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Móng cọc thiết kế theo Tiêu Chuẩn mớiTRANSCRIPT
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 1
1.1. S L THUY T 3
1.1.1. CHN CHIU SU CHN MNG Df V KCH THC CC S B: 3
1.1.2. TNH TON SC CHU TI CA CC: 4
1.1.3.TNH TON S B S LNG CC: 12
1.1.4.B TR CC: 12
1.1.5. KIM TRA I CC 13
1.1.6.TNH THP CHO I MNG: 18
1.1.7. KIM TRA SC CHU TI CA CC V NHM CC : 20
1.1.8.KIM TRA N NH CA T NN DI MI CC V LN MNG CC: 21
1.1.9. KIM TRA CC CHU CU LP: 27
1.1.10. NG DNG SAP2000 KIM TRA CC CHU TI NGANG: 28
1.1.11. C S L THUYT KIM TRA CC CHUYN V NGANG: 37
1.1.12. TNH TON NI LC TRONG CC (theo TCXD 205 -1998) 40
2.1.CC D LIU TNH TON: 43
2.1.1.THNG K S LIU A CHT 1B (trch t phn I): 43
2.1.2.S LIU TNH TON: 44
2.1.3.KHAI BO VT LIU: 44
2.2.TRNH T TNH TON V THI T K MNG C C: 44
2.2.1.CHN CHIU SU CHN MNGDfV KCH THC CC S B: 44
2.2.2. TNH TON SC CHU TI CA CC: 45
2.2.3.TNH TON S B S LNG CC: 53
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 2
2.2.4.B TR CC: 53
2.2.5. KIM TRA I CC 54
2.2.6. KIM TRA SC CHU TI CA CC V NHM CC : 58
2.2.7. TNH THP CHO I MNG: 59
2.2.8.KIM TRA N NH CA T NN DI MI CC V LN MNG CC: 61
2.2.9. KIM TRA CC CHU CU LP: 66
2.2.10.NG DNG SAP2000 KIM TRA CHUYN V NGANG: 67
2.2.11. KIM TRA CC CHU TI NGANG (theo ph lc G TCXD 205 1998): 73
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 3
: THI T K MNG C C
1.1. S L THUY T
1.1.1. CH N CHIU SU CHN MNG Df V C C S B:
1.1.1a.Chn loi cc thi cng ph hp ( theo TCXD 205:1998 Mc 3.2)
1.1.1b.Chiu su t mng Df phi tha mn cc iu kin sau:
- Nu cng trnh khng c tng hm, xung quanh khng c cng trnh ln cn, a cht
tng i thun li th n gin trong thi cng nh p cc, o thi cng i mng
chiu su t y i t 1,5 3,0m m
- Nu cng trnh c tng hm th cao mt trn ca i trng vi cao mt trn ca sn
tng hm thun tin trong thi cng v c li cho vic chu lc ca sn tng hm.
- Nu cng trnh xy chen (xung quanh gip ranh vi cc cng trnh ln cn) th chiu su
t i khng nn qu su v khi thi cng d nh hng n cc cng trnh ln cn.
- Cng cn lu rng, trong mng cc chng ta khng cn thit phi chn chiu su t i
sao cho tha mn lc ngang tc dng ln mng phi nh hn p lc tc dng ca t nn
v trong mng cc phi xt n cc chu ti trng ngang xc nh ni lc v ct thp
trong cc (s c kim tra phn cc chu ti trng ngang).
1.1.1c. ng ca vt liu lm cc:
- Nhng vn chung: cc BTCT ch to sn phi c thit k c th chu c gi tr ni
lc sinh ra trong qu trnh cu, vn chuyn, lp dng, thi cng h cc v chu ti vi h s
an ton v hp l.
+ ng sut cho php ln nht trong cc khi lm vic khng c vt qu 0.33fc .
+ ng sut cho php ln nht do p cc (c th sinh ra hai loi sng ng sut nn v
ko), khng c vt qu gii hn: 0.85fc (cho trng hp sng nn); 0.70 fy (cho
trng hp sng ko); (fc: cng chu nn khi nn tnh b tng; fy: gii hn do ca
thp).
- Yu cu v b tng: da trn iu kin lm vic ca cc, cp bn ti thiu cho b tng
cc c th ly nh sau:
Bng 1.1 Cp bn ti thiu ca b tng lm cc
iu kin p cc Mc b tng Cp bn ca b tng
tng ng Mc b tng (Mpa)
Cc phi p (ng) n chi rt nh
400 B30
iu kin bnh thng v d p
250 B20
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 4
- Yu cu v ct thp dc:
+ Ct thp dc phi tha mn cc iu kin quy nh v cht lng ct thp c th
chu c cc ni lc pht sinh trong qu trnh bc d, vn chuyn, cu lp v p lc
ko cc m-men un ca cng trnh bn tc dng vo cc, cng cn xt n tr ng sut
ko c th pht sinh do hin tng nng nn khi p (ng) cc cc tip theo.
+ Ct thp ch yu cn c ko di lin tc theo sut chiu di cc. Trong trng hp
bt buc phi ni ct thp ch, mi ni cn c tun theo quy nh v ni thp v b
tr mi ni ca cc thanh.
+ Trong trng hp cn tng kh nng chu m-men, thp c tng cng phn u
cc, nhng cn b tr sao cho s gin on t ngt ca ct thp khng gy ra hin
tng nt khi cc chu tc ng xung trong qu trnh p (ng) cc.
+ Trong cc trng hp bnh thng th ct thp dc c xc nh theo tnh ton, hm
lng thp khng nh hn 0,8% ng knh khng nn nh hn 14mm.
+ i vi nhng trng hp sau, nht l cc cc cho nh cao tng, hm lng ca ct
thp dc c th nng ln 1 1,2% khi:
Mi cc xuyn qua lp t cng;
mnh ca cc L/d > 60;
S cc trong i t hn 3 cc.
- Yu cu v ct ai:
+ Ct ai c vai tr c bit quan trng chu ng sut ny sinh trong qu trnh p
(ng) cc. Ct ai c dng mc, ai kn hoc xon. Tr trng hp c s dng mi
ni c bit hoc mt bch bao quanh u cc m c th phn b c ng sut gy ra
trong qu trnh p (ng) cc, trong khong cch bng 3 ln cnh nh ca cc ti hai
u cc, hm lng ct ai khng t hn 0,6% ca th tch vng nu trn.
+ Trong phn thn cc, ct ai c tng tit din khng nh hn 0,2% v c b tr vi
khong cch khng ln hn 200mm. S thay i cc vng c khong cch cc ai ct
khc nhau khng nn qu t ngt.
+ Thp gia cng u cc: thng thng u cc khng b b khi p (ng) hoc p
cc th nn dng li thp 6 50a gia cng u cc (thng b tr 4 lp).
1.1.2. TNH TON SC CHU TI CA C C:
n p i t n t c m c .1. V -2012)
- Trng thi gii hn th nht da vo sc chu ti.
- Trng thi gii hn th hai da vo bin dng ( l n, v ng..) gy cn tr vic
s dng nh bnh thng v cng trnh.
1.1.2.1. SC CHU TI CA C EO CA VT LIU: (3.3.2
TCXD 205-1998):
1.1.2.1.a. Cc chu ti trng tc thi khi p cc:
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 5
- Cng thc tnh ton:
Trong :
R: ng sut trong cc (kN/m2) c tnh nh sau:
+ Vi cc b tng ct thp: R=0.85fc (fc l cp bn ca b tng, kN/m2) - trch
3.3.2 tcxd 205 1998
: din tch tit din ngang ca cc (m2)
: h s un dc ca cc
21,028 0,0000288 0,0016
: mnh ca cc, =lo/r (cc trn hoc cc vung), = lo/b (cc ch nht).
r: bn knh ca cc trn hoc cnh cc vung
b: b rng ca tit din ch nht
l0: chiu di tnh ton ca cc c xc nh nh sau:
+ Khi p (ng) cc:
Hnh 1.1. Trng hp thi cng p (ng)
l0v=1
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 6
Vi:
v = 1.0 (thin v an ton xem ti v tr ni cc l lin kt khp, ti v tr lc tc dng khi
p cc nh ta n)
l chiu di on cc ln nht khi cha p vo t
1.1.2.1.b. Cc chu ti trng ca cng trnh lu di:
- Cng thc tnh ton:
Trong :
R: ng sut trong cc (kN/m2) c tnh nh sau:
+ Vi cc b tng ct thp: R=0.33fc (fc l cp bn ca b tng, kN/m2) - trch 3.3.2
tcxd 205 1998
: din tch tit din ngang ca cc (m2)
: h s un dc ca cc
21,028 0,0000288 0,0016
: mnh ca cc, =le/r (cc trn hoc cc vung), = le/b (cc ch nht).
r: bn knh ca cc trn hoc cnh cc vung
b: b rng ca tit din ch nht
l0: chiu di tnh ton ca cc c xc nh nh sau:
- Khi chu ti trng cng trnh
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 7
Hnh 1.2. Trng hp cc lm vic chu ti trng cng trnh
e bdl L Trong :
L - chiu su thc t.
bd :h s bin dng, I/m, xc nh theo cng thc: ( theo ph lc G3 TCXD
205-1998).
5c
bd
b
Kb
E I
Trong :
K - h s t l ly t bng G1 TCXD 205-1998 (ly theo lp t nh hng
di y i).
le
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 8
bc - Chiu rng quy c ca cc,m
bc=1.5d+0.5 (d=0.4m
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 9
m: H s iu kin lm vic ca t ln lt mi cc v mt bn cc c k
n nh hng ca phng php h cc n sc chng tnh ton ca t, xc
nh theo bng A.3 (TCXD205:1998)
Trong cng thc trn vic ly tng cng chu ti ca t phi c tin hnh trn
tt c cc lp t m cc xuyn qua. Trong trng hp khi san nn cn gt b hoc c th
b xi tri t i, phi tin hnh ly tng sc chng tnh ton ca tt c cc lp t nm
ln lt bn di mc san nn (gt b hoc di ct xi l cc b khi b l).
1.1.2.2.b. Sc chu ti ca cc t cng t nn:(ph lc B TCXD 205-
1998)
psa
s p
QQQ
FS FS
Trong :
sQ : sc khng hng cc hn (xung quanh cc).
pQ : sc khng mi cc hn.
sFS : h s an ton cho thnh phn ma st bn, ly bng 1,5-2,0.
pFS : h s an ton cho sc chng di mi cc ly bng 2,0-3,0.
Thnh phn chu ti do ma st xung quanh cc:
isis lfuQ
Trong :
u : chu vi cc
sif : thnh phn ma st n v gia cc v lp t th i (kN/m2)
: lc dnh gia cc v lp t th i, vi cc b tng ct thp ly
(kN/m2), trong ci l lc dnh ca t nn;
: gc ma st gia cc v t, cc p (ng) b tng ct thp ly
: ng sut hu hiu trong t theo phng vung gc vi mt bn cc
ca lp t th i (kN/m2)
il : chiu dy lp t th i (m)
Thnh phn sc chu mi ca t di mi cc:
ppp qAQ
Trong :
Ap tit din mi cc
qp sc chu ti n v mi cc
Tnh ton sc chu ti n v mi cc:
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 10
Trong :
c: lc dnh ca t ti mi cc (kN/m2),
: Dung trng ca t nn ti mi cc (kN/m3),
ng sut hu hiu ti mi cc (kN/m2).
qc ,N,NN : h s sc chu ti, ph thuc vo ma st trong ca t, hnh
dng mi cc v phng php thi cng.
Sc chu ti mi n v theo cng thc Vesic:
'. . .p c q vq cN N d N .
