua daj cua dub- thaj chaw uas muaj kev cuam tshuam.
Cov khoom no ua rau lub thawv steel girder tus qauv xaiv nyob rau hauv ob lub luag haujlwm: raws li lub luag haujlwm tseem ceeb - nqa girder ntawm beam- hom txuas hniav, thiab raws li ib qho kev sib zog ntawm cov kab hluav taws xob - txhawb nqa txuas (kab - nyob thiab ncua).
Span Ranges los ntawm Cov Qauv Txheej Txheem
Span kev faib tawm ntawm lub thawv steel girder yog nyob ntawm cov qauv txheej txheem uas lub girder ua haujlwm, tsis yog nyob ntawm tus nqi ntev. Tib lub thawv ntu tuaj yeem tshwm sim nyob rau hauv luv luv viaduct ncua lossis hauv tus choj hla dhau ib mais; Qhov txawv yog nyob rau hauv yuav ua li cas loads.
Girder thiab truss systems (tus kheej- txhawb nqa)
Nyob rau hauv no system lub thawv girder spans ncaj qha ntawm kev txhawb nqa thiab tso siab rau nws tus kheej dabtsi yog khoov thiab shear peev xwm; tsis muaj cables lossis yees muab kev thauj khoom ntxiv.
| Kev ncua deb | Tej daim ntawv thov | Box girder configuration |
|---|---|---|
| Txog li 50-100 m | Lub nroog viaducts, nkhaus overpasses | Tsis tu ncua- qhov tob, ib qho - lub thawv cell |
| Txog li 100-250 m | Kev hla dej, kev loj choj | Hloov pauv tau - qhov tob, ib zaug - lossis ob npaug - lub thawv cell |
| Txog li 250-350 m | Cov channel loj navigation | Variable -depth steel-concrete hybrid girder (steel midspan with concrete side spans) |
| Tshaj li kwv yees li 350 m | Economic txwv cheeb tsam rau tus kheej - txhawb nqa girders | Hybrid lossis cable- txhawb nqa qhov ib txwm xav tau; xav tau qhov chaw-kev txiav txim tshwj xeeb |
Cable -txhawb tshuab (stiffening girder)
Hauv cov kab hluav taws xob- nyob thiab ncua kev txuas txuas, cov cables nqa cov thawj ntsug loads thaum lub thawv girder muab torsional nruj, aerodynamic stability thiab lub lawj platform.
| Kev ncua deb | Hom choj | Lub luag haujlwm ntawm lub thawv steel girder |
|---|---|---|
| Kwv yees li 400-1,200 m | Cable -nyob twj ywm choj | Stiffening girder: resists axial compression los ntawm nyob cables ntxiv rau khoov nyob rau hauv load |
| Kwv yees li 1,000-2, 000+ m | Kev ncua choj | Stiffening girder: muab torsional rigidity thiab aerodynamic stability |
Zoo-cov ntaub ntawv piv txwv suav nrog Sutong Choj hauv Suav teb (cable- nyob, qhov loj 1,088 m, steel kem stiffening girder) thiab 1915 Canakkale Choj hauv Qaib Cov Txwv (kev ncua, ncua sij hawm 2,023 m, ntxaib steel kem girder). Tsis muaj qhov ntsuas theoretical sab saud rau cable- txhawb nqa; ntev spans yog tiav los ntawm optimized aerodynamic profiles thiab cable system txuam.
Yam Tseem Ceeb Uas txwv Steel Box Girder Span
Tus kheej - nyhav thiab lub voj voog lub sijhawm khoov
Khoov lub sij hawm los ntawm tus kheej - hnyav nce roughly nrog lub square ntawm lub span. Qhov loj dua yuav tsum tau tiv thaiv lub sijhawm ntxiv qhov hnyav ntxiv, tsim lub voj voog uas ua rau tag nrho - steel girders uneconomical tshaj li ntawm ob peb puas meters; Composite (steel-concrete) girders txuas ntxiv lub hnab ntawv nyiaj txiag me ntsis, thiab dhau li ntawd lub cable- txhawb nqa feem ntau ua haujlwm tau zoo dua.
Deflection thiab nruj txwv
Nyob -load midspan deflection loj hlob sai nrog span. Vim tias lub elastic modulus ntawm cov hlau yog ruaj, ntev tus kheej - txhawb nqa spans xav tau kev sib sib zog nqus girders kom tau raws li qhov deflection txwv los ntawm txoj cai tswj hwm (rau txoj kev loj choj feem ntau nyob rau hauv thaj tsam ntawm L / 500 rau L / 600, thiab nruj rau railway choj), uas tsub kom cov khoom, cua raug thiab erection.
