CHNG 1: THIT K DM CH S LIU THIT K - Loi dm : dm T b tng ct thp d ng lc cng sau.- Chiu di ton dm : L = 30 m- Kh cu K = 7 + 2 x 1,75 m- Ti trng thit k :0,65 HL93- Tao cp d ng lc 15,2 mm- B tng grade 40 (MPa)- Quy trnh thit k : 22TCN 272-05- Ti trng thit k : 0,65HL93, on ngi b hnh 3 KPaNI DUNG TNH TON1. Chn vt liu thp cng cao- S dung tao thp 15,2 mm thp c chng do thp theo tiu chun ASTM A416 Grade 270.- Cng ko quy nh ca thp d ng lc:fpu = 1860 MPa- Gii hn chy ca thp d ng lc:fpy = 0,9.fpu = 1670 MPa- Mun n hi ca thp d ng lc:Ep = 197000 MPa- ng sut trong thp ng sut khi kch:fpi = 0,8.fpu = 1488 Mpa1.1. Vt liu b tng:- Cng chu ko ca b tng tui 28 ngy : fc = 40 MPa- Cng chu nn ca b tng khi to ng sut trc : fci = 0,9.fc = 36 MPa- Mun n hi ca b tng dm: Ec = 0,043.c1,5'cf= 33994,48 MPa- Cng chu ko khi un: fr = 0,63. 'cf= 3,98 Mpa1.2. B TR CHUNG MT CT NGANG CU:Tng chiu di ton dm l 30 m, chiu di nhp tnh ton ca dm l 29,4 m.Cu gm 5 dm c mt ct ch T ch to bng b tng c fc = 40 MPa. Lp ph mt cu gm c 2 lp : lp chng nc dy 1,5 cm, lp b tng asphan trn cng dy 6 cm. Khoa ng cch ngang gia cc dm ch l: S = 2200 mm.2. CHN MT CT NGANG DM CH:Theo iu 22TCN 5.14.1.2.2S b chn dm c mt ct ch T nh sau:Chiu dy bn ts20 cm134Chiu cao dm H 145 cmChiu rng bu dm bb60 cmChiu cao bu hb25 cmChiu dy bng bw20 cmChiu rng bn cnh b1220 cmRng vt cnh 15 cmCao vt cnh 15 cmChiu rng vt bu 20 cmChiu cao vt bu 25 cmPhn hng 135 cm25201515203050100 220 220 135 220 2201.5% 1.5%700/2 25 175 2530700/2 25 175 253011501452020802030255208020302556030Kim tra iu kin v chiu cao kt cu nhp ti thiu:Yu cu:hmin = 0,045LTrong :L: chiu di nhp tnh ton L = 29400 mmhmin : chiu cao ti thiu ca kt cu nhp k c bn mt cu, 0,045L = 0,045.29400 = 1323 mm < h = 1450 mm2.1. Xc nh bn cnh hu hiu :2.2.1. i vi dm giaB rng bn cnh hu hiu c th ly gi tr nh nht ca :-1/4 chiu di nhp = 29400/4 = 7350 mm.- 12 ln dy trung bnh ca bn cng vi s ln nht ca b dy bn bng dm hoc 1/2 b rng bn cnh trn ca dm. = 12 x 200 + max{2 / 2200200 = 3450 mm.- Khong cch trung bnh gia cc dm k nhau: bi = 2200 mm.Kt lun :B rng bn cnh dm hu hiu bi = 2200 mm.2.2.1. i vi dm bin135B rng bn cnh hu hiu c th c ly bng 1/12 ca dm k trong (=2200/2 = 1100) cng vi tr s nh nht ca:-1/8 chiu di nhp = 29400/8 = 3675 mm.- 6 ln dy trung bnh ca bn cng vi s ln nht ca b dy bn bng dm hoc 1/2 b rng bn bng hoc b dy bn cnh trn ca dm. = 6 x 200 + max{4 / 22002 / 200 = 1750 mm.- B rng phn hng = 1350 mm.Kt lun :B rng bn cnh dm hu hiu bc = 1100+1350 = 2450 mm.2. NI LC DM CH DO TNH TI :2.1. Tnh ti ri u ln 1 dm ch:Gi thit tnh ti phn b u cho mi dm, ring lan can + g chn th mt mnh dm bin chu - Ti trng do bn thn dm ch:gDC1(dc)=21,88 kN/m.- Ti trng do dm ngang: gDC1(dn) = 1,35 kN/m- Ti trng do lan can + g chn: gDC2 = 5,98 kN/m- Trng lng cc lp mt cu:gDW= 3,62 kN/mBng tng ktDo TLBT dm ch gDC1(dc)21,88 kN/mDo TLBT dm ngang gDC1(dn)1,35 kN/mDo lp ph mt cu gDW3,62 kN/mDo lan can + va gDC25,98 kN/m2.2. Cc h s tnh ti P (22TCN 272 05, bng 3.4.1-2)Loi ti trng TTGH Cng I TTGH S dngDC : Cu kin v cc thit b ph 1,25/0,9 1DW : Lp ph mt cu v cc tin ch 1,5/0,65 1 Cch xc nh ni lc:Ta tnh ton ni lc dm ch ti 6 mt ct: l/2;3l/8; l/4; l/8;cch gi 0,8m; v trn gi. xc nh ni lc ta v ah cho cc mt ct ri xp tnh ti ri u ln ah.Ni lc c xc nh theo cng thc:+ Mmen: Mu = .p.g+ Lc ct: Vu = .g(p.+ - p.-)Trong :p: din tch ah mmen ti mt ct ang xt.p +: din tch ah lc ct dng ti mt ct ang xt.p -: din tch ah lc ct m ti mt ct ang xt.: H s lin quan n tnh do, tnh d, v s quan trng trong khai thc c xc nh theo 22TCN272-05 mc1.3.2. = iDR 0,95136ng nh hng lc ct ti cc tit din+ =14,70 m2 =0,00 m2+ =13,91 m2 =0,01 m2+ =11,25 m2 =0,22 m2+ =8,27 m2 =0,92 m2+ =5,74 m2 =2,04 m2+ =3,68 m2 =3,68 m2Dah Q0,8L/20,8L/8 L/4 3L/8Dah QL/2Dah QL/8Dah QL/4Dah Q3L/8Dah Qg10,030,90,80,120,70,250,60,370,50,5029,4H s lin quan n tnh do D = 0,95 (22TCN272-05 mc1.3.3)H s lin quan n tnh d R = 0,95 (22TCN272-05 mc1.3.4)H s lin quan n tm quan trng trong khai thc i = 1,05 (22TCN272-05 mc 1.3.5) = 0,95 2.3. Xc nh ni lc:ng nh hng Momen ti cc tit din =11,44 m2 =47,27 m2 =81,03 m2 =101,29 m2 =108,05 m2Dah ML/8Dah ML/4Dah M3L/8Dah M0,8L/20,8L/8 L/4 3L/8Dah ML/229,40,783,225,516,897,35- Trng thi gii hn cng 1:+ Dm trong: Mu= 0,95(1,25.gDC1(dc) + 1,25.gDC1(dn) +1,5.gDW).+ Dm ngoi: Mu= 0,95(1,25.gDC1(dc) + 1,25.gDC1(dn) + 1,25.gDC2 +1,5.gDW).- Trng thi gii hn s dng:+ Dm trong: Mu= 0,95(1.gDC1(dc) + 1.gDC1(dn) +1.gDW).+ Dm ngoi: Mu= 0,95(1.gDC1(dc) + 1.gDC1(dn) + 1.gDC2 +1.gDW).137Bng t hp ni lc do tnh ti gy raMt ct V tr dmMomen do tnh ti (kN.m) Lc ct do tnh ti (kN.m)TTGHC1 TTGHSD TTGHC1 TTGHSDL/2Trong 3537,839 2755,958 39,128 0,000Ngoi 4305,094 3369,761 41,738 0,0003L/8Trong 3316,724 2583,710 142,953 94,443Ngoi 4036,025 3159,151 170,695 115,477L/4Trong 2653,379 2066,968 250,451 187,480Ngoi 3228,820 2527,321 303,298 229,235L/8Trong 1547,805 1205,732 363,653 281,455Ngoi 1883,478 1474,271 442,166 344,1400,8mTrong 374,593 291,806 354,554 354,554Ngoi 455,831 356,796 433,746 433,746GiTrong 0 0 481,339 374,960Ngoi 0 0 585,727 458,4713.NILC DM CH DO HOT TI:3.1. Tnh ton h s phn b hot ti theo ln:Tiu chun 22TCN272-05 cp n phng php gn ng c dng phn b hot ti cho tng dm(22TCN4.6.2.2.2). Khng dng h s ln ca 22TCN272-05 1381750 250PL3500HL93Lan180030001100 2200 22001y1y2y3y4600y53.6.1.1.2) vi phng php ny v cc h s c a vo trong h s phn b, tr khi dng phng php mmen tnh hoc cc phng php n by.Nhng kch thc lin quan:Chiu cao dm H = 1450mm, khong cch gia cc dm: S = 2200mm, chiu di nhp: L = 29400mm.Dm T thuc phm vi p dng nhng cng thc gn ng ca 22TCN272-05 bng 4.6.2.21 v 4.6.2.2a-1. H s phn b hot ti c tnh nh sau.3.1.1.H s phn b hot ti theo ln i vi mmen un:3.1.1.1.Tnh ton phn b hot ti i vi mmen trong cc dm gia.*) Khi cu thit k chu ti cho mt ln t:p dng cng thc trong Bng 4.6.2.2.2a-1 (22TCN272-05):gmg1=1 . 033 . 04 . 0430006 . 01]1