Bng 1.3. Gi tr cc h s sc chu ti theo ca Vesic (1973)
Nq Nc N Nq Nc N
0 1.00 5.14 0.00 24 9.60 19.32 9.44
1 1.09 5.38 0.07 25 10.66 20.72 10.88
2 1.20 5.63 0.15 26 11.85 22.25 12.54
3 1.31 5.90 0.24 27 13.20 23.94 14.47
4 1.43 6.19 0.34 28 14.72 25.80 16.72
5 1.57 6.49 0.45 29 16.44 27.86 19.34
6 1.72 6.81 0.57 30 18.40 30.14 22.40
7 1.88 7.16 0.71 31 20.63 32.67 25.99
8 2.06 7.53 0.86 32 23.18 35.49 30.21
9 2.25 7.92 1.03 33 26.09 38.64 35.19
10 2.47 8.34 1.22 34 29.44 42.16 41.06
11 2.71 8.80 1.44 35 33.30 46.12 48.03
12 2.97 9.28 1.69 36 37.75 50.59 56.31
13 3.26 9.81 1.97 37 42.92 55.63 66.19
14 3.59 10.37 2.29 38 48.93 61.35 78.02
15 3.94 10.98 2.65 39 55.96 67.87 92.25
16 4.34 11.63 3.06 40 64.20 75.31 109.41
17 4.77 12.34 3.53 41 73.90 83.86 130.21
18 5.26 13.10 4.07 42 85.37 93.71 155.54
19 5.80 13.93 4.68 43 99.01 105.11 186.53
20 6.40 14.83 5.39 44 115.31 118.37 224.63
21 7.07 15.81 6.20 45 134.87 133.87 271.75
22 7.82 16.88 7.13 46 158.50 152.10 330.34
23 8.66 18.05 8.20 47 187.21 173.64 403.65
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 11
2.2.2.2.c. Tnh ton sc chu ti ca t theo cng thc ca Nht Bn t kt qu
TN SPT:
Trong :
h s ph thuc vo phng php thi cng cc:
Cc b tng ct thp thi cng bng phng php p (ng):
Cc khoan nhi:
aN : ch s SPT ca t di mi cc;
sN : gi tr trung bnh ca ch s SPT trong lp t ri;
sL : chiu di phn cc nm trong lp t ri,m;
C : gi tr trung bnh ca s ba lc dnh n v trong lp t dnh,
cL : chiu di phn cc nm trong lp t dnh,m.
um: chu vi cc
2.2.2.2.d. Tnh ton sc chu ti ca t theo cng thc ca Meyerhof (1956) t
kt qu TN SPT: (TCXD 205-1998 mc C.2.2)
1 2u p tb sQ K NA K N A
ua
QQ
FS
Trong :
K1: h s, ly bng 400 cho cc p (ng) v bng 120 cho cc khoan nhi.
K2: h s, ly bng 2 i vi cc p v bng 1 i vi cc khoan nhi
N: ch s SPT trung bnh trong khong 1d di mi cc v 4d trn mi cc.
Ntb: ch s SPT trung bnh dc thn cc trong phm vi lp t ri
Ap: din tch tit din mi cc, m2
As: din tch mt bn cc trong phm vi lp t ri), m2
FS: h s an ton p dng khi tnh ton sc chu ti ca cc theo xuyn tiu
chun ly bng 2,5 3,0
Kt lun: Sc chu ti thit k
Thin v an ton, ti trng thit k phi ly gi tr c tin cy ln nht ca
cc gi tr sc chu ti Qai cho php tnh.( dng phng php bnh phng
cc tiu tnh gi tr c trng ca t nn max min4
6
tbtk
Q Q QQ
)
Ngoi ra, khi thi cng khng b ph hoi cc theo vt liu lm cc, sc
chu ti ca cc theo vt liu lm cc (trong trng hp thi cng cc) phi
ln hn sc chu ti cc hn ca cc theo ch tiu t nn.
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 12
1.1.2.3. KIM TRA SC CHU TI CA C
Kim tra cc chu ti trng tm thi ( khi p cc):
1
max
2 tkvl
u
QQ
Q
Cc chu ti trng lu di ( khi chu ti trng cng trnh):
2vl tkQ Q
1.1.3. O S B S NG C C: tt
c
tk
Nn
Q
Trong :
ttN : lc dc tnh ton ti chn ct (ngoi lc tc dng ln mng)
aTKQ : sc chu ti thit k ca cc
: h s xt n do moment v lc ngang ti chn ct, trng i v t nn
trn i, ty theo gi tr ca moment v lc ngang m chn gi tr hp l.
Thng = 1.2 1.5 .
nc: ch l s lng cc s b, cn c kim tra cc bc tip theo.
1.1.4.B TR C C:
Thng thng cc cc c b tr theo hng, dy hoc theo li tam gic.
Khong cch gia cc cc (t tim cc n tim cc): S = 3d 6d
(d: ng knh hay cnh cc), nu b tr trong khong ny th cc m bo c sc
chu ti v cc cc lm vic theo nhm.
t b nh hng n sc chu ti ca cc (do cc lm vic theo
nhm), th nn b tr cc ti thiu l 3d.
Khi b tr cc ln hn 6d th nh hng ln nhau gia cc cc c th b
qua, khi xem nh cc lm vic ring l.
Khi ti ng lch tm hoc kch thc i ln c th b tr sao cho phn lc u
cc tng i bng nhau.
Khong cch t mp ngoi ca cc n mp ngoi ca i t d d
3 2
Nn b tr cc sao cho tm ct trng vi trng tm ca nhm cc.
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 13
1.1.5. KI RA C
1.1.5.1.KIM RA U KIN XUYN TH O
1.1.5.1.a Di tc d ng ca lc dc, chiu cao ca i cc khng cao s b
xuyn thng, khng b xuyn thng hiu cao ca i cc phi tha mn iu kin
sau:
xt cxP P
Pxt lc gy xuyn thng (kN)
Pcx lc chng xuyn thng (kN)
1.1.5.1.b c t ng hp xuyn thng:
Gm hai trng hp xuyn thng nh sau:
ng hp 1: Khi cc cc u nm ngoi y ln ca thp xuyn thng (khi mt bn
ca thp xuyn nghing 1 gc 45o so vi trc thng ng):
Hnh 1.6. Khi mt bn ca thp nn thng nghing 450
bc
hc
h0
hd
h0
45
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 14
(y thp nn thng khng ph ln cc cc)
ng hp 2: Khi y ln ca thp xuyn 45o bao ph mt phn ca cc
- Trng hp ny thp xuyn thng c xc nh nh sau:
Hnh 1.7. Khi mt bn ca thp nn thng nghing gc nh hn 450
(y thp nn thng ng vi gc xuyn ph ln 1 phn cc)
45
a
bc
hc
h0
hd
c
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 15
1.1.5.1.c Xc nh lc gy xuyn thng (Pcx)
Lc xuyn thng Pcx ly bng lc tc dng ln thp xuyn thng, tr i phn lc u cc
nm hon ton trong phm vi thp xuyn thp xuyn thng:
( )
tt
xt i xtP N P
Trong :
ttN - lc dc tnh ton ti chn ct (ly t hp maxttN )
( )i xtP - phn lc u cc nm trong phm vi y ln thp xuyn thng.
thin v an ton phn lc u cc ch do lc dc gy ra (khng xt n moment, lc
ngang, trng lng bn thn i v t nn trn i) v c tnh vi h s vt ti n = 0.9.
( ) .0,91.15
ii xt
PP
Khi kim tra xuyn thng t cc ln i, moment v lc ngang khng gy ra xuyn thng, v
vy ch do lc dc ti chn ct gy ra xuyn thng. Ring xuyn thng t cc ln i, thin
v an ton th lc gy xuyn thng t cc ln i c xt n moment, lc ngang, trng lng
bn thn i v t trn i.
1.1.5.1.d Xc nh lc chng xuyn thng
- ng hp 1: Khi i khng t ct thp ai:
0( ) 0. . .cx cx bt mF P P R u h
Trong :
0h - chiu cao lm vic ca tit din (ly t mt trn ca i n trng tm lp di
ct thp ca i).
btR - cng chu ko ca b tng.
- h s, ly theo bng 1.5.
Bng 1.5 Xc nh h s
Loi b tng B tng nng B tng ht nh B tng nh
1,00 0,85 0,80
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 16
mu - gi tr trung bnh ca chu vi y trn v y di thp y thng hnh thnh khi b
nn thng, trong phm vi chiu cao lm vic ca tit din:
02( 2 )m c cu h b h
Ly sc chng xuyn thc t nhn vi 1 lng 0h
c, khi Pcx c tnh nh sau:
00( ) 0. . . .cx bt m
hP R u h
c
- ng hp 2: Khi i c t ct ai:
Khi trong phm vi thp xuyn thng c t cc ct thp ai thng gc vi mt y i, lc
chng xuyn thng c tnh ton nh sau:
0 0,8cx cx swP P F
cxP - lc chng xuyn ca i khi c t ct ai trong phm vi thp xuyn thng (gi tr ny
ly khng ln hn 2P0(cx).
0cxP - lc chng xuyn ca i khi khng t ct ai (ch do phn b tng chu).
swF - tng ton b lc ct do ct thp ai (ct cc mt bn ca khi thp) chu, c tnh theo
cng thc:
sw sw swF R A
y, swR khng c vt qu gi tr ng vi ct thp CI, A-1.
Khi k n ct thp ngang, Fsw ly khng nh hn 0,5P0(xt).
Khi b tr ct thp ai trn mt phn hn ch gn v tr t ti trng tp trung, cn thc hin
tnh ton b sung theo iu kin (mc 2) cho thp xuyn thng c y trn nm theo chu vi
ca phn c t ct thp ngang.
vng chu xuyn thng, ct thp ngang trong i mng c t vi bc khng ln hn
h/3 v khng ln hn 200mm, chiu rng vng t ct thp ngang khng nh hn 1,5h (vi
h l chiu dy i). Ct thp ngang phi c neo chc chn hai u bng cch hn hoc
kp cht ct thp dc, m bo bn ca lin kt v ca ct thp l tng ng.
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GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 17
1.1.5.2. KI RA U KIN C O C:
ng hp 1: lc chng ct ca b tng c tnh n ct ai: (Trch mc 6.2.3.3
TCVN 5574-2012)
2
2 (1 )b f n bt oR bhQ
c
Trong Q khng nh hn 3 0(1 )b f n btR bh
- b3 xt nh hng ca b tng ly nh sau
+ i vi b tng nng v b tng t ong b3 = 0,6
+ i vi b tng ht nh b3 = 0,5
+ i vi b tng nh c mc theo khi lng th tch trung bnh
D 1900: b3 = 0,5
D 1800: b3 = 0,4
- b2 xt nh hng ca b tng ly nh sau
+ i vi b tng nng v b tng t ong b2 = 2,0
+ i vi b tng ht nh b2 = 1,7
+ i vi b tng nh c mc theo khi lng th tch trung bnh
D 1900 b2 = 1,9
D 1800: dng ct liu nh c b2 = 1,75
dng ct liu nh rng b2 = 1,5
- f h s xt n nh hng ca cnh chu nn trong tit din ch T, ch I
(f = 1)
- n h s nh hng ca lc dc:
0.1 0.1nbt o bt o
N H
R bh R bh
- c chiu di hnh chiu ca tit din nghing nguy him nht ln mt mng theo
phng ang xt.
ng hp 2 : lc chng ct ca b tng khng tnh ct ai : (Trch mc 6.2.3.4
TCVN 5574-2012)
2
4 (1 )b n bt oR bhQc
Trong :
V phi ca cng thc trn ly khng ln hn 02,5 bR bh v khng nh hn
3 0(1 )b n btR bh (h s b3 ly tng t trng hp 1)
- b4 xt nh hng ca b tng ly nh sau
+ i vi b tng nng v b tng t ong b4 = 1,5
+ i vi b tng ht nh b4 = 1,2
+ i vi b tng nh c mc theo khi lng th tch trung bnh
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 18
D 1900 b4 = 1,2
D 1800: dng ct liu nh c b4 = 1,0
- H s n v c c xc nh nh trng hp 1
Hnh 1.8. Vt nt xin
1.1.6. P O
1.1.6.1. S tnh:
Xem i l bn consol c mt u ngm vo mp ct v u kia t do, vi gi thit
i l tuyt i cng
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 19
Hnh 1.9. S cc tc dng lc ln i
1.1.6.2. Ngoi lc tc d ng
Ngoi lc tc dng ln i l phn lc u cc trong phm vi ca dm consol.
