đồ án kỹ thuật xây dựng Nghiên cứu độ tin cậy của mặt cắt ngang dầm hộp cầu bê tông dự ứng lực theo cường độ chịu uốn và chịu cắt

Chuong trinh tinh to6n hem bidu di6n hang thili chiu udn vi chiu c6t d6i vdi mat c6t ngang kdt c,fu nhip ddm hop bc tdng du Ling lucKdt qui xir lf x6c dinh dac trung phan phdi xdc sudt c

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l.l Tinh hinh xiy drmg cdu dem hOp bC r6ng dr img l.rc d Vier Nam 8

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t 0 l 1.3 Dang kdr ca.u nhip ddm hOp BTDIIL thi c6ng bn,rg circ p!_ruorg phdp khric" "" - -, ,

1 { } I .2 Do rirr cay cua let ciu crrng trinh _ l; 1.2.1 Khdi nienl vc! clO tin cAy cia ker cd-u xriJ,,j+rg , i i I.2.2 C6c dinh nghia vd thuat ngrr

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I 3.1 Tinh hinh nghi€n cfrr drig tJung li rhuydr dO tin cay h.ong tinh ' toiin cong trinh ftcn rhdgidi 18

1.3.2 Tinh h)nh nghi€n cLfu ing dung lf rhuydr al0 tin cay rong tinh to6n c6ng trinh n Vidt Nam

1.3.3 M6r sd nhan dinh vd vdn tld nghidn crlu DTC ddi vdi KCCI cdu hidn nay "" " " - :to

chudng 2: PHAN TicH LUA cHoN pHUdNG pHAp DANH GiA DO

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2.1 D0 tin cay ciia kdt cdu nhip ddm h6p bC tong du rirlg luc 28

2.1.1 Cic dai ludng ngiu nhi€n 6nh huong ddn dO tin cAy lim vi€c 'cirakdtcdunhipBTDUL ; 2g 2.1.2 DO tin cay d6c tnnrg cho khi ndng ldm vi€c cua kdt cdu nhip BTDtlL 30

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2.2.1 Cdc dinh nghia vi thuar ngi? 32

2.2.2 C6c thaln s6 d6c trung x6c sudt thdng k€ 33

2.2.3 Xdc sudt srr cd cria kdt cau cong trinh 35

2.2.4 Chi sd d0 tin cey 8 37

2.3 Cdc phuong ph6p x5c dinh chi sd d6 tin cay 38

2.3.l Trudng hqp hlm trang thdi l) him tuydn tinh 40

2.3.2 Truong hqp h)m trang rhdi li him phi tuy6n , 41

2.3.3 X6c d0 tin cAy bing phrrong ph6p Monte-Cailo 42

2.3.4 Xdc d0 tin c6y bing phucrng phdp h)nh hoc ., 44

2.3.5 Tinh todn chi sfi d6 tin cAy tir kdr qui tinh to6n thidt kd 47

chuong 3: NGHTEN ciu IHAN pndr xAc su.{r ctia cAc Brgi.r co.BAN vA oE xuAr rHANc DrdM DANH GrA DO rrN cAy c{re rf,r cAu NHrp DAM HOp BE rONc pu(xc LlJc 4e 3.1 Trinh tu phdn iich quy luit phAn phdi xilc sudt cira cric bidn co ban 49

3.2 Quy luat phdn ph6i x6c sudt cua kich thu6c hinh hoc mat c6t ngang kdt cdu nhip di.m hop bc rdng du fng lirc 52

3.3 Quy luat phan ph6i xric sudl cria cudng d6 be rong kdt cdu nhip ddm

bC tdng du fng luc 56

3-4 Phen pheii x6c sudt crrdng d6 chiu k6o cria c6p drr rlng luc ve c6t th6p thudng - 59

3.4.1 Phan phdi x6c sudt cudng d0 chiu k6o cria cdp du rlng 1rrc 59

3.4.2 Phan phdi x6c suft cudng dd chiu k6o cira ccit th6p thuong 59

- 3.5 Phan phtii x6c sudt cira rlng luc do tii trong gay ra do tei irong 60

3.5.1 Phan phdi x6c su{t cia rinh tii ' 3.5.2 PhAn phdi x6c sudr cfia hoar tai o t0 _ 61

3.5.3 Dac didm phdn phdi xdc sudt cira hi€u fng tii trong n6i chung 61

3.5 X6c dinh tham sd dac trung cia c6c dai luong ngdu nhi€n dai di€n cho srlc kh5ng cia kdt cdu nhip tidm hdp BTDUL vir rlng luc do tii fong gay ra 63

