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V Vn Thun 53KG2 MSSV 9627.53

CHNG LIEN KET

Cau 1-Xac nh kha nang chu lc cua lien ket han oi au gia hai ban thep cotiet dien 270x12mm chu lc trong cac trng hp sau:

-Chu lc keo doc truc

-Chu uon

Giai

Hinh 1.1 hinh 1.2

ng han chu lc keo doc truc N (hinh 1.1)

T ieu kien ben: cwtWn

ftl

N

A

N

N ( Wtl ) cwtf

Trong o:

N:lc keoAw:dien tch tnh toan cua ng han oi au;t:be day tnh toan cua ng han,t=12mm;lw:chieu dai tnh toan cua ng han,lw=b-2t=270-2.12=246mm;

b:chieu dai thc te cua ng han,chnh la chieu rong thep c ban,b=270mm;c:hesoieukienlamviec,c=1;fwt:cng o tnh toan cua ng han oi au khi chu keo.

Khi chu keo,dung phng phap kiem tra thong thngfwt=0,85f=0,85.230 =195,5 N/mm2

f:cng o tnh toan cua thep c ban,oi vi thep c ban dung CCT38 ,o day banthep c ban la t=12mm

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N ( Wtl ) cwtf = 12.246.195,5.1=577116 (N)=57711,6 (daN).

Vay kha nang chu lc cua ban thepla N=57711,6 daN

)ng han chu mo men uon M(hnh 1.2)

)(236617566

1.5,195.246.12

6

6 22

2Nmm

ftlMf

tl

M

W

M cwtwcwt

ww

w

Vay kha nang chu lc cua ban thep la M 2366,2 daNmm

Cau 2:Kiem tra lien ket oi dau dung ng han xien goc =45o,noi hai ban thepday 14mm,rong 250mm; chu lc keo doc truc N=730 kN.

Giai

7300 daN250

7300 daN

14

Hnh 1.3ng han oi au xien chu lc keo N c kiem tra ben theo cac ng suatphap va tiep bang cong thc sau:

Trong o:

w, w: ng suat phap va ng suat tiep trong ng han; : goc nghieng cua ng han so vi phng cua lc truc N,=45o; lw: chieu dai tnh toan cua ng han xien;

cwv

w

w

cwt

w

w

ftl

N

ftl

N

cos

sin

)(32614.245sin

2502

sinmmt

bl

ow

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fwv: cng o tnh toan cua ng han oi au khi chu cat;khi chu cat ta co fwv=fv=0,58f=0,58.2300=1334 daN/cm

2.

Vay

22

22

/1334/11316,32.4,1

2

2.73000

cos

/1955/1131

6,32.4,1

2

2.73000

sin

cmdaNcmdaNftl

N

cmdaNcmdaNf

tl

N

cwv

w

w

cwt

w

w

thoa man ieu kien ben.Cau 3:Tnh va ve lien ket han gia thanh gom hai thep goc co tiet dien

2L140x90x10 (ghep theo phng canh ngan) vi ban thep co tiet dien230x16mm.Thanh chu keo ung tam N=770kN ,han song song vi canh daicua ban thep.

Giai

Hnh 1.4Chon hf=10mm1,2tmin=1,2.16;10mm=1.2.10=10mmthoa man.Theo gia thiet lien ket thep hnh oi xng,lc truc nam gia hai ng han nen tatnh c chieu dai ng han song va ng han mep theo cong thc sau:

cwf

wfh

Nl

min)(

Trong o: hf: chieu cao ng han goc; lw: tong chieu dai tnh toan cua cac ng han; f, s: cac he so chieu sau nong chay cua ng han ng vi cac tiet dien 1

va 2; tra bang 2.6 SGK trang 67 khi dung ng han tay,ta co f =0,7, s =1. fwf, fws: cng o tnh toan chu cat quy c cua thep ng han va thep c

ban;

16

10

140

Lx140x90x107700 daN7700 daN

230

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theo bang 2.4 SGK trang 60 khi dung que han N46 fwf =2000 daN/cm2,

fws =0,45fu=0,45.3800=1710 daN/cm2

(fw)min = min(ffwf;sfws)=min0,7.2000;1710.1=min1400;1710(fw)min =1400daN/cm

2.

