Steel fiber reinforced pob zeb (SFRC) rau qhov hauv ob sab phlu
Tus cwj pwm rub tawm fiber ntau yog kawm sim, xav txog yam xws li cov duab fiber ntau, qhov loj me, thiab lub kaum sab xis inclination. Tsis tas li ntawd, cov tshooj hauv qab no nthuav tawm cov kev sim thiab cov qauv lej sib raug tsim los piav qhia txog steel fiber ntau hauv ob sab phlu.
2. Steel fiber ntau pob zeb nyob rau hauv cheeb tsam load
Raws li tau hais hauv qhov kev taw qhia, cov ntu hauv ob sab phlu yog raug rau cov khoom hnyav heev (piv txwv li cov khoom thauj hauv zos) thaum lub sij hawm tsim kho thiab theem kawg. Qhov tshwm sim tawg tensile kev ntxhov siab feem ntau yog qhov kev txiav txim siab hauv kev tsim thiab yuav tsum tau tawm tsam los ntawm qhov tsim nyog ntxiv. Kev siv steel fiber ntau cov pob zeb ua kom muaj peev xwm ua kom muaj peev xwm ua tau zoo thiab ua rau muaj kev cuam tshuam zoo rau tus cwj pwm tawg nyob rau hauv cov xwm txheej zoo li no. Txhawm rau kom paub qhov zoo ntawm daim ntawv thov ntawm steel fiber ntau pob zeb, tshwj xeeb tshaj yog nyob rau hauv cov ntu ntu, ib qho kev sim thiab cov lej tshawb fawb tau ua tiav ntawm kev thauj khoom thiab kev puas tsuaj ntawm steel fiber ntau pob zeb nyob rau hauv ib feem ntawm qhov chaw thauj khoom.
(1) Kev sim tshawb fawb ntawm SFRC nyob rau hauv cheeb tsam chaw thauj khoom
Txhawm rau ua tus yam ntxwv ntawm kev thauj khoom thiab kev puas tsuaj ntawm SFRC nyob rau hauv cheeb tsam hauv cheeb tsam chaw thau khoom, kev sim tag nrho uas muaj cov tsis muaj fiber ntau thiab cov fiber ntau cuam tshuam txog qhov sib txawv. Cov kev hloov pauv uas tsis yog fiber ntau muaj xws li kev ua vaj tse, qhov loj me, thaj tsam piv, thiab kev thauj khoom eccentricity. Tsis tas li ntawd, cov khoom hauv cheeb tsam hauv cheeb tsam tau faib ua ntu ntu (piv txwv li, taw tes loads) thiab qhov tseeb (piv txwv li, strip loads) raug txiav txim siab, suav nrog ob qho xwm txheej tseem ceeb ntawm kev thauj khoom uas tshwm sim nyob rau hauv ib ncig thiab ntev ntawm cov kab hauv ob sab phlu. Cov yam ntxwv ntawm fiber ntau muaj xws li cov khoom siv fiber ntau (xws li, lub zog, qhov loj me, geometry, thiab nam piv), cov ntsiab lus fiber ntau thiab kev taw qhia, thiab kev sib txuas ntawm ntau hom fiber ntau (piv txwv li, fiber ntau sib xyaw).
Lub hauv paus sib xyaw tsim kev kawm yog tib yam li uas feem ntau siv hauv cov ntu ntu.
Ua piv txwv li 150 mm x 150 mm x 300 mm, cov khoom siv kuaj rau qhov chaw thauj khoom hauv cheeb tsam tau pom.
Kev cuam tshuam ntawm ntau yam ntawm cov khoom thauj khoom thiab tus cwj pwm tawg tau raug tshawb xyuas los ntawm kev txheeb xyuas qhov kawg hauv zos compressive kev ntxhov siab (piv txwv li, qhov kawg ntawm cov kabmob muaj peev xwm), kev ntxhov siab-tsav teb, thiab tsis ua haujlwm thiab cov yam ntxwv tawg. Tom qab ntawd, qee qhov txiaj ntsig tseem ceeb thiab cov kev tshawb pom tseem ceeb tau nthuav tawm.
(2) Cheeb tsam piv thiab fiber ntau ntxiv
Nyob rau hauv qhov kev txiav txim ntawm lub cheeb tsam load nyob rau hauv concentric qhov chaw, thaj tsam ratio (= /=2.25, 4, 9, thiab 16) thiab fiber ntxiv (60 kg / m3 nuv-kawg steel fiber) muaj qhov sib txawv ntawm cov kev ntxhov siab hauv zos thiab kev sib raug zoo ntev ntawm cov pob zeb muaj zog (=84.5 MPa). Qhov cuam tshuam ntawm kev hloov pauv. Nco ntsoov tias nyob rau hauv cov kev tshawb fawb nram qab no, lub zos compressive kev nyuaj siab yog txhais raws li cov ntaub ntawv load faib los ntawm lub loaded cheeb tsam.
