02 cong thuc tinh toan btct 2256
TRANSCRIPT
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CNG THC TNH TON CC CU KIN
KT CU B TNG CT THP
I- CU KIN CHU NN NG TM.1. S b xc nh din tch tit din:
n
bR
kNF =
k : l s k ti mmen un.T chn s b kch thc tit din b, h hoc D.k = 1,1 - 1,5 :ct trong nh : k = 1,1ct bin : k = 1,3ct gc : k = 1,52. Kim tra iu kin n nh:Tit din vung, ch nht:
mnh : 300
= bl
Tit din khc:
mnh : 120min
0 =r
l
Lin kt hai u khp : lo = l(chiu di thc); nu l ct th lthay bng H.Lin kt hai u ngm : l0 = 0,5lLin kt mt u ngm mt u khp : l0 = 0,7lLin kt mt u ngm kia t do : l0 = 2lCt nh nhiu tng nhiu nhp l0 = 0,7l;Ct nh mt tng l0 ly theo bng .
3. Cc loi bi ton:a- Kim tra kh nng chu lc:N (RnFb+ R aFa)Khi cnh ct < 30cm, c theo phng ng thay Rn bng 0,85RnH s un dc tra bng .Bng : H s
=b
lo 8 10 12 14 16 18 20 22 24 26 28 30
=D
lo 7 8,5 10,5 12 14 15,5 17 19 21 22,5 24 26
1 0,98 0,96 0,93 0,89 0,85 0,81 0,77 0,73 0,68 0,64 0,59
b- Tnh ct thp dc:+ Bit Fb, lo, N, Rn, R a
Fa =
a
n
R
FbRN
'
+ Chn v b tr ct thp+ Kim tra hm lng 0,4% a 3,5%
V d :
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Mt ct c hai u lin kt ngm c chiu cao H = 7m, tit din hnh vung 30x30 cmchu mt lc nn N l 100T. Dng b tng mc 200 thp CII (Ra= 2600kg/cm2). Tnh ct thpchu lc ca ct.
Gii:lo = 0,5 x H = 0,5 x 7 = 3,5m.
b = 30
350=
b
lo
= 11,7; j = 0,97
Fa =2600
30.30.9097,0
100000
= 8,91cm2
Chn 4 18 c Fa = 10,18cm2 > 8,91cm2
Bng : Chiu di tnh ton ca ct nh mt tng
c trng ca nh v ct
l0 khi tnh ct trong mt phng
Ca khungngang
Thng gc vi khung ngangKhi c Khi khng c
Lin ktt trong mt phngca hng ct dc
1 2 3 4 5 6 7
1. Nh c cu chyKhi c k nTi trng cu chy
Phn ct didm cu chy
Lin tcKhng lin tc
1,5H11,2H1
0,8 H10,8 H1
1,2H10,8H1
Phn ct trndm cu chy
Lin tcKhng lin tc
2,0H22,0H2
1,5H21,5H2
2,0H22,0H2
1. Nh c cu chyKhi khng k nti trng cu chy
Phn ct didm cu chyca nh
Mt nhpNhiu nhp
1,5H1,2H
0,8 H10,8 H1
1,2H1,2H
Phn ct trndm cu chy
Lin tcKhng lin tc
2,5H22,0H2
1,5H21,5H2
2,0H21,5H2
2. Nh khng ccu chy
Ct c git cp
Phn ct di
ca nh
Mt nhp
Nhiu nhp
1,5H
1,2H
0,8 H
0,8 H
1,2H
1,2HPhn ct trn 2,5H2 0,8H2 2,5H2Ct c tit dinkhng I
Nh mt nhpNh nhiu nhp
1,5H1,2H
0,8 H0,8 H
1,2H1,2H
Ghi ch:H- Chiu cao ton b ct t mt mng n kt cu miH1 - Chiu cao phn ct di t mt mng n mt vai ct (Hd)H2 - Chiu cao phn ct trn t vai ct n kt cu mi (Ht)
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II- CU KIN CHU NN LCH TM (Tit din ch nht).1. t thp i xnga- Tnh lnh tm ban u eoeo = e01 + eng
lnh tm do ni lc e01 =N
M
lch tm ngu nhin eng =25h (do sai s thi cng) nhng lun lun 2cm
b- Tnh h s un dc:
=thN
N1
1
Lc nn ti hn:
Nth = )(4,620
aabb
dh
JEJEK
S
l+
S l h s ti lnh tmKhi eo < 0,05h ly S = 0,84
Khi 0,05h < eo < 5h ly S =
h
e1,0
11,0
0+
Khi e0 > 5h ly S = 0,122Kdh : l h s k ti tnh cht di hn ca ti trng
Kdh = 1+
2
2h
NM
hNM dhdh
+
+
Nu khng tch ring Mdh , Ndh th ly Kdh = 2Nu Mdh ngc du vi M th Mdh mang du m.Nu Kdh < 1 phi ly Kdk= 1.Mdh; Ndh l mmen v lc dc do ti trng di hn gy ra.M un n hi ca thp Ea = 2,1 x 106 kg/cm2
M men qun tnh ca thp: Ja = tbh0 (0,5h - a)2
Gi thit t = 0,8 1,2% (hm lng thp tng cng)
c- Tnh lch tm tnh ton:
e = eo + 2h
- a
e = eo -2
h+ a
d- Xc nh trng hp lch tm
x =bR
N
n .
