HD TKTN Cau Duc Hang

8/2/2019 HD TKTN Cau Duc Hang

1/23

Hng dn TKTN Chu Vit Bnh

Hng dn thit k kcn dm btct lin tc c hng cn bng

i-chn kch thc ban u :1.1- Phn chia khu nhp :

1.1.1-Chiu di nhp chnh L :+Cn c chn nhp chnh :-Khu thng thuyn .-Chiu di phn cu chnh d kin.- Chiu di nhp thng dng l 64, 75, 83, 95, 105,120,130 v 150m .Nhp chnh c chia thnh cc t nh tr Ko , cc t c hng cn

bng Ki v t hp long Kc .1.1.2- Chiu di nhp bin L1:Chiu di hp l : ( )LL 7.06.01 = (1)

Theo iu kin c hng cn bng :01 2lK

KLL

c

c ++

= (2)

Trong : l0- l chiu di on dm c ti ch trn gio c chiu cao khng ion ny xc nh t hai cng thc trn :

( cKLLl =2

110

) (3)

Kc-chiu di t hp long chn 1,5 hoc 2m .V d : Chiu di nhp chinh L=75m, chiu di t hp long KC=2m khi

L1=0,775=52,5m v l0 = 52,5-0,5(75-2) =52,5-36,5= 16m.Hoc cch th hai : chn chiu di t c trn gio l0= 11m.L1=0.5(75-2)+2+11=36,5+13= 49,5mL

1

= 0,66L1.1.3-Chiu di cc t c Ki :Chiu di mi t c Ki chn trong khong 3; 3,5; hoc 4 m v c th

khng bng nhau ,nhng t ngoi cng c chiu di ln hn , sao cho s t ccn bng l s nguyn v trng lng t c nng nht khng vt qu 60 Tn . Saukhi cng chiu di cc t Ki v t hp long Kc , chiu di cn d ca nhp tnhvo t Ko . Chiu di t Ko phi chn t 10 12 m tu thuc vo loi xe c .

1.2-Kch thc hp dm :Nguyn tc thit k l phi chn kch thc hp dm trc sao cho hnh

dng mt ct hp nhn thy cn i,hp l sau mi tin hnh tnh ton kim tra v khng nh nhng iu chn . Vic chn ban u da vo kinh

nghim thit k, vo thit k ca nhng cng trnh xy dng v vo mt scng thc kinh nghim.

1.2.1- Chiu cao hp dm : Chiu cao hp dm thay i theo qui luttuyn tnh hoc theo ng cong . Thng thng mt y dm cong theo ngcong bc 2 , vi chiu cao hp dm ti :

- Mt ct gi : H0 = (1/121/17) L- Mt ct gia nhp : H0,5=(1/40 1/60) L 2,5 m .

1


2/23


1.2.2-Hnh dng mt ct : Tu theo kh cu v chiu cao hp m chnmt trong hai dng mt ct thng dng sau :

a) Hp dm vi kh cu 10,5 m b) Hp dm vi kh cu >10,5m

Chiu rng np hp t0 :- i vi khh cu K 10,5 m , nn chn bng K .- i vi kh cu > 10,5 m nn chn bng 10m .

Chiu dy bn np : - ti gia hp hb=(1/251/40)K 25 cm-ti v tr ngm vi sn hp : hc = (1/121/15 ) t= 6080 cm

Chiu dy cnh hng np hp : 2025cmThnh hp : -Vi kh cu K=7m c th p dng loi sn

thng ng, vi kh cu ln hn nn p dng loithnh nghing vi dc 1/71/10 . Hp cng cao dc cng nh, chiu rng y hp ti mt ct giB= 5,56m m bo n nh ca kt cu nhp theophng ngang. Chiu dy sn W= 3570 cm .

Bn y : - chiu dy ti mt ct gi 50cm , ti mt ct gianhp 25cm . Chiu dy thay i lin tc theo qui lutca mt y.

1.2.3-Cch xc nh chiu cao dm ti mi mt ct :

2


3/23


Chiu di on dm c chiu cao thay i : Lh=(L-bVch-Kc)/2Chiu dy vch ngn ti mt ct gi ly bng chiu rng tr.Ly trc to nh hnh v, gc to ti im gia nhp ,trc 0y quay

xung pha , phng trnh ng cong y dm c dngcbxaxy ++= 2

Xc nh h s ca phng trnh bc 2 bng h phng trnh sau :- Ti x=0, y=0 c=0-Ti x=0 , y=0 2a.0+ b =0 ; b=0-Ti x=Lh, y= (H0 H0.5) a.Lh

2=H0-H0.5

2

5,00

hL

HHa

= (4)

Nhvy ng cong y dm c dng : (5)2.xay =H s a xc nh theo biu thc trn

Thay cc gi tr xi=Ki vo hm (5) xc nh cc gi tr yi t

ng ngChiu cao dm ti mt ct i xc nh theo cng thc :Hi =H0,5 + yi

Bng thut ton tng t ta xc nh chiu dy bn y ti mi mt ct i.Vi y dm c hnh dng ng cong bc 3 ,nu t h trc to nh

trn ta c phng trnh ca ng cong ny :3

.xay =

vi h s3

5,00

kL

HHa

= (6)

Vi dng hp thnh xin chiu rng y dm thay i theo chiu cao dm,

ti mt ct st tr chiu rng ny l bd 0 ti mt ct th i c chiu cao l Hi chiu rngy xc nh theo cng thc : ( )idid HHbb += 00, 2 (7)

trong - xin ca thnh hp :(1/71/10)1.3-Tnh cc c trng hnh hc ca tit din mi t dm :Trong mi t dm chiu cao v chiu dy bn y thay i theo qui lut

tuyn tnh . Trong phm vi mi t , ta coi nh mt ct l khng i v c tit dinly theo mt ct gia ca mi t.

Trong tnh ton xc nh ni lc , s mt ct xc nh tung AH lytheo s lng t c v nh vy cch chia phn t trong s tnh ton trng vicch chia t c .

Xc nh THH tit din hnh hp c th bng nhng ch

ng trnh lpsn bng TURBO PASCAL, EXCEL hoc VISUAL BASIC ,nn dng EXCEL v cth kt ni kt qu tnh THH vi cc trang tnh duyt sau ny . Khng nn dngtin ch tnh THH trong AUTOCAD v khng t ng tnh cho hng lot cc mtct v d ln v chuyn i n v theo t l bn v .

