Amandla okuthwala osekelo akhawulelwa cishe kuzo zonke izimo ukugoba kwengxenye ecindezelwe. Lokhu kuvela kuphela lapho sekufinyelelwe umkhawulo wokugeleza ngemva kokulinganiswa kwezingcindezi kuyo yonke ingxenye ecindezelwe. Kuphela uma kunokwesekwa okuqinile ohlangothini lapho kungakhushulwa khona ingcindezi eceleni etholwayo kuze kufinyelele endaweni yokuqiniswa kwensimbi yokwakha. Ekuhloleni amandla okuthwala kufanele kucatshangelwe ukusatshalaliswa kwangempela kwezingcindezi. Uma kucatshangwa ukusatshalaliswa kwezingcindezi okungumugqa oqondile, amandla okuthwala angabe esalinganiselwa phansi. Izenzakalo zokungazinzi kufanele zihlolwe ngokukhethekile.
Ukudonswa kwezimbobo ezisekelweni ezithwele umthwalo wokugoba
Ohlangothini oludonswayo lwebheki (umthwali) kuba khona ukuncipha kwesigaba njengakuma-mbazo adonswayo (ukuqhekeka kwebhande elidonswayo esigabeni esibuthakathaka). Mayelana nokwenqatshwa kwezimbobo kulokhu kusebenza imithetho efanayo naleyo esebenza kumthambo odonswayo.
Njengoba izimbobo ezigcwaliswe ngama-rivethi ohlangothini olucindezelweyo lwe-beam zithinta kancane kakhulu ukusatshalaliswa kwengcindezi nokuguquka, futhi amandla okuthwala umthwalo avame ukukhawulwa ukugoba eceleni kwebhande elicindezelweyo, ubukhulu bokuba buthakathaka kwesigaba kuma-beam anezigaba ezilinganayo abunawo umthelela omkhulu emthwalweni othwalekayo. Ngakho-ke, kakade F. Hartmann wabuza ukuthi ngabe kuyadingeka yini nhlobo kuma-beam alinganayo ukubala ubuthakathaka obubangelwa izimbobo. Ezinqamulelweni ezingalingani (uhlangothi olucindezelweyo luqinile) ukususa izimbobo ohlangothini oludonswayo lwe-beam kungaba yisici esinqumayo somthamo wokuthwala. Ngaphansi komthwalo ophindaphindeka kaningi, izimbobo zinomthelela omkhulu, ngisho noma zisendaweni ekude kakhulu nemicu esemngceleni.
Namuhla ekubalweni komthamo wokuthwala kwesigaba ekugobeni kusetshenziswa isigaba esikhulu nesigaba esimsulwa (ngaphezu kwezinye izinhlobo ezibalulekile zokuphuka). Ukuphuka ngesigaba esikhulu kwenzeka engxenyeni yesigaba engancishwanga amandla yizimbobo. Ukuphuka ngesigaba esimsulwa kwenzeka esigabeni esinciphisiwe yizimbobo, kanti indawo ethathwa njengebalulekile iyindawo enkulu kuncishiswe indawo yazo zonke izimbobo.
Izikhonkwane entanyeni nasekhanda
Lapho kugoba, ngaphezu kwezingcindezi ezivamile, kuvela nezingcindezi zokugunda, okuthi kubathwali abanezingqimba ezihambisanayo zilingane namandla ahambisana nohlelo Q. Ezigabeni eziyinkimbinkimbi, izingcindezi zokugunda ezindaweni zokuthintana phakathi kwamaphrofayela ahlukahlukene agingqiwe zamukelwa ama-rivet awahlanganisayo. Ukusatshalaliswa kwamandla okugunda T endaweni ephakathi kungu-parabola, kanti ezinyaweni cishe kuwumugqa oqondile. Kubathwali abanezingqimba ezisindayo, T endaweni ephakathi ihluke kancane enanini elijwayelekile Tm, elivame ukwanele ekuhloleni kokuqala.
