1)- Dac diem:•
.
a- Muc dich : la bQ phan che mat duoi cua than thang, nham che bui tir tren rei xuong loai trir hoc kern khong c110nhen giang, dong thoi tang ve n1Y qllan chung c110
cau thang.
b- CiiLL tao:•
b- Giai phap dam thang va tru phu dam thang va tay vin mot nha1111cau thang va
dam chieu nghi diroc lien k~t bang mong thong qua mot tru phu trung gian.
Dau tren va dtnri cua tru phu phai diroc chua du ch6 d~ rap n1Q11gc110tay V!11va
da111thang ve 2 huong, co dO cao chenh nhau bang lnQt bac, (H6-19b)
c- Giai phap dam Ca11don b~y : voi don bdy duoc dat g6i len darn Ca11i1 khoang ghra va se ganh chill dam t11a11g(J dau ngoai, Giai phap nay cling se diroc ap dung c110trutrng
hop cau t11a11gxoay g6c d6i huong kl1011gco chieu 11g111.(H6-19c) 3.4- Tr~I1than thang :
(H6-19a) 1111$tl~n rang cu'a,
3.3- Cau t~o chieu nghi : (H6-19)
Tuy thea vi tri, mat bang va hinh thirc cua chieu nghi rna co th~ ap dung 1 trong
3 giai phap cau tao chidu 11g111:
a- Giai phap darn chieu nghi la bQ phan chiu san chie'u nghi, d011gthoi la diern tira cho cac dam thang cua cac nhanh cau thang,
210
3.2- Lien k~t dam thang V80 dam chien nghi : Dam chleu 11g111thuong diroc ghep bang 2 thep hinh clnr I, U. Da11l thang dlf9~clien k~t van dA1l1chieu nghi bang bulon va thep hinh chir L vdi 11hlt"11gtal11 c1~lnbAI1g g6 CU'11gho~c gal1g. (H6-25)
3.3- K6t c~u.chi~u nghi : Cau t~o chieu nghl clla Call thal1g sat tIlep co cU11g1n(>t 11guyen tac 1111Uãd cau t11allg g6, tuy theo trt1dng h<Jp rna co t11~ap d~lllg giai pl1ap dll11g daln chi~u 11gh}d~ chiu SaIl Cl1i~u nghi va cae d~m thang ho~c giai p11ap dlll1g daln Ca11 d011bay d~ ch!u dam thang - Lien ~~t gitia cac dam thlt"dng dt1Qc ap d~lng giai phap lien
ke't b~ng bulon vdi thep l1inh L. (H6.26)
v.._ Cau t~o cau thang xily Ia.ch da :
3.1- Ghep n6i dam t.hang : Khi cae d~m thang 1{11011gdu dai, cdn phai ghep n6i thi co th~ ap dung giai phap noi bang each d~t li~11dau vdi tal11 che ll10i 116i diroc lien ke't han hoac dinh tan .•
2.1- Hinh tfnrc bac thang : Bac thang duoc t11\).Chien vdi siren chiu 111~tbac bang thep hinh chu L, mat bac 13111bang cac t~m tole co khia hoac dircc lien kgt 11al1hay tam
van go bat dinh vit VaGsuon. Mat bac thang con co th~ lam bang ban betong cot thep di)t VaGkhuon thep hinh chir L d~ lien k~t VaGdam. thang, Doi bac duoc lam bang tole phang, Bac thang d di~ln khoi 11311htai noi thuong dm not nen xay bang gach da, betong
cot thep d~ gat dam thang nharn chong ri set d di~ln tua cua dam. (H6-21)
2.2- Hinh thirc dam thang Dfiam thang sat thep co 2 hinh thirc : 1111111chir nhat, 1111111rang cira,
- Ddm thang 11i1111Clli11111~t: DUl1g cac taln tole day ttt6-12mm nguyen tam hoac dap hinh c1111U, hay ghep vrri thep hinh cl1lt L, hoac co th~ ghep vdi g6 thanh dam r6ng, duoc lap ghep 110ibang dinh tan hay m6i han. (H6-22)
- Dam thang hinh rang' cua : DUI1g cho cac taln tole nguyen d~ cat theo hinh rang cua, 110~c dung thep ban, thep tron d~ tao hinh rang cua tren darn hinh chir nhat.
(H6-23)
2.3- TraIl than thang : (116-24)
- Siron tran thircng duoc lien k~t treo bang thep troll hay thep ball veo ket c~u bac thang,
- Mat tran duoc ca'u tao bang gia! phap to vira lel1 Iuoi thep duoc buot vao siren
.. .).)
hoac co the dUI1g ton phang de lam 111~ttran.
3)- Chi tiet cau tao:•
\
ll11UC)'Cdi~ln_.,cd ban cua v~t li~u sat thep Ia phai son bao tri d~ phong chong ri set.
2)- M6 ta, bQ phan :
211 2.1- Cau thang xay gach : Vai so bac < 6 thl Call thang xay bang gach dat nam hay
d~t nghieng tren lop dat nen da dam chat d~ mot lop betong gach vo hay da dam mac 25 - 30 day t6i thieu 15cm. Neu s6 bac > 6 thi bac thang xay tren vom cuon. CAu thang
xay bang gach, da deu xay bang vita ximang mac 50. (H6-28).
2.2- Cau thang xay bang da :
a- Cdu thang ngoai troi : Bac thang bang da dai 1,20m duoc dat goi len 2 doan
dirong thap co be day 22cm de 2 dau bac thang ngarn van 2 ben tirong it nhat llem.