1]1

1]1

+s ttgttt LKLS S (4.1)trong :S = khong cch gia 2 dm lin k, mm; ta c S = 2200;Ltt= nhp tnh ton ca dm, mm; Ltt = 29400;Kg= tham s cng dc, mm4; ts= chiu dy bn b tng, mm; trong thit k s b ta ly 1]1

3s ttgt LK=1; thay s vo (4.1) ta c:gmg1 = [ ] 411 , 0 0 . 12940022004300220006 , 01 . 03 . 0 4 . 01]1

1]1

+ ;**) Khi cu thit k chu ti cho 2 hoc hn hai ln xe t. gmg2 =1 . 032 . 06 . 02900075 . 01]1

1]1

1]1

+s ttgttt LKLS S (4.2) gmg2 = [ ] 0,579 0 . 129400220029002200075 , 01 . 02 . 0 6 . 01]1

1]1

+ ;Vy: gmg = max (gmg1; gmg2) = 0,579; 3.1.1.2.Tnh ton phn b hot ti theo ln i vi mmen trong cc dm bin.*) Khi cu thit k chu ti cho mt ln t: Tra bng 3.6.1.1.2.1(22TCN272-05) c: m =1,20. Dng nguyn l n by.139Tnh ton cc tung ng nh hng yi:y1 =1,25 ; y2 = 0,593 ; y3 = 0,492 ; y4 = 0,263;y5 = 0Tnh ton cc h s phn b hot ti:gmbHL1 = = m0,5(y4 +y5) =1,20,5(0,263+0) = 0,158gmbPL1 = 0,5(y1 +y2)1,75 = 0,5(1,25+0,593)1,75 = 1,613;gmbLan1= m0,5(y3 +y5)1,3 = 1,200,5(0,492+0)1,3 = 0,383;**) Khi cu thit k chu ti cho 2 hoc hn hai ln xe t.p dng cng thc tnh trong Bng 4.6.2.2.2c-1 (22TCN272-05) ta c:gmb2= e gg(4.3)trong :gmg =h s phn b hot ti theo ln i vi m men i vi dm bn trong; gg =0,5469;e = h s iu chnh phn b ti trng; xc nh theo cng thc sau: e=mmde280077 . 0 +(4.4)de = khong cch gia bn bng pha ngoi ca dm bin v mp trong ca va hoc ro chn giao thng, mm; de = Sk 1750-250 = 1100 -1750 - 250 = -900;e = mmde280077 , 0 + = e = 448 , 0280090077 , 0 +mm;gmb= e gg = 0,448 0,579 = 0,259; La chn h s phn b ti trng theo ln i vi m men trong dm dc bin :V: de = -900 khng nm trong phm vi p dng: -300 de1700 , gb s c ly nh sau:gmbHL = 0,158; gmbPL = 1,613 ; gmbLan = 0,383;3.1.2. H s phn b hot ti theo ln i vi lc ct:3.1.2.1.Tnh ton phn b hot ti i vi lc ct trong cc dm gia.*)Mt ln thit k chu ti:gvg1 = 760036 , 0S+gvg1 : h s phn b ti trngS : khong ca ch gia ca c dm ch (mm)gvg1 =7600220036 , 0 += 0,65**)Hai ln thit k chu ti:gvg2 = 210700 76002 , 0

,_

+S S gvg : h s phn b ti trng1401750 250PL3500HL93Lan180030001100 2200 22001y1y2y3y4600y5 S : khong ca ch gia ca c dm ch (mm) gvg2 =210700 76002 , 0

,_

+S S = 0,45gvg = Max(gvg1,gvg2) = 0,653.1.2.2.Tnh ton phn b hot ti i vi lc ct trong cc dm bin.*) Khi cu thit k chu ti cho mt ln t: Tra bng 3.6.1.1.2.1(22TCN272-05) c: m =1,20. Dng nguyn l n by.Tnh ton cc tung ng nh hng yi:y1 =1,25 ; y2 = 0,593 ; y3 = 0,492 ; y4 = 0,263;y5 = 0Tnh ton cc h s phn b hot ti:gmbHL1 = = m0,5(y4 +y5) =1,20,5(0,263+0) = 0,158gmbPL1 = 0,5(y1 +y2)1,75 = 0,5(1,25+0,593)1,75 = 1,613;gmbLan1= m0,5(y3 +y5)1,3 = 1,200,5(0,492+0)1,3 = 0,383;**) Khi cu thit k chu ti cho 2 hoc hn hai ln xe t. p dng cng thc trong bng 4.6.2.2.2c-1 (22TCN272-05) ta c.gvb2 = e.gmg. Trong ;gvg: l h s phn b hot ti theo ln ca mmen i vi dm bn trong, gmg= 0,544.e: l h s iu chnh phn b ti trng, xc nh theo cng thc sau.e = 0,6 + 3000ed vi de: l khong cch t tim dm bin n mp va, de= -900mm. gvb2 =325 , 0 65 , 0 .30009006 , 0

