THUYT MINH TNH TON N MN HC KT CU B TNG CT THPGVHD: TRN NGUYN HONG UYNSVTH: Trn Ngc Thnh Tr LP: 11DXK1MSSV: 11D053XKTNH TOAN VA CAU TAO SAN SNBETONG COT THEP TOAN KHOI Bi: Thit k dm sn BTCT ton khi c s mt bng nh sau: STT48L1(m)L2(m)(KN/m2)f.pBT B15 Loi thp:Sn Dm phmac2,3 5,2 900 1,2 200 A1 AIIVt liu s dng: - B Tng B15~Mac 200: 'MPaMPa0,75 R8,5 Rkn- Thp sn AI'MPa 225 R175MPa R225 RscswsMPa- Thp dm ph AII 'MPa 280 R225MPa R280 RscswsMPaA. TNH BN SN:* Xt t s:= L2/L1 = 5,2/2,3 = 2,26 > 2 Vy ta xem bn sn l bn dm. Khi tnh ton bn sn ct mt di bn rng 1m theo phng vung gc vi dm ph v ta tnh nh 1 dm lin tc .1.XC NH S V TI TRNG TNH TON BN SN:a. Xc nh s b kch thc cho cc cu kin:*Chn chiu dy bn sn:bh =min 667 , 76 23003011 h mm LmD> => Chnbh = 80 mm.*Chnkch thc dm ph: (nhp = = 5200 mm)+( ) mm 325 433,3 52001611212L161121hdp

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40cm 400mm h Chon dp * ( ) mm 200 100 4002141h2141bdp dp

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200mm bdp Chon*Chnkch thc dm chnh: (Ldc = 3.= 3.2300 = 6900 mm)+ ( ) mm ,5 862 575 690081121L81121hdc dc

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85cm 850mm h Chon dc *( ) mm 425 212.5 8502141h2141bdc dc

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40cm 400mm b Chon dc b. Xc nh nhp tnh ton ca bn: Nhp bin: m 2,09 lmm 20902120234022002300 l2 2t2bl l0b0bdp1 0b + + C b Nhp gia: m 2,10 lmm 2100 200 2300 b l logdp 1 og Chnh lch gia cc nhp: 0.47%2,092,10 2,09.100%ll logog obc. Xc nh ti trng tinh ton: * cc lp cu to sn nh sau;L P G CH L T ceramicl p va l tl p bt ctchu l cl p va t r tt r n- ghch ceramic:310 ; 20 / ; 1,2 mm KNmg g f - va lt: 325 ; 18 / ; 1,3vmm KNmv f - BTCT : 380 ; 25 / ; 1,1btmm KNmb f - Va trt : 320 ; 18 / ; 1,3btmm KNmv f + Ti trng ton phn (tnh trn gii bn rng b=1m).