Local buckling ntawm nyias daim hlau
Ntev spans tsa lub compressive kev nyuaj siab nyob rau hauv flanges thiab webs, uas yuav ua rau lub zos buckling ntawm nyias daim hlau. Longitudinal stiffeners thiab transverse diaphragms daws qhov teeb meem buckling tab sis ntxiv vuam, residual stress thiab fabrication nqi, thiab cov ntsiab lus weld nce yuav tsum tau txiav txim siab nyob rau hauv qaug zog tsim.
Shear lag cuam tshuam
Hauv dav ntev -span box girders, ntsug loads ua rau shear deformation nyob rau hauv dav flanges. Kev ntxhov siab nyob ze ntawm lub webs thiab cov khoom siv flange tej thaj chaw deb siv tsis tau, yog li qhov zoo ntawm flange dav shrinks raws li qhov loj hlob, txo cov kabmob ntawm cov seem.
Aerodynamic cua stability
Sib sib zog nqus girders yuav tsum tau ntev -span txhav ua rau cov cua tiv tauj cheeb tsam thiab intensify vortex-induced vibration thiab flutter txaus ntshai. Cua ruaj khov feem ntau dhau los ua kev tswj hwm rau thaj chaw ntug dej hiav txwv thiab cua daj cua dub, xav tau cua- qhov kev tshawb fawb thiab kev nthuav dav aerodynamic xws li streamlined lossis slotted ntxaib- lub thawv ntu.
Steel Box Girder vs. Lwm Hom Choj
| Yam khoom | Steel box girder | Prestressed qhob lub thawv girder | Cable -nyob twj ywm choj | Kev ncua choj |
|---|---|---|---|---|
| Hom kev sib tw span ntau | 100-350 m (kev txhawb nqa tus kheej) | Txog li 300 m | 250-1,200 m | 1,000-2,000+ m |
| Girder tus kheej - hnyav | Tsawg | Siab (kwv yees 2-3 zaug hlau) | Tsawg rau nruab nrab | Tsawg rau nruab nrab |
| Torsional nruj | Siab heev (kaw ntu) | Siab | High (lub thawv stiffening girder) | High (lub thawv stiffening girder) |
| Aerodynamic kev ua tau zoo | Zoo heev (streamlined profile) | Nruab nrab | Zoo | Zoo heev (twin- xaiv lub thawv) |
| Kev tsim kho ceev | Fast (Factory Segment Fabrication) | Slow (ntawm -site formwork thiab casting) | Nruab nrab | Ntev (ntauwd thiab cable erection) |
| Kev kho mob xav tau | Siab dua (txheej txheej thiab vuam tshuaj xyuas) | Kev tu ncua qis dua | Siab dua (kab kab, yees, anchorages) | Siab dua (tseem ceeb cables, anchorages) |
Tsim qauv thiab cov khoom siv
Steel box girders rau txuas hniav yog tsim thiab fabricated rau cov cai siv rau qhov project jurisdiction:
Cov qib steel:Suav choj steels Q345q thiab Q370q rau GB / T 714; European qib S355J2 thiab S355NL rau EN 10025; US qib ASTM A709 Qib 50 / 50W. Weathering choj steels tej zaum yuav raug teev rau cov ntug dej hiav txwv tej yaam num kom ncua txheej txij nkawm.
Cov lej tsim:JTG D64 rau Suav txoj kev loj steel choj; TS EN 1993-2: European steel txuas hniav; AASHTO LRFD Choj Design Specifications rau US tej yaam num.
Fabrication thiab welding:EN 1090-2 execution classes or AWS D1.5 for bridge welding, with NDT txais raws li qhov project specification.
Kev tiv thaiv corrosion:blasting tu rau Sa 2.5 rau ISO 8501-1 thiab txheej txheej xaiv rau ISO 12944 corrosivity pawg.
Daim ntawv teev npe xaiv rau cov neeg yuav khoom
Txhais cov qauv txheej txheem (tus kheej- txhawb nqa girder / truss, lossis cable- txhawb nqa stiffening girder) ua ntej sib tham txog span.
Txheeb xyuas cov qauv tsim qauv thiab cov qauv thauj khoom (xws li AASHTO HL-93, Eurocode load qauv, lossis lub teb chaws code ntawm lub teb chaws project).