,_

+. V: de = -900mm khng nm trong phm vi p dng: 1700 300 ed (mm).Vy gi tr h s phn b ngang khi tnh momen cho dm bin nh sau:gvbHL =gvbHL1= 0,158141 gvbPL = gvbPL1= 1,613 gvbL =gvbL1=0,3833.2. Xc nh ni lc:Hot ti xe t thit k v quy tc xp ti theo 22TCN3.6.1.3Hot ti xe t trn mt cu hay kt cu ph tr s gm mt t hp ca:+ Xe ti thit k hoc xe hai trc thit k.+ Ti trng ln thit k.Hiu ng lc ca ti trng ln thit k khng xt lc xung kch.Quy tc xp ti:+ Hiu ng ca xe hai trc thit k t hp vi hiu ng ti trng ln thit k .+ Hiu ng ca mt xe ti thit k c c li trc bnh thay i t hp vi hiu ng ca ti trng ln thit k3.2.1. Mmen:Mmen ti mt ct gia nhp cha tnh cc h s:Mxeti = pi.yi; Mln = 9,3.; Mngi = Ppl.Trong :pi: trng lng cc trc xeyi: tung ng nh hng: din tch ng nh hng1424,3 4,31,2Lane, PLDah ML/27,356,755,205,2029,4Dah M3L/84,3 4,31,2Lane, PL29,46,894,206,445,28143Dah ML/44,3 4,31,2Lane, PL29,45,515,214,443,36Dah ML/84,3 4,31,2Lane, PL29,43,223,072,682,14Dah M0,84,3 4,31,2Lane, PL29,40,780,750,660,54Bng tnh Momen do hot ti gy ra ( xt h s 0,65HL93)Ti mt ct L/2Xe titung y1 5,20Mxeti1301,138 kN.m tung y2 7,35tung y3 5,20Xe hai trctung y1 7,35Mxehaitruc1008,15 kN.mtung y2 6,75PL Din tch 108,05 MPL567,2363 kN.mTi trng ln Din tch 108,05 Mlan1004,82 kN.mTi mt ct 3L/8Xe titung y1 4,20Mxeti1242,526 kN.m tung y2 6,89tung y3 5,28Xe hai trctung y1 6,89Mxehaitruc953,18 kN.mtung y2 6,44PL Din tch 101,29MPL531,784 kN.mTi trng ln Din tch 101,29Mlan942,02 kN.mTi mt ct L/4Xe titung y1 5,51Mxeti1014,28 kN.m tung y2 4,44tung y3 3,36Xe hai trctung y1 5,51Mxehaitruc766,84 kN.mtung y2 5,21PL Din tch 81,03MPL425,4272 kN.mTi trng ln Din tch 81,03Mlan753,61 kN.mTi mt ct L/8Xe titung y1 3,22Mxeti604,1852 kN.m tung y2 2,68tung y3 2,14Xe hai trctung y1 3,22Mxehaitruc449,11 kN.mtung y2 3,07PL Din tch 47,27MPL248,17 kN.mTi trng ln Din tch 47,27Mlan439,61 kN.m Ti mt ct cch gi 0,8mXe titung y1 0,78Mxeti148,05 kN.m tung y2 0,66tung y3 0,54Xe hai trctung y1 0,78Mxehaitruc108,95 kN.mtung y2 0,75PL Din tch 11,44MPL60,06 kN.m144Ti trng ln Din tch 11,44Mlan106,39 kN.m3.2.2. Lc ct145Dah QL/24,3 4,31,2Lane, PL0,500,460,350,2129,4Dah Q3L/84,3 4,31,2Lane, PL29,40,630,580,480,33Dah QL/44,3 4,31,2Lane, PL29,40,750,710,600,46Dah QL/84,3 4,31,2Lane, PL0,880,830,730,5829,4Bng tnh Lc ct do hot ti gy ra( xt h s 0,65HL93)Ti mt ct L/2Xe titung y1 0,50Vxeti85,19 kN tung y2 0,35tung y3 0,21Xe hai trctung y1 0,50Vxehaitruc68,58 kNtung y2 0,46PL Din tch +3,68VPL19,29 kNTi trng ln Din tch +3,68Vlan34,18 kNTi mt ct 3L/8Xe titung y1 0,63Vxeti111,59 kN tung y2 0,48tung y3 0,33Xe hai trctung y1 0,63Vxehaitruc86,46 kNtung y2 0,58PL Din tch +5,74VPL30,15 kNTi trng ln Din tch +5,74Vlan53,40 kNTi mt ct L/4Xe titung y1 0,75Vxeti138,00 kN tung y2 0,60tung y3 0,46Xe hai trctung y1 0,75Vxehaitruc104,33 kNtung y2 0,71PL Din tch +8,27VPL43,41 kNTi trng ln Din tch +8,27Vlan76,90 kNTi mt ct L/8Xe titung y1 0,88Vxeti164,40 kN tung y2 0,73tung y3 0,58146Dah Q0,84,3 4,31,2Lane, PL29,40,970,930,830,68Xe hai trctung y1 0,88Vxehaitruc122,21 kNtung y2 0,83PL Din tch +11,25VPL59,09 kNTi trng ln Din tch +11,25Vlan104,67 kN Ti mt ct cch gi 0,8mXe titung y1 0,97Vxeti185,06 kN tung y2 0,83tung y3 0,68Xe hai trctung y1 0,97Vxehaitruc136,19 kNtung y2 0,93PL Din tch +13,91VPL73,03 kNTi trng ln Din tch +13,91Vlan129,37 kNTi mt ct giXe titung y1 1,00Vxeti190,8104 kN tung y2 0,85tung y3 0,71Xe hai trctung y1 1,00Vxehaitruc140,08 kNtung y2 0,96PL Din tch +14,70VPL77,18 kNTi trng ln Din tch +14,70Vlan136,71 kNNh vy ta thy ni lc ti cc mt ct di tc dng ca xe ti ln hn xe hai trc xe ti. Nn ta ch cn kim ton ni lc ca dm ch di tc dng ca t hp:Tnh ti + Xe ti HL93 + Ti trng ln + Ngi i b.3.3. T hp ni lc:3.3.1. T hp theo trang thi gii hn cng I+ T hp mmen theo trng thi gii hn cng I(22TCN227-05 mc 3.4.1.1)Mu = ( )PL VPL IM LL DW DC p DCM g M M M M . 75 , 1 . 75 , 1 . . .1 2 1 1+ + + ++ + T hp lc ct theo trng thi gii hn cng I(22TCN227-05 mc 3.4.1.1)Vu =( )PL VPL IM LL DW P DC p DC PV g V V V V . 75 , 1 . 75 , 1 . . .2 1+ + + ++ Trong :MLL: Mmen do hot ti tc dng ln mt dm ch.( tnh h s phn b ngang)MU: Mmen un tnh ton theo trng thi gii hn cng I ca dm gia.VU: Lc ct tnh ton theo trng thi gii hn cng I ca dm gia.P: H s ti trng dng cho ti trng thng xuyn (22TCN272-05 bng 3.4.1-2)LOI TI TRNGPLn nht Nh nhtDC: Cu kin v cc thit b ph 1,25 0,90DW: Lp ph mt cu v cc tin ch 1,50 0,65147: H s lin quan n tnh do, tnh d, v s quan trng trong khai thc c xc nh theo 22TCN272-05 mc1.3.2. = iDR 0,95H s lin quan n tnh do D = 0,95 (22TCN272-05 mc1.3.3)H s lin quan n tnh d R = 0,95 (22TCN272-05 mc1.3.4)H s lin quan n tm quan trng trong khai thc i = 1,05 (22TCN272-05 mc1.3.5) = 0,95IM= h s xung kch IM = 25%theo 22TCN272-05 bng 3.4.1-1MLL+IM = gMLL{(1+IM) Mxe ti+Mln}VLL+IM = gMLL{(1+IM) Vxe ti+Vln}gM,gv: h s phn b ti trng co mmen v lc ct.3.3.2.H s ti trng v t hp ti trng theo trng thi gii hn s dng I+ T hp mmen theo trng thi gii hn cng I(22TCN227-05 mc 3.4.1.1)Mu = ( )PL IM LL DW DC DCM M M M M + + + ++ 2 1+ T hp lc ct theo trng thi gii hn cng I(22TCN227-05 mc 3.4.1.1)Vu = ( )PL IM LL DW DC DCV V V V V + + + ++ 2 1Trong : MDC1 : Momen do trng lng bn thn dm ch v dm ngang MDC2 : Momen do trng lng lan can, g chn (coi nh dm bin chu) MDW : Momen do trng lng cc lp mt cu MLL: Mmen do hot ti tc dng ln dm ch MPL: Mmen do ngi i tc dng lndm ch VDC1 : Lc ct do trng lng bn thn dm ch v dm ngang VDC2 : Lc ctdo trng lng lan can, g chn (coi nh dm bin chu) VDW : Lc ctdo trng lng cc lp mt cu VLL:Lc ct do hot ti tc dng ln dm ch VPL: Lc ct do ngi i tc dng ln dm chBng tng hp h s phn b ngangK hiu Dm trong Dm binMomenHL93 gMHL930,579 0,158Ln gMLan0,579 0,383PL gMPL0,579 1,163Lc ctHL93 gVHL930,65 0,185Ln gVLan0,65 0,383PL gVPL0,65 1,163BNG T HP NI LC DO HOT TI ( HL93+ngi+ti trng ln)148Trng thi gii hn cng 1Mt ct L/2 3L/8 L/4 L/8 0,8 m GiMomenDm trong 3078,814 2913,712 2355,352 1389,019 338,363 0,000Dm ngoi 2163,770 2035,991 1015,698 958,121 232,480 0,000Lc ctDm trong 152,000 241,021 316,415 399,033 468,701 488,873Dm ngoi 54,512 135,193 185,953 244,096 294,730 309,623Trng thi gii hn s dng Mt ct L/2 3L/8 L/4 L/8 0,8 m GiMomenDm trong 1851,918 1752,609 1416,753 835,500 215,670 0,000Dm ngoi 1301,516 1224,656 983,727 576,313 139,838 0,000Lc ctDm trong 91,428 144,975 190,325 240,020 281,925 294,059Dm ngoi 32,789 81,319 111,851 146,825 177,281 186,239BNG T HP NI LC TRONG DM ( Tnh ti +HL93 + ngi + ti trng ln)Trng thi gii hn cng 1Mt ct L/2 3L/8 L/4 L/8 0,8 m GiMomenDm trong 6616,653 6230,437 5008,731 2936,824 712,956 0,000Dm ngoi 6468,864 6072,016 4244,518 2841,599 688,311 0,000Lc ctDm trong 191,128 383,974 1667,204 762,685 823,255 970,211Dm ngoi 74,527 305,887 489,251 686,262 728,476 895,350Trng thi gii hn s dng Mt ct L/2 3L/8 L/4 L/8 0,8 m GiMomenDm trong 4607,876 4336,319 3483,721 2041,232 507,476 0,000Dm ngoi 4671,277 4383,808 3511,048 2050,584 496,634 0,000Lc ctDm trong 91,428 239,418 377,805 521,474 636,479 669,019Dm ngoi 74,527 196,796 341,087 490,965 611,028 644,710Nhn xt: dm trong chu lc bt li hn dm bin nn s dng gi tr ni lc ti dm gia tnh ton ct thp 4. CC DC TRNG VT LIU CHO DM CH:4.1.Thp:4.1.1.Thp ng sut trc:S dng tao thp 15,2mm.Din tch mt tao l140mm2- Cng ko quy nh ca thp ng sut trc: fpu = 1860 MPa- Gii hn chy ca thp ng sut trc:fpy = 0,9.fpu = 0,9.1860 = 1670 MPa- Mun n hi ca thp ng sut trc:149Ep = 197000 MPa- S dng thp c t chng thp ca hng VSL: Tiu chun ASTM A416 Grade 270.- ng sut trong thp khi ko:fpi = 0,8.fpu = 0,8.1860 = 1488 MPa- ng sut trong thp trong cc giai on s dng:0,83.fpy = 0,83.1670 = 1386,1 MPa- ng sut trong thp sau cc mt mt trong giai on s dng:0,8.fpy = 0,8.1670 = 1336 MPa- Chiu di tt neo : L = 0,002 m/ 1 neo.4.1.2. Ct thp thng:- Gii hn chy ti thiu ca ct thp thanh:fy = 400 MPa- Mun n hi: Es= 200000 MPa.4.2. B tng:T trng ca b tng : c = 24 kN/m3.Cng chu nn ca b tng quy nh tui 28 ngy: fc = 40 MPa.Cng chu nn ca b tng lc bt u t ti hoc to ng sut trc:fci = 0,85.fc = 0,85.40 = 34 MPa.Mun n hi ca b tng dm:Ec= 0,043.c1,5.'cf= 33994,48 MPa.Mun n hi ca b tng dm lc cng ko:Eci = 0,85.Ec = 0,85.33994,48 = 28895,3 MPa.H s quy i hnh khi ng sut (22TCN272-05 mc 5.7.2.2)( )764 , 0728. 05 , 0 85 , 0'1 cfCng chu ko khi un: (22TCN272-05 mc 5.4.2.6)98 , 3 . 63 , 0' c rf fMPa5. CHN V B TR CP D NG LC:5.1. Chn s lng cp d ng lc:Gii hn ng sut ko trong b tong ti th di TTGH s dng (theo TCN 5.9.4.2.2-1): MPa fc162 , 3 40 . 5 , 0 5 , 0, Tr s nh nht ca lc ko trc FP m bo ng sut ko th di khng vt qu gii hn ng sut :MPaIy M MI y e FAFfd IM LL DCd pgpbg162 , 3). (. .++ +Trong :I: l m men qun tnh ca mt ct tnh i ti tit din gia nhp150yd: khong ca ch t trc trung ho n th di ca mt ct tnh i. Ta gi thit ly mt ct khng c ct thp.Ag: din tch nguyn ca mt ct tnh i ti tit din gia nhp.1520602520220 22031760202021145Ta c: Ag= 8368 cm2So= 795247,8 cm3Yd= 95,03 cmI = 21306408 cm4MDC: m men ti mt ct gia nhp trong TTGH s dng do tnh ti giai on 1 v 2 gy ra: MDC = MDC1+MDC2+MDW = 2755,589 kNm.MLL+IM: mmen do hot ti + xung ki ch ti mt ct gia nhp trong TTGH s dng gy ra: MLL+IMMLL+IM= 1851,918 kNm.Gi nh khong cch t y dm n trng tm ct thp DL l a = 200mm, suyra lch tm e = yd - a = 95,03 -20 = 75,03 cm.Thay ca c giatr va ti m c vo biu thc trn ta c FP 3828,664 kN.Theo (TCN 5.9.3-1) gii hn ng sut cho cc b thp d ng lc TTGH s dng sau ton b mt mt l 0,6fpu= 0,6.1860 = 1116Mpa = 1,116KN/mm2psTAF1,116116 , 1664 , 3828psA= 3430,703 mm25.2. B tr ct thp d ng lc:- B tr trong mt phng thng ng:Cc b cp c b tr trong mt phng thng ng theo ng gp khc.ta b tr cc b cp ti mt ct gia dm nh sau:Ta dng loi tao thp D =15,2 mm c din tch 1 tao l 140 mm2S tao cp cn thit: 140703 , 3430 psPSaAn= 25,51 taoChn s tao cp n = 30 tao. Chn 1 b cp gm 5 tao 15,2mm c ng knh b l 60mm. Vy b tr thnh 6 bDin tch thp DL trong dm Aps= 30.140 = 4200 mm2Ta b tr cc b cp trong bu dm nh hnh v di y.1515 6150150145010043213x1002x2006002x2005 66004145012501000700123Chn ng cong trc b cp dng ng cong gy khc c vut trn..+ Xc nh v tr tim ng cp ti tit din gia nhp v ti u neo theo chiu ng (im C)+ Chn v tr im gy ca ng trc l im B. Xc nh c l+ Ni hai im BC, suy ra v tr im A cng tc l bit h.+ Quyt nh bn knh vut cong R (hoc on t) ri suy ra t (hoc R) theo cc cng thc sau:lharctglhtg ; 2. tg R t tgRt + Chiu di cung trn .360. 2ORd + Tung ti mtctcch mt khongxl: tg x l y ). ( (phnnghing b cp) v 2 2) ( x t l R R y + (i vi phn cung trn)S hiu bV tr im un l2h a /2 R t d1 9 0.85 0.4 5.40 2.70 60 2.827 5.6532 7.5 0.7 0.3 5.33 2.67 50 2.328 4.6563 5 0.5 0.2 5.71 2.86 40 1.995 3.989Bng to ct thp ti cc mt ctS hiu ba(m)v tr mt ct x(m)im un B(m)R(m) t(m) y(m) y+a(m)10.4 15.00 9 60 2.8270.000 0.4000.4 11.25 9 60 2.8270.000 0.4000.4 7.50 9 60 2.8270.142 0.5420.4 3.75 9 60 2.8270.496 0.8960.4 1.10 9 60 2.827 0.746 1.146152I III IIb1h1 abh2b2h0.4 0.30 9 60 2.8270.822 1.22220.3 15.00 7.5 50 2.3280.000 0.3000.3 11.25 7.5 50 2.3280.000 0.3000.3 7.50 7.5 50 2.3280.000 0.3000.3 3.75 7.5 50 2.3280.350 0.6500.3 1.10 7.5 50 2.3280.597 0.8970.3 0.30 7.5 50 2.3280.672 0.97230.2 15.00 5 40 1.9950.000 0.2000.2 11.25 5 40 1.9950.000 0.2000.2 7.50 5 40 1.9950.000 0.2000.2 3.75 5 40 1.9950.125 0.3250.2 1.10 5 40 1.9950.390 0.5900.2 0.30 5 40 1.9950.470 0.670Tnh to trng tm ca cc b ct thp ti cc mt ctTo trng tm cc b cp ti cc tit dinMt ctTrng tm ca cc b so vi y dm api (m)TT cc bap(m)1 2 3 4 5 615,00 0,400 0,300 0,200 0,10 0,10 0,10 0,2011,25 0,400 0,300 0,200 0,10 0,10 0,10 0,207,50 0,542 0,300 0,200 0,10 0,10 0,10 0,223,75 0,896 0,650 0,325 0,10 0,10 0,10 0,361,10 1,146 0,897 0,590 0,10 0,10 0,10 0,490,30 1,222 0,972 0,670 0,10 0,10 0,10 0,536. Tnh cc c trng hnh hc ca mt ct tnh i:6.1.c trng hnh hc tit din trong giai on 1(trc khi bm va):Khi cha bm va mt ct dm chu lc l mt ct gim yu do cc l lun cc b cp d ng lcTrc trung ho trong giai on 1 l trc I-IDin tch mt ct b gim yu:A0=h.b + b2.h2 + b1.h1- AlM men tnh i vi mp di ca tit dinSx=b.h.(h+h1/2)2 + b1.h12/2 + b2.h2.(h+h1+h2/2) Al.aPKhong cch t trc 0-0 ca mt ct n mp trn v mp di:y1d=Sx/A0; y1t =h-y1dM men qun tnh tnh i c xt n gim yu:153I0 = b1.h13/12+b1.h1.(y1d-h1/2)2+b.h3/12 + b.h.( y1d -h/2+h1)2+b2.h23/12+b2.h2.( y1d -h2/2+h1+h)2+Al.(y1d-aP)2C TRNG HI NH HO C GIAI OA N IMt ct L/2 L3/8 L/4 L/8 0,8m Giap(cm) 20,00 20,00 22,36 36,18 48,89 52,73A0(cm2) 8339,74 8339,74 8339,74 8339,74 11871,74 11871,74Sx(cm3) 794.682,60 794.682,60 794.615,88 794.225,34 1.061.368,35 1.061.259,91y1d(cm) 95,29 95,29 95,28 95,23 89,40 89,39y1t(cm) 49,71 49,71 49,72 49,77 55,60 55,61I0(cm4) 21146760,8 21146760,8 21156650 21208190,32 24442175,9 24450544,76.2 c trng hnh hc tit din trong giai oa n II(sau bm va):Trc trung ho trong giai on 2 l trc II-IIH s tnh i t thp sang b tng:Vi mt ct gia nhp:+ Xc nh Atd: Din tch mt ct tnh iAtd = A0 + n.Aps + Xc nh Std: Mmen tnhmt ct tnh iStd = S0 + n.Aps.ap + Xc nh ydtd: Mmen tnhmt ct tnh iydtd = tdtdAS