Tnrong hop chieu ngang cua cau thang rong thi phai xay cac tuong chiu do bac each
khoang 1,20m khi s6 bac > 6 thl cac ch~u b~c duqc xay cu6n de tiet ki~m v~t li~u - Neu phan duai nha kh6ng c6 tang ham thi cau thang xay bang nhfrng phien da 1i~n kh6i, neu nha co tang hfim can lay anh sang va thong gio thi t<;liehieu cao ngang tam ctta clla tang ham can d~t cac b~c thang co d~c thung a khoang gifra.
£)~ nuoc mua khong chay van nha, b~c tren cung nen d~t thap hem ntn nha IClTI, d6ng thai cac m~t b~e can lam hoi doc ra ngoai v6i dQ doc 1 - 5%.
B~c tam cap chiu tiii tr9ng nh~ han so v6i tuang ngoai cua nha, do do can cau t~o
Cdu thang 118.yCUl1g da diroc thuc hien i1 ben trong 11113,trong cac dinh t11lJOc6, co ke't CaLl tuong xay cuon vorn c11!U hrc, Cdu thang xay bang da, gach chi duoc ap dung d
1111Uãllg11C1ikhong co In~c11 nU"c1Cngam.
2)- Chi tiet cau tao:•
'")
a- Bac thang xay bang gach co the d~t nam vien gach, nhung 11e11d~t nghieng vien
"
gach de tao bac tren khdi n~ll betong.
b- Bac thang bang dB. duoc gia cong d~ co tie't dien theo 1111111c11111111~t110~c hinh da giac mot khoi hay 2 nhanh voi miii bac nho ra nr 2 - 4cm, cao 4 - Bern. Ngoai ra COIl co 1111Lfngbac thang bang da diroc dec gQt thea hinh thirc d~c bi~t d~ xay CfiLlthang co than thang tron hay xoan tron ac. (H6-27)
1.3- Pham vi ap d¥llg : Cau thang nay thmrng duoc dem ap d~111gtai cac 11gB.ra
VaG (J bell ngoai 11118.,Call duoc goi CllU11g la bac tam cap tuy so bac CO t11~ 1111i'eLI11dl1 3 bac .•
1.2-Hinh thtrc b~c thang:
1.1- V~t li~u : Bac cau thang diroc C3U tao bang each xay gach hay da , voi gach thi dung loai gach da duoc ep 2 1~11hie san xuat, bao dam chat luong tot, thanh vuong
canh thang - V di da thi dung loai da Cl111g~d~c chac (granit, diorit, banzan) chiu mai 1n011 11118.11mat 1111ung khong tron, hoac dec tha1111 tang dai 1,20m d~ la111bac thang.
1)- Hac diem:• .,
212
- Vu diem : Cau thang betong cot thep toan khoi co d¢ cirng va 6n dinh cao, khong
bi han che boi tieu chuan hoa, hinh thirc da dang thoa man moi yeu cau tham my cua
, , ,
kien true. Ap dung trong cong trinh dan dung bang betong cot thep va co yeu cau dac biet ve tao hlnh thAm my.
- Nhuqc di~m : Ton cot pha, toc d¢ thi cong va dua vao Slr d~ng ch~m. .
1.2- H~ thong ket cau chiu I"c : ffinh thuc ket cau chiu Ilfc co 2 lO<:li : Ban va ban dam.
- Ciiu thang hlnh (huc ban: Than thang la m¢t ban ph~ng, ban ch!u toan b<)tai trQng tac d~ng len cau thang, ban tlfa len tUOng ho~c tl;la tren dam do chieu nghl va chieu t6'i, hlnh (hue ket cau nay thfch hqp nh!p cau thang llh6 : 4,50m va h~p 1,50m, chiu tai trc;>ng tuang d6i nho. (H6-32).
khe bie'n dang gura 2 b{>phan d~ khong bi anh huong Idn nhau nhu eo hien tttqllg lun khong deu. (H6-29)
b- Cnu thang trong nhd :
bl- Cdu thong co tluu: thang tltcing :
Bac da diroc d~t d dau ngam VaGtinrng, dau kia gat tren dam thang ballg thep hoac bang' betong eot thep. Chieu nghi co th~ lam bang etong cot thep hay xay cuon, mot . dau ti vao dam chieu nghi, dau kia ngam VaG tuong. Truong hop c:1u thang d gnra 2
tircng, khi chieu ngang cua than thang hep thi bac thang dircc chon ngam d 2 dau VaG tirong chiu, khi chieu ngang cua than thang r{>11g1,50m thi xay cu6n vom ti VaG2 tuong dQCtheo than thang d~ chiu dd bac thang. (H6 ..30)
b2- Cdu. tluing co than thong tron : Cau thang loai nay cau tao thea kieu xoe nan
quat, cac bac co 1 dam C11011glel1 nhau theo chieu thting dU'11g,can dau kia ngam VaG tuong chiu theo dirong vong xoan tron De len cao dan tung bac, phan dau bac t11311gke chong len nhau co dirong kmh 30cln, phan dau ngam VaGtirong co doan am sau 12cm.
<)
o In6i bac thang chieu rong giira bac tran dinrng biroc phai du rong d~ dat chan (25 ..
3Dcln) sau khi dii trir phan goi tua cua bac dat k~ li~11ben tren - C11i~u day mep dinri cua bac thang 1{11011gI1h6 hen 3Delll. (1-16-31)