C th tham kho trang kt qu ca chng trnh tnh ton cc THH catit din dm hp bng EXCEL sau y. Trong v d c 8 t chia v tnh c Jy,trong n TKTN khng cn tnh Jy .

3


4/23


s hiumc

Chiu di

t li(cm)

Chiucao tit

din Hcm

Chiudy bnyhb

cm

Chiurngbn

y bcm

Din tch

tr rnh focm2

Din tch

tnh ifbtcm2

v tr trctrung ho

yo cm jxcm4

jycm4

0 0 620 50.0 650 140533 143628 278.8 6345689543 105610796351 450 528.0 43.8 650 126197 129151 229.2 4253577215 93297844002 300 476.0 40.3 650 118099 120912 202.0 3283841398 86342961663 300 431.0 37.2 650 111079 113751 178.8 2560022827 80313927374 300 392.3 34.6 650 105060 107592 159.3 2021917078 75144609125 300 359.6 32.4 650 99964.9 102356 143.2 1623464609 70768874906 350 328.3 30.3 650 95085.9 97337 128.1 1289017255 66578626677 350 303.6 28.6 650 91237.6 93347 116.4 1056502569 63273506328 350 284.7 27.3 650 88297.6 90267 107.8 896828544.6 6074849866

Ch : Cc c trng hnh hc phi tnh theo mt ct hnh hp thc t,khngc tnh theo mt ct qui i thnh tit din ch T. Mt ct qui ich dng tnh duyt cng .

ii-tnh ton xc nh ni lc :2.1 - Xc nh tnh ti :

Tnh ti giai on I gm :- trng lng bn thn mi t dm :

tdiiiI Flp ,, 5,2=

-ti trng thi cng : trng lng ng di chuyn, cc thit b v ngipI, tc= 0.02B 0.2 T/m .

-trng lng xe c, vn khun ,gin gio PXE : ti trng ny tp trung tti v tr cch u hng 1m v c tr s t 6080T , tu theo thit k ca xe c .

Tnh ti giai on II :-1m di lan can : tnh theo thit k c th , nu cha c s liu tm ly

0,2T/m .-1 m di g chn bnh ( i vi l ngi i cng mc ) : 0.324 T/m-1 m di l ngi i lp ghp : 0.45 T/m .

- lp ph mt cu :( )

3,2.

2

..5.007.0B

Bip

II

m

+= T/m

i : dc ngang cu %B :chiu rng cu to mt cu ( m) .

Trng lng bn thn dm c dng phn b hnh bc thang , trng lng xe cl ti trng tp trung cn cc tnh ti khc l ti trng phn b u .

H s ti trng :- i vi trng lng bn thn dm, lan can, g chn =1.25- i vi lp ph mt cu = 1.5

4


5/23


-i vi hot ti v ti trng thi cng ly theo trng thi gii hn tnh tonH s phn phi ti trng = S ln xe mm- h s ln xe nu 2 ln ly bng 1,0; ba ln m=0,85H s xung kch ( 1+IM) =1,25 .

2.2 Nguyn tc chung :

Ni lc tnh ton dm BTCT lin tc c hng gm m men un Mi , lc ctQi ti tt c cc mt ct cui t c .

Nguyn tc tnh ton :1- S lm vic ca dm lin tc c hng ph thuc vo bin php cng ngh

thi cng, c th l trnh t hp long v thi im h kt cu nhp xung gi chnh.2- Mi loi ti trng tc dng ln kt cu nhp theo mt s tnh ton ring, v

vy lp s tnh ca kt cu nhp cn c theo trng thi tc dng ca tng ti trngv xc nh ni lc trong tng s ring theo nguyn l c lp tng tc, sau t hp cc gi tr ni lc theo nguyn l cng tc dng.

Phng php tnh ton :

i vi s tnh nh, theo s tnh ton xy dng v lp cc cng thctnh ni lc v chuyn v theo phng php ca c hc kt cu .i vi cc s siu tnh, thc hin theo 2 bc :1-S dng chng trnh SAP , tnh theo s phng c cc AH .2-Cht ti cc ng nh hng xy dng cc ng bao ni lc .Cht ti trc tip ngay trong SAP d b nhm ln v h s, v khng thng nht

c v nguyn tc xp ti on xe di ng.2.3- Xc nh ni lc trong dm lin tc 3 nhp, thi cng theo cng ngh:

hp long nhp bin trc, hp long nhp gia sau khi h KCN xunggi chnh.2.3.1- Xc nh m men un ti cc mt ct dm cng xon trong qu trnh

c hng cn bng :Trong giai on ny kt cu nhp lm vic theo s khung T. Sau khi hp

long vi on c trn gio ca nhp bin v h xung gi chnh th s nykhng tn ti, trng thi cn bng mi ca h c xc lp li v kt cu nhp lmvic theo s gin n mt tha . V vy gi tr ni lc tnh phn ny c gi tr kim tra cng ca cc mt ct dm trong giai on thi cng v ti trng tai bin ,xc nh cc mt mt ng sut trong qu trnh cng ko cc b ct thp DL. S ny cn xc nh cc chuyn v ca u hng trong mi giai on c ,cn c vo iu chnh cao vn khun, to vng kin trc cho nhp c.

S tnh xc nh m men un ca nhp : cng xon mt u ngm, khu

tnh ton +=i

iiI KKL1

0,21 (8)

Ti trng tc dng : PI,i ; PI,tc , PXE .

1- Do trng lng bn thn cc t dm PiI :+ Ti mt ct gi MI,i

0-0 :

5


6/23


- Do t K0 :2

2

00,00

0,

dPM

I

I = (9)

- Do t K1 :

++=

2

1

011,

00

0,

00

1,

dddPMM III (10)

- Do t Kn :

++=

2

1

0

,001,

00,

n

n

innInInIdddPMM (11)

+ Ti mt ct th K :

+=

n

k

in

K

iiiI

kk

iI

dddPM

2

1

1

,,(12)

2- Do ti trng thi cng :

2

2

,

,

==

n

ki

itcI

kk

iTC

dP

M (13)

3- Do trng lng xe c :(14)

=

=

1

,

n

ki

iXE

KK

iXE dPM

Nn tnh m men un dm cng xon bng bn tnh EXCEL v lp thnh haibng phc v cho nhng ni dung tnh duyt sau ny . Bng th nht l cc gitr m men ti mt ct nh tr trong qu trnh c hng v Bng th hai tnh gi trm men ti cc mt ct sau khi kt thc c hng cn bng .