+ Xc nh yttd: Mmen tnhmt ct tnh iyttd = h - ydtd + Xc nh Itd: Mmen tnhmt ct tnh iItd = I0 + n.Aps. (yttd-ap)2 C TRNG HI NH HO C GIAI OA N IIMt ct L/2 3L/8 L/4 L/8Ca ch g i 0,8m G in 5,795 5,795 5,795 5,795 5,795 5,795ap(cm) 20,000 20,000 22,361 36,181 48,891 52,728A0(cm2) 8339,740 8339,740 8339,740 8339,740 11871,740 11871,740Atd(cm2) 8583,130 8583,130 8583,130 8583,130 12115,130 12115,130Sx0(cm3) 794682,600 794682,600 794615,875 794225,338 1061368,348 1061259,913Sxt(cm3) 799550,400 799550,400 800058,346 803031,323 1073267,865 1074093,327y2d(cm) 93,154 93,154 93,213 93,559 88,589 88,657154795 , 548 , 33994197000 betongthepEEny2t(cm) 51,846 51,846 51,787 51,441 56,411 56,343Itd(cm4) 22818742,00 22787148,00 22442423,00 21800247,00 32143324,00 32266217,007. TI NH CC TN HAO NG SU T :Tng mt mt ng sut trc trong kt cu cng sau c xc nh theo TCN 5.9.5.1:PR PCR PSR ES P PA PF PTf f f f f f f + + + + + Trong :PFf : mt mt do ma st (MPa)PAf : mt mt do thit b neo (MPa)ES Pf : mt mt do co ngn n hi(MPa)PSRf : mt mt do co ngt (MPa)PCRf : mt mt do t bin ca b tng (MPa)2 PRf : mt mt do t chng ca ct thp DL (MPa)7.1. Tn hao do ma st:Mt mt do ma st gia cc b thp ng sut v ng bc c tnh theo cng thc:

,_

,_

+ KXePJfPFf 1 .Trong : fPj: ng sut trong b thp ng sut trc ti thi im kch, gi nh fpj=0,75fpu=1395MPa.X:chiu di b thp ng sut trc t u kch n im ang xt(mm)K: h s ma st lc ly theo bng 5.9.5.2.2b-1; K = 6,6.10-7: h s ma st ly theo bng 5.9.5.2.2b-1; = 0,23: tng gi tr tuyt i thay i gc ca ng cp ng sut trc t u kch gn nht n im ang xt.Bng tnh mt mt ng sut do ma stBOMt ct L/2 3L/8 L/4 L/80,8mGi1Khong cch tnh t im t kch(cm)1500,00 1125,00 750,00 375,00 110,00 30,00x(mm) 15217,00 11300,06 7533,37 3766,69 1104,89 301,33 (radian) 0,0942 0,0942 0,0942 0,0942 0,0942 0,0942kx+. 0,0319 0,0292 0,0267 0,0242 0,0224 0,02191-e-( kx+.)0,0314 0,0288 0,0264 0,0239 0,0221 0,0216fpj(MPa) 1395 1395 1395 1395 1395 1395fPF(MPa) 43,735 40,184 36,761 33,329 30,898 30,1641552Khong cch tnh t im t kch(cm)1500,00 1125,00 750,00 375,00 110,00 30,00x(mm) 15190,5 11298,89 7532,60 3766,30 1104,78 301,30 (radian) 0,0931 0,0931 0,0931 0,0931 0,0931 0,0931kx+. 0,0316 0,0290 0,0265 0,0239 0,0221 0,02161-e-( kx+.)0,0311 0,0286 0,0261 0,0236 0,0219 0,0214fpj(MPa) 1395 1395 1395 1395 1395 1395fPF(MPa) 43,369 39,840 36,416 32,983 30,553 29,8183Khong cch tnh t im t kch(cm)1500 1125 750 375 110 30x(mm) 15156,5 11306,11 7537,41 3768,70 1105,49 301,50 (radian) 0,0997 0,0997 0,0997 0,0997 0,0997 0,0997kx+. 0,0331 0,0305 0,0280 0,0254 0,0237 0,02311-e-( kx+.)0,0325 0,0300 0,0276 0,0251 0,0234 0,0229fpj(MPa) 1395 1395 1395 1395 1395 1395fPF(MPa) 45,390 41,904 38,483 35,053 32,624 31,8904,5,6Khong cch tnh t im t kch(cm)1500 1125 750 375 110 30x(mm) 15000 11250 7500 3750 1100 300 (radian) 0,0000 0,0000 0,0000 0,0000 0,0000 0,0000kx+. 0,0101 0,0075 0,0050 0,0025 0,0007 0,00021-e-( kx+.)0,0100 0,0075 0,0050 0,0025 0,0007 0,0002fpj(MPa) 1395 1395 1395 1395 1395 1395fPF(MPa) 13,950 10,475 6,992 3,501 1,028 0,280Tng Hao (MPa)174,343 153,354132,637111,86797,158 92,7137.2. Tn hao do bin dng neo:Mt mt do thit b neo tnh theo cng thc sau:) / .( L E L fPA Trong :L : Tng bin dng ca neo v b tng di neo, ly bng 2mm.L: Chiu di trung bnh ca b cp.E: m un n hi ca thp, E = 197000MPaDo bin dng neoB cp s 1 2 3 4 5 6L(mm) 2 2 2 2 2 2E(MPa) 197000 197000 197000 197000 197000 197000L(mm)30434 30313 30313 30000 30000 30000fPA(MPa)12,946 12,998 12,998 13,133 13,133 13,133156PF f PF f PF f 7.3. Tn hao do co ngn n hi:Mt mt do co ngn n hi v bn cht l khi cng b sau gy ra mt mt cho b trc (cc c trng hnh hc s c tnh cho giai on 2): cgpciPPESfEENNf1 Trong :N: s lng cc b cp d ng lc ging nhauEP: m un n hi ca thp DL (MPa)Eci: m un n hi ca b tng lc truyn lc (MPa), Eci=0,043.25001.541.25=34521MPafcgp: tng ng sut b tng trng tm cc b thp d ng lc do lc d ng lc sau khi kch v t trng ca cu kin cc mt ct m men max (MPa). i vi kt cu ko sau vi cc b cp c dnh bm ly ti mt ct gia nhpF: lc nn trong b tng do ng sut trc gy ra ti thi im sau kch, tc l xy ra do ma st v tt neo.e: lch tm ca trng tm cc b thp so vi trc trung ho ca tit dinAPS: tng din tch ca cc b cp ng sut trcA: din tch mt ct ngang dm MTTBT: m men do trng lng bn thn dmDo co ngn n hiMt ct L/2 3L/8 L/4 L/8 0,8m Gifpj(MPa) 1395 1395 1395 1395 1395 1395fpF(MPa) 174,343 153,354 132,637 111,867 97,158 92,713fpA(MPa) 13,133 13,133 13,133 13,133 13,133 13,133APS(cm2) 42 42 42 42 42 42F(KN) 5.071,60 5.159,75 5.246,77 5.334,00 5.395,77 5.414,45A(cm2) 8583,130 8583,130 8583,130 8583,130 12115,130 12115,130e(cm) 73,15 73,15 70,85 57,38 39,70 35,93I(cm4) 22818742,00 22787148,00 22442423,00 21800247,0032143324,00 32266217,00MTTBT(KNcm) 275.595,78 258.371,05 206.696,84 120.573,16 29.180,58 0,00fcgp(KN/cm2) 0,90 0,98 1,13 1,11 0,67 0,66157eIMIe FAFfTTBTcgp + 2.PS pA pF pjA f f f F ) ( fcgp(MPa) 9,0 9,8 11,3 11,1 6,7 6,6Ep/Eci5,71 5,71 5,71 5,71 5,71 5,71N 6 6 6 6 6 6fpES(MPa) 42,67 46,80 53,88 52,80 32,07 31,577.4.Tn hao do hin tng co ngt:Mt mt do co ngt b tng trong cu kin ko sau c xc nh theo cng thc: fpSR= 93 0,85.H(TCN 5.9.5.4.2-2)Trong : H l m tng i ca mi trng, ly trung bnh hng nm(%). y ta ly H=85%.fpSR=93 0,85.85 = 21(MPa)7.5. Tn hao do t bin ca b tng:Mt mt d ng sut do t bin c th ly bng:fpCR=12,0.fcgp 7.fcdp0 (22TCN272-05 5.9.5.4.3-1)Trong :fcgp: ng sut b tng ti trng tm thp d ng lc lc truyn lc (MPa)fcdp: thay i ng sut b tng ti trng tm thp d ng lc do ti trng thng xuyn, tr ti trng tc ng vo lc thc hin d ng lc. Ga tr fcdpcn c tnh cng mt ct hoc cc mt ct c tnh fcgp (MPa). Nh vy fcdp l thay i ng sut do tnh ti giai on hai gy ra:lhDW DCcdpIe M Mf). (2 + Mt ct L/2 3L/8 L/4 L/8 0,8m Gifcgp(MPa) 9,0 9,8 11,3 11,1 6,7 6,6MDC2(KNcm) 64610,91 60572,728 48458,182 28267,27 6841,12 0MDW(KNcm) 39112,2 36667,771 29334,217 17111,62 4141,28 0e(cm) 73,15 73,15 70,85 57,38 39,70 35,93I(cm4) 22818742 22787148 22442423 21800247 32143324 32266217fcdp(MPa) 3,325 3,122 2,456 1,194 0,136 0,000fpCR(MPa) 84,334 96,162 118,690 124,797 79,917 79,6257.6.Tn hao do t chng ca cp DL:1587.6.1. Ti lc truyn lc:S dng cc tao thp c chng thp nn mt mt do do lc truyn lc c tnh theo cng thc:pjpypjpRffftf . 55 , 0 .40) 24 log(111]1