( ) (3, 5 9, 6) 1 13,1s s sq g p b + + kN/mS cu to v s tnh ton bn sn: AHnh 3. S xc nh nhp tnh ton ca bn2.XC NH NI LC TRONG BN SN:+Mmen nhp bin v gi bin: 2 21 1max 11 1113,1 1, 99 4, 71 /s obM q L kN m + Mmen ln nht gi th hai:2 21 1min 11 1113,1 2 4.76 /s oM q L kN m +Mmen ln nht cc nhp gia v gi gia:maxmin2 21 116 1613,1 2 3,28 /s oM q L kNm t t t++++++++++++++++++++++++++++Hnh4 .3.TNH TON CT THP BN SN:a/ Tnh ct thp: V bn sn c coi nh dm lin tc c tit din ch nht (1000 x 80) -Chiu cao tnh ton ca bn:ho = hb a = 80 15 = 65 mm. (Chn a = 15 mm) -Ct thp bn sn s dng loi thp AI: MPa Rs225 -B tng B15: MPa Rb5 , 8 ,iu kin hn ch khi tnh theo s do l 3 , 02 plbh RMmo b b m 2 1 1 so b bR bh RsA-Kim tra hm lng ct thp: % 4 , 1 37 , 0 % 05 , 02255 , 8max min sb bosRRpl bhA - Tnh ct thp theo bng di y:Tit din M(kN/m)msA) / (2m mmChn thp(%)) (mmd a (mm)) / (2m mmAscNhp bin, gi bin4,71 0,146 0,159 351,39 8 110 352 0.53Gi 2 4,76 0,146 0,159 351,39 8 110 352 0,54Nhp gia, gi gia3,28 0,101 0,107 236,47 6 110 254 0.36b. B tr thp: Xem bn v Xt t l: 9,63,52, 74sspg mm Lo gpss500 2000 25 , 0 25 , 0 3 1 < < chn: mm L Lob o500 i vi cc bn c dm lin kt bn bin, vng gch cho trn hnh 5, c gim 20% lng thp so vi kt qu tnh c. cc gi gia v cc nhp gia:, 185 8 , 230 8 , 02mm As chn) 202 ( 140 62mm A as Ct thp chu mmen m dc theo cc gi m v pha trn dm chnh c xc nh nh sau:{200 6% 50,aAct ssA gi gia = 2102 8 , 203 5 , 0 mm + Chn ct thp cu to (phn b): do 2 < = = 2,1 < 3 F cu to = 20% . Fa bin = 0,2 . 2,86 = 0,57 (cm2); chn 6 a = 300 (Fa=0,94cm2) B. TNH DM PH:S tnh:Dm ph l dm lin tc 3 nhp, vi cc gi ta l dm chnh. Nhp tnh ton: -Nhp bin:dc tb 2b h c 400 300 200l l 5200 4950mm 4,95m2 2 2 2 2 2 + + -Nhp gia:g 2 dcl l b 5200 400 4800mm 4, 8m -Chnh lch gia cc nhp:4, 95 4, 8.100% .100% 3,125%4,8ob ogogl ll 3) Ti trng tc dng ln dm ph: a.Hot ti: Pdp = n. .= 1,2 . 900. 1,9= 2052 (kG/m) b.Tnh ti:=.+ n. . .(-) = 310.1,9 + 1,2. 2500.0,2.(0,4-0,08) = 781 (kG/m). c.Ti trng ton phn:= Pdp + = 2052 + 781 = 2833 (kG/m).* Xt t s:=2833781 = 3,62;tra bng ph lc III => k = 0,284) Tnh biu bao ni lc:a. Lc ct: Tung biu lc ct c xc nh nh sau:QA = 0,4= 0,4. 2696. 4,95 = 5338,08 kG QB,tr = 0,6. = 0,6.2696. 4,95 = 8007,12 KGQB,ph = QC = 0,5.= 0,5. 2696.4,8 = 6470,4 kG.b. Mmen:-Mmen dng trit tiu cch mp gi B mt on: +Ti nhp bin:x =0,15 .=0,15.4950 = 742,5 mm+ Ti nhp gia: x = 0,15.= 0,15. 4800 = 720 mm.-Mmen m trit tiu cch mp gi B mt on: x= k.= 0,28. 4950 = 1386 mm.