Thng thng i vi mng nng, khi tnh ton ct thp th ti trng tc dng l
ti trng rng (khng xt n trng lng bn thn mng v t nn trn mng).
Tuy nhin khi tnh i cc, v hu nh tt c cc lc u truyn ln cc cc, c
bit l i cc nm trong lp t yu v vy, phn lc t nn (t yu) khng
kh nng chu c trng lng i v t nn trn i.
V vy, thin v an ton, khi tnh ton ct thp trong i cc, ngoi ngoi lc tnh
ton tc dng ln cc, cn xt n trng lng bn thn i v t nn trn i.
1.1.6. . Xc n m m nt t ng i c c ai p ng)
i iM = P l Trong :
M: moment trong i ti mp ct
Pi : phn lc u cc th i tc dng ln bn consol
li : khong cch t lc Pi n mp mt ngm ca bn consol.
1.1.6.4. Tnh ton ct thp
Tnh thp cho i nh thanh chu un tit din ch nht :
m
b b 0
M =
R bh
m = 1 - 1 - 2
0A R b bss
R bh
R
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 20
1.1.7. KIM TRA SC CHU TI CA C C V NHM C C :
1.1.7.1. Kim tra sc chu ti ca cc n
Ti trng tc dng ln cc :
max 2 2
tttt tt
y i x i
i i
M xN M yP
n x y
Trong :
n : s lng cc
xi, yi : khong cch t tim cc th i n trc i qua trng tm cc cc ti mt
phng y i
ttxM : tng moment ti y i quay quanh trc x ti trng tm nhm cc
ttyM : tng moment ti y i quay quanh trc y ti trng tm nhm cc
Kim tra sc chu ti ca cc :
max
min 0
aTKP Q
P
Nu Pmin < 0, th phi kim tra cc chu nh:
Qa nh + W > minP
W: trng lng ca cc (ly h s vt ti do trng lng bn thn < 0.9)
Qa nh: sc chu nh an ton ca cc (sc chu ti cho php ca cc do phn ma
st gy ra).
Khi kim tra cc chu nh nn kim tra kh nng chu lc ti cc mi ni cc v kh nng
chu ko ca cc.
Cng cn lu rng, cng thc xc nh phn lc u cc trn c quan nim l i
cc cng tuyt i. V vy, khi i cc c kch thc ln nh mng cc i bng hoc
i b th i khng c xem l cng tuyt i. V vy, khi xc nh ni lc trong i
v phn lc u cc, th cn gii theo phng php phn t hu hn.
1.1.7.2. Kim tra sc chu ti ca nhm cc:
- H s nhm:
21
1221
90
)1()1(1
nn
nnnn
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 21
Trong :
arctand
s
d : ng knh cc, m
s : khong cch gia cc cc, m
1n : s hng cc
2n : s cc trong mi hng
Sc chu ti ca nhm cc:
nh
a aQ n Q
1.1.8.KIM TRA NH CA T N D V
LN MNG C C:
1.1.8.1. Xc n k c t c khi mng quy c:
D tnh ln ca nhm cc c da trn m hnh mng khi quy c. C ba cch xc
nh mng khi quy c nh sau:
ng hp 1: Cc i qua nn nhiu lp
n 1.1 Mng khi quy c cc i qua nhiu lp t
b
LTB
B D
A C
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 22
Ranh gii mng quy c
Pha di l mt phng AC i qua mi cc c xem l y mng;
Pha trn l mt t san nn BD, vi AB = l su t mng (t mt t n cao
trnh mi cc);
Pha cnh l cc mt phng ng AB v CD qua mp ngoi cng ca hng cc bin
ti khong cch Ltb tan / 4tb nhng khng ln hn 2d (d: ng knh hoc cnh cc
vung) khi di mi cc c lp st bi vi ch s st IL> 0,6; khi c cc xin th cc mt
phng ng ni trn i qua mi cc xin ny:
i itb
tb
l
L
Trong :
i : gc ma st trong ca lp t c chiu dy li
Ltb: su h cc trong t k t y i, tb iL l .
Ch thch:
Nu trong chiu di ca cc c lp t yu (bn, than bn) dy hn 30 cm th kch
thc y mng quy c gim i bng cch ly Ltc l khong cch t mi cc n y
lp t yu;
Trng lng bn thn ca mng quy c gm trng lng cc v t nm trong phm
vi mng quy c.
ng hp 2: Cc i qua nn ng nht
n 1.11 Mng khi quy c qua nn ng nht.
b
LTB
B D
A C
2/3LTB
1/3LTB
o
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 23
Ranh gii mng quy c k i t nn l ng nht
Cch xc nh mng quy c tng t cch 1, ch khc l ly gc ma st bng 30o cho
mi loi t k t su 2Ltb/3
Ranh gii ca mng quy c khi cc xuyn qua mt s lp t yu ta vo lp t
cng cch xc nh mng quy c nh m t trong cch 1, ring gc m ly bng 30o k
t su 2L1/3, vi L1 phn cc nm di lp t yu cui cng
Ranh gii ca mng quy c khi t nn nm trong phm vi chiu di cc gm nhiu
lp c sc chu ti khc nhau.
Chiu rng v chiu di bn mng quy c l y hnh khi c cnh m rng so vi
mt ng ca hng cc bin bng cho n su 2Ltb/3, t tr xung n mt
phng mi cc gc m bng 30o.
su t mng quy c l ti mt phng mi cc.
ng sut ph thm phn b trong t nn, di mi cc c th tnh ton theo li gii
Boissinesq vi gi thit bn mng quy c t trn bn khng gian n hi.
ln ca mng quy c c tnh theo phng php quen bit nh i vi mng
nng trn nn thin nhin.
ng hp 3: Cc i qua lp t yu v lp t tt
n 1.1 Cc i qua lp t yu v lp t tt
b
LTB
B D
A C
2/3LTB
1/3LTB
o
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 24
1.1.8.2. Kim tra n n t nn di y mng k i quy c:
iu kin n nh nn di mng khi quy c l:
tc
tc II
tb qu
qu
Np R
A
max 1.2
tc
tc II
tb qu
qu
Mp p R
W
min 0
tc
tc
tb
qu
Mp p
W
Trong :
tctbp - p lc trung bnh tiu chun di y mng khi quy c.
max
tcp - p lc ln nht di mng khi quy c.
min
tcp - p lc nh nht di y mng khi quy c.
tcN - tng lc dc ti tm y mng khi quy c (bao gm lc dc ti chn ct, trng lng bn thn ca i cc, cc, t trn i v phn t nm trong
mng khi quy c).
tcM - tng moment y mng khi quy c ly bng M ti tm y i
quW - moment chng un ca tit din mng khi quy c (2
6
qu qu
qu
B LW khi moment
quay theo hng Lqu hoc ngc li 2
6
qu qu
qu
L BW khi moment quay theo hng Bm)
Lqu, Bqu- chiu di v chiu rng ca mng khi quy c.
II
quR - sc chu ti ca t nn di y mng khi quy c (tnh ton theo trng thi
gii hn th II, ging nh mng n).
1.1.8.3. Kim t a ln ca mng khi quy c:
gh
S S
ghS - ln gii hn c xc nh theo bng H.2 (TCXD205:1998)
S ln trung bnh ca t nn di y mng khi quy c
Cc bc tnh ln ca mng khi quy c theo phng php tng phn t.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 25
Bc 1: Xc nh p lc gy ln
'tc
gl tb i ip p h
'
i ih - ng sut c hiu theo phng ng do trng lng bn thn t nhin ca t nn gy ra ti y mng khi quy c.
tc
tbp - p lc tiu chun trung bnh ca t nn di y mng khi quy c.
Bc 2: Chia lp phn t
Chiu dy ca lp phn t c xc nh theo iu kin sau:
(0.4 0.6)i quh B
Tuy nhin, hin nay v c cc chng trnh tnh ton bng my tnh nn chiu dy lp
phn t nn chia cng nh t c chnh xc cao.
Bc 3: Xc nh ln ca lp phn t th i. chiu dy hi
B3.1. Xc nh 1i : ng sut trung bnh chnh gia lp t th I trc khi c cng
trnh (do trng lng bn thn t nn gy ra (c hiu ))
1 ' 'i v i ih
B3.2. Xc nh 2i : ng sut trung bnh chnh gia lp t th I sau khi c cng
trnh (do trng lng bn thn t nn gy ra v ng sut do pgl gy ra ti chnh gia lp
t th i).
2 1i i zi
zi - ng sut do pgl gy ra ti chnh gia lp t th I, c tnh theo ng sut do ti
trng ngoi phn b u gy ra. 0.zi glk p
k0 ph thuc vo ,qu
qu qu
Lz
B B
c tra bng 1.4:
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 26
Bng 1.4 Bng xc nh h s k0 (Bng C1 TC N 362)
B3.3. Xc nh ln Si 1 211
i ii i
i
e eS h
e
1ie - h s rng ca t gia lp t th I trc khi c cng trnh, ng vi 1i , c
ni suy t ng cong nn ln (e, ) ca lp t c lp phn t th i.
2ie - h s rng ca t gia lp t th I sau khi c cng trnh, ng vi 2i , c
ni suy t ng cong nn ln (e, ) ca lp t c lp phn t th i.
Bc 4: iu kin tnh ln trong phm vi nn
' 5vi zi
Khi t iu kin trn th t nn c xem l n khng ng k.
Cng lu rng, iu kin trn p dng cho mng nng, nhng i vi mng khi
quy c, mc gim ng sut do ti trng ngoi gy ra gim rt chm theo su, v
vy nn tnh ln cho tt c cc lp n khi no ln Si rt nh so vi tng ln th
dng phn tnh ln.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 27
Bc 5: Xc nh tng ln ca nn theo phng php tng phn t
iS S
1.1.9. KIM TRA C C CHU CU LP:
Khi b tr cc mc cu trong cc, nn b tr sau cho moment cn th trn v moment cn th di bng nhau. Mt s trng hp c bit nh sau:
- S mc cu (thng trong iu kin dng cc)
Hnh1.13. S b tr mc cu trong trng hp dng cc
2
1 0.068M qL
- S 2 mc cu (thng trong iu kin cu cc):
0.293L
L
M1
q
0.207L 0.207L
L
M2
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 28
Hnh 1.14. S b tr mc cu trong trng hp cu cc
2
1 0.0214M qL
Ghi ch: Trong trng hp cc ch b tr 2 mc cu th thng dng mc cu trong
s cu cc dng cc, khi moment ln nht trong cc l 20,068M qL .
ng q: ti trng bn thn ca cc quy v phn b theo chiu di c tnh theo
cng thc: q=K d2 (K=(1.2-2) s ng ph thuc vo phng php vn chuyn cc)
1.1.10. NG D NG SAP2000 KIM TRA C C CHU TI NGANG:
Ti trng ngang tc dng ln cc c tnh bi
Trong :
H: lc ngang tc dng vo i mng (kN).
n: s lng cc
Khi tnh ton cc chu ti ngang, t quanh cc c xem nh mi trng n hi bin dng
tuyn tnh c trng bng h s nn Cz.