Trong :t: thi gian t lc to ng sut trc n lc truyn lc, t=5ngyfpj: ng sut ban u trong b thp vo cui lc ko (MPa)fpj=0,75fpu - fpES - fpF - fpAfpy: cng chy quy nh ca thp d ng lc (MPa)Mt ct L/2 3L/8 L/4 L/8Ca ch g i 0,8m GiFpu(MPa) 1860 1860 1860 1860 1860 1860fpES(MPa) 42,67 46,80 53,88 52,80 32,07 31,57fpF(MPa) 174,343 153,354 132,637 111,867 97,158 92,713fpA(MPa) 12,946 12,998 12,998 13,133 13,133 13,133fpj(MPa) 1395 1395 1395 1395 1395 1395fpy(MPa) 1674 1674 1674 1674 1674 1674fpR1(MPa) 20,545 20,545 20,545 20,545 20,545 20,5457.6.2. Saukhi truyn lc:[ ] ) .( 2 , 0 . 4 , 0 . 3 , 0 138 .100302 pCR pSR pES pE pRf f f f f + Mt ct L/2 3L/8 L/4 L/8Ca ch g i 0,8m GifpF(MPa) 174,343 153,354 132,637 111,867 97,158 92,713fpES(MPa) 42,67 46,80 53,88 52,80 32,07 31,57fpSR(MPa) 21 21 21 21 21 21fpCR(MPa) 84,334 96,162 118,690 124,797 79,917 79,625fpR2(MPa) 14,269 14,953 14,616 16,248 22,753 23,2307.7. Tngcc tn hao ng sut:T NG CC TN HAO NG SUTMt ct L/2 3L/8 L/4 L/8 Ca ch g i 0,8m GifpF174,343 153,354 132,637 111,867 97,158 92,713159fpA12,946 12,998 12,998 13,133 13,133 13,133fpES42,67 46,80 53,88 52,80 32,07 31,57fpSR21 21 21 21 21 21fpCR84,334 96,162 118,690 124,797 79,917 79,625fpR120,545 20,545 20,545 20,545 20,545 20,545fpR214,269 14,953 14,616 16,248 22,753 23,230fpT(MPa) 370,107 365,807 374,366 360,392 286,572 281,8198. KIM TON THEO TRANG THI GII HN CNG I :Trng thi gii hn cng phi c xem xt n m bo cng v s n nh c v cc b v ton th c d phng chu c cc t hp ti trng quan trng theo thng k c nh ra cu chu c trong tui th thit k ca nTrng thi gii hn cng dng kim ton cc mt cng v n nh.8.1. Kim ton cng un:Cng thc kim ton i vi trng thi gii hn cng 1:Mu .MnMmen tnh ton Mu trng thi gii hn cng 1:Mu i i M . Kt qu Mu ca dm gia c tng kt trong mc IV.3.3Sc khng un tnh ton Mr = .MnTrong : : h s khng un c quy nh 22TCN272-05 mc 5.5.4.2, dng cho un v ko b tng ct thp ng sut trc. = 1,0.Mn : Sc khng un danh nh(tnh ton sc khng un danh nh 22TCN272-05 mc 5.7.3.2)Phn b ng sut theo hnh ch nht (22TCN272-05 mc 5.7.2.2)Quan h t nhin gia ng sut b tng chu nn v c th coi nh mt hnh ch nht tng ng bng 0,85.fc phn b trn mt gii hn bi mt ngoi chu nn ca mt ct v ng thng song song vi trc trung ho cch th chu nn ngoi cng mt khong cch a = 1.c. Khong cch c phi tnh vung gc vi trc trung ho. H s 1 ly bng 0,85 i vi b tng c cng khng ln hn 28 MPa vi b tng c cng ln hn 28 MPa, h s 1 gim theo t l 0,05 cho tng 7 MPa vt qu 28 MPa, nhng khng nh hn tr s 0,65.Vi b tng c cng chu nn khi un/Cf = 40 ( MPa ) > 28(MPa)thih s:1 = . 76 , 072805 , 0 85 , 0

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cfSc khng un danh nh:( i vi mt ct ch T theo 22TCN272-05 mc 5.7.3.2.2.1)Mn = ( )

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+

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+

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+

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2 2. . . 85 . 02.2.2.1/ ' ' 'ff w c s y s s y s p ps pshah b b fad f Aad f Aad f A 160Coi m t c t chicoc t the p ng su t tr c chi u l c khi o : Mn = ( )

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+

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2 2. . . 85 . 02.1/ff w c p ps pshah b b fad f A Trong :+ Aps : Din ti ch ct thp d ng lc trong vu ng chu ko, Aps = 4200( mm2 ).+ fpu: Cng chu ko tiu chun ca thp d ng lc, fpu = 1860 MPa.+ As: Din tch ct thp thng chu ko, c th chn As = 0.+ A's:Din tch ct thp thng chu nn, c th chn A's = 0+ 1 = 0,76+ b : B rng ca nh chu nn, b = 2200 mm.+ dp: Khong cch t th chu nn ngoi cu ng ti trng tm ct thp d ng lc, + fps : ng sut trung bi nh trong bothp ng sut trc sc khng danh nh