Bng cc gi tr m men ti nh tr Bng 2

Gi tr tiu chun G tr tnh ton

Trngthic

t th

Chiudi t

(m)

Tnh tit dm(Tn/m)

Do tnhti dmM0-0I,pT.m

Do titrng thi

cng M0-0I,pT.m

Do xec

M0-0XE

CngT.m

Do tnhti dmM0-0I,p

Do titrng thi

cngM0-0I,p

Do trnglng xe

cM0-0XE

CngT.m

0 4.5 33.34 -337 -2.03 -210 -5500 -371 -2.63 -294 -6671 3 30.54 -887 -5.63 -390 -1283 -975 -7.31 -546 -1522 3 28.65 -1660 -11.03 -570 -2242 -1826 -14.33 -798 -2633 3 27.02 -2633 -18.23 -750 -3402 -2896 -23.69 -1050 -3974 3 25.63 -3786 -27.23 -930 -4744 -4165 -35.39 -1302 -550

5 3.5 24.38 -5343 -40.00 -1140 -6524 -5878 -52.00 -1596 -7526 3.5 23.29 -7116 -55.23 -1350 -8522 -7828 -71.79 -1890 -9797 3.5 22.44 -9100 -72.90 -1560 -10733 -10010 -94.77 -2184 -12288 3.5 21.81 -11294 -93.03 -1770 -13157 -12423 -120.93 -2478 -15029 3.5 21.35 -13704 -115.60 -1980 -15799 -15074 -150.28 -2772 -1799

10 3.5 21.04 -16337 -140.63 -2190 -18668 -17971 -182.81 -3066 -212211 4 20.85 -19632 -172.23 -2430 -22234 -21595 -223.89 -3402 -252212 4 20.76 -23243 -207.03 -2670 -26120 -25568 -269.13 -3738 -2957

6


7/23


m men ti cc mt ct trong giai on c hng cn bngBng 3

Gi tr tiu chun

S hiu

mt ct

Chiu di

t (m)

Tnh tit dm

(Tn/m)

Do tnh ti

dm Mk-kI,pT.m

Do ti trng thi

cng Mk-kI,tcT.m

Do trng lng

xe cMk-kXE

CngT.m

M0-0 4.5 33.34 27181.45 245.03 2910 30336.48M1-1 3 30.54 22096.73 202.50 2640 24939.23M2-2 3 28.65 19069.39 176.40 2460 21705.79M3-3 3 27.02 16308.38 152.10 2280 18740.48M4-4 3 25.63 13797.85 129.60 2100 16027.45M5-5 3.5 24.38 11524.23 108.90 1920 13553.13M

6-63.5 23.29 9155.56 87.03 1710 10952.59

M7-7 3.5 22.44 7078.88 67.60 1500 8646.48M8-8 3.5 21.81 5282.31 50.63 1290 6622.93

2.3.2- Xc nh m men trong cc giai on cht ti tip theo:Dm lin tc 3 nhp c hng theo cng ngh h xung gi chnh trc khi hp

long nhp gia chu ti theo cc s :+ i vi tnh ti giai on I+ti trng thi cng + 1/2 trng lng xe c v 1/2

trng lng t hp long kt cu nhp lm vic theo s dm gin n mttha.(S 1)

+ Sau khi cng ct thp th di chu m men dng, h gio kt cu nhp

lm vic theo s dm lin tc chu hiu ng do ct xe c v ti trng thicng,bin dng n hi ca dm vng ngc tr li ,xut hin m men d ti tngt nh tc dng ln dm ti trng ngc du vi chiu tc dng ca ti trng thi cngv trng lng xe c.

+ i vi tnh ti giai on II gm trng lng cc lp ph mt cu,trng lnglan can,l ngi i v di phn cch cng, hot ti kt cu nhp lm vic theo s dm lin tc.

c im ca dm thi cng theo cng ngh ny l ti trng thi cng c xtnh t hp chnh v cn tc dng n kt cu c trong giai on khai thc .

i vi tnh ti v ti trng thi cng lp biu ni lc.i vi hot ti phi xy dng ng bao.Gia tr ni lc dng cho tnh ton l ng bao tng hp cng i s theo tng

mt ct t ng bao ni lc do hot ti v t cc biu ni lc do tnh ti v titrng thi cng.

Trnh t tnh ton nh sau :S 1 : Giai on sau khi thi cng xong t hp long nhp gia .

7


8/23


a- Trn nhp L1 ca dm gin n mt tha :1-Gi tr m men ti cc mt ct do trng lng bn thn PIi:Phn lc gi u nhp :

( )( )( )

( )

+

+=

42

2

101

00

1

cc

c

c lLGllLpll

LA (15)

Mmen ti mt ct gia t l0 :

82

12

00

00

lPAlMl = (16)

M men ti mt ct cui t th n(k t t K0) :

( )( )

2.

2

00

0 ccn

llpllAM

++= (17)

M men ti mt ct cui t th n-1 :

( )( )2

2

001

nn

ncnn

dpdllpAMM ++= (18)

( )( )2

2

11

10012

++=

nn

nnncnn

dPddPllpAMM

( )2

2

221

0023

++= nn

n

n

iicnn

dPddPllpAMM (19)

......

8

KoK1K2K3K4 K1 K2 K3 K4

lo lc

4xd lk

p4MC5

a) s cng ngh

a) s tnh ton

P

PPkch

l1l/2l/2l1

c) Biu m men un

mntc

Pxe Gc


9/23


2- M men ti cc mt ct do tnh ti thi cng phn b u PI,tc v trng lng xec Pxe:

Phn lc:( )

= xexe

c

tcIp dL

PlLL

PL

A282

122

1

,

1

(20)

Ti mt ct cch u nhp khong cch x1 :

2

2

1,

1

xpxAM

tcI

pP = (21)

Kt qu tnh th hin trong cc bng :m men ti cc mt ct nhp 1 tnh theo s 1 Bng 4

S hiumt ct

Khongcch X1

(m)

Chiu dit di(m)

Tnh tidm PI,i(T/m)