Trong :
- K: h s t l, kN/m4, c ly theo bng G1 tiu chun 205-1998:
- z: su v tr cc, m, k t mt t i vi cc i cao, hoc y mng i vi
cc i thp.
y n gin trong qu trnh gn iu kin bin ca h s nn ta chn K, z ti v
tr gia lp cn xt, ri ly cng em gn cho tng lp t.
Ti mt phn cch cc lp t ta tnh ring cc h s n hi ( cng ca l xo khi
khai bo) mang c tnh ca c lp trn v lp di nn ta s tnh ring cc gi tr ti cc lp
phn cch ny).
Ch dn sa d ng SAP2000:
File->New model-> Grid Only->Ok
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 29
Hnh 1.15. ng dn SAP2000
Hiu chnh li ct: Kch chut chn Edit -> Modify/Show System->OK
Hnh 1.16. ng dn SAP2000
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 30
Hnh 1.17. ng dn SAP2000
Hiu chnh li ct vi khong cch l b dy cc lp t (z), cc ct (x,y ).
Khai bo vt liu: Define-> Materials-> Add New Material-> Chn vt liu l
Concrete-> Weight =0 (khng cn xt n trng lng bn thn cc)-> nhp Modul E
vi tng loi b tng->OK
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 31
Hnh 1.18. ng dn SAP2000
.
Khai bo tit din cho cc: Define-> Frame Sections: To cc COCc kch thc l
kch thc ca cc.
Hnh 1.19. ng dn SAP2000
Khai bo tit din cho i cc: Define-> Area-> Sections..: To cc COCc kch
thc l kch thc ca cc.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 32
Hnh 1.19. ng dn SAP2000
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 33
Dng Draw Frame/Cable Element v cc v Quick Draw Area Element v i cc
Hnh 1.21. ng dn SAP2000
Gn tit din b tng vo cc: Chn cc-> Assign-> Frame-> Frame sections->chn
COC.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 34
Hnh 1.22. ng dn SAP2000
Gn tit din b tng vo i cc: Chn i cc-> Assign->Area->Sections->chn
DAI COC.
Chia 4 cc thnh tng on gn iu kin bin: Chn cc ->Edit ->Edit lines->
Devide Frames-> Nhp s on cn chia vo Devide into Specified Number-> OK.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 35
Hnh 1.23. ng dn SAP2000
Gn cng l xo cho cc on va mi chia: Chn i tng cn gn-> Assign -
>Joint -> Springs : Nhp cc h s nn Cz va tnh c.(iu chnh h trc ta
sang h trc Global).
Hnh 1.24. ng dn SAP2000
Gn ti trng ln cc: Chn trng tm ca i cc-> Assign ->Joint Loads-> Forces
ri nhp ti trng.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 36
Hnh 1.25. ng dn SAP2000
Chy chng trnh SAP2000: bm F5-> Run Now.
Xem kt qu gii ni lc SAP2000:
Hnh 1.26. ng dn SAP2000
Xem chuyn v
Hnh 1.27. ng dn SAP2000 Xem momen
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 37
1.1.11. S L THUY T KIM TRA C C CHUYN V NGANG:
(Tnh ton theo phng php ca SNIP II 17 77)
Chuyn v ngang v gc xoay ca u cc tha mn iu kin sau:
Trong :
, - nhng gi tr tnh ton tng ng chuyn v ngang (m), v gc xoay (radian)
ca u cc.
, - nhng gi tr tng ng chuyn v ngang (m), v gc xoay (radian) ca u
cc. c quy nh t nhim v thit k nh cng trnh.
Khi tnh ton cc chu ti trng ngang, t quanh cc c xem nh mi trng n hi
bin dng tuyn tnh c trng bng h s nn Cz (kN/m3).
Khi khng c nhng s liu th nghim, cho php xc nh s liu tnh ton ca h s
nn Cz ca t quanh cc theo cng thc:
Trong :
K h s t l (kN/m4) c ly theo bng G1 (TCXD 205:1998).
Z su v tr tit din cc (m ) k t mt t i vi cc i cao, hoc k t mt t
i vi cc i thp.
Bng G1- h s t l K
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 38
Tt c tnh ton c thc hin theo chiu su tnh i ca v tr tit din cc trong t
v c chiu su tnh i h cc trong t xc nh theo cng thc sau:
Trong :
Z, l chiu su thc t v tr tit din cc trong t v chiu su h cc thc t (mi cc)
trong t tnh t mt t vi cc i cao v t y i vi cc i thp (m).
- h s bin dng (1/m) xc nh theo cng thc:
Trong :
K h s t l (kN/m4)
Eb m un n hi ban u ca b tng cc khi nn v ko (kN/m2), ly theo
tiu chun b tng ct thp.
I momen qun tnh tit din ngang ca cc (m4)
bc chiu rng quy c ca cc (m), c ly nh sau:
Khi d 0.8 th ly bc = d + 1m
Kkhi d < 0.8 th ly bc = 1.5d +0.5m
Tnh ton chuyn v ngang ca cc theo cng thc:
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 39
Trong :
H v M gi tr tnh ton ca lc ct (kN) v momen un (kNm) ti u cc.
chiu di on cc (m) bng khong cch t y i cc n mt t.
y0, chuyn v ngang (m) v gc xoay ca tit din ngang ca cc (radian)
mt t vi cc i cao, mc y i vi cc i thp v c xc nh nh
sau:
Trong :
H0 gi tr tnh ton ca lc ct (kN), ly H0 = H
M0 gi tr tnh ton ca lc ct (kNm), ly M0 = M + Hl0
chuyn v ngang ca tit din (m/kN) bi lc H0 = 1
chuyn v ngang ca tit din (1/kN) bi momen M0 = 1
gc xoay ca tit din (1/kN) (hoc kNm) bi lc H0 = 1
gc xoay ca tit din (1/kN) (hoc kNm) bi lc M0 = 1
Chuyn v = v v c xc nh theo cng thc:
Trong :
- cc h s khng th nguyn ly theo bng G2 (TCXD 205:1998) ty
thuc vo chiu su tnh i ca phn cc trong t le, khi le nm gia hai gi tr
trong bng G2 th ly theo gi tr gn hn tra bng
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 40
1.1.12. TNH TON NI LC TRONG C C (theo TCXD 205 -1998)
Khi tnh n nh ca nn quanh cc, phi kim tra iu kin hn ch p lc tnh ton
ln t mt bn ca cc theo cng thc
Trong :
p lc tnh ton ln t (kN/m2) mt bn ca cc ti su z (m) k t mt t cho
cc i cao v t y i cho cc i thp.
khi lng th tch tnh ton ca t (kN/m3)
- ng sut c hiu theo phng thng ng trong t (kN/m2) ti su z.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 41
gi tr tnh ton ca gc ma st trong () v lc dnh (kN/m2)
h s, ly bng 0.6 cho cc nhi v cc ng, bng 0.3 cho cc cc cn li
h s, ly bng 1 tr trng hp tnh mng cho cc cng trnh chn ly bng 0.7
h s k n phn ti trng thng xuyn trong tng ti trng, tnh theo cng thc:
momen do ti trng thng xuyn (kNm) tnh ton tit din mng ti mc m cc
momen do ti trng tm thi (kNm)
n h s, ly bng 2.5 tr cc trng hp sau y
a) Nhng cng trnh quan trng
+ khi le 2.5 ly n = 4
+ khi le 5 ly n = 2.5
+ khi le nm gia cc tr s trn th ni suy n
b) Mng mt hng cc chu ti trng lch tm thng ng, nn ly n = 4 khng ph
thuc vo le .
Ch thch:nu p lc ngang tnh ton ln t khng tha mn iu kin trn nhng
lc ny sc chu ti ca cc cha tn dng ht v chuyn v ca cc nh hn tr s cho php
khi chiu su tnh i ca cc le> 2.5 th nn lp li vic tnh ton vi h s t l K gim i
(iu G.2 ca TCXD 205:1998). Vi tr s mi ca K cn kim tra bn ca cc theo vt
liu, chuyn v ca cc cng phi tun theo iu G.14
Khng cn tnh ton n nh t nn quanh cc c b rng tit din d m, vi chiu
di trong t ln hn 10d, tr trng hp cc c h vo bn hoc t st trng thi
chy hoc do chy.
p lc (kN/ ), moment un (kNm), lc ct (kN) trong cc tit din cc c
tnh theo cng thc sau (trch t mc G7 ph lc G ca TCXD 205:1998):
(
)
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 42
Trong :
K h s t l
, c ngha nh cc cng thc ni phn trc
chiu su tnh i, ty theo su thc t z m xc nh , , .
c ngha nh ni phn trc
A1, A3, A4, B1, B3, B4,C1,C3,C4, D1, D3, D4 cc h s tra bng G3
N ti trng tnh ton dc trc ti u cc.
Momen ngm tnh ton Mng (kNm) khi tnh cc ngm cng trong i v u cc khng b
xoay, tnh theo cng thc sau:
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 43
y ngha ca cc k hiu u ging nh nh cng thc nu trn. Du m c
ngha l vi lc ngang hng t tri sang phi, momen truyn ln u cc t pha ngm c
hng ngc vi chiu kim ng h.
2.1.CC D LIU TNH TON:
2.1.1.THNG K S LIU A CHT 1B (trch t phn I):
Chn v tr t mng ti h khoan 3 (HK 3) c cc s liu a cht di bng sau:
Bng 2.1:Thng k a cht ti h khoan 3 (HK3).
STT
Lp Dung trng t nhin Dung trng y ni
Lc dnh C (kN/m2) Gc ma st trong (o) (
su m) (kN/m3) (kN/m3)
tc 1 2 tc 1 2 Ctc C1 C2 tc 1 2
1
2a
18,99
9,255
9,542
6,884 8,057
121'
1017' 113'
(-1.3-
>-3.4) 12,2 11,027 1343' 1258'
2
2b
20,033
10,407
18,27
16,148 17,018
1524'
1452' 155'
(-3.4-
>-3.4) 20,386 19,516 1556' 1543'
3
3
19,81
10,04
33,164
21,237 25,886
1440'
1359' 1415'
(-3.4-
>-5.0) 45,09 40,441 1519' 153'
4
4
19,435
19,302 19,357
9,815
9,726 9,762
14,242
12,497 13,164
144'
1323' 1340'
(-5.0-
>-8.6) 19,568 19,514 9,904 9,868 15,987 15,32 1444' 1428'
5
5
19,4
19,264 19,324
9,875
9,761 9,811
7,294
3,807 5,162
1349'
1257' 1317'
(-8.6-
>-
11.0)
19,536 19,476 9,989 9,939 10,782 9,427 1441' 1422'
6
6a
18,508
18,44 18,47
9,301
9,25 9,27
2,739
0,195 1,142
2647'
2614' 2627'
(-11->-
15) 18,58 18,55 9,36 9,34 5,263 4,316 2719' 277'
7
6b
19,248
19,185 19,209
9,901
9,851 9,869
2,943
1,33 1,91
2935'
2915' 2923'
(-15->-
40.7 19,311 19,288 9,951 9,932 4,47 3,89 2954' 2946'
8
7
20,22
20,19 20,202
10,53
10,485 10,504
38,063
33,797 35,424
1647'
1543' 167'
(-40.7-
>-
50.0)
20,25 20,238 10,575 10,556 42,328 41,701 1750' 1726'
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 44
2.1.2.S LIU TNH TON:
Hnh 2.1 Hnh 2.2
2.1.3.KHAI BO VT LIU:
- B tng B30c Rb=17Mpa=17000kN/m2; B20c Rb=11.5Mpa=11500kN/m
2
- Thp AII c Rs=280Mpa= 280000kN/m2.
