Dab tsi yog Steel Box Girders thiab Phaj Girders?
A steel box girderyog lub hollow, kaw-section beam fabricated los ntawm welding steel daim hlau rau hauv ib lub duab plaub, square los yog trapezoidal cross-section. Vim hais tias cov seem raug kaw, nws tsim ib tug nruam shear flow nyob rau hauv torsion thiab muaj siab heev torsional rigidity. Lub thawv girders yog dav siv nyob rau hauv nkhaus choj, ntev -span cable- nyob thiab ncua kev kawm ntawv choj, nroog elevated txoj kev loj thiab hnyav- lub luag hauj lwm crane girders.
A steel phaj girderyog ib qho ua tau -up I- zoo li tus (los yog H- zoo li tus) beam sib sau ua ke los ntawm vuam lossis bolting ib tus phaj - lub vev xaib thiab sab saum toj / hauv qab flange phaj - ua ke nrog stiffeners. Nws yog ib qho qhib seem uas muaj txiaj ntsig zoo hauv kev tawm tsam ntsug bending raws nws cov axis muaj zog, thiab nws yog feem ntau siv rau hauv kev txhawb nqa yooj yim thiab txuas ntxiv kev loj, kev lag luam crane khiav thiab hloov girders.
Ob hom yog kev cai -fabricated structural tswv cuab es tsis yog dov txheem seem. Qhov kev xaiv ntawm lawv yog tswj hwm los ntawm kev ncua ntev, txoj kev thauj khoom, qhov nkhaus, kev siv nkag thiab lub neej- nqi mus ncig. Phau ntawv qhia no piav qhia txog qhov sib txawv ntawm cov txuj ci thiab muab txoj hauv kev xaiv cov tswv yim rau cov choj thiab cov phiaj xwm tsim.
Qhov tseem ceeb sib txawv ntawm ib saib
| Cov khoom sib piv | Steel Box Girder | Steel Phaj Girder |
|---|---|---|
| Hla -section | Kaw duab plaub, square lossis trapezoid | Qhib I lossis H duab |
| Torsional nruj | High (kaw shear flow) | Tsawg (qhib seem, xav tau bracing) |
| Flexural cwj pwm | Zoo heev nyob rau hauv tag nrho cov lus qhia | Zoo heev txog lub zog axis nkaus xwb |
| Shear tsis kam | Qhia los ntawm ob lossis ntau lub vev xaib | Nqa los ntawm ib lub vev xaib |
| Ntiaj teb no stability | Kev tiv thaiv siab rau lateral -torsional buckling | Yuav tsum tau lateral bracing thiab stiffeners |
| Fabrication complexity | Siab (lub hlwb, ntau stiffeners, puv -kev nkag welds) | Nruab nrab (planar sib dhos, automated kab ua tau) |
| Qhov chaw sib dhos | Feem ntau welded ntu, siab - qhov siab vuam | Feem ntau siab -lub zog bolted splices |
| Tej daim ntawv thov | Curved ramps, ntev spans, dav decks | Ncaj nruab nrab spans, crane girders, hloov kab teeb |
| Kev tu | Npog void, dehumidification xav tau, qhov chaw me me | Loj dua qhov chaw, kev tshuaj xyuas yooj yim dua |
Cov qauv kev ua tau zoo piv
Torsional tawv
Lub thawv kaw hla -section tsim lub kaw shear flow thaum twisted, uas txwv tsis pub warping thiab muab ntau dua torsional tsis kam tshaj qhov qhib kuv -section ntawm qhov hnyav zoo sib xws. Qhov no ua rau lub thawv girders tus qauv xaiv rau kab rov tav nkhaus txuas hniav thiab rau decks loaded eccentrically los ntawm cov tsheb hnyav.