M mendo tnh ti

dm

M mendo ti

trng thicng

Cng gitr tiuchun

Cng gi trtnh ton

M10 0 0

M9 713.12

M 8 35.5 3.5 21.81 -5108.5 -1611.0 -6719.5 -7713.66M 7 39 3.5 22.44 -7060.6 -1783.5 -8844.0 -10085.15M 6 42.5 3.5 23.29 -9292.7 -1958.4 -11251.1 -12767.94M 5 46 3.5 24.38 -11816.9 -2135.8 -13952.7 -15775.11M 4 49 3 25.63 -14223.8 -2289.8 -16513.6 -18622.88M 3 52 3 27.02 -16867.6 -2445.6 -19313.1 -21733.58M 2 55 3 28.65 -19761.9 -2603.2 -22365.0 -25122.16M 1 58 3 30.54 -22922.5 -2762.6 -25685.0 -28806.04

M 0 62.5 4.5 33.34 -28207.1 -3005.0 -31212.1 -34934.33b- Trn on mt hng Lh :

M men ti cui t th n ( k t t K0): 0=nM

M men ti mt ct cui t th n-1 :

22

12

1

nn

ncnn

dpdGMM = (22)

22

2

11

112

+= nnnnn

c

nn

dPddP

GMM (23)

22

222

1

23

+= nn

n

n

ii

c

nn

dPdP

GMM .... (24)

2- Do ti trng thi cng pI,tc, :0, =ntcM

2

2

,

ktc

ktc

xPM = (25)

9


10/23


=kn

n

ik dx

Do trng lng xe c, trng tm cch gia nhp 1 khong l dxe

+= xe

c

xexe d

l

xPM 22 (26)

m men ti cc mt ct nhp 2 tnh theo s 1 Bng 5

S hiumt ct

Khongcch X 2

(m)

Chiu dit di(m)

Tnh tidm PI,i(T/m)

M mendo tnh ti

dm

M mendo ti

trng thicng vxe c

Cng gitr tiuchun

Cng gi trtnh ton

1 2 3 4 5 6 7 8

M 8 22.5 3.5 21.81 -5748.6 -1190.6 -6939.2 -7871.28

M 7 26 3.5 22.44 -7617.7 -1417.6 -9035.3 -10222.37M 6 29.5 3.5 23.29 -9766.9 -1647.0 -11414.0 -12884.76M 5 33 3.5 24.38 -12208.1 -1878.9 -14087.0 -15871.53M 4 36 3 25.63 -14543.9 -2079.6 -16623.5 -18701.81M 3 39 3 27.02 -17116.6 -2282.1 -19398.7 -21795.03M 2 42 3 28.65 -19939.8 -2486.4 -22426.2 -25166.13M 1 45 3 30.54 -23029.3 -2692.5 -25721.8 -28832.53M 0 49.5 4.5 33.34 -28207.3 -3005.0 -31212.3 -34934.58

Gii thch k hiu :

l0-chiu di on nhp c trn gio.

lc-chiu di t hp long.P0-tnh ti phn b ca on l0.L1-khu ca nhp bin.L- khu nhp chnh.Gc-trng lng t hp long v gio vn khun treo c t ny.PI,tc-ti trng thi cng 0.2T/mPxe-trng lng xe c.di- chiu di t c hng th i .dxe-khong cch t gia nhp chnh n trng tm xe c.x1- khong cch t u nhp n mt ct cn tnh

x2-khong cch t cui mt hng n mt ct cn tnhS 2 : Giai on d ti trng thi cng - chuyn xe c ra khi cu.Sau khi hp long, cha tho d vn khun ngoi tin hnh cng ko ct thp

th di ca nhp gia v di chuyn xe c ra khi cu, tho d cc ti trng thicng khc . Cc ti trng ny vn nm trn nhp gy nn bin dng cho dm,khi d ti ra khi nhp dm n hi tr li nhng do lc ny dm l lin tc,chuyn v b khng ch v s gy ra ni lc trong dm. Chng ta gi hin tng nyl hiu ng d ti .

10


11/23


Trong giai on hp long nhp gia trng lng t hp long cng vi vnkhun truyn ln hai u hng ca s mt tha di dng lc tp trung bng(PHlong+Ptreo)/2 . Sau khi tho d vn khun treo, on hp long lin kt vo vinhp ch, kt cu nhp lm vic theo s dm lin tc hon chnh . Hai lc tptrung c gii phng v thay th bng trng lung ca t hp long di dng ti

trng phn b trn chiu di t hp long .Nhvy vi s 2 l s dm lin tc, chu tc dng ca cc ti trng:1- Trnglng xe c ( khng c quang treo v vn khun) lc tp trung

tc dng ti nhp gia, cch mt ct gia nhp khong cch l dxe theohng ngc vi trng lc, h s ti trng 1,0

2- Ti trng thi cng- lc phn b 0,2T/m tc dng trn sut nhp bin btk v nhp gia theo hng ngc vi hng ca trng lc, h s 1,0

3- Ti trng do d vn khun treo t hp long lc tp trung bng 1/2Gct ti hai u mt tha theo hng ngc vi hng ca trng lc.

4- Tnh ti t hp long ti trng phn b bng P0 tc dng trong phm vichiu di t theo hng trng lc.

S dng SAP2000 Nonlinear tnh ni lc , s l dm lin tc , ccphn t l cc t khng gii phng lin kt hai u ( Release no ), trong miphn t cng coi nh khng i v ly theo cng ca mt ct gia t.iu kin ni t ( Restrains) hai m v mt tr gii phng R2 v U1, mt trch gii phng R2 , ti trng gm ti trng phn b -PI,tc c m t l Uniformload tc dng trn tt c cc phn t ca nhp 1 v nhp 2, cc ti trng tp trung( concentrated load) l -Pxe t ti v tr cch mt ct gia nhp mt khong l dxev pha nhp 1, -Gc/2 t hai im cch mt ct gia nhp 2 mt khong lc/2, titrng phn b +P0 tc dng trn phn t t hp long. (Trc to trong SAPkhng trng vi trc to phng trnh ng cong y dm).