3.6.1 Xric dinh c6c hang sd trong him bidu dicn trang thdi chiu udn vd chiu c6t cira kdt cdu nhip ddm h6p bC tong dd fng 1uc 63

3.6.2.X6c dinh c6c tham sd dac trung cira c6c bidn cd ban trong ha,m ' rrang thdi ctia kdt ca'u nhip ddm h6p bC tong drr dng l1rc 63

3.7 Lua chon, dd xudt thang didm ddnh gi6 d0 tin cdy cfia kdt c{u nhip ddm hdp bC tong dU irg Uc 67

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4.l Xdc clinh cdc bidn co bin trong cdc hlm bidu tliOn trang rhdi chiu u6n vd chiu cit ctra kdt ctiu nhip ddm hop bC tOng du ring lrrc 74

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cria kdt cdu nhip dem hop b€ tong du fng luc

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chiu c6t d6i vdi mat c6t ngang kdt c,fu nhip ddm hop bc tdng

du Ling lucKdt qui xir lf x6c dinh dac trung phan phdi xdc sudt cudng

dO cria b€ tong, kich thudc hinh hoc mat cit ngang vi tinh

todn do tin cay cira mot sd kdt c{u nhip ddm hop bc tong drrfng luc & Vict Nam

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him mdt dd xdc sudt crla DLNN X

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kb ki,vong todn cta dai lLrong ngiu nhi€n X

ld phrrrrng sai cua dai luong ngiu nhidn X

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him mat dO phan phdi x6c sudt ciia rlng lrrc do tii

trong gay ra

gi6 tri gidi han cria srlc kh6ng

gi6 tri gidi han cira fng luc do tii trong gdy ra

gi6 tri v6 hurrng cira kdt qui chudn ho6 phan ph6i

x6c sudt cila sfc khdng R

gi6 tri vd huong cria kdt qui chudn hod phan phdi

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thdng nhfit Theo sd li€u ncu trong Nien gidm duong bd nim 2002 do CucDrrong b0 Vict Nam ban hlnh [l8], Vict Nam c6 khoing 7.879 cdng trinh cduc6c loai vdi tdng chidu ddi ld 223.818m 'Irong sd d6, trdn he thdng qu6c 16 c6

4.239 cN vdi tdng chi6u dii li 144.539m, trdn cdc dudng tinh c6 3.640 cdu

v6i tdng chidu ddilit79.279m Kdt qui th6ng k€ phAn loai cdu bc tong du fng

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nhung lai chidm 61,127o vd sd h.rong.

Trong khoing 10 ndm trd lai Cdy, dang kdt cdu nhip cdu BTDUL khdu d0

l6n vi trung binh tlang la giii ph6p chir ydu trong xAy tlLmg ciu nrii chung &

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MCN hinh hop BTDIIL thi cong theo phuong phrip ciLie hing, rhic ddy vd dfctai ch6 trcn dd gi6o khoing rrcn 50 cdu, vdi tdng chidu dli gdn 10.000m Sdcdn lai li c6c crlc kdt cdu nhip don giin BTDUL mat c6t ngang hinh chf T,

hinh cht I, ddm hOp bin tlac, ban r6ng, ddm Super Tee v.v c6 khdu d6 tit15,0m d6n 40,0m

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hc thdng kdt cdu ha tdng giao thdng van di Viet Nam Vd chdt lrrdng thidt kd,

thi cong vd khai thdc nhtng loai c6ng tdnh niy ctng rdt da dang, phu thuOcvdo trinh d0 cong nghc cua nhi thdu thi cong, tu vdn thidt kd, chir ddu trr, don

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chi tlrroc thdng qua c6c phuong phdp kidm tra chdt ludng thi cong vd nghi€m

thu theo c6c phdong ph6p <idn giAn, kh6ng thd phin 6nh dring d4c didm ngdu

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tinh todn diinh gi6 khi nang chiu luc cira cdrrg rfinh cdu th6ng qua vi0c khio

s6t, thu thap c6c sd li€u thdng k€ nhfrng ydu t6 li0n quan lh xu huong hi'9n dai

vd tlem lai hi€u qui trong quin lf chdt luong cOng trinh'