-Tung biu bao mmen tnh theo cng thc:2d.l .q M ,theo bng sau:Nhp Tit din H s .Tung M,(kG.m)Mmax Mmin (kG.m) Mmax MminBin0120,425.L300.0650.0900.0910.07566058,74----04296594560114954450.020-0,0715--1321-4723Gia670,5L0.0180.0580.0625-0.0343-0.014761225,84--110235513826-2100-900c.Biu bao mmen v lc ct:5.Tnh ct thp dc: Rn = 85 kG/cm2; Ra = Ra = 2800 kG/cm2.a) Kim tra kch thc tit din dm: * Theo iu kin mmen: = 2. .nMRb= 2. 66058, 7485.20= 13cmGi thit a= 4cm => hdp = 40 - 4 = 36 cm > hdp chn*Theo iu kin lc ct: [Q] = ko.Rn.b.ho = 0,35.85.20.(40-4) = 21420kG > Qmax =5627kGNh vy tit din chn (200x400)mm l hp l/b.Tit din chu mmen m: coi dm lm vic theo tit din ch nht (15x30) cmgi thit a = 4cm => ho = h a = 26 cm;Ti cc gi B,C tit din chu mmen m, ta s dng cc cng thc tnh ct thp nh sau:A =tra bng : Suy ra,Fa =. .b oMRh =.2800.36M ;gi tr ghi trong bng bn.c.Tit din chu mmen dng: Coi tit din lm vic l ch T (hc = 8; bc ; h = 40; b= 20)cm.-Xc nh b rng cnh tham gia chu nn: Sc,chiu rng 1 bn cnhSc . = 1/2 . 199 = 99,5cmSc . = 1/6. 480 = 80 cm => chn Sc = 72 cmSc 9= 9.8 = 72cm. - B rng bn cnh l:bc = + 2Sc = 20 + 2.72 =164 cm;- Gi thit a = 4cm => ho = h a = 40 4 = 36cm*V tr trc trung ha:Mc = Rn.bc.hc.(ho 0,5hc) = 85.164.8.(36 0,5.8) = 3568640 kGcmTa thy: Mmax = 324300 kGcm < Mc = 3568640 kGcm => Trc trung ha i qua nhnh ca tit din ch T; ta tnh tit din nh tit din ch nht (164 x 40)cmd.Tnh chn ct thp: trong bng di y. (BT mac 200: A Ad = 0,3)Tit din M(kG.cm)A= = 0,5(1+ = Chn thp (%) ,cm2 ,%Gi B (15x30)254800 0,116 0,6152 4,1093166,03 2,4 1,5Nhp bin (135x30)324300 0,147 0,6059 5,309212 +2166,28 -1,3 0,2Nhp gia (135x30)211200 0,096 0,6212 3,373116 +2124,27 3,7 0,126) B tr ct thp: (chi tit trn bn v)7) Tnh ct ngang v ct xin:+ Kim tra iu kin tnh ton:Q = k1.Rk.b.ho = 0,6. 7,5.20.36 = 3240kG < Qmax = 5627 kG; _phi tnh ct ai.+ Xt mt ct c lc ct ln nht: Qmax = 5627 kG , ho = 36cm-Chn ai 6, Fd = 0,283cm2, ai 2 nhnh => n = 2; u = 150mm-Tnh bc ai cc i: =21,15. . .k oRb hQ= 21,15.7, 5.20.365627 = 39,73mm-Chn bc ai u =150 mm, bo m u min{ / 2 ;; 150} = min{150;155;150}mm-Lc ct ct ai chu c:6, 03 a R .n.F 1750.2.0,283q 6KG/ cmu 15-Kim tra iu kin tnh ct xin: 10133 2 2b k o Q 8R bh q 8.7,5.20.36 .66,03KG> Qmax =5627 kG;vy khng cn phi t ct xin cho dm ph.8) Tnh v v biu bao vt liu:Tit din Ct thp Fa(cm2)a(cm)ho(cm2)= =1- (Tm)=Ra.Fa.ho1612Nhp bin (135x30)2 226,282,263,233,136,7736.90,0260,0090,9870,9966,382,33Gi B(30x60)326,034,023,33,336,736,70,02490,01670,9880,9926,124,1Nhp gia (135x30)1 224,272,263,193,136,8136.90,01760,0090,9910,9964,362,33-Biu bao vt liu:9.Xc nh im ct l thuyt v on ct thc t: (xem chi tit cch tnh dm chnh).Ta c bng tnh ton nh sau:K hiu x (cm) Q (kG) d (cm) 20d (cm)W= . +5d;(cm)L=(cm)Nhp binXnb_2A 262,7 20080 1,6 32 141 403,7Nhp giaXng_2C 55,3 163009 1,6 32 116 171,3Gi BXg_1B 21,6 23947 1,6 32 166,6 188,2