Kt qu tnh ton theo s ny cho ta biu ni lc .S 3 : Dm lin tc chu tnh ti giai on II v hot ti .S dng s tnh nh s 2 nhng thm nhng ti trng sau :1- Tnh ti giai on 2 .2- ng k ln Li theo nhng cch xp ti bt li cho mi mt ct tnh ton.3- Xe ti thit k ba trc ng k di dng xe Vehicle4- Xp ti trng ln theo ln ng k nh l ti trng pn b xp tnh .5- Ti trng on ngi

Lp cc t hp ti trng ly ra cc ng bao m men ca cc t hptheo s 3

Kt qu tnh ton tp hp theo bng Tng hp ni lc .Gi tr tng hp l kt qu

cng i s cc gi tr ni lc mi mt ct tnh theo 3 s xp ti nu trn.

11


12/23


Khi xc nh nilc trong dm lin tcc hng theo cngngh ny cn phi lu hin tng xut hin m

men m ti mt ct gianhp, m men ny xuthin do hai nguynnhn : 1- hiu ng d ti

2- khi hot ti xpln hai nhp bin .Nguyn nhn 1 c thkhc phc bng binphp gim trng lngca xe c hoc c thb hn xe c trong giai

on hp long . i vinguyn nhn th hai cn xem xt li vic phn phi t l gia nhp bin v nhp gia,nhp bin cng ln th m men ny cng ln. C th trit tiu gi tr m men m gianhp bng tng tnh ti giai on II , lp to dc ngang c thi cng sau khi hplong ,khng cng vi np hp nh vn thng lm . Nu cc gii php trn khngkhc phc c phi b tr thm ct thp ST np hp trong phm vi lC + hai tcui, hoc thay i cng ngh.

biu m s 1

+

+

=

biu m s 2

ng bao m s 3

ng bao m tnh ton

biu m s 3 chu tnh ti II

Bng tng hp ni lc ti cc mt ctBng 6

Gi tr ng

bao M tnh theos III

Gi tr M tnh ton trong giai

on khai thcS hiumt ct

Gi tr

M tnhtheos I

Gi tr

M tnhtheos

IIM(-) M(+) M(-) m(+)

u nhp

1/2 l0 n-n M1 M2 M

(-)3 M

(+)3 =M1+M2+M

(-)3 =M1+M2+M

(+)3

....1-1

Gi (0-0)

1-1...

n-n1/2 L

- K hiu tn cc mt ct trng vi tn t d s dng. Nhng mt ct ctrng nh u nhp,gia nhp c trn gio , mt ct gi v gia nhp chnh cnghi r d theo di.

12


13/23


2.4- Xc nh ni lc trong dm lin tc 3 nhp, thi cng theo cng ngh:hp long nhp bin , hp long nhp gia sau mi h KCN xung gichnh.

Sau khi hp long nhp bin tin hnh cng ko ct thp y hp nhp bin v h gio c nh, KCN lm vic theo s khung T mt u ta,mt u hng chu

ti trng l trng lng bn thn dm v ti trng thi cng + trng lng xe c. Vis ny tip tc hp long nhp gia , chu thm trng lng b tng t hp longv trng lng ca gio vn khun t ny. Sau khi cng ko ct thp th dinhp gia,tho b lin kt tm trn hai tr, KCN lm vic theo s dm lin tc tatrn cc gi cht. H lm vic theo trng thi cn bng mi i vi mi ti trng tcdng ln n . V vy ni lc do tnh ti giai on I cng tnh trn s dm lin tc,gi tr m men trong giai on c hng cn bng xc nh kim tra dm tronggiai on thi cng .

2.5- Bin php xc nh ni lc trong cc s cu khung dm lin tcnhiu nhp thi cng theo cng ngh c hng.

Nhng tr

ng hp : Cu khung dm lin tc 4 nhp, khung dm lin tc 5 nhpcch cht ti ln dm xc nh ni lc tnh ton ph thuc vo bin trnh t hplong cc nhp v thi im tho b lin kt tm trn nh tr .

V d xt s khung dm lin tc 4 nhp , vi bin php thi cng nh sau :- c hng cn bng t nh tr T1. ng thi c hng cn bng t nh tr T2

( tr khung) .- c ti ch trn gio c nh on dm l0 ca nhp N1.- Hp long nhp bin . Cng v ko ct thp th di nhp bin N1.- Tho b lin kt v gi tm trn tr T1.- Hp long nhp gia N2. Cng v ko ct thp th di nhp N2.- D chuyn xe c v ti trng thi cng khi nhp N1 v N2.

- c hng cn bng t nh tr T3. c ti ch trn d gio c nh on dm l0ca nhp N4.

- Hp long nhp bin N4. Cng v ko ct thp th di nhp bin N4.- Tho b lin kt v gi tm trn tr T3.- Hp long nhp gia N3 . Cng v ko ct thp th di nhp N3.- Tho d xe c v ti trng thi cng .- Thi cng mt cu v cc kin trc trn cu.Vi trnh t cng ngh nh trn s xp ti v cng tc dng ni lc xc

nh gi tr tnh ton ca ni lc nh sau :+ S 1 gm : Dm gin n mt tha (bn tri) + Khung T( gia)+ dm gin

n mt tha ( bn phi ) chu tnh ti giai on I ( trng lng bn thn v 1 phnxe c+ ti trng thi cng).

+ S 2 : Khung dm 2 nhp chu hiu ng d ti xe c.+ S 3 : Khung dm lin tc 4 nhp chu tc dng ca hiu ng d ti xe c

trn nhp N3 .+ S 4 : Khung dm lin tc chu tnh ti phn b giai on II v hot ti .

13


14/23


iii-chn v b tr ct thp ch3.1- Loi ct thp

Ct thp dng loi b cp gm cc tao xon 7 si. ng knh tao c th chnloi 12,7mm hoc 15,2mm. S tao trong 1 b nn chn loi nhiu tao gm 9, 12hoc19 tao . Tiu chun v qui cch vt liu tham kho trong ti liu tra cu km

theo tp hng dn ny .Trc ht tnh chnh lch m men m tnh ton ly theo bng tng hp ti cc

mt ct k tip nhau Mi , chn M nh nht v M ln nht lm cn c chnloi b ct thp v s lng b neo ti cui mi t .

3.2- Xc nh s b ct thp neo ti mt ct cui mi t :3.2.1- Kch thc mt ct qui i ca hp dm :

Mc ch ca vic qui i mt ct l xy dng cc cng thc tnh duytcng thun li. Nguyn tc qui i l i t tit din hnh hp, hnh phc tpsang tit din ch I c chiu cao , chiu dy sn v din tch lm vic khng i.