Do o )(551.1400.0,177000

)( mincm

fhNl

cwf

w

Lay chieu dai thc cua ng han song va ng han mep bang 55 cm (hnh 1.5)Ro rang lwmin 4hf =40 va lw 40mm;lw 85fhf =85.0,7.1=59,5 cm(ng han goc canh);

Hnh 1.5Bai 4-Thiet ke moi noi cho hai ban thep co tiet dien 200x12mm ; chu lc keo doc

truc N=500 kN theo hnh thc lien ket phang co hai ban ghep va ng han goccanh.Giaie cac ban ghep truyen c lc, yeu cau:Abg ATrong o: Abg: tong dien tch tiet dien cac ban ghep; Abg =2.bbg .tbgA: dien tch tiet dien cau kien c ban;A=200.12=2400mm2.Abg A2.bbg .tbg 2400mm

2b .tbg 1200mm

2

Chon bbg=120 mmtbg = 10 mm

tnh chieu dai ng han theo cong thccwf

wfh

Nl

min)(

Trong o : N=50000 daN

7700 daN7700 daN23

0

16

10

14

0

Lx140x90x10

550

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Chon hf =10mm a am bao hf 1,2tmin=1,2.min10;12mm=12mm (fw)min= min(ffwf;sfws)=min0,7.2000;1710.1==min1400;1710

(fw)min=1400daN/cm2

Do o )(7,351.1400.0,1

50000

)( min

cm

fh

Nl

cwf

w

Lay chieu dai thc cua ng han song va ng han mep bang 40 cm (hnh 1.6)Ro rang lwmin 4hf =40 va lw 40mm;lw 85fhf =85.0,7.1=59,5 cm(ng han goc canh)

Hnh 1.6

Bai 5:Xac nh kha nang chu lc cua moi noi hai ban thep dung ng han goccanh,hnh thc lien ket phang co hai ban ghep chu lc truc.Biet: Ban thep co tiet dien 14x200mm,khoang cach gia hai ban thep 10mm. Ban ghep co tiet dien 8x180 mm,dai 200mm Chieu cao ng han hf=8mm.Giai

NN

12

10

10

120

10400 400

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Hnh 1.7

Chon hf=8mm kiem tra ieu kien hf1,2tmin=1,2.14;8mm=1,2.8=9,6mm

thoa mano ben cua ng han c kiem tra ong thi theo hai tiet dien 1 va 2 Tiet dien 1 (theo vat lieu ng han)

cwf

wff

flh

N

1 cwfwff flhN 1

Tiet dien 2 (theo vat lieu cua thep c ban tren bien nong chay)cws

wfs

flh

N

2 cwswfs flhN 2

Trong o:+ hf: chieu cao ng han goc;hf=0,8cm+ lw: tong chieu dai tnh toan cua cac ng han; lw=4lw=4.200=800mm+ f, s: cac he so chieu sau nong chay cua ng han ng vi cac tiet dien 1

va 2; f=0,7, s=1,0.+ fwf, fws: cng o tnh toan chu cat quy c cua thep ng han va thep c

ban; fwf=2000 daN/cm2, fws=0,45fu =0,45.3800=1710 daN/cm

2.+c:he so ieu kien lam viec lay bang 1.

Do o: cwfwff flhN 1 N10,7.0,8.80.2000.1=89600daN/cm

2

cwswfsflhN 2 N21.0,8.80.1710.1=109440daN/cm2

Vay N=minN1;N2= min89600;109440daN/cm2= 89600daN/cm2.

NN

180

200 10 200

14 8

8

200

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Bai 6:Thiet ke moi noi cho ban thep tiet dien 260x14mm,chu lc keo doc trucN=490kN theo hnh thc lien ket phang co hai ban ghep va bu long ng knh16mm,ng knh lo bulong 18mm.