Nu x < oho th lnh tm lnNu x oho th lch tm b
Bng : Tr s oCng chu ko tnh ton ca
ct thp (kg/cm3)Tr s o ng vi b tng
200# 250# - 300# 350# - 400# 500# 3000 0,62 0,58 0,55 0,52
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e- Tnh ct thp dc, Trng hp lch tm ln (x < oho)- Nu x > 2a
Fa = Fa =)'ah('R
)x5,0he(N
oa
o
+
- Nu x 2aFa = Fa =
)'ah(R
'Ne
oa
- Kim tra li hm lng min = 0,4% max = 3,5%
% =o
aa
h.b
'FF +100%
V t ( l hm lng tng cng)Nu khc nhiu vi t gi thit th dng tnh li Nth v ( ch nn ly 0,25%), Trng hp lnh tm b (x > oho)
- Tnh x, nu eo 0,2h0 thx= h - 00
0
e4,1h
h5,08,1
+
nu e0 > 0,2h0 thx = 1,8 (eogh - eo) +ohoeogh = 0,4 (1,25h -oho)
Fa = Fa =)'ah('R
)'x5,0h('bxRNe
oa
on
Kim tra li
V d :Tnh ct thp i xng cho mt ct lp ghp c tit din b = 40cm, h = 60cm, b tng
mc 200, ct thp nhm A-II, chiu di tnh ton l0 = 7,8m. Ni lc tnh ton M = 26Tm, N =96T, trong Mdh = 12Tm, Ndh = 61,3T.
Gii:Tra cc s liu: Rn = 90kg/Cm2; Ra = 2800kg/cm2; Eb= 240000 kg/cm2
Ea = 2100000 kg/cm2; 0 =0,62;Ao = 0,428. lch tm eo1 = M/N = 26/96 = 0,27m = 27cm. lch tm ngu nhin ly bng eng =
h/25 = 60/25 = 2,4cm. lch tm eo = 27 + 2,4 = 29,4cm.Gi thit a =a = 4cm; ho = 60 - 4 = 56cm.
604,290 =
h
e= 0,49
Tnh S =286,0
0491,0
11,01,0
1,0
11,0
0
=+
=++
h
e
Kdh= 1 +3,09626
3,03,6112
+
+
= 1,555
Jb =12
6040
12
33 =
bh= 720.000cm4
Gi thit t% = 1%, tnh Ja = tbh0 (0,5h - a)2 = 0,01 x 40 x 56 (30 -40)4 = 15142 cm4Tnh lc dc ti hn
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Nth = 78493910151421,2720240555,1
286,0
720
4,6 62
=
+ kg
=139,1
939,784
961
1
1
1=
=
thN
N
e = 1,139 x 29,4 + 30 -4 = 59,5 cmXc nh chiu cao vng chu nn:
x = cmbR
N
n
6,264090
000.96=
=
x < 0h0 = 0,62 x 36 = 34,7 cm; x> 2a = 8cmXy ra trng hp nn lch tm ln. Tnh Fa
Fa = Fa =)456(2800
)3,13565,59(96000
)'ah(R
)x5,0he(N
0a
0
+
=+
= 11,08 cm2
Kim tra: =5640
08,11
= 0,00495 = 0, 495% > min = 0,2%
t = 1005640
08,1108,11
+
= 0,99%, tc l sai lch so vi gi thit 1% l khng ng k.