Din tch tham gia lm vic ca hp dm bao gm ton b cc b phn nm

trong phm vi hp v mt phn ca hai cnh hng.Phn din tch ca cnh hng tham gia lm vic c chiu di 6hc tnh t

im ct ca ng ko thng theo mt ngoi thnh hp vi mt np hp .hc l chiu dy trung bnh ca cnh hng

2

ngc

c

hhh

+=

Qua y ta c nhn xt : chiu di cnh hng hp l ca hp l 6hc .

- Chiu dy bn np qui i : ht = (2Fc+2F2+F1+2Fvt)/(B-2t1)- Chiu rng bn np qui i : bc = B-2t1- Chiu dy bn y qui i : hd= (2Fvd+Fd)/bd

trong

t1= t-6hc , t- chiu di cnh hng np hpFc=6hc

2

14


15/23


nu t 6hc th t1=0 v Fc= h'c tF1 = t0ht

( )( )

+++=

22

vtng

vtng

thhbwhhF

( ) 21 += dng hhHH Fw = 2wH'Fd =bdhd +h

2d

Fvt ,Fvd din tch cc vt trn v vt di .

3.2.2- Xc nh s b s lng b ct thp ST, th trn ti cc mt ct:+ Xc nh h s iu chnh 1 theo cng thc :

05,07

2885,0

1

= cf

0,65 ( 5.7.2.2 TCN 272)

trong f'c - cng nn qui nh ca b tng dm tui 28 ngy (Mpa)+ Khong cch t mp ngoi chu nn n trng tm ca ct thp ch dp:

Tm ly theo gi tr :2

ngt

p

hhHd

+= mm

+ Chiu cao vng chu nn ti a : pdc 42,0= mm

a'=c'1+ Din tch ct thp ST :

=

2

adf

MA

ppu

tt

ps

fpu- cng chu ko qui nh ca ct thp ST (Mpa)Mtt- m men tnh ton ti mt ct tnh theo t hp trng thi gii hn

cng I ( N.mm)

Lu i n v 1T.m = 9,8106 N.mm+ Din tch mt b ct thp : Aten = nst ast .

nSt - s tao trong mt b ct thpast - din tch mt tao ct thp (mm

2)+ S b ct thp ti mt ct :

ten

ps

tenA

An = b

+ Ln lt tnh theo trnh t trn chn s b ct thp ti mi mt ct .+Cng tnh nh vy i vi ct thp chu m men dng.

S lng cc b ct thp tnh cho tng mt ct cui cc t c ,s b ny i quamt ct v neo li cui t c tip theo . Ti mi mt ct cc b ct thp phi btr i xng nhau qua trc thng ng.

15


16/23


Nh vy s lng v chng loi b ct thp c chn xut pht t t c hngcui cng v gi tr ca m men khai thc.

C th cc b ct thp trn c s tao trong mt b khc vi ct thp th dinhng nn s dng thng nht cng mt loi tao 12,7 hoc 15,2 .

S b ct thp neo ti mi mt ct phi l 2 hoc 4 b

bng thng k chn cc b ct thp th trn

S hiumt ct

S b ctthp cn b

tr ti mimt ct theom men thi

cng

S b ctthp cn b

tr ti mimt ct theom men khai

thc

Tng s bti mi mt

ct( Max )

S b neoti mi mt

ct

S b thct sau khib tr ct

thp

nh tr n0 01-1 n1 (n0-n1)22-2 n2 ... ... ...

3.3- B tr ct thpCt thp chu m men m b tr trn np hp theo hai cch :- Chy thnh tng hng song song, cui mi t c nhng b no b ngt

th neo thng vo mt ct.- B tr thnh 2 hoc 3 hng tp trung khu vc nch hp, khi neo b cp

phi un cong theo phng ngang v un xin xung theo phng ng neo vov tr gn ch tip gip nch v sn hp .

Hng ct thp hng trn cng cch np hp (1012) cm , cc hng cchnhau mt khong bng ng knh ng ghen ng +3,8 (cm) . Cc b trong mthng cng t cch nhau ng + 4 cm .

im neo phi cch nhng b i thng gn nht mt khong cch b+Bb- ghi trong bng Qui cch b tr neo ti u dm vi CK=23 , tc l bng

+(2234) cm.Trn mt bng cc b i song song vi nhau, i xng vi ng tim ca

nch hp khi gn n im kt thc ca ct thp th un cong i no v tr neo.im un nn chn sao cho :

1- Cch u neo mt khong t nht l (200+T)cm m bo iu kin

trc im neo ct thp phi c on thng t nht l 2m. T l chiu di tip tuynca ng cong bn knh R.2- Nm trong phm vi mt t c, cch im ni ng (T+20)cm vic

t v ni ng ghen c d dng .im un theo mt phng ngang v mt ng l trng nhau do v thc t

cc b ct thp un cong theo khng gian trong mt mt phng nghing .Cch xc nh v tr im un :

16


17/23


18/23


khong cch ny xc nh theo cng thc :( )

p

pu

psc

ddcysyspups

d

fkAwf

hwbffAfAfAc

+

+=

285,0

285,0

1

1

mm ( 5.7.3.1.1-3)

As - din tch ca cc ct thp th

ng chu ko (mm2

)A's - din tch ca cc thanh ct thp thng chu nn (mm2)

fy- gii hn chy ca ct thp thng chu ko ( Mpa)f'y- gii hn chy ca ct thp thng chu nn ( Mpa) .dp - khong cch t mp chu nn n trng tm ca cc b ct thp DL

khong cch ny xc nh theo bn v b tr ct thp (mm) .Nu c tnh c theo ( 5.7.3.1.1-3) mang du m lc c ngha vng b tng

chu nn nm trong phm vi bn c h'd , phi tnh li c theo cng thc :

p

pu

psdc

ysyspups

d

fkAbf

fAfAfAc

+

+=

185,0

mm (5.7.3.1.1-4)

2- Trng hp ko DL ngoi thuc v khi nim ct thp khng dnh bm :

+=

c

p

pepsl

cdff 6300 ( 5.7.3.1.2-1)

fpe - ng sut c hiu trong ct thp sau khi cng ko tm ly bng 0,8fpulc - chiu di c hiu ca b ct thp tnh gia hai u neo (mm)

s

i

cN

ll

+=

2

2( 5.7.3.1.2-2)

li- chiu di tng on b cp i qua cc neo nh v hoc cc im un (mm)

Ns - s lng neo chuyn hng nm gia hai u neo ca cc b ct thp .Chiu cao vng b tng chu nn c trong trng hp ny xc nh theo cng

thc :( )

wf

hwbffAfAfAc

c

ddcysyspups

285,0

285,0

1

1

+= mm (5.7.3.1.2-3)

Nu c tnh c mang du m tnh li theo cng thc :

dc

ysyspups

bf

fAfAfAc

185,0

+= ( 5.7.3.1-4)

4.2-Xc nh sc khng un tnh ton : ( N.mm)a) Vi trng hp c > h'd : ( 5.7.3.2.2-1)

( )

+

+

=22

285,0222

1

d

ddcsyssysppspsn

hahwbf

adfA

adfA

adfAM

b) Trng hp c h'd : ( 5.7.3.2.3)

18


19/23


+

=222

adfA

adfA

adfAM syssysppspsn

a- chiu cao biu ng sut qui i ca b tng chu nn a=1c .