GiaiChon ban ghep moi ban day tbg =10mm=1cm

Kch thc ban ghep: Abg A

Trong o:

Abg: tong dien tch tiet dien ngang cua cac ban ghep; Abg=2Abg=2.1.26=52cm2.

A: dien tch tiet dien cua cau kien c lien ket;A=26.1,4=36,4

Abg Ac thoa man.

oi vi boulone (tho, thng, tinh), so lng boulone can thiet c tnh theo cong

thc: cbN

Nn

min

Trong o: [N]minb = min([N]vb, [N]cb);

Kha nang chu cat cua mot boulone c tnh theo cong thc:[N]vb=fvbbAnv =1500.0,9 .2,01.2=5427 daN

Trong o:

fvb: cng o tnh toan chu cat cua vat lieu boulone;Trang thai lam viec chucat,cap o ben cua boulone la 4.6 tra bang 1.10 phu luc co fvb=1500 daN/cm

2

b: he so ieu kien lam viec cua lien ket boulone; b=0,9.

A: dien tch tiet dien ngang cua than boulone;A=2,01cm2

nv: so lng mat cat tnh toan cua boulone, phu thuoc vao so lng cau kienchu lc c lien ket; Khi co ba cau kien: nv = 2;

Kha nang chu ep mat cua mot boulone c tnh theo cong thc:[N]cb = fcbbd(t)min =4650.0,9.1,6.1,0=6696daN/cm

2.

Trong o:fcb: cng o tnh toan chu ep mat cua boulone;tra bang 1.11 phu luc I ng vi

thep CCT38 co fu=380N/mm2 fcb=4650 daN/cm

2.

(t)min : tong chieu day nho nhat cua cac ban thep cung trt ve mot pha;

(t)min=1,0 cm.

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Do o [N]minb = min5427;6696daN/cm2=5427 daN/cm2.

Vay cbN

Nn

min =

1.5427

49000 =9,03;lay n=10 boulone.

Boulone c bo tr nh hnh 1.8

Hnh 1.8

Yeu cau cau tao khi bo tr thoa man,that vay:

240

256

24

1650405,2

80

64

8

435325,2

t

dd

t

dd

Kiem tra ban thep giam yeu theo cong thc: blfn

A

N

Trong o:

An: dien tch tiet dien thc cua ban thep c lay nh sau:

oi vi boulone (tho, thng, tinh)

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Hnh 1.9

Khi boulone bo tr song song, tiet dien kiem tra la tiet dien 1-1(hnh 1.9):

An = A A1 =26.1,49=27,4cm2.

Trong o:

A1: dien tch giam yeu do cac lo boulone gay ra;A1 = mtd1 = 5.1,0.1,8=9 cm

2

m: so lng lo tren mot hang boulone;m=5 inh.

t: chieu day cau kien mong nhat;t=1,0cm

d1: ng knh lo boulone;d1=1,8cm.

./25301,1.2300/3,17884,27

49000

A

N22

n

cmdaNcmdaNf bl

Ban thep u ben

Bai 7:Xac nh kha nang chu lc cua lien ket sau:Dung bu long ng knh 18mm,ng knh lo bu long 20mm

Giai

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Lc tac dung len mot bu long do M gay ra c xac nh theo cong thc:

cbi

bl Nlm

Ml

m

NN min2

maxmax

max

2

min

l

lmNM

icb

Trong o:

oi vi bu long (tho, thng, tinh)

[N]minb = min([N]vb, [N]cb);

- Kha nang chu cat cua mot boulone c tnh theo cong thc:

[N]vb=fvbbAnv =1500.0,9.2,54.2=6858 daN/cm2

Trong o:fvb: cng o tnh toan chu cat cua vat lieu boulone;Trang thai lam viec chucat,cap o ben cua boulone la 4.6 tra bang 1.10 phu luc I co fvb=1500 daN/cm

2

b: he so ieu kien lam viec cua lien ket boulone; b=0,9.A: dien tch tiet dien ngang cua than boulone;A=2,54cm2

nv: so lng mat cat tnh toan cua boulone, phu thuoc vao so lng cau kienchu lc c lien ket; Khi co ba cau kien: nv = 2;

-Kha nang chu ep mat cua mot boulone c tnh theo cong thc:

[N]cb = fcbbd(t)min =4650.0,9.1,8.0,8=6026,4 daN/cm2.