Flexural Peev Xwm
Nyob rau hauv ib lub thawv girder, sab saum toj thiab hauv qab flange daim hlau yog dav thiab ua rau lub sij hawm loj ntawm inertia, muab siab thoob ntiaj teb flexural muaj peev xwm nyob rau hauv ob qho tib si cov lus qhia. Lub phaj girder concentrates cov khoom hauv ob lub flanges sib cais los ntawm ib lub vev xaib sib sib zog nqus; Nws ua tau zoo heev rau lub ntiajteb txawj nqus loads ua vertically, tab sis nws lateral (tsis muaj zog-axis) nruj yog txwv.
Shear Resistance thiab Stability
Shear nyob rau hauv ib lub thawv girder yog sib koom los ntawm ob lossis ntau lub webs, thiab cov diaphragms sab hauv txwv cov webs tiv thaiv shear buckling, yog li nyias webs tuaj yeem siv nyiaj txiag. Lub phaj girder tso siab rau ntawm ib lub vev xaib; sib sib zog nqus slender webs yuav tsum tau transverse thiab longitudinal stiffeners los tiv thaiv kab pheeb ces kaum shear buckling. Rau tib lub laj thawj, phaj girders muaj kev cuam tshuam ntau dua rau lateral -torsional buckling thiab xav tau cov txheej txheem bracing rau qhov ntev unbraced.
Fabrication, Erection thiab Maintenance
| Yam | Steel Box Girder | Steel Phaj Girder |
|---|---|---|
| Vuam thov | Tag nrho -kev nkag welds, txwv sab hauv ntau- xovtooj vuam, xav tau NDT | Feem ntau yog fillet lossis ib nrab -kev nkag welds; distortion yooj yim rau kev tswj |
| Khw muag khoom prefabricated | Segments (ib -cell lossis multi-cell) ua hauv khw, thauj mus rau qhov chaw | Tag nrho los yog segmented girders; cov khoom sib dua, kev thauj mus los tsawg dua |
| Qhov chaw sib dhos | Ntu txuas nrog vuam; kev tswj kev sib raug zoo yog qhov tseem ceeb | Feem ntau siab -lub zog bolted splices; ceev installation |
| Kev nqa | Heavy tus kheej - hnyav, loj - tonnage cranes yuav tsum tau | Qhov hnyav nruab nrab, tsawg xav tau ntawm crane muaj peev xwm |
| Kev tiv thaiv corrosion | Cov kab noj hniav uas nyob ib puag ncig xav tau txheej txheej sab hauv lossis dehumidification; cheeb tsam sab nraud yog me me | Txhua qhov chaw raug; txhaj tshuaj blasting, txheej thiab tshuaj xyuas yog yooj yim |
Rau lub thawv girders, kev tswj kom zoo cia siab rau cov txheej txheem vuam tsim nyog (WPS), tsis yog -kev sim ua kom puas tsuaj ntawm cov pob qij txha tseem ceeb thiab khw muag khoom sib dhos ntawm cov ntu sib xws. Rau cov phaj girders, automated vuam kab thiab cov qauv ntsuas qhov ntev yog feem ntau txaus. Ob hom yog muab nrog cov ntaub ntawv pov thawj zeb thiab kev kho mob saum npoo xws li kev tua blasting rau Sa 2.5 nrog zinc-nplua nuj primer thiab xov coats, nyob rau hauv txoj kab nrog ISO 12944 rau qhov project corrosivity qeb.
Yuav Ua Li Cas Xaiv Ntawm Lub Thawv thiab Phaj Girders
Xaiv ibsteel phaj girderThaum txoj kev sib dhos ncaj nraim, txoj kev thauj khoom feem ntau yog ntsug thiab pob nyiaj siv nruj: nws tuaj yeem ua ntau yam - ua los ntawm cov kab siv tshuab, sib dua rau kev thauj mus los thiab nqa, thiab txuas nrawm nrog siab - lub zog bolts. Nws yog ib qho pov thawj kev daws teeb meem rau kev txhawb nqa yooj yim thiab txuas mus ntxiv nyob rau hauv nruab nrab ntau yam, crane girders thiab lub tsev hloov kab teeb.