Qhia kom meej lub lawj dav, pes tsawg lub hlwb thiab seb puas yuav tsum muaj lub lawj orthotropic steel.
Muab cov qib steel thiab cov kev xav tau cuam tshuam (Charpy) rau qhov kev pabcuam kub.
Qhia qhov chaw corrosion thiab yuav tsum tau txheej txheej (ISO 12944 qeb).
Txhais ntu ntev txwv raws li kev thauj khoom thiab nqa khoom, thiab txoj kev erection (crane lifting, launching or cantilever assembly).
Pom zoo rau QC cov ntaub ntawv: daim ntawv pov thawj cov ntaub ntawv, cov ntaub ntawv soj ntsuam vuam, cov ntawv ceeb toom qhov ntev thiab khw muag khoom ua ntej- cov ntaub ntawv sib dhos.
Thov ib tug Steel Box Girder Fabrication Quote
FAQ
Dab tsi yog qhov siab tshaj plaws ntawm lub thawv steel girder?
Tsis muaj ib qhov siab tshaj plaws. Tus kheej- txhawb nqa lub thawv steel girders yog kev lag luam mus txog kwv yees li 300-350 m. Raws li cov hlua khi ruaj khov ntawm cov hlua khi hlua khi thiab cov hlua khi hlua khi, steel lub thawv girders tau ua rau ntawm cov spans loj tshaj 1,000 m; Lub 1915 Canakkale ncua kev txuas choj nyob rau hauv Qaib Cov Txwv, nrog ib tug 2,023 m lub ntsiab ncua, siv lub thawv steel stiffening girder.
Vim li cas lub thawv steel girder sib dua li lub pob zeb pob zeb?
Cov qauv hlau muaj lub zog ntau dua - mus rau - qhov hnyav piv dua li cov pob zeb muaj zog, yog li lub thawv steel girder ntawm qhov sib npaug thiab muaj peev xwm hnyav ib feem ntawm qhov sib npaug ntawm lub pob zeb sib npaug. Txo qhov hnyav tuag txo cov loads ntawm piers, foundations thiab, nyob rau hauv cables - txhawb nqa choj, ntawm pylons thiab cables.
Dab tsi deflection txwv siv rau steel box girders?
Deflection txwv yog teem los ntawm txoj cai tswj hwm thiab nyob ntawm seb tus choj hom. Txoj kev loj steel lub thawv girders feem ntau tsim los ua neej nyob -load deflection txwv nyob ib ncig ntawm L/500 txog L/600, thaum cov kev tsheb ciav hlau siv cov kev txwv nruj dua. Tus nqi pes tsawg yuav tsum tau muab los ntawm qhov project code, tsis yog xav.
Thaum twg kuv yuav tsum xaiv ib lub steel -paj hybrid girder es tsis txhob ntawm tag nrho cov - steel girder?
Hybrid girders, nrog ib tug steel midspan thiab pob zeb sab spans, yog muaj nyob rau hauv lub 250-350 m band ntawm nruam nruam- ncej choj. Lawv ua ke lub teeb nruab nrab ntawm cov hlau nrog qhov nruj thiab kev lag luam ntawm cov pob zeb sab nraud, thiab muaj kev sib tw qhov twg tag nrho cov - steel girders ua tsis zoo tab sis tsis tas yuav muaj kev txhawb nqa cable.
Vim li cas steel lub thawv girders nyiam rau qhov ntev?
Peb yam khoom tseem ceeb tshaj plaws: cov seem kaw muab tshwj xeeb torsional txhav; lub streamlined profile txhim kho aerodynamic stability thiab tsa lub flutter -tseem ceeb cua ceev; thiab lub zog siab -rau- qhov hnyav piv cia lub girder tiv thaiv lub sijhawm khoov loj nrog cov khoom siv tsawg dua li qhib phaj girders.
Puas tuaj yeem nkhaus thiab sib txawv - qhov tob lub thawv girders tuaj yeem tsim tau?
Yog lawm. Lub thawv girders nrog curved alignment, widening thiab variable depth yog niaj hnub fabricated nyob rau hauv cov ntu nrog CNC txiav thiab neeg hlau los yog submerged arc vuam, ces sim - sib dhos hauv khw ua ntej xa khoom. Qhov kawg geometry yuav tsum ua raws li lub khw pom zoo kos duab los ntawm tus choj tsim.