Mr = Mn - h s khng un ly bng 1,0

4.3- Tnh duyt cng theo m men :Mr Mtt

Mtt - mmen un tnh ton theo t hp ti trng trng thi cng I. (N.mm)

V-tnh duyt iu kin v cng theo lc ct i vimt ct thng gc :V tr tnh duyt ti tt c cc mt ct c tnh duyt theo m men , tc l ti v tr stvi vch ngn trn nh tr v cui mi t .

iu kin phi tnh duyt :

pctt VVQ +> 5,0 (N) (8.5.2.4-1)

trong : - h s sc khng ly bng 1,0.Vc - sc khng ct danh nh ca b tng (N)

vvcc dbfV = 083,0 (5.8.3.3-3)

- h s kh nng nt xin ca b tng, tra bng di y.bv - chiu rng hu hiu ca bng dm, ly v tr nh nht (mm)dv - chiu cao chu ct ca bng dm ly theo gi tr nh nht trong

hai gi tr l 0,72h v 0,9dc . (mm)dc -chiu cao tnh t mp b tng chu nn n trng tm ca ct thp

chu ko ( bao gm c ct thp DL v ct thp thng) (mm)Vp - thnh phn phn lc ca lc cng trong cc b ct thp DLtheo phng ca lc ct Q ( mang du + nu ngc vi hng calc ct Q ) (N) .

Nu ngc li khng cn tnh duyt ch b tr theo cu to .5.1- B tr ct thp ai :Ct thp ai b tr theo cu to hoc theo yu cu chng ct v chng xon phim bo nhng yu cu sau y :1- Bc ct ai s :

+ Nu Qtt < 0,1f'cbvdv th : s 0,8dv 600mm+ Nu Q tt 0,1f'cbvdv th : s 0,4dv 300mm

2- Din tch ti thiu ca ct thp ai :

y

v

csf

sbfA 083,0

s- bc ca ct ai (mm)fy- gii hn chy ca ct thp ai khng vt qu 420 (Mpa).

5.2- Xc nh sc khng ct ca tit din :5.2.1- Sc khng ct do ct ai chu :

19


20/23


( )

s

ggdfAV

vyv

s

sincotcot += (N) ( 5.8.3.3-4)

trong : - gc nghing ca ct ai so vi trc dm ()Av - din tch ca cc nhnh ct ai trong phm vi bc s (mm

2) - gc nging ca ng sut nn ch xc nh theo bng 5.8.3.4.2-1 c in

km sau y. Trong bng ny cc thng s phi tnh gm :+ ng sut tip trong b tng v:

vv

ptt

db

VQ

= (Mpa) ( 5.8.3.4.2-1)

+ Bin dng ca ct thp chu ko x :

002,0

cot5,05,0

+

++

=pspss

popstttt

v

tt

xAEAE

fAgQNd

M

(5.8.3.4.2-2)

Nu tnh ra x mang gi tr (-) th gi tr tnh c em nhn vi h s Fc :

pspsscc

pspss

cAEAEAE

AEAEF

+++=

trong cc cng thc ny :Ntt - lc nn do ct thp ST chiu ln phng dc trc ( N)Ac - din tch phn b tng chu ko tnh bng din tch ca phn t 1/2 chiu

cao h ca dm cho n ht phn chu ko . ( mm2)As - din tch ct thp thng chu ko.Aps - din tch ct thp DL th chu ko .fp0- ng sut trong ct thp DL khi ng suttrong b tng xung quanh n bng 0 . (Mpa)

Ec,Es ,Eps - m uyn n hi ca b tng ct thpv b cp DL ( Mpa) .

cc fy

5,1=cE 043,0 yc -t trng ca

b tng 2400kg/m3

x

h

0,

5h Ac

Es = 2105 Mpa

Eps = 1,97105 Mpa

i vi dm c chiu cao di 400mm th : = 2,0 = 450

5.2.2- Sc khng ct danh nh ca mt ct :V pscn VVV ++= (N) ( 5.8.3.3-1)

Cc thnh phn hng dn tnh trn .5.3- Tnh duyt chng ct :

Vn Qtt

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21/23


Vi-tnh duyt iu kin chng nt theo trng thi gii hns dng :

Cc ni dung chng nt sau y c xt theo trng thi gii hn s dng .6.1- Gii hn cng ca ct thp v b tng trong tnh ton chng nt :6.2- Tnh cc thnh phn ca mt mt ng sut trc :

6.2.1- Mt mt do bin dng ca thit b neo :

ps

Bo

pA EL

f4,0

= Mpa

Lbo - chiu di ca b ct thp tnh t dai u neo mm .6.2.2- Mt mt do ma st thnh ng ghen :

( )( )+= KxpjpF eff 1 Mpa ( 5.9.5.2-2)

fpj - ng sut trong ct thp khi ang cng bng kch , c th ly bng 0,9fpu Mpa

K- h s ma st lc tnh trn mi mm chiu di ct thp ly bng 6,610-7

- h s ma st trt , ly bng 0,15 .- tng cc gi tr tuyt i ca cc gc un ca b ct thp so vi ng trc

ca b tnh t im neo kch ( nu ko bng 1 kch ) hoc t im neo kchgn nht ( nu ko bng 2 kch) n mt ct xt ( Rad) .