Chn ct thp mi pha 3 22 (Fa = 11,4cm2). Ct ai dng 6 (khng di 1/4 x 22 =5,5mm) vi khong cch u = 30cm (nh hn 15 x 2,2 = 33cm).
4. t thp khng i xnga. Tnh lch tm ban u e0 (nh mc 1)b. Tnh h s un dc (nh mc 1)c. Tnh lch tm tnh ton e, e(nh mc 1)d. Xc nh trng hp lch tm.
Nu e0 e0gh = 0,4 (1,25h - 0h0) cu kin chu nn lch tm ln.Nu e0 < eogh cu kin chu nn lch tm be. Tnh ct thp dc) Trng hp lch tm ln
Fa =)'(' 0
2
0
ahR
bhRANe
a
no
Fa ='
a
a
'
a
a
0n0 FR
R
R
NbhR+
) Trng hp lch tm b
Khi e0 0,2h0 tnh xx= h - (1,8 +
0
5,0
h
h- 1,4 0) e0
Khi e0 > 0,2h0x= 1,8 (e0gh - e0) + 0h0
Fa =)'ah(R
)x5,0h(bRNe
0
'
a
0n
Khi e0 0,15h0, Fa t theo cu to. Khi e0 < 0,15h0
Fa =)'ah(
)ax5,0(bR'Ne
0a
n
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a = aRh
e'1
0
0
Kim tra li hm lnga v a phi > 0,002 bh0min < = a +a < max
> 0,25% tnh li Nth v Vi =
2
t+
V d :Thp s liu nh v d 2 nhng yu cu tnh ct thp Fa v F a khng i xng.Gii:Tnh e0 = 1,139 x29,4 cm,tnh e0gh = 0,40 x (1,25 h - 0h0)= 0,40 (1,25 x 60 - 0,62 x 56) = 16,1 cm < e0 = 33,4cm
Nh vy phi tnh ct thp theo trng hp lch tm ln.Fa =
2
2
0
'
a
2
0n0 cm04,6)456(2800
564090428,05,5996000
)'ah(R
bhRANe=
=
Kim tra a% = 1005640
04,6
= 0,267 % > min = 0,2%
Fa = ''
0
a
a
a
a
on FR
R
R
NbhR+
= 04,62800
9600056409062,0+
= 16,39cm2
Chn ct chu nn l 2 20 (Fa = 6,28cm2
) v ct chu ko l 2 25 + 2 22 (Fa =17,42cm2). Chn ct ai nh sau: ng knh 8mm khong cch 30cm.
V d :Cc s liu u ging nh v d 2 nhng ni lc tnh ton l: M = 9,36Tm; N = 260T
trong Mdh = 5Tm; Ndh = 180 TGii:Tnh e0 c th n lch tm ngu nhin:
e0 cm6260
93660
25
1=+
S = 65,01,0
60
61,0
11,0=+
+
Kdh = 1+ 68,13,026036,9
3,01805=
++
S dng nhng kt qu tnh v d trn
Nth = KG66
210218,110151421,2720240
68,1
65,0
720
4,6=
+
=27,1
1218
260
1
1=
e0 = 1,27 x 6 = 7,62
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eogh = 16,1 cm ; h >e0 tc l ri vo trng hp lch tm b.e0 < 0,15h0 = 0,15 x 56 = 8,4cmTnh Fa vi x c tnh nh sau:
x = h - cm8,4862,762,04,156
605,08,1 =
+
e = e0 + ah
2 = 7,62 + 30 - 4 = 33,62
Fa =291,21
)456(2800
)8,485,056(8,48409062,33260000cm=
Fa c tnh nh sau:e = 0,5h - e0 - a = 30 - 7,62 - 4 = 18,38cm;
a =Ra2
0
0 /241956
62,7128001 cmKG
h
e=
=
Fa = 49,9)456(2419
)48,485,0(8,48409038,18260000=
cm2
Famin = 0,002 x 40 x56 = 4,48 cm2< FaChn ct thp Fa l 2 28 + 225 (Fa = 22,14cm2), chn ct thp Fa l 2 25 (Fa =
9,82cm2, ct ai chn 8, bc u = 30cm.