Nws tuaj yeem pom los ntawm qhov kev ntxhov siab-txav nkhaus uas ntxiv cov hlau fibers tuaj yeem ua rau qhov kawg hauv zos compressive kev nyuaj siab ntawm pob zeb (txog 47%). Piv nrog rau cov pob zeb zoo tib yam, nws tuaj yeem pom tias qhov cuam tshuam ntawm steel fibers ntawm lub peev xwm thauj khoom yog qhov tseem ceeb ntawm thaj tsam ntau dua.
Raws li kev cia siab, qhov kawg hauv cheeb tsam compressive kev ntxhov siab ntawm cov pob zeb thiab steel fiber ntau kuj nce ntxiv nrog kev nce thaj tsam, uas yog vim qhov cuam tshuam ntawm cov pob zeb nyob ib puag ncig. Nyob rau hauv cov ntaub ntawv ntawm lub cheeb tsam loads nyob rau hauv qhov chaw, proportional kev sib raug zoo ntawm qhov kawg hauv zos compressive kev nyuaj siab thiab lub square root ntawm cheeb tsam piv yuav txiav txim kom meej. Txij li thaum cov nyhuv txwv tsis tiav nyob rau hauv rooj plaub ntawm lub dav hlau thauj khoom hauv cheeb tsam chaw thau khoom, qhov nce hauv qhov kawg hauv zos compressive kev ntxhov siab yog qhov tsawg. Hauv qhov no, nws pom tau tias yog proportional rau lub voos xwmfab hauv paus ntawm thaj tsam piv. Cov kev sib raug zoo no muab lub hauv paus rau kev suav cov kev ntxhov siab hauv zos uas muaj zog SFRC tuaj yeem tiv taus.
Tsis ntev tom qab ncav cuag qhov siab tshaj plaws kev ntxhov siab, qhov kev ntxhov siab-txav nkhaus ntawm PC tau pom qhov txo qis, qhia tias cov qauv tau raug puas ntsoog thaum lub sijhawm kuaj. Hauv qhov sib piv, SFRC nthuav tawm cov yam ntxwv ntawm kev maj mam txo qis kev ntxhov siab nrog kev hloov pauv ntau ntxiv, sib xws rau kev coj tus cwj pwm tsis ua haujlwm. Nyob rau hauv cov ntaub ntawv ntawm ib nrab cheeb tsam load planar tis, qhov no tshwm sim tsis tshua pom tseeb vim hais tias nws tsis tag nrho constrained.
Hom kev puas ntsoog ntawm lub zog siab PC thiab SFRC cov qauv, nrog cov kev ntxhov siab cuam tshuam cuam tshuam qhov sib txuam. Zuag qhia tag nrho, tsis pom qhov tawg lossis tawg tau pom rau PC thiab SFRC kom txog thaum ze rau qhov kawg ntawm qhov kawg. Tsis ntev tom qab, tag nrho cov qauv PC ua tsis tiav nyob rau hauv ntau dua los yog tsawg fragmented tej yam kev mob, tshwj xeeb tshaj yog nyob rau hauv cov ntaub ntawv ntawm high-lub zog pob zeb, nrog ib tug ntse txo nyob rau hauv lub load-tsav nkhaus. Rau cov cheeb tsam loj, ib qho kev sib cais loj loj tau tsim thoob plaws hauv qhov kev sim thiab nkag mus rau sab saum toj mus rau hauv qab, thaum nyob rau thaj tsam me me, cov qauv PC tau tawg tag. Hauv qhov sib piv, txhua tus qauv SFRC tau khaws lawv txoj kev ncaj ncees mus txog thaum kawg ntawm qhov kev xeem thiab nthuav tawm ntau cov qauv tawg. Nyob rau hauv ib cheeb tsam loj, cov kab nrib pleb ua ke nrog me me ntawm cov pob zeb ua pob zeb feem ntau tshwm sim nyob rau sab sauv ntawm SFRC cov qauv. Raws li thaj tsam piv tau txo qis, cov kab nrib pleb thiab qhov sib txawv yuav tsim ntau thiab ntau dua nyob rau hauv qis ib nrab thiab.