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PPu PSdck f f . 1+ hf: Chiu dy cnh chu nn ca cu kin, l chiu dy quy i t cnh trn ca dm, hf = 21 mm+ bW : Chiu rng bn bng, bW = 200 mm.ng sut trung bnh trong tao cp ng sut trc fps c th ly nh sau :fps = fpu.(1-pdck.) < fpu = 1860000 ( KN/m2 ).k = 2.(1,04 - pupyff) = 0,28+ Gii hn chy ca tao thp cp 270 fpy = 0,9.fpu (22TCN272-05 mc5.4.4.1-1)( )ppups w cf w c y s s s pu psdfA k b fh b b f f A f A f Ac. . . . . 85 , 0. . . . 85 , 0 . . .'1'1' '+ +Sau khi tnh c c, nu c < hf tc trc trung ho i qua cnh. Khi c th coi l mt ct hnh ch nht. Theo 22TCN272-05 5.7.3.2.3 khi chiu dy cnh chu nn h > c xc nh theo phng trnh trn th sc khng un danh nh Mn c th xc nh theo cc phng trnh trn Trong phi thay b bng bf.Cng thc xc nh c vit li:ppups f cy s s s pu psdfA k b ff A f A f Ac. . . . . 85 , 0. . .'1' '+ +M t ct L/2 3L/8 L/4 L/8Ca ch g i 0,8map(mm)200 200 224 362 489dp(mm)1250,00 1250,00 1226,39 1088,19 961,09c(mm)-439,5561 -439,5561 -437,4259 -423,6229 -408,4950161Ti nh la i c(mm)150,6023 150,6023 150,6727 151,1477 151,7090fps ( MPa )1797,2530 1797,2530 1796,0151 1787,6621 1777,7914a(mm)114,4578 114,4578 114,5113 114,8723 115,2988Mn (kN.m)9317,92794 9317,92794 9133,268976 8052,283946 7057,69807Mr(kN.m)9317,92794 9317,92794 9133,268976 8052,283946 7057,69807Mu(kN.m)6616,6526 6230,43652 5008,731254 2936,823515 712,955845K t lu na t a t a t a t a t8.2. Kim tra hm lng ct thp ng sut trc:+ Lng ct thp ti a theo iu (5.7.3.3.1) phi tho mn iu kin:42 , 0 cdcdc = dp (do coi As = 0)c : khong cch t th chu nn ngoi cng n trc trung hoKim tra hm lng ct thp ng sut trc ti aM t c t L/2 3L/8 L/4 L/8 Ca ch g i 0,8mc(mm)150,6023 150,6023 150,6727 151,1477 151,7090dp(mm)1250,00 1250,00 1226,39 1088,19 961,09c/dp0,120 0,120 0,123 0,139 0,158c/dp 0,42 0,42 0,42 0,42 0,42K t lu na t a t a t a t a t+ Lng ct thp ti thiu theo iu (5.7.3.3.2), phi tho mn iu kin: Mr > min(1,2Mcr,1,33Mu)Trong :Mr : sc khng nt c xc nh trn c s phn b ng sut n hi v cng chu ko khi un, fr (22TCN272-05 5.4.2.6)Fr = 0,63.'cf= 0,63. 40= 3,984 MPaTrong trng thi gii hn s dng, ng sut ko trong b tng y dm do cc loi ti trng l: ( )( )000002 2 1.. .I y MIy e PAPIy M M M Mfdtddj jtddIM LL DW DC DC+ + + ++Trong :Pj = Aps.(0,8.fpy - (mt mt)) ;MPa.mm2Thay vo ta c:f = 1,098 MPaNh vy Mcr l mmen gy thm cho dm ng sut pha di ca b tng dm t n ng sut ko:f fI y Mrtddcr 6 210 ..Kim tra hm lng ct thp ng sut trc ti thiuMt ct L/2 3L/8 L/4 L/8 C.g i 0,8m162Mdc1(dn)+ Mdc2+Mdw+MLL+IM224385,120212004,641171070,302100697,09225716,905y2d(cm) 93,154 93,154 93,213 93,559 88,589Itd(cm4)22818742,0022787148,0022442423,0021800247,0032143324,00Aps4200 4200 4200 4200 42000,8.fpy1336 1336 1336 1336 1336mt mat 370,107 365,807 374,366 360,392 286,572Pj(Mpa.mm2)4056752,534074811,424038864,6674097554,794407597,76A0(cm2) 8339,74 8339,74 8339,74 8339,74 11871,74e(cm) 75,29 75,29 72,92 59,05 40,51y0d(cm) 95,29 95,29 95,28 95,23 89,40I0(cm4)21146760,821146760,821156649,9921208190,3224442175,9Mttbt (kN.cm) 236402,46221627,306177301,845103426,0763 25030,72f(Mpa) 1,19 -0,06 -3,02 -6,81 -8,62fr(MPa) 3,948 3,948 3,948 3,948 3,948fr - f(MPa) 2,763 4,005 6,964 10,761 12,568Mcr(kN.m) 676,702 979,609 1676,761 2507,445 4559,999Mu4607,876 4336,319 3483,721 2041,232 507,4761,2Mcr812,043 1175,531 2012,114 3008,934 5471,9991,33Mu6128,475 5767,305 4633,350 2714,838 674,943Min(1,2.Mcr;1,33.Mu) 812,043 1175,531 2012,114 2714,838 674,943Mr9317,928 9317,928 9133,269 8052,284 7057,698Kt lun at at at at at8.3. Tnh ct ai v kim ton ct trng thi gii hn Cng I:Cng thc tnh sc khng ct:Vr = .VNTrong : : h s sc khng trong 22TCN272-05 5.5.4.2 => = 0,9.VN: sc khng ct danh nh phi c xc nh trong 22TCN272-05 5.8.3.3Sc khng ct danh nh phi c xc inh bng tr s nh hn ca:'+ + + p v v c np s c nnV d b f VV V V VV. . . 25 , 0'21Trong :Do b qua ct thp thng. Vs = 0Vc = 0,083..v v cd b f . .;: lc ct do b tng.163Vs = sg g d f Av y v sin ). cot .(cot . . +Av: din tch ct thp chu ct trong c ly S (mm2) Av = 2.As (ai 2 nhnh)Av = 2.3,1416.1,22/4= 2,26 cm2fy = 420 MPa gii hn chy ti thiu quy nh ca thanh ct thp.= 450 : go c nghing cu a ng su t ne n che o truy n l c c xa c i nh trong 22TCN272 - 05 5.8.3.4: Go c nghing cu a c t the p nghing v i tru c do c = 900s = 200 mm: c li c t the p ai.Vp : thnh phn lc ng sut tr c c hiu trn hng lc ct tc dng l dng nu ngc chiu vi lc ct (N) Vp = (Pe)sin ( gc hp bi phng nm ngang vahng cp), Vp > 0 nu ngc chiu vi lc ct. gc nghing ca ct thp ngang so vi phng trc dc = 900 bv : b rng bng c hiu bv = 194 mm( ng v i m t c t cha mr ng) bv = 594 mm( ng v i m t c t amr ng)dv: chiu cao chu ct c hiu lc ly bng c ly do thng gc vi trc trung ho gia hp ko do un (dv), nhng khng ly t hn tr s ln hn ca 0,9.dp v 0,72.hM t ct L/2 3L/8 L/4 L/8Ca ch g i 0,8m G idp(cm) 1250,00 1250,00 1226,39 1088,19 961,09 922,72a(cm) 114,4578 114,4578 114,5113 114,8723 115,2988 115,4515dp-a/2 (cm)1192,7711 1192,7711 1169,1333 1030,7583 903,4432 864,99650,9dp(cm) 1125,00 1125,00 1103,75 979,38 864,98 830,450,72h(cm) 104,40 104,40 104,40 104,40 104,40 104,40dv(cm) 1192,77 1192,77 1169,13 1030,76 903,44 865,00S : c ly ct thp ai (mm)C ly ct thp ngang khng c vt qu tr s sau:Nu Vtt < 0,1.fc.bv.dv => s 0,8.dv 600mm; (22TCN272-05 5.8.2.7-1)Nu Vtt 0,1.fc.bv.dv => s 0,4.dv 300mm; (22TCN272-05 5.8.2.7-2)C 0,1.fc.bv.dv = 0,1.40.197.562,5.10-3 = 443,25 kN` chn s 0,8 dv = 0,8.562,2 = 450 mm 600 mm chn s = 200 mmAv: din tch ct thp chu ct trong c ly s (mm2) Av = 2.As (ai 2 nhnh)Av = 2.3,1416.1,22/4= 2,26 cm2: h s ch kh nng ca b tng b nt cho truyn lc ko tra bng 22TCN272-05 5.8.3.4.2.cho n = 2,0 ; = 450+ Xa c i nh Vp:71sin . .ii p p pf A V Trong o :164Aps = 5880 (mm2): di n ti ch ca c tao ca pFp :ng su t trong ca p sau m t ma t, giatri ng v i m i m t c t.Pj = Aps.(0,8.fpy - (mt mt)) ; MPa.mm2i : go c l ch cu a ca p i so v i phng ngang.M t ct L/2 3L/8 L/4 L/8Ca ch g i 0,8m G iAps(mm) 4200 4200 4200 4200 4200 4200fp4,0567525 4,074811 4,038864 4,097554 4,4075977 4,42756075Bo1(sin) 0,0002 0,0002 0,073 0,073 0,073 0,073Bo2(sin) 0,0002 0,0002 0,078 0,078 0,078 0,078Bo3(sin) 0,0002 0,0002 0,087 0,087 0,087 0,087Bo4-6(sin) 0,0002 0,0002 0,00025 0,00027 0,00029 0,0023sin 0,0012 0,0012 0,23875 0,23881 0,23887 0,2449Vp(kN) 0,020 0,021 4,050 4,110 4,422 4,554Vs(kN) 5660,892 5660,892 5548,706 4891,979 4287,741 4105,273DUY T CC MT CTM t ct L/2 3L/8 L/4 L/8Ca ch g i 0,8mG iVp(kN) 0,020 0,021 4,050 4,110 4,422 4,554Vc (kN)24,294 24,294 23,812 20,994 56,341 53,943Vs(kN) 5660,892 5660,892 5548,706 4891,979 4287,741 4105,2730,25.fc.bv.dv2313,976 2313,976 2268,119 1999,671 5366,452 5138,079Vn15685,206 5685,206 5576,569 4917,083 4348,504 4163,771Vn22313,996 2313,996 2272,168 2003,781 5370,874 5142,633Vr = 0,9.Min(Vn1;Vn2) 2082,597 2082,597 2044,952 1803,403 3913,654 3747,394V 191,128 383,974 1667,204 762,685 823,255 970,211K t lu n at a t at at a t at9. KI M TOA N D M THEO TRA NG THA I GII HA N SDU NG:9.1. Cac gii ha n ng su t trong b tng: ng su t trong b tng c ti nh tra ng tha i gi i ha n s du ng.Ca c gi i ha n i v i ca c m c ng su t trong b tng khi ti nh toa n c ng b tng yu c u(22TCN272-05 5.9.4.2) la :+ Lu c cng ke o :Gi i ha n ng su t ke o : 0,25.'cif= 0,25. 40= 1,581 > 1,38 MPa=> gi i ha n ng su t ke o 1,38 MPa (22TCN272-05 5.9.4.1.2-1)fDC1 + fPS1 1,38 MPa gi i ha n ng su t ne n : 0,55.fci = 0,55.34 = 18,7 MPa165FDC1 + fPS1 20,4 MPaLu c cng ke o chicota i tro ng DC1 val c do ng su t tr c+ Lu c khai tha c sau ca c m t ma t Gi i ha n ng su t ke o trong b tng la :0,5.'cf= 0,5. 40= 3,162 MPa.fDC1 + fDC2 + fDW + fLL+IM + fDN + fPSF 0,5. 'cf= 3,162 MPaGi i ha n ng su t ne n trong b tng la (22TCN272-05 5.9.4.2.1-1)- Do DL vaca c ta i tro ng th ng xuyn:0,45. fc = 0,45.40 = 18 MPa.fDC1 + fDC2 + fDW + fPSF - 18 MPa- Do t ng DL h u hi u, ta i tro ng th ng xuyn, ca c ta i tro ng nh t th i, vata i tro ng ta c du ng khi v n chuy n vab c x p:0,6. fc = 0,6.40 = 24 MPa.fDC1 + fDC2 + fDW + fLL+IM + fDN + fPSF - 24 MPa9.2. Tinh toan cac ng sut mep trn (nen lam):9.2.1. Xet luc cng keo: ng su t do d ng l c:000. .I y e PAPfti iDUL+ Do t tro ng ba n thn:00.Iy Mftttbtttbt Trong o : Pi = Apa.(0,8.fpu - fm t ma t) v i fm t ma t = fpF + fpA + fpES 9.2.2.Xet luc khai thac: ng su t do d ng l c:000. .I y e PAPfti iDUL+ Do ti tro ng ba n thn:00.Iy Mftttbtttbt Trong o : Pi = Apa.(0,8.fpu - fm t ma t) v i fm t ma t = fpF + fpA + fpES + fpCR + fpSR + fpR Do ti nh ta i giai oa n 1:111.Iy MftDCDC Trong o: MDC : mmen do ti nh ta i giai oa n 1Do ti nh ta i giai oa n 2:tdtDW DCDCIy M Mf21). ( + 166Trong o: MDC : mmen do ti nh ta i do d m chuvad m ngang MDW : mmen do ti nh ta i ca c l p phuDo hoa t ta i:20.Iy MfdIM LLIM LL++ 9.3. Ti nh toan cac ng sut mep di (ne n lam):9.3.1. Xet luc cng keo: ng su t do d ng l c:000. .I y e PAPfti iDUL Do t tro ng ba n thn:00.I y MfdttbtttbtTrong o : Pi = Apa.(0,8.fpu - fm t ma t) v i fm t ma t = fpF + fpA + fpES 9.2.1. Xet luc khai thac: ng su t do d ng l c:000. .I y e PAPfdi iDUL Do t tro ng ba n thn:00.I y MfdttbtttbtTrong o : Pi = Apa.(0,8.fpu - fm t ma t) v i fm t ma t = fpF + fpA + fpES + fpCR + fpSR + fpR Do ti nh ta i giai oa n 1:001.I y MfdDCDCTrong o: MDC : mmen do ti nh ta i giai oa n 1Do ti nh ta i giai oa n 2:tddDW DCDCIy M Mf01). ( +Trong o: MDC : mmen do ti nh ta i do d m chuvad m ngang MDW : mmen do ti nh ta i ca c l p phuDo hoa t ta i:20.Iy MfdIM LLIM LL++Ca c sli u: pstdy y e 0; yps; I0; I1; I2; yd0; yt1; yd1; yd2; yt2; ati nh.Thay sva o ca c cng th c trn ta cok t quacho ba ng sau:+ Lu c cng ke o:GIAI OA N CNG KE OM t ct L/2 3L/8 L/4 L/8 Ca ch g iG i1670,8mPj4056752,532 4074811,42 4038864,67 4097554,79 4407597,762 4427560,75e 75,29 75,29 72,92 59,05 40,51 36,67Mttbt236402,46 221627,306 177301,845 103426,0763 25030,72 0y1t49,71 49,71 49,72 49,77 55,59706937 55,61y1d95,29 95,29 95,28 95,23 89,40 89,39I121146760,8 21146760,8 21156650 21208190,32 24442175,9 24450544,7A08339,74 8339,74 8339,74 8339,74 11871,74 11871,74fdul2,316 2,326 2,078 0,765 0,349 -0,037fttbt-0,5557 -0,5210 -0,4167 -0,2427 -0,0569 0,0000f 20.4 20.4 20.4 20.4 20.4 20.4fth trn1,760 1,805 1,662 0,522 0,292 -0,037K t lu n at at at at at atfdul-18,627 -18,710 -18,107 -15,779 -10,244 -9,665fttbt1,065 0,999 0,798 0,464 0,092 0,000f 1,38 1,38 1,38 1,38 1,38 1,38fth d i-17,562 -17,711 -17,308 -15,315 -10,152 -9,665K t lu n at at at at at at+ Lu c khai thc:GIAI OA N KHAI THA CM t ct L/2 3L/8 L/4 L/8Ca ch g i 0,8mG iPj4056752,532 4074811,42 4038864,67 4097554,79 4407597,762 4427560,75e 73,154 73,154 70,852 57,379 39,698 35,929Mttbt236402,46 221627,306 177301,845 103426,0763 25030,72 0Mdc1(dn)14586,075 13674,4453 10939,5563 6381,407813 1544,4 0Mdw39112,29 36667,7719 29334,2175 17111,62688 4141,28 0Mdc264610,91 60572,7281 48458,1825 28267,27313 6841,12 0MLL+IM185191,797 175260,900 141675,309 83550,013 21567,0450y1t49,71 49,71 49,72 49,77 55,60 55,61y2t51,85 51,85 51,79 51,44 56,41 56,34y1d95,29 95,29 95,28 95,23 89,40 89,39y2d93,15 93,15 93,21 93,56 88,59 88,66A08339,74 8339,74 8339,74 8339,74 11871,74 11871,74I121146760,80 21146760,80 21156649,99 21208190,32 24442175,90 24450544,70168I222818742,00 22787148,00 22442423,00 21800247,00 32143324,00 32266217,00fdul2,112 2,121 1,882 0,604 0,267 -0,112fttbt-0,006 -0,005 -0,004 -0,002 -0,001 0,000fdcgd1-0,0003 -0,0003 -0,0003 -0,0001 0,0000 0,0000fdcgd2-0,0024 -0,0022 -0,0018 -0,0011 -0,0002 0,0000fLL+IM-0,0042 -0,0040 -0,0033 -0,0020 -0,0004 0,0000f -24 -24 -24 -24 -24 -24fth trn2,099 2,110 1,873 0,598 0,266 -0,112K t lu n at a t a t at a t atfdul-18,237 -18,318 -17,730 -15,471 -10,113 -9,546fttbt-0,0107 -0,0100 -0,0080 -0,0046 -0,0009 0,0000fdcgd10,0007 0,0006 0,0005 0,0003 0,00006 0,00000fdcgd20,00423 0,00398 0,00323 0,00195 0,00030 0,00000fLL+IM0,0076 0,0072 0,0059 0,0036 0,0006 0,0000f 3,162 3,162 3,162 3,162 3,162 3,162fth d i-18,235 -18,316 -17,729 -15,470 -10,113 -9,546K t lu n at a t a t at a t at10. TI NH VO NG C U:10.1. Tinh v ng do d ng l c:I EL Fie eeg ccpi..) (6 82 2