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III- CU KIN CHU KO. (Tit din ch nht)1. Cu kin chu ko ng tm
Fa =aR
N; min = 0,4%
2. Cu kin chu ko lnh tm (tit din ch nht)
eo =N
Mkhi eo 0,5h a: lch tm b
khi e0 > 0,5h a: lch tm lna- Lch tm b
Fa =)'ah('R
Ne
oa
Fa =)'ah(FR
Ne
oaa
'
e = 0,5h eo a
e = 0,5h + eo - a = a + a min = 0,1%.b- Lch tm ln
Fa =)'ah(R
bhRANe
o
'
a
2
0no
e= eo 0,5h + a
Fa =a
aaono
R
FRbhRN ''++
c- Kim tra kh nng chu lc
x =bR
N'FRFRn
a
'
aaa
Khi 2a x < ohoNe Rnbx (ho 0,5x) + RaFa (ho a)Khi x > oho thay x = oho vo cng thc NeKhi x < 2a; Ne RaFa (ho a)d- Tnh theo lc ctiu kin Q koRn bhoko = 0,35 vi BT 400#.Khi Q k1Rkbh0 0,2N, t ai theo cu to nh cu kin chu un.
Khi Q > k1Rkbh0 0,2N, tnh ai m bo iu kin:Q 2,8 d0ok qh)N2,0bhR( k1 = 0,6 i vi thanh chu kok1 = 0,8 i vi bn chu koq tnh nh trong cu kin chu un
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IV- CU KIN CHU UN. (Tit din thng gc)1. Tit din ch nhth0 = h - a
A = 20bhR
M
n
Nu A A0 tnh theo ct nNu A0 < A < 0,5 tng h hoc tnh theo ct kpDng thp c Ra 3000 Kg/cm3 thA0 = 0,428 khi BT- 200#A0 = 0,412 khi BT = 250 300#a. t ct n:- T A tra bng 4-11 c hoc, hoc tnh = 1- A21 ; = 0,5 (1 + A21 ); l t s ca chiu cao vng nn (x) v chiu cao tnh ton ca
tit din (h0)Bi ton:
- Tnh din tch ct thp dc Fa
Fa =Ra
bhRn 0
hoc Fa =0hR
M
a
Kim tra >min ; max =a
n
R
R0
0 = 0,62 khi BT- 200#0 = 0,58 khi BT-250 300#
Bi ton:- Kim tra kh nng chu lc lc khi bit b, h, Fa, b tng v thp
=0bhR
FR
n
aa, t tra bng 4-11 ra A hoc A =(1- 0,5)
[M] = ARnb 20h
V d :Tnh ct thp (Fa) cho dm c tit din ch nht vi kch thc b x h = 25 x 50cm. Dng
mc b tng 200, thp nhm CII, mmen tnh ton l M = 17,6Tm.Gii:
B tng 200 c Rn = 90Kg/cm3;gi thit a = 4cm; h0 =504= 46cm
A =2462590
1780000
= 0,37 < A0 = 0,428
= 1 - 37.021 = 0,49 25mm.
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V d :Mt dm c tit din ch nht vi kch thc b x h = 20 x 45cm, trong tit din vng
ko t 320 nhm AII, mc b tng 200; h0 = 45 - 3 = 42cm.Gii:B tng mc 200 c Rn = 90kG/cm3Thp nhm AII c Rn 2800kG/cm3
3 20 c Fa = 9,41 cm2
=422090
280041,9
= 0,349 < 0 = 0,42
A = 0,349 (1- 0,5 0,349) = 0,288Mgh = 0,288 90.20.422
= 914458 kgcm = 9,14 Tm
b- t ct kpBi ton: Tnh din tch ct thp dc:
Ct chu nn: Fa =)'(
0
'
2
00
ahRbhRAM
a
n
Ct chu ko: Fa = 0'0
a
a
n
a
n FR
R
R
bhR+
Bi ton: Kim tra kh nng chu lc khi bit b, h, Fa, Fa b tng, thp.
=0
''
bhR
FRFR
n
aaaa
Nu > 0 [M] = A0Rnb 'a'
a
2
0 FRh + (h0 a)
Nu 2,73Tm - khng bo m kh nng chu lc, phi tng ct thp v tnh
li.Tng ct ai thnh 10, f = 0,785cm2. Tng ct dc thnh 4 22, Fa = 15,2cm2.Tnh li c m = 0,0000338; x = 15,76cm.
