Qhov kev ntxhov siab-strain nkhaus yog qhov tseem ceeb graphical sawv cev ntawm cov khoom siv tus cwj pwm, thiab nws cov yam ntxwv tseem ceeb muaj qhov cuam tshuam ncaj qha thiab muaj txiaj ntsig zoo rau kev tsim H-beam cov tswv cuab
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1. Modulus ntawm Elasticity (E): Qhov Kev Nyuaj Siab Tsis Txaus
Tus nqi: Rau ob qho A572 Qib 50 thiab Qib 60, cov qauv ntawm elasticity yog qhov tseem ceeb zoo ib yam: E ≈ 29,000 ksi (200 GPa). Qhov no yog cov cuab yeej ntawm cov hlau siv lead ua lattice thiab tsis muaj kev cuam tshuam loj heev los ntawm cov alloying nruab nrab lossis qib zog.
Kev Tsim Nyog: Qhov no txhais tau hais tias qhov muab H- ntu ntu (piv txwv li, W18x35) yuav muaj tib yam elasticity thiab deflection raws li kev pabcuam thauj khoom, tsis hais seb nws yog ua los ntawm Gr.50 lossis Gr.60 steel. Qhov kev xaiv ntawm qib tsis ua rau lub nqaj "stiffer." Qhov txiaj ntsig ntawm lub zog siab dua yog nyob rau hauv nws lub peev xwm nqa tau ntau duaua ntejyielding, tsis nyob rau hauv txo deflections nyob rau hauv kev pab cuam tej yam kev mob. Deflection tswj yog tswj hwm los ntawm ntu lub sijhawm ntawm inertia (I) thiab E, uas yog tas li.
2. Yield Strength (Fy): Qhov pib ntawm Yas Deformation
Gr.50: Tawm pib ntawm kev ntxhov siab ntawm 50 ksi.
Gr.60: Tawm pib ntawm kev ntxhov siab ntawm 60 ksi.
Qhov cuam tshuam: Qhov no 20% siab dua qhov pib yog qhov txiaj ntsig kev lag luam tseem ceeb. Rau ib lub teeb nyob rau hauv dabtsi yog khoov, nws lub sij hawm yas muaj peev xwm (Mp=Fy * Z) ncaj qha proportional rau Fy. Yog li ntawd, Gr.60 beam muaj 20% siab dua qhov kawg flexural zog dua li tib seem hauv Gr.50. Qhov no tso cai rau ib qho me me, sib zog seem rau tib lub zog xav tau, lossis muaj peev xwm thauj khoom ntau dua.
3. Yield Plateau thiab Strain Hardening
Ob qib qhia txog qhov sib txawv ntawm cov qoob loo toj siab - thaj tsam ntawm cov yas deformation ntawm ze li qhov kev ntxhov siab tas li tom qab pib yielding. Qhov no yog qhov tseem ceeb rau kev coj tus cwj pwm ductile thiab kev ntxhov siab redistribution.
Ntev ntawm Plateau: Qhov ntev ntawm lub toj siab no cuam tshuam los ntawm Yield - rau -Tensile Strength Ratio (Fy/Fu). A572 Gr.50, nrog rau tus qauv Fu / Fy piv ntawm ~ 1.30, feem ntau muaj qhov ntev, ruaj khov toj siab tshaj Gr.60, uas muaj qhov sib piv ntawm ~ 1.25. Qhov no yog qhov hloov maj mam tab sis tseem ceeb rau kev tsim seismic, qhov twg yuav tsum muaj cov yas deformation ntau.
4. Tensile zog (Fu) thiab caj dab
Tom qab cov qoob loo ntawm toj siab, cov khoom siv los ntawm kev sib zog ua kom tawv nqaij (kev ntxhov siab nce ntxiv nrog rau lub zog) kom txog thaum nws ncav cuag lub zog tensile kawg (Fu).
Gr.50: Fu Ntau dua lossis sib npaug li 65 ksi.
Gr.60: Fu Ntau dua lossis sib npaug li 75 ksi.
