Ukuvikela ukuqiniswa ekugqwaleni
Ngokwe-Eurocodes zanamuhla kubekwe ubukhulu obuncane boqweqwe oluvikelayo lukakhonkolo (cnom). Ubukhulu balolo qweqwe lukakhonkolo buyibanga elincane kakhulu ukusuka ebusweni bangaphandle besakhi se-reinforced concrete kuya ekuqiniseni kokuqala. Ezintweni zomugqa lokhu kuyisibambo sokubophisa, kanti ezintweni zendawo lokhu kuyinsimbi yokuqinisa engezansi yobude. Uqweqwe oluvikelayo oluyinhloko luchazwa kanje: cnom = cmin + Δcdev
cmin ungqimba oluncane oluyisivikelo oludingekayo, inani lalo elincike ezimweni zokunamathela kukakhonkolo nensimbi yokuqinisa, izimo zemvelo, ukumbozwa kwensimbi yokuqinisa, njll. Δcdev inani elimelela ukuphambuka ekwenzeni. Ngokuya ngesigaba sokuchayeka kwento kakhonkolo oqinisisiwe kukhona amanani ahlukahlukene obukhulu obujwayelekile bongqimba oluyisivikelo; luvame ukuba phakathi kuka-2,5 cm no-3,5 cm. Ezisekelweni kuthathwa ukuthi ngu-5cm.
Ukuziphatha kodaka lukasimende nokakhonkolo lapho kushiswa futhi kupholiswa kaningi
Amandla kakhonkolo omusha angakhuliswa ngokushesha ngokuwushisa kancane kancane ngomhwamuko noma ngokuwubamba emanzini afudunyezwa kancane kancane, bese upholiswa kancane. Ngale ndlela, ngemva kwenqubo yosuku olulodwa kuvela amandla afinyelelwa ngenkambiso evamile ngemva kwamasonto ambalwa. Izinga lomphumela lincike kusimende kanye nohlobo lwe-aggregate, kanti ngakolunye uhlangothi ngemiphumela engcono kakhulu kufinyelelwa ngokhonkolo ongenawo amafutha kunokhonkolo onamafutha.
Uma ukufudumeza nokupholisa kwenziwa phakathi kwemikhawulo ebanzi, ku-elementi kakhonkolo kuzovela ukucindezeleka okukhulu uma ukufudumeza nokupholisa kwenziwa ngokushesha. Esimweni esinjalo, ikakhulukazi uma lokhu kuphindaphindwa kaningi, kufanele kubhekwe ukuvela kwemifantu engena ukusuka ngaphandle iye ngaphakathi, ithinte izici zomshini zikakhonkolo. Kulokhu, ama-cement ahlukahlukene aziphatha ngendlela ehlukile, yingakho ngenhloso yokusetshenziswa okusebenzayo kunconywa ukukhetha i-cement ngokucophelela.
Ukudlulisa ukushisa kukakhonkolo
I-coefficient yokudlulisa ukushisa kukakhonkolo incike ezimfanelweni zengxube kanye nosimende, enanini likasimende, enanini lamanzi okuhlanganisa, kumswakama kakhonkolo, kanye nasezingeni lokushisa. Ngezivivinyo ngamapuleti 10 cm ubukhulu futhi akhonkholo omiswe kakhulu, i-coefficient yokudlulisa ukushisa λ kutholwe ukuthi ingu 1,163 W/mK ku 10 oC, kanti ngamapuleti kakhonkolo owahlala emanzini ifinyelela ku 2,326 W/mK. Amapuleti amakhulu ayenikeza ama-coefficient aphezulu kakhulu wokudlulisa ukushisa; inani eliphezulu kakhulu lalingu 2,38 W/mK.
Ukunwebeka kukakhonkolo ngenxa yokushisa
Ukunwetshwa kuncike kakhulu ku-aggregate, bese kuthi kumswakama kakhonkolo, kanye nasosimendeni uqobo. Amanani omkhawulo aziwayo kuze kube manje ku 0 kuya ku 40 oC angaba cishe 6 kuya ku 13*10-6 m/m ngedegree ngayinye.