Mt =120C
882C55694016x12
+
Tm c C = 89,7cm; Mt = 3,38Tm.Kim tra Mx = 3 < Mtd = 3,38Tm. Tit din kh nng chu lc.
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MT S CNG THC V BNG TRA THIT K KT CU B TNG CT THP.
SN1. an sn n lm vic hai phng:Mmen nhp trong phng ngn Mi1 = mi1PMmen nhp trong phng di Mi2 = mi2PMmen gi trong phng ngn M i1 = -ki1 PMmen gi trong phng ngn M i2 = -ki2 PCc h s mi1, mi2, ki1, ki2 xem bng 1 - 19 (i l loi bn tu theo lin kt xung quanh).P = (g + p) l1l22. an sn lin tc lm vic hai phng.a- Mmen nhp.Trong phng ngn: Mi1 = m11P + mi1PTrong phng di: Mi2 = m12P + mi2Pm11, m12, mi1, mi2 tra bng 1 - 19
P = 212ll
Pg
+
P = 21.2ll
P
g, p ti trng thng xuyn v tc thi trn 1m2 an sn.b- Mmen gi tip gip:
2'ii MMM
+=
=1iM -ki1P
=2iM -ki1P3. Truyn ti trng t an sn hai phng v dm di dng tng ng.
Khi hai pha c ti trng dng tam gic qt = 185 ql
Khi hai pha c ti trng dng hnh thang qt = k.ql1
Bng : H s k truyn tiL2/l1 1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2
K 0,625 0,681 0,725 0,761 0,791 0,815 0,835 0,852 0,867 0,880 0,891
DM4. Tnh Mmen ca dm lin tc theo phng php gn ng
K hiu:S khi dm gi t doS khi dm gi ln dn ln hnS khi dm c cng ctCng thc Mmen: M = kql2
Dm 2 nhp
CT
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MNGMng na. Mng n chu ti ng tm
Din tch mng Fm=cmtbd
tc
HR
N
R cng t nntb= 2T/m3.Fm = A x B;A = (1 1,6)Hom chiu su chn mng Chiu cao lm vic ca mng theo iu kin xuyn thng
Hom = 0,5 ( )
+
+cc
k
bhPR
N5,0
75,0
P=mF
N; hc v bc l kch thc tit din ct.
Chiu cao lm vic theo iu kin chu un
Hom =ncRh
AP
4,0
.
l1 =2
chA ; A l cnh ln ca mng
Thp y mng
Trong phng di Fa A=oma
A
HR9,0
M
Trong phng ngn FaB=oma
B
HR9,0
M
MA = 0,125 pB(A- hc)2MB = 0,125 pA (B - bc)2
b. Mng n chu ti lch tm Kch thc mngA = e0 (2 + 5,2055,1 k )
k =( ) 2
0omtbd
tc
meHR2,1
N
e0 =m
AB
N
Mtc
tc
=; ; m = 1 1,6
Kim tra
=
A
e
BA
N 061.min
max
dR2,1max
dRmin Chiu cao mng
Hom = l1nc
tb
Rh
A
4,0
'
tb = min + (max - min)
+ A
hc25,075,0
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1) Kt cu khng chu tc ng trc tip v thng xuyn ca ma nng:Bng : Khong cch ln nht gia cc khe co gian snhit cho php khng cn
tnh ton (i vi h kt cu khng chu tc ng trc tip v thng xuyn ca manng)
Kt cuKhong cch ln nht gia cc
khe co gin (m)
1. Khung lp ghp(k c trng hp c mi bng kim loi hoc g) 70
2. Kt cu lp ghp bng cc tm c 603. Khung ton khi hoc na lp ghp 604. Kt cu tm c ton khi hoc na lp ghp 50
2) Kt cu chu tc ng trc tip v thng xuyn ca ma nng:i vi kt cu chu tc ng trc tip v thng xuyn ca ma nng nh: Lp mt mi
nh, ban cng, mth ng, khong cch khe co gin nhit m phi ph hp vi tiu chunTCVN 5718 - 1993: Mi v sn b tng ct thp trong cng trnh xy dng - Yu cu k thutchng thm nc. (Bng )
Bng : Khong cch ti a ca khe co gin nhit m, theo hai chiu vung gc(i vi kt cu chu tc ng trc tip v thng xuyn ca ma nng)
Loi kt cu Khong cch ti a (m)- Lp b tng chng thm ca mi khng c lpchng nng.- Tng chn mi bng b tng ct thp
9
- Lp b tng chng thm ca mi c lp chng nng tyu cu k thut, quy nh ti iu 4 ca TCVN 5718 -1993
- Kt cu b tng ct thp khc chu tc ng trc tip cabc x mt tri.