Trong o:

fcb: cng o tnh toan chu ep mat cua boulone;tra bang 1.11 phu luc I ng vi

thep CCT38 co fu=380N/mm2 fcb=4650 daN/cm2.(t)min : tong chieu day nho nhat cua cac ban thep cung trt ve mot pha;

(t)min=0,8cm.

Do o [N]minb = min6858; 6026,4 daN/cm2=6026,4 daN/cm2.

Vay

25

)2515.(56026,4.1.2 222

max

2

min l

lmNM

icb M421848 (daNcm)

Hay la M=421848 (daNcm).

Cau kien b giam yeu do lo bu long nen can kiem tra ben cac ban thep theo cong

thc: c

n

fW

M

Wn mo men khang uon cua tiet dien giam yeu.

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6

0,2.4,1.6

6

31.4,1

66

tb=Wn

222

1

2

td

m =221,43 cm3

Trong o :

m:so lng lo tren mot hang(co phng vuong goc vi phng cua lc);m=6

t:chieu day cau kien;t=1,4cm

d1 :ng knh lo bu long;d1=2,0cm

Do o 1.23001,190543,221

421848 c

n

fW

M ban thep u ben.

t

b

d1

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CHNG DAM THEPBai 1-Cho dam to hp han nhp 10m cua he san trong o cac dam at cach nhau

5m,tai trong tieu chuan gc=27kN/m2;hoat tai pc=5kN/m2.Tiet dien gom banbung 1100x10mm va hai ban canh 450x20mm.Hay kiem tra tiet dien dam ve

o ben theo moomen va lc cat.Giai

pc

gc

10 m

l

b b bb b b

1

2 2

1Hnh 2.1

2-2

1100

10

450

20

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Tai trong toan phan q= gc.g + pc.p=27.1,1+5.1,2=35,7 kN/m2.

Tnh toan vi dai ban co be rong b=5mq=35,7.5=178,5/m.

Dien tch tiet dien dam:

A=Aw+A

f=10.1100+2. 450.20=29000 mm2

Mo men quan tnh va mo men khang uon cua tiet dien dam oi vi truc trung hoax-x la:

Ix=Iw+ If=tw.hw3/12+2(bftf

3/12 +bftfhf2/4)=10.11003/12+2.(450.203/12+450.20.11202/4)

Ix=6755.106 mm4.

Wx=2Ix/h=2.6755.106/1160=35.106mm3

q

10 m

hw=1100

hf=

1120

h=1160

bf=450

tw=10

tf=20

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Mo men tnh cua mot na tiet dien dam vi truc trung hoa x-x

363622

fw 2,8.102,8.108

1120450.20.+

8

110010.

2.

8=S+S=Sx mmm

htb

ht fff

ww

ng suat phap ln nhat tai th ngoai cung cua tiet dien nay la: cx

fWM

Vi M=ql2/8=(178,5.102).102/8=223125 daNm2=223125.106daNmm

26

6

637535.10

223125.10

mm

daNf

W

Mc

x

Cau 2:Kiem tra ben,kiem tra o va tnh lien ket han gia canh vi bung cua damto hp sau:Dam gian nhp L=10m chu tong tai trong phan bo eu tieu chuanqtc=45 kN/m;he so vt tai =1,15 .Dam co tiet dien ch I ghep t ba banghep,kch thc,kch thc moi ban canh la 300x16mm,va ban bung la1000x8mm.o vong cho phep la/l=1/400.

Cau 3:Cho dam to hp han nhp 14m cua he san trong o cac dam at cach nhau3m,tai trong tieu chuan gc=24kN/m2;hoat pc=6kN/m2.Tiet dien day gom :ban bung1250x10mm va hai ban canh 450x20mm.Tai v tr cach goi ta 2,5m,hay thay oitiet dien dam bang cach oi be rong canh,gi nguyen chieu day ban canh va tietdien ban bung.Dung ng ng han oi au xien e noi canh.Biet he so vttai g=1,1;p=1,2.