x- chiu di on b ct thp tnh t im neo kch ni trn n mt ct xt (mm)Nu b cp un cong trong c mt phng ng v mt phng ngang , th phitnh bng cch cng vc t :

yx22 +=

6.2.3- Mt mt do co ngn n hi ca b tng :( )

cgp

ci

ps

pES fE

E

N

Nf =

2

1Mpa ( 5.9.5.2.3b-1)

N- s lng cc b ct thp chu m men m .Eci - m uyn n hi ca b tng lc truyn DL ti mt ct xt Mpa

fcgp- tng ng sut b tng trng tm ca cc b ct thp do lc nn trc vtnh ti DC ti mt ct nh tr . Mpa.

fpe -ng sut c hiu trong ct thp sau khi truyn DL ln dm ly bng 0,74fpuAc0 - din tch mt ct nh tr ( khng c vch) tr rnh ca b tng mm

2

Ic0 - m men qun tnh ca mt ct nh tr tr rnh ca b tng mm4

00

0

0

p

c

ppepsDC

c

pepscgp d

I

dfAM

AfAf

= Mpa (5.9.5.2.3b-2)

MDC - m men do tnh ti s 1 ti mt ct nh tr vi hs ti trng =1 .dp0 - khong cch t trng tm cc b ct thp DL n trng tm ca tit din

hp dm ti nh tr mm .6.2.4- Mt mt do co ngt ca b tng :

( )HfSR 85,093= Mpa

21


22/23


H- m ca mi trng ly trung bnh trong nm ( %) tm ly l 70%6.2.5- Mt mt do t bin ca b tng :

0712 = cdpcgppCR fff ( 5.9.5.4.3-1)

fcgp- tng ng sut b tng trng tm ca cc b ct thp theo cng thc(5.9.5.2.3b-2) nhng tnh mt ct ang xt mt mt ng sut trc .

fcdp - chnh lch ng sut do ti trng thng xuyn trong b tng ti trng tmct thp DL so vi thi im to d ng lc ti mt ct ang xt

0

0'''''

0 p

c

pepsp

c

epsp

p

c

DW

cdp dI

dfA

A

fAd

I

Mf += Mpa

MDW - m men un do tnh ti giai on 2 v hiu ng d ti ti mt ct ang xtvi h s ti trng l =1 .

Gi tr p' l ch ct thp th chu nn .6.2.6- Mt mt do t chng ca ct thp :

pCRpSRpESpFpsR fffff += 2,04,03,01382 (5.9.5.4.4c-2)

6.3- Tnh duyt mt ct theo iu kin chng nt trong giai on s dng :6.3.1- ng sut c hiu sau cc mt mt :

= fff pyp 9,0 6.3.2- Tnh duyt i vi ng sut nn trong b tng:

cc

c

psp

c

psp

c

c

DC

c

c

DC fdI

fA

A

fAd

I

Md

I

M++ 45,02

0

1 Mpa (5.9.4.2.1-1)

Ac, Ic - din tch v m men qun tnh ca tit din tnh i sang tit din b tng,ti v tr tnh duyt , coi mt ct lm vic n hi ( mm2, mm4)

dc- khong cch t trng tm tit din hp dm n mp b tng chu nn mm

6.3.3- Tnh duyt i vi ng sut ko trong b tng :

cs

c

psp

c

psp

s

c

DC

s

c

DC fdI

fA

A

fAd

I

Md

I

M'5,02

0

1 ++ Mpa (5.9.4.2.2-1)

ds khong cch t trng tm tit din dm n mp chu ko ca b tng mm .6.4- Tnh duyt cng trong ct thp DL trong giai on s dng :

pup

c

SD

p fdI

Mnf 8,0

0+ Mpa ( 5.9.3-1)

n- t l m uyn n hi .

dp0 - khong cch t trng tm tit din n trng tm b ct thp mmMSD tnh vi t hp : DC+DW+CR+SH+TG+EL

22


23/23


Bng gi tr v .

x x1000/f'c -0.2 -0.15 -0.1 0 0.125 0.25 0.5 0.75 1 1.5 2

0.05 27 27 27 27 27 28.5 29 33 36 41 43 6.78 6.17 5.63 4.88 3.99 3.49 2.51 2.37 2.23 1.95 1.72

0.075 27 27 27 27 27 27.5 30 33.5 36 40 42 6.78 6.17 5.63 4.88 3.65 3.01 2.47 2.33 2.16 1.9 1.65

0.1 23.5 23.5 23.5 23.5 24 26.5 30.5 34 36 38 39 6.5 5.87 5.31 3.26 2.61 2.54 2.41 2.28 2.09 1.72 1.45

0.125 20 21 22 23.5 26 28 31.5 34 36 37 38 2.71 2.71 2.71 2.6 2.57 2.5 2.37 2.18 2.01 1.6 1.35

0.15 22 22.5 23.5 25 27 29 32 34 36 36.5 37 2.66 2.61 2.61 2.55 2.5 2.45 2.28 2.06 1.93 1.5 1.24

0.175 23.5 24 25 26.5 28 30 32.5 34 36 35.5 36 2.59 2.58 2.54 2.5 2.41 2.39 2.2 1.95 1.74 1.21 1

0.2 25 25.5 26.5 27.5 29 31 33 34 34.5 35 36 2.55 2.49 2.48 2.45 2.37 2.33 2.1 1.82 1.58 1.21 1

0.225 26.5 27 27.5 29 30.5 32 33 34 34.5 36.5 39 2.45 2.38 2.43 2.37 2.33 2.27 1.92 1.67 1.43 1.18 1.14

0.25 28 28.5 29 30 31 32 33 34 35.5 38.5 41.5 2.36 2.32 2.36 2.3 2.28 2.01 1.64 1.52 1.4 1.3 1.25Ban u cho mt gi tr v d 270 , thay vo cng thc (5.8.3.4.2-2) xc nh x , theox tra bng tm ' , tip tc thay vo cng thc trn x c nh 'x v tra bng tm '' chon khi gi tr gia hai ln tra chnh lch khng qu 10% .vii- tnh duyt cng :1-Xc nh vng do hot ti x (1+IM)+ cng ca tit din l EIg vi

- Muyn n hi E ca b tng xc nh theo cng thc := ccc fyE

5,1043,0 yc -t trng ca b tng 2400kg/m

3

- Ig m men qun tnh tit din nguyn ca b tng2- iu kin tnh duyt :

Lf800

1

3- Xc nh vng do cc ti trng tc dng lu di bng vng do hot ti nhnvi h s bng 4,0 .

23

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