2.2.TRNH T TNH TON V THI T K MNG C C:
2.2.1.CH N CHIU SU CHN MNG Df V C C S
B:
- Chn thi cng cc ch to sn, bin php thi cng p cc.
- Chn chiu su t i cc: m 0.2fD
- Chn cc thng s v cc:
Kch thc tit din cc : 0.4m x 0.4m 2m 16.0pA
Chn chiu di cc l : 10m x 3 =30 m
Vi chiu di ca cc nh vy th mi cc s cm vo lp 6b l lp t ct
Chn chiu cao i : 0.8 mdh
on cc ngm vo i : 0.6 m
on cc neo vo i l : m 1.0nl
=> su t y i n mi cc: l=30-0.6=29.4 m
Din tch ct thp (theo tiu chun 205-1998 mc 3.3.3.b):
4 2(0.8% 1.12%) 16 10 (0.8% 1.12%) 1280 1792 mms pA A = =
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 45
Chn ct dc : 422
Chn din tch thp trong cc : 22
mm 15214
224
sA
Chn ct ai : 10a200
2.2.2. TNH TON SC CHU TI CA C C:
2.2.2.1. SC CHU TI CA C EO CA VT LIU: (3.3.2
TCXD 205-1998):
2.2.2.1.a. Cc chu ti trng tc thi khi p cc:
1vl bQ A R
Trong :
- R: cng chu nn tnh ton ca b tng B30 lc p cc R=30x0.85=25.5 Mpa
- Ab=0.4x0.4=0.16 (m2) din tch tit din ngang ca cc b tng.
- : h s nh hng bi mnh ca cc tnh theo cng thc thc nghim .
=1.028-0.0000288x 2-0.0016x
=l0/r
Khi pcc :0
0
10. 1 10 10( ); 25
0.4
ll l x m
r
(khi p cc xem cc 2 u khp)
=1.028-0.0000288x 252-0.0016x 25=0.97
- Sc chu ti khi p cc:
3
1 0.97 0.16 25.5 10 3957.6( )vl bQ A R x x x kN
2.2.2.1.b. Cc chu ti trng ca cng trnh lu di:
2vl bQ A R
Trong :
- R: cng chu nn tnh ton ca b tng B30lc cc chu ti trng cng trnh lu
di R=30x0.33=9.9Mpa
- Ab=0.4x0.4=0.16 (m2) din tch tit din ngang ca cc b tng.
- : h s nh hng bi mnh ca cc tnh theo cng thc thc nghim .
=1.028-0.0000288x 2-0.0016x
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 46
=le/r
- Khi chu ti trng cng trnh
e bdl L Trong :
- L=29.4m chiu su thc t.
- bd :h s bin dng,I/m, xc nh theo cung thc:
5c
bd
b
Kb
E I
Trong :
- bc=1.5d+0.5=1.5x0.4+0.5=1.1m (d=0.4mH s bin dng:
- Chiu di cc trong t tnh i:
18.0245.05
0.4
el
r
=1.028-0.0000288x 45.052-0.0016x 45.05=0.897
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 47
- Sc chu ti khi p cc:
3
2 0.897 0.16 9.9 10 1421.6( )vl bQ A R x x x kN
. . . . X NH SC CHU TI CA T NN: (3.3.2 TCXD 205-1998):
2.2.2.2.a. Sc chu ti ca cc theo ch tiu c l ca t nn (ph lc A-TCXD 205-
1998): tcatc
QQ
K
Trong :
- : 1.6 ( ty thuc vo s lng cc ly theo A1-TCXD 205-1998).
- : sc chu ti tiu chun tnh theo t nn ca cc n.
( )tc R p p f si iQ m m q A u m f l m= 1 (h s iu kin lm vic ph thuc no nc lp t).
mR=1.1 (h s iu kin lm vic ca t di mi cc). (A3-
TCXD205-1998)
mf=1 (h s iu kin lm vic ca t mt bn cc). (A3-TCXD205-
1998)
qp=3800 kN/m2vi su mi cc=29.4m.(A1-TCXD205-1998).
Ap=0.16m2 tit din cc
Bng 2.2:Thng k ma st hng theo ch tiu c l
p z (m)
su t ung b n i
(m)
iu dy t c t cc (m)
ui
(m)
ng t i t
Ma st
hng
n v fs
(T/m2)
s iu kin lm
vic m
a st bn Qsi
2a 2
1.4 1.4
1.6 0.5 1.4 1
3.136 3.4
3 3.4
2.9 1.6
1.6 0.23 4.92 1
12.595 5
4
5 4.6 1.8 1.6 0.3
3.92 0.96 11.290
6.8
6.8 6.4 1.8 1.6 0.39
3.25 0.98 9.360
8.6
5
8.6 7.9 1.2 1.6 0.76
0.88 0.9 1.690
9.8
9.8 9.1 1.2 1.6 0.76
0.88 0.9 1.690
11
6a
11 10.7 2 1.6
Ct mn 4.67 1 14.944
13
13 12.7 2 1.6 4.87 1 15.584
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 48
15
6b
15 14.7 2 1.6
Ct va n mn
5.07 1 16.224
17
17 16.7 2 1.6
5.27 1 16.864
19
19 18.7 2 1.6
5.47 1 17.504
21
21 20.7 2 1.6
5.67 1 18.144
23
23 22.7 2 1.6
5.87 1 18.784
25
25 24.7 2 1.6
6.07 1 19.424
27
27 26.7 2 1.6
6.27 1 20.064
29
29 28.7 2 1.6
6.47 1 20.704
31
31 29.9 0.4 1.6
6.59 1 4.218
31.4
Qsi 2222.176
( ) 1 (1.1 3800 0.16 2222.176) 2890.976( )tc R p p f si iQ m m q A u m f l kN
Sc chu ti cc theo ch tiu c l 12890.976
1806.86( )1.6
tca
tc
QQ kN
K
2.2.2.2.b. Sc chu ti ca cc t cng t nn:(ph lc B TCXD 205-1998)
2
psa
s p
QQQ
FS FS
Trong :
- sQ : sc khng hng cc hn (xung quanh cc)
- pQ : sc khng mi cc hn
- FSs : h s an ton ca ma st hng (FSs=2)
- FSp: h s an ton ca sc khng mi cc (FSp=3)
Thnh phn chu ti do ma st xung quanh cc:
isis lfuQ
Trong :
- u : chu vi cc
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 49
- sif : thnh phn ma st n v gia cc v lp t th i (kN/m2)
-
: lc dnh gia cc v lp t th i, vi cc b tng ct thp ly
(kN/m2).
: gc ma st gia cc v t, cc p b tng ct thp ly
: ng sut hu hiu ca lp t th i (kN/m2),
trong bng
thng k.
- il : chiu dy lp t th i (m)
Bng 2.3: Tnh ton thnh phn chu ti do ma st xung quanh cc.
p z (m) li (m) ui(m) i ci
(kN/m2)
'i (kN/m
3)
i (kN/m
2)
si
(kN/m2)
Qsi (kN)
2a 2
1.4 1.6 10.283 6.884 9.255 12.957 6.750 15.120 3.4
3 3.4
1.6 1.6 13.983 21.237 10.04 27.468 20.053 51.336 5
4 5
3.6 1.6 13.383 12.497 9.726 53.006 18.440 106.215 8.6
5 8.6
2.4 1.6 12.95 3.807 9.761 82.226 17.336 66.568 11
6a 11
4 1.6 26.23 0.195 9.25 112.440 31.051 198.728 15
6b 15
16.4 1.6 29.25 1.33 9.851 211.718 61.564 1615.438 31.4
Qs Tng thnh phn chu ti do ma st xung quanh cc 2053.4048
Thnh phn sc chu mi ca t di mi cc:
ppp qAQ
Trong :
-
-
Tnh ton sc chu ti n v mi cc: (TCXD 205-1998):
Trong :
- c: lc dnh ca t ti mi cc (kN/m2), 21.33 kN/mc
- : Dung trng ca t nn ti mi cc (kN/m3), 39.851 kN/m
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 50
- ng sut hu hiu ti mi cc (kN/m2).
- qc ,N,NN : h s sc chu ti, ph thuc vo ma st trong ca t, hnh dng mi
cc v phng php thi cng.
Bng 2.4: ng sut hu hiu bn thn lp t nn.
z
(m) li (m)
'i (kN/m
3)
i = 'i *li
(kN/m2)
2a 1.3
2.1 9.255 19.436 3.4
3 3.4
1.6 10.04 16.064 5
4 5
3.6 9.726 35.014 8.6
5 8.6
2.4 9.761 23.426 11
6a 11
4 9.25 37.000 15
6b 15
16.4 9.851 161.556 31.4
ng sut hu hiu bn thn t nn ti mi cc 'v
292.496
Bng 2.5: Bng tra cc h s sc chu ti tnh theo cng thc ca Vesic.
Nq Nc N Nq Nc N
0 1.00 5.14 0.00 24 9.60 19.32 9.44
1 1.09 5.38 0.07 25 10.66 20.72 10.88
2 1.20 5.63 0.15 26 11.85 22.25 12.54
3 1.31 5.90 0.24 27 13.20 23.94 14.47
4 1.43 6.19 0.34 28 14.72 25.80 16.72
5 1.57 6.49 0.45 29 16.44 27.86 19.34
6 1.72 6.81 0.57 30 18.40 30.14 22.40
7 1.88 7.16 0.71 31 20.63 32.67 25.99
8 2.06 7.53 0.86 32 23.18 35.49 30.21
9 2.25 7.92 1.03 33 26.09 38.64 35.19
10 2.47 8.34 1.22 34 29.44 42.16 41.06
11 2.71 8.80 1.44 35 33.30 46.12 48.03
12 2.97 9.28 1.69 36 37.75 50.59 56.31
13 3.26 9.81 1.97 37 42.92 55.63 66.19
14 3.59 10.37 2.29 38 48.93 61.35 78.02
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 51
15 3.94 10.98 2.65 39 55.96 67.87 92.25
16 4.34 11.63 3.06 40 64.20 75.31 109.41
17 4.77 12.34 3.53 41 73.90 83.86 130.21
18 5.26 13.10 4.07 42 85.37 93.71 155.54
19 5.80 13.93 4.68 43 99.01 105.11 186.53
20 6.40 14.83 5.39 44 115.31 118.37 224.63
21 7.07 15.81 6.20 45 134.87 133.87 271.75
22 7.82 16.88 7.13 46 158.50 152.10 330.34
23 8.66 18.05 8.20 47 187.21 173.64 403.65
Ti lp 6b c c=1.33(kN/m2), '= .851 (kN/m3) 029.25 tra bng c:
28.43cN , qN 16.93, 20.105N
Sc chu ti mi n v theo Vesic:
21.33 28.43 292.496 16.93 9.851 0.4 20.105 5069 kN/mpq
20.4 5069 811.04 kNp p pQ A q
Sc chu ti cc hn ca t nn:
2 2053.4048 811.04 2864.44 kNu s pQ Q Q
Sc chu ti c p p t cng t nn:
2
2053.4048 811.041297.05 kN
2 3
psa
s p
QQQ
FS FS
2.2.2.2.c. Tnh ton sc chu ti ca t theo cng thc ca Nht Bn t kt qu
TN SPT:
Trong :
- h s ph thuc vo phng php thi cng cc, i vi phng php p cc
- aN : ch s SPT ca t di mi cc, aN = 15 ba.