Xaiv ibsteel box girderThaum tus choj yog nkhaus los yog skewed, thaum nyob loads yog eccentric, thaum ntev spans los yog dav decks yuav tsum tau tsawg piers, los yog thaum ib tug du, niaj hnub tsos thiab tsis tshua muaj txij nkawm thaj chaw yog qhov tseem ceeb. Lub thawv girders kuj tseem nyiam rau cov txuas hniav hauv thaj chaw cua siab vim tias qhov kaw qhov profile tuaj yeem ua tau zoo li aerodynamically, thiab rau cov phiaj xwm kev tsim tawm.
Ob hom yuav tsum tau tsim los rau kev tswj hwm txoj cai ntawm thaj av qhov project - piv txwv li AASHTO LRFD hauv North America, Eurocode 3 (EN 1993) hauv Tebchaws Europe, lossis GB 50017 / GB 50010 series hauv Suav teb - siv cov qib steel qauv xws li ASTM A709 Qib 50, GB / 150, lossis EN 1591 Q355/Q420 nrog rau weldability thiab toughness yuav tsum tau.
Tau txais ib qho Kev Xaiv Dawb Girder Review thiab Cov Lus Hais
Cov lus nug nquag
Dab tsi yog hom loj ntawm lub thawv girders?
Lub thawv girders raug cais los ntawm tus ntoo khaub lig- seem zoo li duab plaub, trapezoidal los yog voj voog, thiab los ntawm kev teeb tsa ntawm tes raws li ib qho -cell, multi- cell los yog ntau -box girders. Lub thawv trapezoidal (daim duab peb sab- hauv qab) steel lub thawv yog muaj nyob rau hauv ntev -span cable- nyob thiab ncua txuas hniav vim nws cov kev ua haujlwm aerodynamic.
Vim li cas lub thawv girders nyiam rau cov choj nkhaus?
Ib tug nkhaus choj lawj yog loaded ob leeg vertically thiab torsionally. The closed box section resists twisting with a closed shear flow and needs no external bracing, which keeps the deck compact and allows tight horizontal radii without excessive distortion.
Puas yog phaj girders pheej yig dua lub thawv girders?
Feem ntau yog rau qhov yooj yim, ncaj spans. Phaj girder fabrication yog planar thiab yooj yim dua automated, cov khoom siv yog siv ze rau qhov nruab nrab axis tsuas yog qhov xav tau, thiab erection yog ceev nrog bolted splices. Kev sib piv nyob ntawm qhov dav, lawj dav, qib steel thiab qhov chaw nyob, yog li xav tau kev kwv yees engineering rau txhua qhov haujlwm.
Yuav ua li cas vuam thiab tshuaj xyuas yuav tsum siv rau lub thawv girders?
Lub ntsiab seams feem ntau yog tag nrho -kev nkag welds ua raws li kev tsim nyog vuam txheej txheem specifications (WPS) thiab tshuaj xyuas los ntawm ultrasonic (UT), radiographic (RT) los yog sib nqus particle (MT) kuaj. Cov ntaub ntawv siv tau suav nrog AWS D1.5 rau kev txuas txuas txuas thiab EN 1090 rau kev ua tiav cov qauv hlau.
Lub phaj girder puas tuaj yeem siv tau ntev?
Yog lawm, nrog rau lub vev xaib sib sib zog nqus thiab cov txheej txheem bracing, phaj girders tuaj yeem ncua kev ncua deb, tab sis dhau ntawm ib qho kev nthuav dav ntxiv rau cov hlau ntxiv rau stiffeners thiab bracing ua rau lub thawv girder pheej yig dua, tshwj xeeb tshaj yog qhov chaw torsion lossis curvature koom nrog.
Dab tsi steel qib feem ntau yog siv rau choj girders?
Cov qib muaj xws li ASTM A709 Qib 36/50/50W rau US tej yaam num, EN 10025 S355J2 thiab S355NL nyob teb chaws Europe, thiab GB/T 714 los yog GB/T 1591 qib xws li Q355 thiab Q420 hauv Suav teb. Qib kawg yog nyob ntawm qhov muaj zog tawm los, toughness ntawm qhov tsim kub thiab weldability yuav tsum tau ntawm qhov project.