Qhov siab dua Fu ntawm Gr.60 yog siv ncaj qha rau hauv kev sib txuas tsim kev suav (xws li, thaiv shear, net seem rupture).
5. Ductility: Tag nrho Elongation
Qhov chaw nyob rau hauv qhov kev ntxhov siab- txoj kab nkhaus sawv cev rau lub zog nqus ua ntej tawg.
Gr.50: Tsawg kawg elongation=21%.
Gr.60: Tsawg kawg elongation=18%.
Qhov no suav nrog Gr.60 qhov txo qis me ntsis, kev lag luam tawm -tawm rau nws lub zog ntau dua.
Design Implication Summary:
Serviceability Limit State (Deflections): Tsis txawv. Deflections yog suav nrog E=29,000 ksi rau ob qib. Cov tswvcuab loj (I) yog qhov tswj tau.
Strength Limit State (Yielding): Qhov txawv loj. Tso cai rau kev ntxhov siab thiab tsim lub zog (φ * Rn) yog suav nrog cov txiaj ntsig Fy (50 lossis 60 ksi). Qhov no cuam tshuam ncaj qha rau cov tswv cuab xaiv los ntawm cov rooj tsim.
Plastic Design & Seismic Performance: Cov duab ntawm qhov nkhaus tseem ceeb. Lub lav Fy / Fu max ntawm A992 (0.85) ua rau nws zoo dua rau kev tsim cov pob khawm yas. Rau A572, Gr.50's feem ntau ntev yield toj siab tej zaum yuav nyiam tshaj Gr.60 rau qhov tseem ceeb ductile nthuav dav hauv seismic systems, tshwj tsis yog tias qhov hnyav ntawm Gr.60 yog qhov nyuaj.
Kev txiav txim siab txog kev ruaj ntseg: Rau cov tswvcuab uas muaj kev cuam tshuam rau buckling (kem, tom qab cov kab tsis muaj kev txhawb nqa), qhov siab dua Fy ntawm Gr.60 tuaj yeem yog ob- ntaj ntug. Thaum nws nce squash load (Po=Fy * Ag), nws kuj nce qhov kev ntxhov siab ntawm qhov elastic buckling tshwm sim. Kem nkhaus qauv account rau qhov no, thiab cov txiaj ntsig tsis yog ib txwm linear. Ib kem slender yuav pom tsawg lub peev xwm nce los ntawm Gr.50 mus rau Gr.60 dua li cov kab teeb ci hauv kev khoov.
Table: Kev nyuaj siab-Txoj kev nkhaus tus yam ntxwv & tsim cuam tshuam
| Yam ntxwv | A572 Gr.50 | A572 Gr.60 | Qhov Tseem Ceeb Tsim Kev cuam tshuam |
|---|---|---|---|
| Modulus (E) | 29,000 ksg | 29,000 ksg | Tsis muaj. Deflection zoo tib yam rau tib seem. |
| Yield Point (Fy) | 50 ksg | 60 ksg | Thawj tus tsav tsheb . 20% siab dua tsim lub zog hauv yielding/bending/shear. |
| Yield Plateau | Ntev (siab dua Fu / Fy) | Shorter (qis Fu / Fy) | Influences yas pob khawm rotation muaj peev xwm; Gr.50 ntxiv ductile. |
| Tensile zog (Fu) | 65 ksg | 7 5 ksg | Ncaj qha cuam tshuam kev sib txuas rupture zog. |
| Ductility (Elongation) | 21% min | 18% min | Gr.50 muaj peev xwm ntau dua rau cov yas deformation. |
Hauv kev xaus, thaum qhov tawv (E) zoo ib yam, qhov kev ntxhov siab -strain curves ntawm Gr.50 thiab Gr.60 qhia cov dab neeg sib txawv txog lub zog thiab ductility. Tus tsim qauv yuav tsum xaiv cov qib raws li qhov tseem ceeb tshaj plaws yog qhov ua tau zoo tshaj plaws (Gr.60) lossis qhov siab tshaj plaws ductility thiab dav dav yas toj siab (Gr.50), nrog rau kev nkag siab tias kev pabcuam deflections tsis cuam tshuam los ntawm qhov kev xaiv no.