Cau 4:Kiem tra on nh tong the cua dam to hp han nhp 10m,tai trong tnh toanphan bo eu tren dam la 60kN/m.Tiet dien dam gom :Ban bung 1000x10mm vahai ban canh 400x20mm.Biet chieu dai tnh toan ngoai mat phang dam cua canhnen l0=10m.

Cau 5.Hay kiem tra on nh cuc bo cua ban canh va ban bung,neu bien phap sly neu khong am bao ieu kien on nh cuc bo(ve cau tao va xac nh kch thccu the ) cho dam thep tiet dien ch I to hp han (hai canh nh nhau ) chu taitrong tnh,co tiet dien ban canh la 600x20mm va ban bung la 1750x14mm.

Cau 6. Cho dam to hp han nhp 12m tai trong tnh toan phan bo eu tren dam la200kN/m.Tiet dien dam gom: ban bung 1100x10mm va hai ban canh320x20mm;sn goi mut au dam co tiet dien 320x12mm.Hay ve va kiem trasn goi.

cv

wx

ftI

VS

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CHNG COT THEP

Cau 1:Xac nh kha nang chu nen ung tam cua cot thep ac cao 10m,lien ketngam chan cot va khp au theo ca hai phng.Cot co tiet dien ba ban

thep:Ban bung 450x10mm,hai ban canh 450x20mm.Giai:

Xac nh cac ac trng hnh hoc:

cmicmi

cmIcm

yx

y

6,11225

30379

A

I;22

225

107059

A

I

.3037912

1.4545.2.2;107059

12

45.4445.49=I

.cm25245.1,045.2.2A

yx

433

433

x

2

Tnh toan ve o manh:

do mot au ngam mot au khp nen he so chieu dai tnh toan =0,7

am bao ve o manh.

h=490

hf=470

hw=450

b=4

50

tf =20

10

b0=220

y y

x

x

120606,11

1000.7,0

5,4522

1000

max

y

yy

x

xx

il

i

l

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Kiem tra on nh tong the:

T max=60 va f=23kN/cm2 tra bang he so phan phu luc co =min=0,811,

daNAfNfA

Ncc 419434225.811,0.1.2300min

min

Vay kha nang chu nen ung tam cua cot thep la N =419434 (daN).

Cau 2.Kiem tra tiet dien cot ac chu nen ung tam N=1100kN,cot cao 7 m ,lienket hai au khp theo ca hai phng.Cot co tiet dien la ban thep gom:Ban bung450x12mm;hai ban canh 450x22mm.

Giai

Xac nh cac ac trng hnh hoc:

cmicmi

cmIcm

yx

y

5,11252

33419

A

I;22

252

44,119470

A

I

.3341912

2,1.4545.2,2.2;44,119470

12

45.8,4345.49,4=I

.cm52245.1,245.2,2.2A

yx

433

433

x

2

Tnh toan ve o manh:

b=450

tf =22

hw=450

hf=472

h=494

b0=219

12

y y

x

x

N

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120615,11

700.1

3222

700

max

y

y

y

x

xx

i

l

i

l

do hai au khp nen he so chieu dai tnh toan =1am bao ve o manh.

Kiem tra on nh tong the:

T max=61 va f=23kN/cm2 tra bang he so phan phu luc co =min=0,811

224

min

/1.2300/23,538252.811,0

10.11cmdaNcmdaNf

A

Nc

thoa man ieu kien on nh tong the.

Kiem tra on nh cuc bo:

o manh quy c 02,210.1,2

2300.61

6

E

f

o manh gii han cua ban bung:

w

w

w

w

t

h

t

h

f

E

f

E

t

h

t

h

w

w

w

w

3,262,5722,30.907,12300

10.1,202,2.35,02,135,02,1

5,372,1

45

6_

w

w

w

w

t

h

t

hthoa man va ong thi ban bung khong can at sn ngang.

o manh gii han cua ban canh.

ff t

b

t

b 00

17

2300

10.1,202,2.1,036,01,036,0

954,92,2

9,21

6_0

0

f

E

t

b

t

b

f

f

ban canh am bao ieu kien on nh

cuc bo.