18
Bng : Cp chng nt v gii hn ca b rng khe nt
Loi kt cuCp chng nt v gi tr ca
b rng khe nt gii hn (mm)ng vi loi ct thp c dng
Thpthanh, dy
thpthng
Dy thpcng
caod 4mm
Dy thpcng
caod 3mm
1. Kt cu chu p lc ca cht lng hoc hI Cp 1 Cp 1 Cp 12. Kt cu nm di mc nc ngm3. Kt cu chu trc tip p lc ca vt liu ri Cp 3
0,25Cp 20,10
Cp 20,05
4. Kt cu ngoi tri hoc trong t, trn mc ncngm
Cp 30,30
Cp 20,15
Cp 20,05
5. Kt cu ni c che ph Cp 30,35
Cp 30,15
Cp 20,15
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Ghi ch:(1). B rng khe nt gii hn cho trong bng ng vi tc dng ca ton b ti trng, k c
di hn v ngn hn. i vi kt cu cp 3 khi ch kim tra ring vi ti trng di hn, gii hnb rng khe nt c gim i 0,05mm.
(2). nhng vng chu nh hng ca nc mn, gim b rng khe nt gii hn 0,1mm
i vi cp 3, gim 0,5mm i vi cp 2. Nu sau khi gim m b rng khe nt gii hn bngkhng th nng kt cu ln thnh cp 1.(3). i vi nhng cng trnh tm c nin hn s dng di 20 nm cho php tng b
rng khe nt gii hn ln 0,5mm.Bng : Tr s gii hn ca bin dng fgh
Loi cu kin Gii hn vng1. Dm cu trc vIa/ Cu trc quay tay
b/ Cu trc chy in(1/500)L(1/600)L
2. Sn c trn phng, cu kin ca mi v tm tng treo (khi tnh tmtng ngoi mt phng), nhp L:
a/ L < 6mb/ 6 L 7,5mc/ L > 7,5m
(1/200)L3cm
(1/250)L3. Sn vi trn c sn v cu thang, nhp L:a/ L < 5m
b/ 5 L 10mc/ L > 10m
(1/200)L2,5cm
(1/400)L
Ghi ch:(1). L l nhp tnh ton ca dm hoc bn k ln 2 gi. i vi cc cng xn, dng L = 2
L1 vi L1 l vn ca cng xn.(2). Khi thit k kt cu c vng trc th lc kim tra v vng cho php tr i vng nu khng c nhng hn ch g c bit.
(3). i vi cc cu kin khc khng nu trong bng th gii hn vng c quynh tu theo tnh cht v nhim v ca chng nhng gii hn khng c ln qu 1/150nhp hoc 1/75 vn ca cng xn.
(4). Khi quy nh vng gii hn khng phi do yu cu v cng ngh sn xut v cuto m ch do yu cu v thm m th tnh ton f ch ly cc ti trng tc dng di hn.