Ukumelana nokulayishwa okuphindaphindiwe
1. Amandla okucindezela ngaphansi kokukhathala. Umqondo wamandla ngaphansi kokukhathala usetshenziswe lapha ngomqondo ojwayelekile; ekusetshenzisweni kobuchwepheshe kufanele kuhlale kushiwo amandla okukhathala (ukucindezela, ukudonsa, ukucindezela nokudonsa ngokushintshana, ukugoba, ukusika, ukusika okuhlanzekile, ukugoba) kanye nendlela yokulayisha (kuphela okuzolile, kuphela okuvamile, kancane okuzolile futhi kancane okuvukayo).
Amandla okucindezela ekukhathaleni ngenxa yomthwalo ozinzile: kufanele kulindelwe ukuthi ukumelana nomthwalo wesikhathi eside kube okungenani ¾ wamandla avela ekuhlolweni okujwayelekile kokucindezela.
Amandla okucindezela ekukhathaleni ngenxa yemithwalo ephindaphindwayo (amandla ayisisekelo ashukumisayo): kuye kwabonakala ukuthi amandla ayisisekelo ashukumisayo okucindezela ezinsikeni zikakhonkolo ezakhiwe ngokwehlukahlukene, ikakhulukazi ngamanani ahlukahlukene kasimende nangosayizi abahlukene bezinhlayiya, angaphansi okungenani kuka 0,5 wamandla ephrism ngaphansi komthwalo ojwayelekile kuze kube ukuphuka. Lapho kwakusetshenziswe 260 imijikelezo yomthwalo ngomzuzu; inani eliphelele lemijikelezo lapho leli nani lamandla ayisisekelo ashukumisayo lalibalwa khona lalingamashumi amabili ezigidi ezimbili. Ngokwanda kwenani lemijikelezo ngomzuzu (kwahlolwa ngo 10 kuya ku 450 imijikelezo ngomzuzu), kwanda futhi inani lokuphindaphinda elaliholela ekuphukeni.
Amandla acindezelayo ekukhathaleni ngenxa yesenzo esihlanganyelwe semithwalo engaguquki nemithwalo ephindaphindwayo: Lapho emithwalweni ephindaphindwayo kwengezwa imithwalo engaguquki, khona-ke ngokwanda kwemithwalo engaguquki amanani ama-amplitude emithwalo ephindaphindwayo, ejwayele ukuphindaphindwa izigidi ezimbili zezikhathi, ayancipha. Ngokwesibonelo, isith. 1 sibonisa ukuthi ama-amplitude emithwalo ephindaphindwayo S ayengu:
- ekulayishweni okuzolile ku-σu = 6 kg/cm2 S = 109 kg/cm2
- ekulayishweni okuzolile ku-σu = 118 kg/cm2 S = 39 kg/cm2
- ekulayishweni okuzolile ku-σu = 157 kg/cm2 S = 8 kg/cm2
Umd. 1
Fig. 2
2. Amandla okugoba okhonkolo lapho kukhathala. Ukuhlolwa okuboniswe esith. 2 kweziphinde ezazigcinwa zihlala zimanzi kubonise, ngaphansi komthwalo oyisisekelo we-dynamic ukuthi amandla okugoba lapho kukhathala angama-28 kg/cm2, kanti amandla ajwayelekile okugoba ayengama-53 kg/cm2, okuhambisana nesilinganiso 0,53.
Ukhonkolo olula
Ukhonkolo olula (ukhonkolo onesisindo esingaphansi kuka-18 kN/m3) utholakala ngokusebenzisa ama-aggregate alula, anama-pores njenge: ipumisi, i-slag evela eziko elikhulu, i-boiler slag, futhi ngokusebenzisa udaka olunesihlabathi semvelo noma sokwenziwa kanye nofulawa onezithasiselo ezikhiqiza igesi ngesikhathi sokulungiselela udaka (ukhonkolo onegesi) noma ezibangela ukuvubuka kudaka (ukhonkolo onegwebu).
Ukhonkolo olula, phakathi kwezinye izinto, usetshenziswa kakhulu ekwenzeni ama-block okwakha nezinsimbi ze-pumice zezindonga nophahla; esimweni esomile uyingqayizivele njengomqhuba wokushisa omubi; amandla awo aphakathi nendawo, kodwa kulungiseka kalula, ngakho-ke ama-block alula ezindongeni ezithwala umthwalo zezakhiwo zokuhlala angakhiqizwa ngokuzethemba.