Umd. 1
Izikhonkwane ekhanda (sl. 1b) kumele zonke zifake ndawonye amandla enkulunkulu TK < TH. Amandla enkulunkulu phakathi kwamalamela ngamanye ebhande asengaphansi kakhulu futhi asabalaliswa, esimweni esiku-sl. 1c, ezikhonkwaneni eziningi kakhulu.
Ukunwetshwa komthwali
Ukunwetshwa kobude kweshidi eliqondile kuyadingeka lapho ukuphakama kweshidi kukhulu kunobubanzi bamashidi akhona. Kungase kudingeke futhi ngenxa yokukhiqizwa nokuthutha. Izixhumi namarivethi ekunwetshweni kobude kwesisekelo esisodwa kufanele kwamukele wona lawo mandla TL, obengaba nawo ishidi elinganwetshiwe esixhumaneni sobude. Njengoba ukuncipha ngenxa yezimbobo ezisekhini kufana nalokho eshidini eliqondile, ukujiya kwesekhini kumele kube kukhulu noma kulingane nobukhulu bezimbambo.
Sl. 2 - Isandiso sobude beshidi eliqondile
Isandiso esiphambene ngaphansi komthwalo wokugoba singambozwa ngezindlela ezahlukene ngamabhande okubopha. Sl. 3 ikhombisa amathuba amaningi esandiso seworshop, lapho kuqhubekiswe kuphela ishidi elime mpo. Uma amabhande okubopha ekhona kuphela phakathi kwama-angle irons ebhande (sl. 3a), kuhlala kunemigqa engamboziwe yeshidi elime mpo ngaphansi kwama-angle irons ebhande. Ngaleso sikhathi ama-angle irons nama-rivet endaweni yesandiso seshidi elime mpo athwala umthwalo omkhulu kakhulu, ngakho lolu hlobo lwezandiso kufanele lukhawulelwe ekuxhumaneni okungabalulekile okunamandla amancane. Kuhlale kufanele kukhethwe isandiso esimbozwe ngokuphelele. Amabhande okubopha akhethekile emilenzeni emile yama-angle irons athwala izingcindezi ezinde zalo mcu, kodwa abamba kancane kakhulu ekuthwaleni amandla aseduze. Ukuthuthuka okuthile kwalokho kulethwa yi-sl. 3c. Uma amandla emakhulu kufanele kulwele amabhande okubopha ngobude bonke beshidi elime mpo (sl. 3d), okucabanga ukuthi ama-angle irons ebhande kufanele anqanyulwe. Amabhande okubopha athola ukujiya komlenze we-angle iron, futhi lapho ama-angle irons ebanzi kakhulu kusetshenziswa ama-spacer okulinganisa ukuze kongiwe ekujuleni okungadingekile kwebhande.
Sl. 3 - Ukwengezwa okunqamulelayo (kwaseworkshop) kwephepha elime mpo
Ukwengezwa kwephepha elime mpo ngaphansi komthwalo wamandla anqamulelayo: Umthwali endaweni yokwengezwa uthwala kuphela Q (M = 0). Ekwengezweni okunobude obulinganayo bezikhonkwane (sl. 4) kufanele kucatshangwe ukuthi amandla ezikhonkwaneni NiQ acishe ahambisane nengxenye yendawo efanele e*t yokuhlanganiswa kokwengeza, okungukuthi amandla ezikhonkwaneni asatshalaliswa njengezingcindezi zokugunda ngobude bomthwali, NiQ = e*t*τi = e*Ti. Nokho lapho kusayenziswa ubukhulu kubalwa ngokwabiwa okulinganayo kuzo zonke izikhonkwane n, NiQ = Q/n.
Umfanekiso. 4 - Ukuqhubekela phambili kweshidi eliqondile nokwabiwa kwamandla okushefa ahambayo
Sl. 5 kubonisa ukuxhumana komhlangano wasefekthri kwephepha eliqondile (ama-engeli aqinisiwe namalamela aqhubekiselwe kwenye indawo).