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V i = 0,333.E.I = 0,34.21,146.106 = 7,19.106 kN.m2 F: lc nn trong b tng do ng sut trc gy ra ti thi im sau kch(xem phn tnh hao ng sut do co ngn n hi)ec: khong cch t trc trung ho n trng tm cc b cp ti mt ct L/2eg: khong cch t trc trung ho n trng tm cc b cp ti mt ct gi=> 62 210 . 19 , 74 , 29 . 6 , 5071) 359 , 0 7315 , 0 (6333 , 087315 , 0

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pi = 0,0530 m = 53,0 mm 10.2. Ti nh vo ng do ta i tro ng th ng xuyn:10.2.1. Tinh vo ng do tro ng l ng ban thn d m:Ti t di n ti nh lam t c t gia m y u ti L/2I = 21,146.1010 mm4 E = 33994,48 MPaE.I = 7,188.106 kNm2 gDC = 21,88 kN/m16964 410 . 188 , 74 , 29 . 88 , 213845..3845 I E L gDCgi = 0,0296m = 29,6 mm 10.2.2.Tinh vo ng do tro ng lng ba n mt cu, lp phu , lan can, gchn:Ti t di n ti nh lam t c t ti nh i ti L/2:I = 22,818.1010 mm4 E = 33994,48 MPaE.I = 7,75.106 kNm2 6442 ) ( 110 . 75 , 74 , 29 ). 98 , 5 62 , 3 35 , 1 (3845E.I). (3845 + ++ + L g g gDC dn DC DWgi=0,0148 m = 14,8 mm Trong o : gDW, gDC1(dn), gDC2 : ati nh ph n trc.Nh v y vo ng co n d: = 53,0 29,6 14,8 = 11,3 mm 10.3. Ti nh vo ng tc th i do hoa t ta i coxet lc xung kich:+ vo ng ti nh cho d m gia n n: vo ng ta i m t c t x do l c t p trung P t u d m a vab.a bPLX) .(. . . 6. .2 2 2x b LL I E x b Px (x < a)V i x = L/2I EL Px. . 48.3 + vo ng gi a d m do xe HL93 (x = 14,7 m)S t ta i ti nh vo ng:4,3 4,314,729,435kN 145kNTi t di n ti nh vo ng latoa n bm t c t ngang c u:E.I = 7,76.106 kNm2 170Tru c 35 kN : x = 14,7 m, a = 19,0m, b = 10,4m ) 7 , 14 4 , 10 4 , 29 (4 , 29 . 10 . 76 , 7 . 67 , 14 . 4 , 10 . 352 2 2635x0,00211 m = 2,11 mm Tru c 145 kN : x = 14,7m, a = 14,7m, b = 14,7m 6314510 . 76 , 7 . 484 , 29 . 145x 0,00989 = 9,89 mm Tru c 145 kN : x = 14,7m, a = 10,4m, b = 19,0 m ) 7 , 14 19 4 , 29 (4 , 29 . 10 . 76 , 7 . 619 . 7 , 14 . 352 2 26145x0,00850 = 8,5 mm T ng vo ng do hoa t ta i:LL+IM = (2,11+9,89+8,5) = 20,5 mm vo ng cho phe p:mmL75 , 3680029400800 V y vo ng do hoa t ta i m bo yu c u.171