Thdi han khai thdc cira KCCT n6i chung c6 thd bi suy giim do nhidu ydutei rinh hrrong tir khau thiet kd, thi cong, quan li khai th6c v'v ' do tinh chdt

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trung cho su lem vice cira KCCT tlrrdi tr{c tlung cira rdt nhidu dai luong beit

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dinh vi thay ddi theo thdi gian Mat kh6c, viOc tl6nh gi6 chdt lrrong lim viOc vi

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_ phan dch, d6nh gid khi nang chiu luc khong su c6 cria KCCT dqa

co s& kdt qu6 th& nghi€m, kidm tra thu rhap cdc sd rieu thdng kc vd di;

tdc ddng va sfc kheng cira cOng trinh.

- X6c dinh thdi gian khai rh6c an I:oin, du b6o tudi tho vdL du ffi cur

(st1c kh6ng) cria KCCT khi bi6i duryc rop ouv quy lu{t t,,Ar vd r,; x6c v4^ ^.-ai , sudt su cd c6 t}6.r.

Tini to6n didu chinh chd tld khai th6c vi rhdi han khai rh6c

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fhici ke

- Ddnh giri trang thiii Ling suar bicn dang vi quri rrjnh tich lug

crla KCCT trong kho6ng thdi gian khai th6c,

dd drr b6o rrang thi4ic6ng trinh

- Nghidn ctiu xay dung ciic h6 so DTC trong cric ti€u chudn

c6ng vd hudng d6n rinh to6n d6nh gi6 chdf ldong cong rrinh v.v

ViCc rlng dung li thuydt DTC rrong rinh to6n d6i v6i KCCI ve xi

hQ thdng ti€u chudn xdy drmg dang duoc nhidu qudc gia, ,a

"f,,f" quinhidu nhi khoa hoc rr€n rhd gidi quan ram ngf,i.n

.fu tfOl, U|l, l2gi,,

Trong ti€u chudn thi6t kd cdu duong b0 cira M! AASHTO LRFD t78l

hi6n nay, clng nhu trong cdc ti€u chudn cira c6c nu6c vi khu vuc kh6c nhuBS5400 (Vuong qudc Anh); Euro Code (ci4c nudc thenh vien li€n minh ChAu

Au) phdn l6n cric h€ sd vd tii trong, vat li€u t16 duoc qui tlinh tt kdt qui

nghien crfu cria cdc du 6n, chudng trinh da dud c tridn khai thuc hien t€n co s&thu rhep, thdng kc sd li€u thuc td vd phan tich tinh to6n theo li rhuydt x6c sudtthdng k6 vi ly thuydt DTC Trong d6, c6 nhidu nhi khoa hoc tren thd gi6i dac6 nhfng d6ng g6p l6n ddn vi6c nghi€n crlu ring dung ly rhuydr DTC d6i vdi

cong trinh cdu va xay dung he thdng ti€u chudn thidt kd hi€n nay nhu: NowakA:S [103], t1041, I1231, Christensen P T., t861, [87], Baker M.J [87], Faber

M H., Sorensen J.D t901, Frangopol M [91], Peter Tanner [1061, PoulLinneberg Pedersen [07], Iffland, J S B., [93], Sherif El-Tawil [110], Tarek

N Kudsi [12], Vrouwenvelder A.C.W.M [115], I-d-xi-lev-xki [123], TrircovV.P !331, Iu-ma-sev V M [135] v.v

- Trong hO th6ng ti€u chudn cdu duong mdi cira Nga hdu hdr c6c hC sei rei

trong v) cudng dO lthuc chdt ld nhfng h€ sd DTC rieng) cfing de dudc xaydqrng dr.ra ftCn co sd nghi€n crlu thdng kd vir phAn tich rheo li rhuydt DTC,

didn hinh ld: Ti0u chudn thidt kd cdu cfing CHuII 2.05.03-84* [129]; TiCuchudn thrl nghi€m cdu CHuII 3.06.07-86 [130]; Tidu chudn thi c0ng cdu ctingCHtr[ 3.06.04-91 [31] v.v HC s6 di rrong vi hd sd srlc khdng trong ciictiOu chudn niy ddu ttrroc qui dinh rr) kdr qui cira ciic du dn, chuong trinh

nghien cdu trcn co s6 phan rich ddnh gid theo l)t rhuyer xdc su6i drji vdi czic

sfi lieu thdng k6 Vi€c nghi€n cfu rfurg dung li rhuydt DTC trong tinh to6n

KCCT v)L xay dung hc rhdng tiCu chudn tld drroc nhidu nhi khoa hoc cila Ngathuc hi6n tir ddu thap kj 80 trd lai day.