- pA
: din tch tit din mi cc, Ap= 0.16 m2
- sN : gi tr trung bnh ca ch s SPT trong lp t ri, ba.
- baN s 7.13
10
151515161391817109
- sL : chiu di phn cc nm trong lp t ri, m 4.20sL
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 52
- C : gi tr trung bnh ca s ba lc dnh n v trong lp t dnh,
ba 12.45
121314158
C
- cL : chiu di phn cc nm trong lp t dnh: 9.7m 4.26.36.11.2= cL
- um=4x0.4 (m): chu vi cc.
Sc chu ti cc hn tnh theo cng thc Nht Bn:
3 30 15 0.16 0.2 13.7 20.4 12.4 9.7 4 0.4 353.88 3538.8( )uQ T kN
Sc chu ti tnh theo cng thc Nht Bn:
2.2.2.2.d. Tnh ton sc chu ti ca t theo cng thc ca Meyerhof (1956) t kt
qu TN SPT: (TCXD 205-1998 mc C.2.2)
4 1 2
1( 10 )a p tb s c cQ K NA K N A L CA
FS
Trong :
- K1=400 (cc p).
- N=15 ch s SPT ca t di mi cc
- Ap: din tch tit din mi cc, Ap= 0.16 m2
- K2=2 (cc p).
- Ntb gi tr trung bnh ca ch s SPT trong lp t ri, ba.
9 10 17 18 9 13 16 15 15 1513.7
10tbN ba
- As = Ac =4d=4x0.4=1.6 (m): chu vi cc.
- Lc=9m chiu di phn cc nm trong lp t ri.
- Ls=20.4m chiu di phn cc nm trong lp t ri.
- C : gi tr trung bnh ca s ba lc dnh n v trong lp t dnh,
ba 12.45
121314158
C
Sc chu ti cc hn ca t nn tnh theo cng thc Meyerhof:
4 1 2 10
400 15 0.16 2 13.7 1.6 20.4 10 9 12.4 1.6
3639.93( )
u p tb s s c cQ K NA K N A L L CA
kN
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 53
Sc chu ti tnh theo cng thc Meyerhof:
4 1 2
1( 10 )
1(400 15 0.16 2 13.7 1.6 20.4 10 9 12.4 1.6)
3
1213.31( )
a p tb s s c cQ K NA K N A L L CAFS
kN
Kt lun : Sc chu ti thit k: 4
1 1806.86 1297.05 1179.6 1213.31 1374.205( )4 4
ai
tb
Q
Q kN
Dng phng php bnh phng cc tiu xc nh gi tr c trng ca t nn ( Ti
trng thit k).
max min4 1806.86 4 1374.205 1179.6 1413.88( )6 6
tbtk
Q Q QQ kN
Sc chu ti cc hn ca t nn:
2 3 4max(Q ;Q ;Q ;Q ) max(2890.97;3036.16;3538.8;3639.93)
3639.93
u tc u u uQ
kN
2.2.2.3. KIM TRA SC CHU TI CA C
Cc chu ti trng tm thi ( khi p cc):
1
max
2 2 1413.88 2827.76( )3957.6( )
3639.93
tk
vl
u
Q kNQ kN
Q kN
=>Tha iu kin chu lc tm thi
Cc chu ti trng lu di ( khi chu ti trng cng trnh):
2 1421.6( )) 1413.88( )vl tkQ kN Q kN
=>Tha iu kin chu lc lu di.
2.2.3. O S B S NG C C:
45201.2 3.83
1413.88
tt
tk
Nn
Q
Chn 4 cc
Trong : h s xt n nh hng ca momen v lc ngang. ( )
2.2.4.B TR C C:
- Khong cch 2 cc: (3 6 ) 1.2 2.4( )s d d m
Chn s=1.7m (khong cch trn cng 1 hng)
- Din tch y i cc : 2m 6.25 =5.25.2 = A
- Khong cc t mp cc bin n mp i: mm 200a
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 54
- Chiu cao i mng hd=0.8m
- B tr cc nh hnh v:
Hnh 2.3:B tr mng cc
2.2.5. KI RA C
2.2.5.1.KI RA U KIN XUYN TH O
- S cc trong thp xuyn thng: 1xtn cc.
- iu kin chng xuyn thng: cxxt PP
- Chn 0.1 ma , chiu cao lm vic ca tit din: 0 0.8 0.1 0.7 mdh h a
- Lc gy xuyn thng: 2
( ) 2
0.9 4520 0.354520 (4 ) 1811.68kN
1.15 4 0.4xt tt i xtP N P
- Kch thc thp xuyn bmxhm= 2x2(m) (0,6+2x0,7=2 (m) ct c kch thc 0,6x0,6m).
- Thp xuyn c xc nh li nh hnh sau:
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 55
Hnh 2.9: Thp xuyn thng
=>c=0.55m
- Lc chng xuyn thng: 2
00
0.71 900 5.2 4169.45kN
0.55cx bt m
hP = R u h
c
Trong :
1 : H s iu kin lm vic ca b tng
2900 kN/mbtR : Cng chu ct ca b tng B20
mu
: Chu vi trung bnh ca thp xuyn thng,
0.6 0.6 2 2 5.2( )m c c m mu b h b h m
0.55mc : Xc nh nh hnh v. (Khong hnh chiu t mp ct n tm cc).
0 0.8 0.1 0.7 mh : Chiu cao lm vic ca tit din (gi s thp t st trn u
cc)
Nhn thy: 4169.45 kN 1811.68kNcx xtP = P
Vy i cc tha iu kin xuyn thng.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 56
2.2.5.2. KI RA U KIN C O C:(Tnh theo tiu chun
6.2.3.4 TCVN 5574-2012)
- iu kin chng ct (khng c ct ai): 2
4 (1 )b n bt oR bhQc
Trong :
b4=1.5 xt nh hng ca b tng (=1.5 i vi b tng nng)
n h s nh hng ca lc dc:
0.1nbt o
N
R bh
c chiu di hnh chiu ca tit din nghing nguy him nht ln mt mng .
24520 22 2 2.5 4795tt tt tb fN N xD xS x x kN
140 114 0.8 231.2tt tt tty y x dM M H xh x kNm
142 123 0.8 240.4tt tt ttx x y dM M H xh x kNm
max max
max/min 2 2
tttt tt
y x
i i
M xN M yP
n x y
Bng 2.6:Ti trng tc dng ln cc cc
c xi yi xi 2 yi
2 xi
2 yi2 Pi(KN)
1 -0.85 0.85 0.7225 0.7225
2.89 2.89
1201.46
2 0.85 0.85 0.7225 0.7225 1337.46
3 -0.85 -0.85 0.7225 0.7225 1060.04
4 0.85 -0.85 0.7225 0.7225 1196.04
Xt theo phng x :
- Lc ct :
2 4 1337.46 1196.04 2533.5Q P P kN
- Lc chng ct ca b tng :
2
4 (1 )b n bt ob
R bhQ
c
Trong :
b4=1.5 xt nh hng ca b tng (=1.5 i vi b tng nng)
n h s nh hng ca lc dc:
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 57
31140.1 0.1 0.1 7.2 10900 2.5 0.7
xn
bt o bt o
HN
R bh R bh
c chiu di hnh chiu ca tit din nghing nguy him nht ln mt mng theo
phng x.
2900 kN/mbtR : Cng chu ct ca b tng B20
Lc chng ct ca b tng :
2 3 2
4 (1 ) 1.5 (1 7.2 10 ) 900 2.5 0.7
0.55
3028.46( ) 2533.5( )
b n bt ob
R bh xQ
c
kN Q kN
Bn cnh theo iu kin lm vic ca btng ta xt thm :
3 2
3 0
0
(1 ) 0,6.(1 7,2.10 ).900.2,5x 0,7 665.26( )3028.46( )
2,5 2,5.11500.2,5.0,7 50312.5( )
b n bt
b
b
R bh kNQ kN
R bh kN
Tha iu kin chu ct theo phng x.
Xt theo phng y :
- Lc ct :
1 2 1201.46 1337.46 2538.92( )Q P P kN
- Lc chng ct ca b tng :
2
4 (1 )b n bt ob
R bhQ
c
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 58
Trong :
b4=1.5 xt nh hng ca b tng (=1.5 i vi b tng nng)
2900 kN/mbtR : Cng chu ct ca b tng B20
n h s nh hng ca lc dc:
31230.1 0.1 0.1 7.8 10900 2.5 0.7
y
n
bt o bt o
HN
R bh R bh
c chiu di hnh chiu ca tit din nghing nguy him nht ln mt mng theo
phng x.
Lc chng ct ca b tng :
2 3 2
4 (1 ) 1.5 (1 7.8 10 ) 900 2.5 0.7
0.55
3030.27( ) 2538.92( )
b n bt ob
R bhQ
c
kN Q kN
Bn cnh theo iu kin lm vic ca btng ta xt thm :
3 2
3 0
0
(1 ) 0,6 x(1 7,8.10 ) x 900 x 2.5x 0,7 666.66( )3030.27( )
2,5 2,5 11500 2,5 0,7 50312.5( )
b n bt
b
b
R bh kNQ kN
R bh x x x kN
Tha iu kin chu ct theo phng y.
2.2.6. KIM TRA SC CHU TI CA C C V NHM C C :
2.2.6.1. Kim tra sc chu ti ca cc n
- Ti trng ln nht tc dng ln cc:
24520 22 2 2.5 4795tt tt tb fN N xD xS x x kN
140 114 0.8 231.2tt tt tty y x dM M H xh x kNm
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 59
142 123 0.8 240.4tt tt ttx x y dM M H xh x kNm
max max
max/min 2 2
tttt tt
y x
i i
M xN M yP
n x y
Bng 2.7:Ti trng tc dng ln cc cc
c xi yi xi 2 yi
2 xi
2 yi2 Pi(KN)
1 -0.85 0.85 0.7225 0.7225
2.89 2.89
1201.46
2 0.85 0.85 0.7225 0.7225 1337.46
3 -0.85 -0.85 0.7225 0.7225 1060.04
4 0.85 -0.85 0.7225 0.7225 1196.04
Pmax=1337.46 kN0 (Tha)
2.2.6.2. Kim tra sc chu ti ca nhm cc:
- H s nhm:
21
1221
90
)1()1(1
nn
nnnn
Trong : o24.137.1
4.0arctanarctan
s
d
d: ng knh cc, d = 0.4 (m)
s=1.7m: khong cch gia cc ccn1: s hng cc: 31 n
n2: s cc trong mi hng 67.12 n
853.02290
2)12(2)12(24.131
Sc chu ti ca nhm cc:
0.853 4 1413.88 4824.16 kN 4795kNnh tta tkQ n Q N
Kt lun: H cc kh nng chu ti.