Umfanekiso. 5
Ukugoba ngamandla avamile: Abathwali abalayishwa ngesikhathi esifanayo ngamamomenti okugoba namandla avamile balinganiselwa ngokwemigomo efanayo nangokucabangela ukusatshalaliswa kokucindezeleka ngomugqa oqondile. Uma izinzipho zisuswa ngokuphelele kuwo womabili amabhande, isiphambano esisebenzayo nendawo yomugqa onguziro akuxhomeki esimweni somthwalo, ngakho-ke izingcindezi ezivela ku M no N zingahlanganiswa kalula. Umthwalo wezinzipho ekugcineni utholakala ngokuhlanganisa amandla avela ezimweni zomthwalo eziyingxenye M, noma N.
Ukusekelwa nokuxhunywa kwesiphathi
Lapha kuzobhekwa kuphela isixazululo esivame kakhulu phakathi kwezixazululo eziningi. Lapho kuhlolwa, kufanele njalo kucatshangwe ngamandla engeziwe atholakala ekuchezukeni kwezibalo zokumelana ezijwayelekile noma ezisondelene nezilinganisweni.
Ukusekelwa okulula kwensika eyodwa epuletini elingaphezulu lenye into yokwakha kufika emqondweni lapho kukhona ukuphakama okukhulu kokwakha okutholakalayo. Isimo esivamile yixhumo eliqinile elinamairivethi noma amabhawodi. Ku-fig. 6 kuboniswe ukusekelwa okujwayelekile kwamapurlin e-I aqhubekayo ekwakhiweni kwezakhiwo, okuyinto futhi egwema ukubhoboza emilenzeni emincane ye-I. Ezimweni ezinjalo izinsika kufanele zivikelwe ekugingqikeni nasemandleni aseceleni (fig. 7 no 8). Ekwakhiweni kwamabhuloho izinsika zivame ukuhlanganiswa (fig. 9); ukusekelwa okunganyakazi kwensika yobude ensikeni ewela yona (fig. 10). Ezimandleni amakhulu okusekela, izinsika kufanele ziqiniswe ngama-angle iron afakwe phakathi noma ngamaphrofayili ashiselwe (fig. 8 kuya ku 10). Ezinsikeni eziyinkimbinkimbi umthwalo kufanele udluliselwe emgogodleni.
Isith. 6 - Ukuqiniswa kwamapurlin
Umf. 7 no 8
Sl. 9 no 10
Ukuxhuma kwembambo: Emd. 11 no 12 kuboniswe izixhumanisi ze-I-beam, ezisetshenziswa ekwakheni njengezixhumanisi ezijwayelekile. Ukusika kuthola ukugobile okukhulu, ukuze kugwenywe ukuqhekeka kwembambo yesisekelo. Ukubanjwa okuvumelana nezimo kokuxhumana kwembambo kuletha ukwanda okuthile kwamandla okubamba umthwalo. Ukuguquka okuchaziwe empeleni akunangozi uma umthwalo unokuthula kakhulu, njengasemabhulohweni amadala.
Sl. 11. - Ukuxhumana okujwayelekile kwemishayo ye-I enesiphambano sokugcina esime mpo
Umfan. 12 - Ukuxhumana okuvamile okunamaphethelo asikiwe emigqeni ye-I
Izixhumanisi eziqinile ekugobeni zenziwa lapho kudingeka isixhumanisi ngaphandle kokushintsha i-engeli (izisekelo eziqhubekayo, amakhona aqinile ezinhlaka) noma lapho kunobungozi bokuhluleka ngenxa yokukhathala ngaphansi komthwalo oguquguqukayo, ikakhulukazi emabhulohweni esitimela. Kungasetshenziswa ama-lamellae okuqhubeka, izixhumanisi eziqinile ekugobeni. amakhona aqinile ekugobeni, amakhona ezinhlaka.