(3) Fiber hom thiab sib tov
Los ntawm txoj kev tshawb fawb ntawm kev rub tawm tus cwj pwm ntawm cov hlau fibers, nws tuaj yeem ua pov thawj tias cov khoom ntawm cov fibers kuj muaj kev cuam tshuam loj rau kev thauj khoom thiab kev puas tsuaj ntawm SFRC nyob rau hauv cheeb tsam chaw thau khoom. Qhov kawg hauv zos compressive kev ntxhov siab ntawm lub zog siab SFRC npaj siv ntau hom steel fibers ntawm cov ntsiab lus fiber ntau ntawm 60kg / m3 (spatial load distribution, δ=9) yog qhia. Piv nrog rau PC, qhov nce ntawm qhov kawg hauv zos compressive kev nyuaj siab yog li ntawm 28% mus rau 51%. Raws li kev cia siab, lub zog siab nuv-kawg loj-loj fibers (Lh60) tau tshwm sim ua tau zoo tshaj plaws hauv kev nce qhov kawg ntawm kev thauj khoom. Txawm li cas los xij, qhov kev sim pom tau tias SFRC npaj siv lub zog loj-loj fibers tsuas yog nce qhov kawg ntawm kev nqa lub peev xwm los ntawm 15% piv nrog SFRC npaj nrog ib txwm muaj zog loj-loj fibers (L60), txawm hais tias cov txiaj ntsig ntawm rub-tawm kev kuaj pom tias qhov kawg load-bearing muaj peev xwm ntawm high-strength fiber Lub rub-tawm load yog yuav luag ob zaug ntawm ib txwm muaj zog fibers.
For SFRC prepared using fiber blends, positive synergistic effects can be observed for certain combinations of fiber types. In high-strength concrete, however, this effect is only evident at relatively high fiber contents (>80-100 kg/m3). Kev tshawb fawb ntawm cov fiber ntau sib txawv tau pom tias kev sib xyaw ua ke ntawm qhov sib txuas ntawm microfibers thiab cov fibers ncaj ncaj tau ua pov thawj tias qhov zoo tshaj plaws nyob rau hauv xws li kev thauj khoom. Txawm hais tias qhov kawg hauv zos compressive kev nyuaj siab ntawm ob fiber ntau sib piv yog yuav luag zoo ib yam, nws tuaj yeem pom tias SFRC nrog 50% loj-loj fibers thiab 50% microfibers (SFRC L60+S60) muaj tus cwj pwm zoo dua hauv theem tom qab tawg (Piv rau SFRC L40+M40+S40). Vim qhov kev txhawb zog ntawm cov fiber ntau sib xyaw, nws qhov kev cuam tshuam zoo ntawm kev coj tus kheej thiab kev coj tus cwj pwm tawg yog qhov tseeb tshwj xeeb rau kev thauj khoom hauv zos eccentric.
(4) Fiber Orientation
Nws paub zoo tias cov fibers ua raws li cov kev taw qhia ntawm tensile kev nyuaj siab muaj qhov zoo tshaj plaws tawg-bridging muaj peev xwm. Nyob rau hauv cov ntaub ntawv ntawm lub cheeb tsam chaw thau khoom, lub cracking tensile kev nyuaj siab perpendicular mus rau lub loading kev taw qhia feem ntau txwv lub tolerable lub zos compressive kev nyuaj siab thiab dominates hom tsis ua hauj lwm. Yog li, kev taw qhia ntawm fiber ntau tuaj yeem xav tias yuav muaj kev cuam tshuam loj rau kev thauj khoom thiab kev puas tsuaj ntawm SFRC raws li kev thauj khoom hauv zos. Txhawm rau kawm txog cov txiaj ntsig no, kev taw qhia fiber ntau tau tswj hwm los ntawm kev tsim cov qauv hauv ntsug thiab kab rov tav formwork, thiab cov chaw thau khoom hauv cheeb tsam tau ua tiav ntawm SFRC.
Qhov feem pua ntawm cov hlau fibers (60 kg / m3 nuv-kawg loj-loj fibers) nyob rau hauv peb spatial cov lus qhia (x, y, z) txheeb ze rau cov kev taw qhia loading yog ntsuas los ntawm cov khoom siv electromagnetic, thiab SFRC cov qauv npaj los ntawm ntsug thiab kab rov tav pwm. raug piv. (150 hli x 150 hli x 300 hli). Nyob rau hauv kab rov tav pwm qauv, kwv yees li 46% ntawm cov fibers tau taw qhia hauv kev thauj khoom. Yog li ntawd, piv rau cov qauv sawv ntsug, cov fibers tsawg dua yog taw qhia raws li ob qho kev qhia perpendicular rau cov kev taw qhia kev thauj khoom, uas sib haum rau lub ntsiab tensile kev ntxhov siab cov lus qhia ntawm lub zos load faib. Cov txiaj ntsig tau pom tias qhov kawg hauv zos compressive kev ntxhov siab tus nqi ntawm cov qauv npaj rau hauv kab rov tav pwm yog txo qis (txog 23%). Tsis tas li ntawd, tom qab ncav cuag qhov kawg hauv zos compressive kev nyuaj siab, qhov kev ntxhov siab-txav qhov nkhaus yog tus cwj pwm los ntawm kev poob qis hauv kev ntxhov siab, nthuav tawm tus cwj pwm tsis zoo. Cov nyhuv no kuj tau pom nyob rau hauv cov ntaub ntawv sim ntawm cov cheeb tsam ywj pheej.