2.2.7. P O
Bng 2.8:Ti trng tc dng ln cc cc
c xi yi xi 2 yi
2 xi
2 yi2 Pi(KN)
1 -0.85 0.85 0.7225 0.7225
2.89 2.89
1201.46
2 0.85 0.85 0.7225 0.7225 1337.46
3 -0.85 -0.85 0.7225 0.7225 1060.04
4 0.85 -0.85 0.7225 0.7225 1196.04
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 60
Hnh 2.4: Mt bng mt ct ngm i mng
- Tnh thp t theo phng X:
2 2 4 4 1337.46 0,55 1196.04 0,55 1393.425i iM Pl P l P l kNm
2 2
0
1393.4250,11 0,441
0,9.11500.2,5.0,7m R
b b
M
R bh
1 1 2. 1 1 2 0,11 0,1167m
3 2 20 0,1167.0,9.11500.2,5.0,7 7.55 10 7550280000
b bs
s
R bhA m mm
R
an ton v gim bt chi ph thi cng chn thp 1625 c 27856 mmsA
Khong cch ct thp : 2500 50 2
15016
a mm
- Tnh thp t theo phng Y:
1 1 2 2 1201.46 0,55 1337.46 0,55 1398.056i iM Pl Pl P l kNm
2 2
0
1398.0560,11 0,441
0,9.11500.2,5.0,7m R
b b
M
R bh
1 1 2. 1 1 2 0,11 0,1167m
3 2 20 0,1167.0,9.11500.2,5.0,7 7.55 10 7550280000
b bs
s
R bhA m mm
R
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 61
an ton v gim bt chi ph thi cng chn thp 1625 c 27856 mmsA
Khong cch ct thp :2500 50 2
150 mm16
a
Vy chn thp b tr theo phng x: 1625 a150mm
B tr thp tng t theo phng y: 1625 a150mm
2.2.8.KIM TRA NH CA T N D V
LN MNG C C:
. .8.1. Xc n k c t c khi mng quy c:
Hnh 2.5: B tr khi
mng
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 62
Bng 2.9:Gi tr trung bnh ca gc ni ma st (cn ca TTGH II
p z
(m)
hi
(m) i (
o) ihi
2a 2
1.4 11.05 15.47 3.4
3 3.4
1.6 14.25 22.8 5
4 5
3.6 13.667 49.2012 8.6
5 8.6
2.4 13.283 31.8792 11
6a 11
4 26.45 105.8 15
6b 15
16.4 29.383 481.8812 31.4
ng 29.4 707.0316
c ni ma st t ung b n 24.05
- Tnh ton gc nh hng ca mng khi:
24.056.0125
4 4
ootb
2 tan 2.1 2 tan(6.0125 ) 29.4 8.29 moqu quL B X hi
- Din tch y mng quy c:
28.29 8.29 68.72 mqu qu quA L B x
2.2.8.2. Kim t a iu kin n nh ca t nn di y mng quy c:
- Sc chu ti cc hn t nn di y mng quy c:
'1 2 ( * )II qu II II IItc
m mR A B B h D c
k
Trong :
- m1 =1.2 v m2 = 1.3 (ct mn bo ha nc L/HA =1.098; B =5.3865; D =7.78
- cII= 1.91 (kN/m2): Lc dnh ca t su di y mng quy c ly
theo TTGH II.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 63
- II*=9.738 (kN/m
3): trng lng ring trung bnh ca lp t nm trn mi
cc theo TTGH II.
- II=9.869 (kN/m
3): trng lng ring trung bnh ca lp t nm di mi
cc theo TTGH II.
- h: su y mng quy c tnh t y mng.
Bng 2.10: Tnh ton gi tr tb.
z
(m) li (m)
'i (kN/m
3)
i = 'i *li
(kN/m2)
2a 1.3
2.1 9.255 19.436 3.4
3 3.4
1.6 10.04 16.064 5
4 5
3.6 9.762 35.143 8.6
5 8.6
2.4 9.811 23.546 11
6a 11
4 9.27 37.080 15
6b 15
16.4 9.869 161.852 31.4
ng sut hu hiu bn thn t nn ti mi cc 'v
293.121
Trng lng ring trung bnh ca lp t nm trn khi mng quy c
tb 9.738
=>Sc chu ti cc hn ca t nn di y mng khi quy c:
21.2 1.3 (1.098 8.29 9.869 5.3865 29.4 9.738 7.78 1.91) 2569.06 kN/m1.0
IIR
- Lc tc dng ln y mng quy c
y
tc
y
x
tc
x
qu
tc
qu
W
M
W
M
A
Np
max
Trong :
452022 2 68.72 68.72 9.738 29.4 4 0.16 29.4 (25 9.738)
1.
15
26915.63kN
tc tc
qu tb f qu qu i coc coc coc bt tbN N D A A h n A L
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 64
140 114 0.8219.3
1.15 1.15 1.15 1.15
tt ttytc x d
y
M H xh xM kNm
142 123 0.8209.04
1.15 1.15 1.15 1.15
tttty dtc x
x
H xhM xM kNm
- ng sut ln nht ti y mng quy c :
y
tc
y
x
tc
x
qu
tc
qu
W
M
W
M
A
Np
max
2
max 3 3
2
26915.63 219.3 209.046 6 396.18 kN/m 1.2
68.72 8.29 8.29
1.2 2569.06 3082.87 kN/m
IIp x x R
- ng sut nh nht ti y mng quy c :
y
tc
y
x
tc
x
qu
tc
qu
W
M
W
M
A
Np
min
2
max 3 3
26915.63 219.3 209.046 6 387.16 kN/m 0
68.72 8.29 8.29p x x
- ng sut trung bnh ti y mng quy uc :
2 226915.63 391.67kN/m 2569.06 kN/m68.72
tc
qu
tb II
qu
Np R
A
Kt lun: Vy mng tha iu kin n nh.
2.2.8.3. Kim t a ln ca mng khi quy c:
- Kim tra ln mng khi quy c theo phng php tng phn t qua cc bc:
p lc gy ln:
' '
1 1 1 1 2 1
2
( ( ) )
391.67 1.3 18 (9.255 (2 1.3) 9.738 29.4) 122.26 /
gl tb i i tb a f tb cocp p xl xh p h x D h xL
kN m
Pha di khi mng l lp ct ng nht.Chia thnh tng lp 0,5m.
Bng2.11:Mu c kt 3-11
p sut (kN/m2)
25 50 100 200 400 800
s ng
0.769 0.751 0.725 0.69 0.654 0.61
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 65
ng cong nn ln do cc p lc
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 66
591.658 665.748 0.635 0.630 0.17
36.9 -5.5 1.327 0.557 68.10 618.798
648.405 716.504 0.631 0.626 0.14
37.4 -6 1.448 0.509 62.23 678.012
710.086 772.316 0.627 0.623 0.12
37.9 -6.5 1.568 0.462 56.48 742.160
Tng l n 3.96
Tng ln S3.96 (cm) Mng tha yu cu ln.
2.2.9. KIM TRA C C CHU CU LP:
Cc b tr 2 mc cu v dng mc cu trong s cu cc dng cc.
q=K d2=1.5x25x0.4
2=6 (KN/m)
- Khi cu cc:
Hnh 2.7: Ni lc khi b tr 2 mc cu
Moment ln nht : M1=0.0214qL2=0.0214x6x10
2=12.84(KNm)
- Khi dng cc:
Hnh 2.8: Ni lc khi b tr 1 mc cu
0.207L 0.207L
L
M2
0.293L
L
M1
q
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 67
Moment ln nht :M2=0.068qL2=0.068x6x10
2=40.8(kNm)
- M=max(M1;M2)=M2=40.8 (kNm)
- Tnh thp trong cc:
2 2
0
40.80.08 0.441
0.9 11500 0.4 0.35m R
b b
M
R bh x x x
Tha iu kin s dng ct n
1 1 2 1 1 2 0.08 0.084m x
4 2 20.084 0.9 11500 0.4 0.35 4.34 10 4.34280000
b b os
s
R bh x x x xA x m cm
R
Vy thp chn trong cc l 2 22 mi pha (As =7.6 cm2) l tha mn.
2.2.10.NG D NG SAP2000 KIM TRA CHUYN V NGANG:
M hnh ha t xung quanh cc l mi trng n hi tuyn tnh (m hnh
Winkler) bng phn mm SAP2000V14, vi h s nn p dng tiu chun TCXDVN
205:1998 ca cc lp tng ng nh sau:
Bng 2.13: H s t l tra theo bng G1 TVXD 205-1998
Lp hi (m) IL K (kN/m4) Tn lp
2a 1.4 0.5 5000 St pha ct ln t si sn trng thi do mm
3 1.6 0.23 6620 St ln ct trng thi do cng
4 3.6 0.3 6200 St pha ct trng thi do cng
5 2.4 0.76 2500 Ct pha st trng thi do
6a 4 - 4000 Ct mn trng thi bi ri
6b 16.4 - 6000 Ct mn trng thi cht va
- Chia cc theo phng ng thnh tng on nh, mi on cc c chiu di 0.1
mt, chiu rng 0.4 m. Ta c cc h s K quy i nh sau:
Cz1=z*K1=0.05x(0.1/20.45000) =5 kN/m
Cz2 = Cz3 = Cz4 =.= Cz13 = 0.7x(0.10.45000) = 140kN/m
Cz14 = 1.4x(0.10.45000+0.10.46620)/2 = 325.36 kN/m
Cz15 = Cz16=.= Cz29 = 2.2x(0.10.46620)= 582.56 kN/m
Cz30= 3x(0.10.46620+0.10.46200)/2 = 769.2 kN/m
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 68
Cz31= Cz32 =.=Cz65= 4.8x(0.10.46200)= 1190.4 kN/m
Cz66= 6.6x(0.10.46200+0.10.42500)/2 =1148.4 kN/m
Cz67= Cz68 =.=Cz89= 7.8x(0.10.42500) =3120 kN/m
Cz90= 9x(0.10.42500+0.10.44000)/2 = 1170 kN/m
Cz91= Cz92 =.= Cz129= 11x(0.10.44000 )= 1760 kN/m
Cz130= 13x(0.10.44000+0.10.46000)/2 = 2600kN/m
Cz131= Cz132 =.=Cz293= 21.2x(0.10.46000) = 5088 kN/m
Cz294= 29.4x(0.1/20.46000) = 3528kN/m
cng quy v l xo gn di mi cc:
122.26 68.72265205.404( / )
0.2 4 0.2 0.0396
gl qu
m
lun
p AC kN m
n S
Vt liu:
B tng B30c Rb=17Mpa=17000kN/m2; B20c Rb=11.5Mpa=11500kN/m
2
Thp AII c Rs=280Mpa= 280000kN/m2.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 69
. .1 .1. n t p ng x
Bng 2.14: Tng hp ni lc cc the phng x (m hnh 3D)
M hnh t ti ngang Kt qu m men Kt qu lc ct Kt qu
chuyn v
Trn cc c ni lc ln nht
(2D)
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 70
T kt qu xut ra t SAP2000, ta c cc gi tr m men, lc ct v chuyn v ngang nh
sau:
maxmax
`
max
33.72kNm
28.51 kN
U 0.005 m 5 m
m
zx
x
x
t a i n
Q
gmM
* Kim tra cc chu momen:
max
2 2
33.720.0505 0.432
0.9 14500 0.4 (0.4 0.05)
1 1 2 1 1 2 0.0505 0.05184
1 0.5 1 0.5 0.05184 0.9741
zm R
b o
m
M
R b h
Din tch thp yu cu:
max
4 2 2 2
33.72
0.9741 280000 (0.4 0.05)
3.53 10 m 353 mm =760 mm (2 22)
yc zs
s o
s
MA
R h
A
Vy ct thp trong cc m b iu kin chu lc momen un do ti ngang.
* Kim tra cc chu ct:
max 28.51 kNxQ
Kim tra iu kin tnh ct ai :
0 max0 6 0 6 1050 0.4 0.4 0 05 88.2 kN 28.51 kNbt. R b h = . . = > Q =
Vy cc tha iu kin chu ct.
* Kim tra chuyn v u cc
Chuyn v u cc l Umax = 5 mm < 1%Lcc = 29.4 mm.