Njengesakhi esidala ukuvuvukala kagesi kukhonkolo enomoya kusetshenziswa impuphu ye-aluminium. Kuye ngenani lezithasiselo kanye nezinye izimo, kutholakala impahla enezimbotshana eziningi noma ezimbalwa, enesisindo esimweni esomile esingaba ngu-3 kN/m3 kuya phezulu.
1. Isisindo sevolumu sikakhonkolo okhanyayo. Nge-pumice yemvelo kungaqinisekiswa izisindo zevolumu – uma kucatshangwa isimo esomile ku-105 oC – kusukela ku-7 kN/m3 kuya phezulu, ngamandla okucindezela we-2 MPa. Isisindo sevolumu esingalindeleka cishe siyisamba se-aggregate nosimende usesimweni esixegayo. Ikhonkrithi enegesi enesisindo sevolumu esingaphezu kuka-8 kN/m3 ngokuvamile ayifaneleki ngokobuchwepheshe.
2. Amandla acindezelayo kakhonkolo olula. Ngokhonkolo wokugcwalisa kungafinyelelwa amandla angu-8 MPa ngaphandle kwezinyathelo ezikhethekile, kanti ngamatshe amancane ingafinyelela ngisho ku-12 MPa. Kudingeka ukuhlola okuqhubekayo kokufaneleka. Ukhonkolo onembobo (ukhonkolo wegesi kanye nokhonkolo wegwebu) ufanele izindonga ezithwala umthwalo kuphela emva kokuqina ngaphansi kwengcindezi yomusi. Ngempahla eluhlaza efanele kungaqinisekiswa isisindo seyunithi esingu-6 kN/m3 namandla acindezelayo angu-5 MPa.
3. Amandla okugoba kakhonkolo olula. Ubudlelwano phakathi kwamandla okugoba namandla okucindezela buye babonakala, ngaphakathi kwemingcele yezidingo ezisebenzayo, bubukhulu ngokulinganiselayo, kanti njengoba amandla ekhula lobu budlelwano buyehla.
4. Izinga lokuncipha kukakhonkolo olula. Izinga lokuncipha lincike kakhulu ekunwebekeni kwe-aggregate, kanye nenani lengxenye ye-cement esiqinile; ukuncipha kukakhonkolo olula kukhulu kunokuncipha kukakhonkolo wegrabile. Ukhonkolo owenziwe ngezinhlayiya zezitini ukhombise phakathi nonyaka owodwa izinga lokuncipha eliphelele elicishe libe ngu-0,65 mm/m. Izingxenye ezilethwe zisanda kwenziwa ze-pumice yemvelo, ezinyangeni 14 m zifinyele cishe ngo-0,8 mm/m. Amasampula kakhonkolo wegesi kanye nekakhonkolo wegwebu aqina emoyeni abonise ukuncipha okukhulu kakhulu, ngisho nangaphezu kuka-2 mm/m. Akufanele kukhohlwe ukuthi wonke ukhonkolo lapho umanziswa yimvula neqhwa elincibilikile uyakhukhumala, bese kamuva lapho womile uphinde unciphe.
Isith. 3
5. I-coefficient yokuhambisa ukushisa. I-coefficient yokuhambisa ukushisa yehla ngokwanda kwesisindo somthamo, futhi ngaphansi kwezinye izimo ezifanayo iba ncane kakhulu uma izimbobo zayo zomoya zincane futhi zisatshalaliswe ngokulinganayo. Kuwo ukhonkolo wokugcwalisa owomile emoyeni bekungukuthi (λ = 0,4625 ku 9 kN/m3; λ = 0,58 – 0,7 ku 12 kN/m3; λ = 0,81 – 1,05 ku 16 kN/m3). Ku-gas concrete owomile emoyeni idatha inikezwa ku-fig. 3.
ISAZISO:
- 0,1 kcal/mhoC = 0,1163 W/mK
- 0,1 kg/dm3 = 100 kg/m3 = 1 kN/m3