Tom lai tiet dien cot a kiem tra thoa man ieu kien on nh.

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Cau 3.Xac nh kha nang chu nen ung tam cua cot thep rong cao 10m,lien kethai au la khp theo ca hai phng.Cot co tiet dien la hai thep 36,at cach nhau450mm tnh t mat ngoai, cac ban giang co tiet dien 250x10mm,at cach nhau1000mm tnh t truc en truc.

Biet cac ac trng hnh hoc cua thep 36 :-Dien tch tiet dien A=53,4cm2.

-Mo men quan tnh oi vi truc x song song vi canh Ix=10820 cm4.

- Mo men quan tnh oi vi truc y song song vi bung Iy=513 cm4

-Ban knh quan tnh oi vi truc truc x song song vi canh ix=14,2 cm.

- Ban knh quan tnh oi vi truc truc y song song vi bung ix=3,1cm.

-Khoang cach t trong tam en canh ngoai cua bunh z0=2,68cm.

Giai

N

10

000

250

1000

450

y

x

y0

yx0

x360

2,68 2,68444,64

36

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Xet s lam viec theo phng truc thc x-x:

1204,702,14

1000

x

xx

i

lCot am bao yeu cau ve o manh theo truc thc x-x.

Vi x=70,4 va f=230N/mm2 tra bang va noi suy ta c =0,779

Kiem tra ieu kien on nh tong the:

)(1915344,53.2.779,0.1.230022

11 daNAfNfA

Nxcc

x

Hay N1 =191534 daN

Cot lam viec theo phng truc ao y-y:

Khoang cach trong tam hai nhanh cot la:C=h-2z0=45-2.2,68=39,64 (cm).

Khoan cach tron tam cua cac ban giang la a=100cm.

Mo men quan tnh cua ban giang la Ib=tbdb3/12=1.253/12=1302,08 cm4

o cng n v, n cua cac oan nhanh cot va ban giang

2,05

1156,0

100.08,1302

64,39.5130 aI

CIn

b

y

do o o manh tng ng 210 y

daNAE

N

i

l

i

l

cmA

Ii

cmA

CII

oth

fy

yo

f

y

y

y

y

y

f

yoy

7074874,55

4,53.2.10.1,2.14,32.

4,5585,492,24

2,2431

)2501000(

)(6,204,53.2

5,42980

)(5,429804

4,53.64,395132

42

2

62

2

2222

0

422

2

Theo ieu kien ben ta co:

daNAfNfA

Ncc

2456404,53.2.1.23002.2

2

2

N2=245640(daN).

ta co:N=min{[N1];[N2];[Nth]}=[N1]= 191534 daN

Vay kha nang chu nen ung tam cua cot la 191534 daN.

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Cau 4.Kiem tra tiet dien cot rong chu nen ung tam N=1300kN,cot cao 5,5 m ,lienket hai au khp theo ca hai phng. Cot co tiet dien la hai thep 30,at cachnhau 380mm tnh t mat ngoai,cac thanh bung xien dung thep goc L50x5,goc taobi truc cua thanh xien va truc cua nhanh cot =500.

Biet cac ac trng hnh hoc cua thep 30 :-Dien tch tiet dien A=40,5cm2.

-Mo men quan tnh oi vi truc x song song vi canh Ix=5810 cm4.

- Mo men quan tnh oi vi truc y song song vi bung Iy=327 cm4

-Ban knh quan tnh oi vi truc truc x song song vi canh ix=12 cm.

- Ban knh quan tnh oi vi truc truc y song song vi bung ix=2,84cm.

-Khoang cach t trong tam en canh ngoai cua bung z0=2,52cm.