Vy tha iu kin bin dng.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 71
. .1 . . n t p ng y
Bng 2.15: Tng hp ni lc cc the phng y
M hnh t ti ngang Kt qu m men Kt qu lc ct Kt qu
chuyn v
Trn cc c ni lc ln nht
(2D)
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 72
T kt qu xut ra t SAP2000, ta c cc gi tr m men, lc ct v chuyn v ngang nh
sau:
maxmax
m
`
ax
36.84kNm
30.76 kN
U 0.0053 m 5 3
. mm
zx
x
x
t a i ngmM
Q
* Kim tra cc chu momen:
max
2 2
36.840.0465 0.432
0.9 17000 0.4 (0.4 0.05)
1 1 2 1 1 2 0.0465 0.0476
1 0.5 1 0.5 0.0476 0.976
zm R
b o
m
M
R b h
- Din tch thp yu cu:
max
4 2 2 2
36.84
0.9760 280000 (0.4 0.05)
3.85 10 m 385 mm =760 mm (2 22)
yc zs
s o
s
MA
R h
A
Vy ct thp trong cc m b iu kin chu lc momen un do ti ngang.
* Kim tra cc chu ct:
max 30.76kNyQ
Kim tra iu kin tnh ct ai :
0 max0 6 0 6 1200 0.4 0.4 0 05 100.8 kN 30.76kNbt. R b h = . . = > Q =
Vy cc tha iu kin chu ct.
* Kim tra chuyn v u cc
Chuyn v u cc l Umax = 5.3mm < 1%Lcc = 29.4 mm.
Vy tha iu kin bin dng.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 73
2.2.11. KIM TRA C C CHU TI NGANG (theo ph l c G TCXD 205
1998):
Momen ti chn i chuyn thnh lc dc trong ct, nn cc khng c momen tc
dng.Ch c lc ngang tc dng u cc (tng ng y i).
- Momen qun tnh tit din ngang ca cc:
- Mun n hi ca b tng B30:
- Chiu rng quy c cc:
V nn theo TCXD 205:1998
- H s nn:
Trong K h s t l (kN/
Khi tnh ton cc chu ti trng ngang, thc cht cc ch lm vic vi mt on
cc c chiu di tnh t y i cn gi l chiu su nh hng ca nn t khi
cc chu ti trng ngang
Chiu su nh hng c xc nh t cng thc thc nghim
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 74
Hnh 2.9: su nh hng ca cc
Bng tra K
Lp hi (m) IL K (kN/m4) Tn lp
2a 1.4 0.5 5000 St pha ct ln t si sn trng thi do mm
3 1.6 0.23 6620 St ln ct trng thi do cng
4 3.6 0.3 6200 St pha ct trng thi do cng
5 2.4 0.76 2500 Ct pha st trng thi do
6a 4 - 4000 Ct mn trng thi bi ri
6b 16.4 - 6000 Ct mn trng thi cht va
4
5000 1.4 6620 1.6 6200 3.6 2500 2.4 4000 4 6000 16.4
29.4
5453( / )
i i
i
k l x x x x x xK
l
kN m
=>H s bin dng:
- Chiu di cc trong t tnh i:
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 75
- Tra bng G2 ph lc G ca TCXD 205:1998 phn cc ta ln t vi
ta c cc h s nh sau:
- Chuyn v ngang ca tit din cc bi lc n v gy ra:
- Chuyn v ngang ca tit din cc bi lc n v gy ra:
- Gc xoay ca tit din cc bi lc n v gy ra:
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 76
- Lc ct v momen un ti u cc:
- Chuyn v ngang v gc xoay ca cc ti cao trnh mt t:
- Tnh ton chuyn v ngang v gc xoay ca u cc theo cng thc:
chiu di cc t y i n mt t, cc i thp
Kim tra chuyn v ngang ti u cc:
Nh vy cc tha iu kin v chuyn v ngang
Kim tra chuyn v xoay ti u cc:
Cc gi tr chuyn v ca u cc theo c hai phng u gn bng 0, iu ny
ni rng vic tnh ton lm ng.
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 77
2.2.12. TNH TON NI LC TRONG C C (theo TCXD 205 1998):
p lc (kN/ ), moment un (kNm), lc ct (kN) trong cc tit din cc c
tnh theo cng thc sau (trch t mc G7 ph lc G ca TCXD 205:1998):
(
)
Trong : ( Xt theo phng chu lc ln hn: phng y trong h chn)
, ,
, - chiu su tnh i, , vi
Cc h s A1, A3, A4, B1, B3, B4, D1, D3, D4 tra bng G3 ph lc G TCXD 205:1998
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 78
Bng 2.16: Momen dc thn cc
Z s vi y i cc,m )
Ze su quy i t a bng,m )
A3 B3 C3 D3 Mz
(kNm)
0 0 0 0 1 0 -36.84
-0.2 0.1 0 0 1 0.1 -31.82
-0.3 0.2 -0.001 0 1 0.2 -26.86
-0.5 0.3 -0.004 -0.001 1 0.3 -22.00
-0.6 0.4 -0.011 -0.002 1 0.4 -17.37
-0.8 0.5 -0.021 -0.005 0.999 0.5 -12.83
-1.0 0.6 -0.036 -0.011 0.998 0.6 -8.53
-1.1 0.7 -0.057 -0.02 0.996 0.699 -4.54
-1.3 0.8 -0.085 -0.034 0.992 0.799 -0.74
-1.4 0.9 -0.121 -0.055 0.985 0.897 2.72
-1.6 1 -0.167 -0.083 0.975 0.994 5.79
-1.7 1.1 -0.222 -0.122 0.96 1.09 8.66
-1.9 1.2 -0.287 -0.173 0.938 1.183 11.25
-2.1 1.3 -0.365 -0.238 0.907 1.273 13.51
-2.2 1.4 -0.455 -0.319 0.866 1.358 15.45
-2.4 1.5 -0.559 -0.42 0.781 1.437 18.23
-2.5 1.6 -0.676 -0.543 0.739 1.507 18.59
-2.7 1.7 -0.808 -0.691 0.646 1.566 19.81
-2.9 1.8 -0.956 -0.867 0.53 1.612 20.75
-3.0 1.9 -1.118 -1.074 0.385 1.64 21.55
-3.2 2 -1.295 -1.314 0.207 1.646 22.13
-3.5 2.2 -1.693 -1.906 -0.271 1.575 22.86
-3.8 2.4 -2.141 -2.663 -0.941 1.352 22.77
-4.1 2.6 -2.621 -3.6 -1.877 0.917 22.82
-4.4 2.8 -3.103 -4.718 -3.408 0.197 33.19
-4.8 3 -3.541 -6 -4.688 -0.891 20.89
-5.5 3.5 -3.919 -9.544 -10.34 -5.854 13.70
-6.3 4 -1.614 -11.73 -17.919 -15.08 -5.78
Hnh 2.10: Biu momen dc thn cc
-7
-6
-5
-4
-3
-2
-1
0
-60.00 -40.00 -20.00 0.00 20.00 40.00
m n dc t n cc z k m)
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 79
Bng 2.17: Lc c t dc thn cc
Z s vi y i cc,m )
Z su quy i t a bng,m )
A4 B4 C4 D4 Qz(kN)
0.0 0 0 0 0 1 30.8
-0.2 0.1 -0.005 0 0 1 30.6
-0.3 0.2 -0.02 -0.003 0 1 30.1
-0.5 0.3 -0.045 -0.009 -0.001 1 29.3
-0.6 0.4 -0.08 -0.021 -0.003 1 28.2
-0.8 0.5 -0.125 -0.042 -0.008 0.999 27.0
-1.0 0.6 -0.18 -0.072 -0.016 0.997 25.5
-1.1 0.7 -0.245 -0.114 -0.03 0.994 23.8
-1.3 0.8 -0.32 -0.171 -0.051 0.989 22.1
-1.4 0.9 -0.404 -0.243 -0.082 0.98 20.3
-1.6 1 -0.499 -0.333 -0.125 0.967 18.4
-1.7 1.1 -0.603 -0.443 -0.183 0.946 16.5
-1.9 1.2 -0.716 -0.575 -0.259 0.917 14.7
-2.1 1.3 -0.838 -0.73 -0.356 0.876 12.9
-2.2 1.4 -0.967 -0.91 -0.479 0.821 11.2
-2.4 1.5 -1.105 -1.116 -0.63 0.747 9.5
-2.5 1.6 -1.248 -1.35 -0.815 0.652 8.0
-2.7 1.7 -1.396 -1.613 -1.036 0.529 6.6
-2.9 1.8 -1.547 -1.906 -1.299 0.374 5.4
-3.0 1.9 -1.699 -2.227 -1.608 0.181 4.2
-3.2 2 -1.848 -2.578 -1.966 -0.057 3.1
-3.5 2.2 -2.125 -3.36 -2.849 -0.692 1.4
-3.8 2.4 -2.339 -4.228 -3.973 -1.592 -0.1
-4.1 2.6 -2.437 -5.14 -5.355 -2.821 -1.4
Hnh 2.11: Biu lc c t dc thn cc
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
-5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0
c ct Qz k )
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 80
Bng 2.18: Gi tr p lc ngang
Z su s vi y i,m)
Z su quy i t a bng,m)
A1 B1 C1 D1 k z
(kPa)
0.0 0 1 0 0 0 5000 0.00
-0.2 0.1 1 0.1 0.005 0 5000 1.86
-0.3 0.2 1 0.2 0.02 0.001 5000 3.58
-0.5 0.3 1 0.3 0.045 0.004 5000 5.13
-0.6 0.4 1 0.4 0.08 0.011 5000 6.50
-0.8 0.5 1 0.5 0.125 0.021 5000 7.67
-1.0 0.6 0.999 0.6 0.18 0.036 5000 8.62
-1.1 0.7 0.999 0.7 0.245 0.057 5000 9.36
-1.3 0.8 0.997 0.799 0.32 0.085 5000 9.89
-1.4 0.9 0.995 0.899 0.405 0.121 5000 10.21
-1.6 1 0.992 0.997 0.499 0.167 6620 13.74
-1.7 1.1 0.987 1.095 0.604 0.222 6620 13.68
-1.9 1.2 0.979 1.192 0.718 0.288 6620 13.39
-2.1 1.3 0.969 1.287 0.841 0.365 6620 12.93
-2.2 1.4 0.955 1.379 0.974 0.456 6620 12.32
-2.4 1.5 0.937 1.468 1.115 0.56 6620 11.60
-2.5 1.6 0.913 1.553 1.264 0.678 6620 10.76
-2.7 1.7 0.882 1.633 1.421 0.812 6620 9.86
-2.9 1.8 0.843 1.706 1.584 0.961 6620 8.94
-3.0 1.9 0.795 1.77 1.752 1.126 6620 8.05
-3.2 2 0.735 1.823 1.942 1.308 6200 6.19
-3.5 2.2 0.575 1.887 2.272 1.72 6200 5.40
-3.8 2.4 0.347 1.874 2.609 2.195 6200 4.61
-4.1 2.6 0.033 1.755 2.907 2.724 6200 4.62
-4.4 2.8 -0.385 1.49 3.128 3.288 6200 5.72
-4.8 3 -0.928 1.037 3.225 3.858 6200 7.84
-5.5 3.5 -2.928 -1.272 2.463 4.98 6200 19.63
-6.3 4 -5.854 -5.941 -0.927 4.548 6200 39.63
-
GVHD: Ths. Hong Th Thao
NHM MNG CC Trang 81
Hnh 2.12: Biu p lc ngang
D = 0.4 m < 0.6 m nn khng cn kim tra iu kin n nh t nn quanh cc
-7.0
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
0.00 10.00 20.00 30.00 40.00 50.00
p lc ngang (kPa)