- Amapheshana okuqhubekisela phambili – Uma kudingeka kuhlanganiswe izinsika ezilele endaweni efanayo, khona-ke womabili amabhande angaphezulu ahlanganiswa ngephepha noma ngebhande lokuqhubekisela phambili. Ngale ndlela ama-rivethi okuhlanganisa akhululwa emandleni okuhudula futhi kugwenywa ukuguquka okukhulu komumo.
Sl. 13 - Ukuxhumana ngelamela lokuqhubeka
Sl. 14 - Ukuxhumeka kwezinsika ezinde a) webhuloho lomgwaqo omkhulu; b) webhuloho lesitimela
- Izixhumi eziqinile ekugobeni – Lolu hlobo lwesixhumi lutholakala kuma-cantilever aqinile ezindlela zabahamba ngezinyawo zamabhuloho emigwaqo. Uma ama-moment emancane, ipuleti lazo eliqondile lixhunywa kuphela ngamasheya amabili phakathi kwamakhona okuqinisa okuxhasa okuyinhloko. I-moment efakwe idluliselwa, ngokusebenzisa ukuqinisa, kuyo yonke ukuphakama kokuxhasa okuyinhloko, okungukuthi ifakwa emabhande ayo njengesihlanganiso samandla.
Sl. 15 no 16
- Ama-engeli aqinile ekugobeni – Ama-engeli aqinile ekugobeni phakathi kwezinsika nama-beam aphansi ezakhiweni kufanele aklanywe ngendlela yokuthi i-engeli ingashintshi futhi kungabi bikho ukweqa okuthile kwengcindezi endaweni ethile. Ukuxhumana okuthembekile ema-engeleni kuvela, isibonelo, ngokwesith. 16 lapho kusetshenziswa amapuleti anamaphiko noma ngokwesith. 100 lapho i-moment yokubambeka emabhande esinsika yamukelwa njengokuhlangana kwamandla.
- Ama-engeli ohlaka – Kuma-frame anama-poligoni, isandiso singakhiwa endaweni yokuphuka uma umehluko we-engeli umncane; izinduku ezihlanganisiwe zimbozwa ngamabhande njengenduku edonswayo necindiziweyo. Amandla wokujika agxilile endaweni yokuphuka futhi kumele amukelwe ngokwesekwa okuqinisa. Ku-sl. 101 qaphela umehluko ekumbozweni kwesandiso kanye nokuqiniswa, kuye ngencazelo ye-moment yokugoba namandla okuchezuka. Uma amandla emakhulu futhi umehluko we-engeli umkhulu, kugwenywa ukuthi isandiso sifinyelele engxenyeni yohlaka egobile kakhulu. Izandiso eziseduze namakhona ohlaka zivumela isimo sokwakheka esingcono futhi zenze ukwakhiwa kube lula. Izibonelo ezinezandiso ezijwayelekile eziboshiwe ohlangothini zombili zendawo yokuphuka ziboniswa yiz. 102a no sl. 102b, lapho khona i-engeli iqukethe ingxenye eshiselisiwe. Ku-sl 103 kuboniswa ukuxhumana okuqinile ekugobeni kwensika yohlaka ne-crossbeam eqhubekayo.
Isith. 17a
Umfan. 17b
Izixhumanisi ezitshekile: Ezixhumanisweni ezazixoxwa kuze kube manje, izimbambo bezimi ziqondane ngokuphelele. Kodwa uma i-engeli ingeyona eqondile, khona-ke ama-angle bars (sl. 18) ayaphendulwa, kuma-engeli acijile kakhulu kusetshenziswa ama-wedge spacers. Sebenzisa izibopho zokuqhubeka kanye nezingcezu zokusekela uma kudingeka njengasezixhumanisweni eziqondile. Amapuleti okuxhumanisa agobile (sl. 19) axhunywe nge-excentricity enkulu namandla angeziwe abalulekile. Ukwenziwa kwezixhumanisi ezitshekile kusizwa lapho kusetshenziswa ama-plate okuxhumanisa ashiselwe (sl. 20).
Fig. 18
Umf. 19
Umz. 20