Nyob rau hauv cov ntaub ntawv ntawm qhov chaw thauj khoom hauv cheeb tsam, kev cuam tshuam ntawm qhov tseem ceeb ntawm kev taw qhia ntawm cov fibers nyob ntawm qhov kev taw qhia pouring ( ntsug / kab rov tav formwork) yog qhov tseem ceeb dua, vim qhov no lub ntsiab Tensile stresses ua feem ntau nyob rau hauv ib tug transverse kev taw qhia (perpendicular rau lub kev taw qhia ntawm kev thauj khoom).
• Fiber loj:
Ntawm tus kheej fiber ntau thiab matrix qib, tus cwj pwm rub tawm ntawm tus kheej fibers yog tswj los ntawm cov xwm txheej cuam tshuam, fiber ntau, thiab fiber ntau inclination lub kaum sab xis txheeb ze rau qhov tawg. Ib qho kev ntsuas ib nrab yog tsim los uas kwv yees lub zog rub tawm-kev sib raug zoo ntawm ib qho fiber ntau, uas nyob ntawm txoj hauj lwm ntawm qhov chaw fiber ntau ntawm lub ntiajteb txawj nqus, thiab lub kaum sab xis ntawm lub dav hlau tawg. Tus qauv muaj peev xwm ntes tau lub ntsiab mechanisms qhib thaum lub sij hawm rub-tawm txheej txheem ntawm ib leeg steel fiber embedded nyob rau hauv lub pob zeb matrix (hook kawg straightening, qhob spalling, thiab fiber breakage), coj mus rau hauv tus account sib txawv configurations ntawm fiber ntau hom thiab lub zog, pob zeb muaj zog, fiber ntau inclination lub kaum sab xis, thiab embedding ntev.
• Kev tawg loj:
Nyob rau theem ntawm kev tawg cov kab nrib pleb nyob rau hauv fiber-reinforced qhob composite, fibers dhau los ntawm cov kab nrib pleb yog qhib thiab muab ib tug residual tom qab tawg lub zog uas yog nyob ntawm fiber ntau cov ntsiab lus thiab fiber ntau orientation. Hauv cov qauv SFRC multilevel, cov lus teb tom qab tawg yog kwv yees los ntawm txoj kev sib cais uas suav nrog cov lus qhia fiber ntau anisotropy los ntawm kev sib koom ua ke ntawm kev sib raug zoo ntawm kev sib raug zoo ntawm txhua tus neeg fibers dhau los ntawm kev tawg.
• Cov qauv qhov ntev:
Ntawm cov qauv ntsuas, tus cwj pwm tom qab kev tawg yog raug ntes los ntawm cov qauv sib cais raws li condensed interface ntsiab. Cov ntsiab lus cuam tshuam tau muab tso rau ntawm cov ntsiab lus tsis tu ncua (ntim cov ntsiab lus), uas tso cai rau cov pob txha tawg yuav tsum tau ua kom pom tseeb thiab ncaj qha muab cov ntaub ntawv tawg dav. Tus cwj pwm ntawm cov ntsiab lus cuam tshuam yog tswj hwm los ntawm kev sib cais-kev sib cais los ntawm ntau qib SFRC qauv ntawm qhov tawg nplai. Txhawm rau txhawm rau txhawm rau muaj cov hlau tuav, ib qho mesh-yooj yim sib cuag-raws li sawv cev ntawm cov hlau tsis sib xws kuj tau tsim. Cov hlau tuav tau ua qauv raws li cov ntsiab lus truss thiab txuas mus rau cov pob zeb matrix ntawm kev txwv nyob nruab nrab ntawm cov ntsiab lus tswj ntawm cov hlau bar ntsiab lus thiab lawv cov ntsiab lus projection hauv cov khoom ntim ntim. Cov txheej txheem khij nyhiab yog muab rau hauv cov kev txwv, thiab cov elastic-yas v.Mises yield nto thiab linear hardening ntawm cov hlau raug txiav txim siab.