Giai

Ta co khoang cach trong tam hai nhanh cot C=h-2z0=380-2.2,52=374,96 mm

x

x

y y

50o

x0

x0

300

374,96 2,522,52

380

30

N

5500

315

630

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Cau 5.Kiem tra ben ban giang cua cot rong hai nhanh chu nen ung tamN=200000 daN.Nhanh c lam bang thep hnh 36 ,hai nhanh ghep hai bancanh hng vao nhau dat cach nhau (tnh t mat ngoai) h=75cm va c lienket vi nhau bang cac ban giang tiet dien 300x10(mm) at cach nhau 120

cm(khoang cach tam cua cac ban giang).He so uon doc cua cot oi viphng truc ao a c xac nh la x=0,8523.Khoang cach t trong tam tietdien thep hnh 36 en mep ngoai ban bung cua no la 2,99cm.

Giai

300

y

x

y0

yx0

x360

750

1200

29,9 29,9444,64

36

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Cau 6.Kiem tra kha nang chu lc cua thanh bung trong cot rong 2 nhanh chu nenung tam N=215000 daN.Nhanh c lam bang thep hnh 33,hai nhanh ghepna canh hng vao nhau,at cach nhau (tnh t mat ngoai )h=75cm.He thanhbung co s o tam giac khong co thanh bung ngang,thanh bung nghieng vi

nhanh cot mot goc =450.He so uon doc cua cot theo phng truc ao a cxac nh x=0,8674 .Thanh bung la thep goc L50x5 dien tch tiet dien la 4,8cm2,ban knh quan tnh nho nhat cua tiet dien la 0,98 cm.Thep hnh 33 cokhoang cach t trong tam tiet dien en mep ngoai ban bung cua no la 2,90cm.He so ieu kien lam viec cua cau kien c=1,cua thanh bung la =0,75.

Giai

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Ta co C=750-2.29=692mm

Kiem tra tiet dien cot theo truc ao

c

x

fA

N

22 /2100/5,5330

50,46.8674,0

215000cmdaNfcmdaN c (vo ly)khong thoa man.

Xac nh lc cat quy c:

He thanh giang va ban giang c tnh toan vi lc cat, Vf sinh ra khi cot buon doc quanh truc ao;c xac nh theo cong thc:

.25428674,0

215000.

2300

10.06,22330.10.15,7233010.15,7

666

daNN

f

EVf

Trong o:

N: lc doc tnh toan cua cot;

= f(0);theo gia thiet =x=0,8674.

Lc cat, Vs tac dung tren mot mat rong cua cotVs = Vfnr =2542.0,5=1271daN.

x

x

y y

45o692

1384

692

692

750

336

x0

x0

29 29692

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nr = 0,5 : cot rong hai nhanh;

Chieu dai thanh bung:

ld=lf/(2.cos)=1384/(2.cos450)=97,86(cm).

Lc doc trong thanh bung xien:

daNn

VN

t

sd 5,1797

45sin.1

1271

sin 0

Trong o:

nt = 1, he thanh bung tam giac.

o manh ln nhat cua thanh bung:

15010098,0

86,97

min

dmax i

ld

tra bang he so phan muc luc theo o manh dmax=100 va cng o tnh toan

f=23 kN/cm2 ta c min=556,25/103=0,556(noi suy).Kiem tra thanh bung theo cong thc:

2

min

/172575,0.23005,6768,4.556,0

5,1797cmdaNf

A

Nc

t

d

ay c=0,75(theo gia thiet)

thoa man.

CHNG DAN THEP

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V Vn Thun 53KG2 MSSV 9627 53

Cau 1.Cho mat bang nha xng khong co cau truc nhp L=15m,chieu dai nhaB1=36m,bc khung B=3,6m;mai lp ton,dan mai lien ket vi cot.Cot cao 6mtnh t mat mong en nh cot.Hay chon s o he thanh bung cho dan va ve so khung ngang.

Cau 2.Cho dan thep dang hnh thang co mai lp bang panel loai 1,5x6m;nhp dan27m;dan lien ket cng vi cot.Hay ve s o hnh dang dan hp ly va chonthanh bung xien th 3 tnh t au dan.Biet lc nen trong thanh N=-30400daN,

ban ma day 14mm.

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