Bng : Chn kch thc tit din (b h.cm) ca dm b tng ct thpTI
trngt snkg/m
Nhp dm (m)
3 3,5 4 4,5 5 5,5 6 6,5 7
1000 10 25 10 30 15 30 15 35 20 35 20 40 20 40 20 45 20 451200 10 30 10 30 15 30 15 35 20 35 20 40 20 45 20 45 20 451400 10 30 15 30 15 35 15 35 20 40 20 40 20 45 20 45 20 501600 15 30 15 30 15 35 15 40 20 40 20 45 20 45 20 50 20 501800 15 30 15 35 20 35 20 40 20 40 20 45 20 45 20 50 20 502000 15 30 15 35 20 35 20 40 20 45 20 45 20 45 20 50 20 552400 15 35 20 35 20 40 20 40 20 45 20 45 20 50 20 50 20 55
2800 15 35 20 35 20 40 20 45 20 45 20 50 20 50 20 50 20 553200 20 35 20 40 20 40 20 45 20 50 20 50 20 50 20 55 20 603600 20 35 20 40 20 40 20 45 20 50 20 50 20 55 20 55 20 60
-
7/31/2019 02 Cong Thuc Tinh Toan Btct 2256
20/21
Bng : Chn chiu dy an sn loi lm vic mt phng (ld : ln > 2) (cm)Hot titrn sn(kG/m2)
Chiu di phng ngn ln (m)
1,6 1,8 2,0 2,2 2,4 2,6 2,8 3,0
200250300350400450500600700800900
1000
Bng : Tr s A, ,A A
0,01 0,995 0,010 0,32 0,840 0,2690,02 0,990 0,020 0,33 0,835 0,2750,03 0,985 0,030 0,34 0,830 0,2820,04 0,980 0,039 0,35 0,825 0,2890,05 0,975 0,048 0,36 0,820 0,2950,06 0,970 0,058 0,37 0,815 0301
0,07 0,965 0,068 0,38 0,810 0,3090,08 0,960 0,077 0,39 0,805 0,3140,09 0,955 0,085 0,40 0,800 0,3200,10 0,950 0,095 0,41 0,795 0,3260,11 0,945 0,104 0,42 0,790 0,3320,12 0,940 0,013 0,43 0,785 0,3370,13 0,935 0,122 0,44 0,780 0,3430,14 0,930 0,130 0,45 0,775 0,3490,15 0,925 0,139 0,46 0,770 0,3540,16 0,920 0,147 0,47 0,65 0,3590,17 0,915 0,156 0,48 0,760 0,3650,18 0,910 0,164 0,49 0,755 0,3700,19 0,905 0,172 0,50 0,750 0,3750,20 0,900 0,180 0,51 0,745 0,3800,21 0,895 0,188 0,52 0,740 0,3850,22 0,890 0,196 0,53 0,735 0,3900,23 0,885 0,204 0,54 0,730 0,3940,24 0,880 0,211 0,55 0,725 0,3990,25 0,875 0,219 0,56 0,720 0,4030,26 0,870 0,226 0,57 0,715 0,4080,27 0,865 0,235 0,58 0,710 0,412
0,28 0,860 0,241 0,59 0,705 0,4160,29 0,855 0,248 0,60 0,700 0,4200,30 0,850 0,255 0,61 0,695 0,424
7-8
6-7
8-9
9-10
10-11
-
7/31/2019 02 Cong Thuc Tinh Toan Btct 2256
21/21
0,31 0,845 0,262 0,62 0,690 0,428
Bng : Din tch ct thp trn (cm2) khi bit khong cch v ng knh thp(Tnh cho 1 m chiu rng an)
Khongcch thp
(cm)
ng knh (mm)6 6/8 8 8/10 10 12 14 16
7 4,04 5,60 7,19 9,20 11,21 16,16 21,99 27,737,5 3,77 5,20 6,71 8,60 1,470 15,08 20,52 26,818 3,54 4,90 6,29 8,10 9,81 14,14 19,24 25,149 3,14 4,40 5,59 7,20 8,72 12,57 17,10 22,3410 2,83 3,90 5,03 6,40 7,85 11,31 15,39 20,1011 2,57 3,60 4,57 5,86 7,14 10,28 13,99 18,2812 2,36 3,30 4,19 5,40 6,54 9,42 12,83 16,76
12,5 2,26 3,10 4,02 5,20 6,28 9,05 12,32 16,0813 2,18 3,00 3,87 5,00 6,04 8,70 11,84 15,47
14 2,02 2,80 3,59 4,60 5,61 8,08 11,00 14,3615 1,89 2,60 3,35 4,30 5,23 7,54 10,26 13,4116 1,77 2,50 3,14 4,10 4,91 7,07 9,62 12,5717 1,66 2,30 2,46 3,80 4,62 6,65 9,05 11,8318 1,57 2,20 2,79 3,60 4,36 6,28 8,55 11,1719 1,49 2,10 2,65 3,40 4,13 5,95 8,10 10,0820 1,41 2,00 2,51 3,20 3,39 5,65 7,69 10,05
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