d Viet Nam c6 nhidu r6c gii nhu Nguydn Vin Ph6 vd tldng nghidp t461,t441, [48], [49], Phan Vdn Khoi [34], Lc Xudn Huj,nh t291, [30], Nguycn Vidt

Trung [24], t691, t7ll, Trdn Dfrc Nhi€m t401, t441, [45], Nguycn Xudn Ch(nh4

[17], Bni Drlc Chinh [16], v.v di c6 cdc cOng trinh nghiOn cfu ring dung 1!thuydt DTC dd glli c6c bdi todn liOn quan ddn tinh to6n, d6nh giri cr4c KCCTn6i chung, tl6nh gi6 cdng ngh€ thi cOng bC t0ng, x6c dinh ddc tlidm phan phdix6c sudt cia bC t0ng vh brrdc tldu nghidn cdu x6c dinh ciic hd sd vrrot tii.

TrOn co s& ph6t tridn cr4c phrrong phdp phen tich DTC, ring dgng c6ngnghC tin hoc vd x6c tlinh du.c yeu cdu d6nh gi6 DTC ddi vdi kdt cdu nhipBTDIJL da xay dung 6 ViCt Nam tong ttldi gian qua, tdc gii dt chon dd rii

"Nghi€n crhu illnh giti ilQ tin cQy cfia mdt cdt ngang ildm h p cdu bA fing

d( ttng hlc theo didu kian cudng aI6 chiu udn vii chiu cdt" Phddng hudng

giii quydt vdn dd khoa hoc trong niy ld vi€c ring dung lf thuydt x6c sudt, lf

thuydt DTC, cong nghc tin hoc vd c6c s6 li€u thuc td dd nghi€n crfu m0 hinhbii to6n DTC, xay dmg phuong phdp giii bii to6n ddnh gi6 DTC cria mat c6t

ngang (MCN) ddm hop cdu BTDIIL.

2 X6c tlinh pham vi bii torin ddnh gi6 d0 tin cAy cria mat cdt ngangddm hop bd tong du ring lrrc

Vi€c dr4nh gi6 DTC ddi v6i kdt ciiu nhip ddm hdp BTDUL l) vdn dd rdtphfc tap do phdi thu thapddy di vd xir lf cric sei li€u rhdng kd Hon nia, ngay

ci khi c6 dri c6c sd li6u th6ng kd, rhi vi€c ddnh gi6 chinh x6c DTC cua dangk6t c{u nhip ddm h6.p BTDUL y6u cdu phai thuc hien khdi luong cong vi€c rdtl6n, ddng thdi ddi vdi kdt cflu nhip ddm hOp BTDUL li dang kdt cdu si€u tinh,

n€n h€ thdng c6c chi s6 DTC thanh phdn (chi sd DTC cira cr{c MCN) c6 inh

huong rdt phrlc tap ddn DTC cria h€ thdng N6i c6ch kh6c, vi€c xay dungphuong ph6p dd xdc dinh ddy tlir chi s6 DTC thdnh phdn vi mrlc tld inh hu6ngcira chring d6i vdi DTC chung cfia kdt cdu si€u tinh dang ddm h6p BTDUL.

Do d6, luan 6n gidi han vi6c tidp cAn ve phan tich DTC cua kdt cdu nhip

ddm hop BTDUL rh6ng qua vi€c phAn tich vi diinh gi{ DTC cira cdc MCN,

ddc bi€t chri f tdi c6c MCN ddm h6p c6 DTC lim vi€c thdp nhdt, nhu nhimg

khdu ydu nh{t cira toin h6 thdng (duoc xem nhu h€ thdng m6c ndi tidp nhrr

dang k6r cdu nhip ddm BTDUL ddn giin), md chrra dd cdp duoc tdi vi€c d6nh

gi6 hC thdng chi sd DTC cing nhu m6i quan he giila c6c chi sd DTC cia cr4c

MCN trong toan he th6ng kdt cdu nhip ddm nhu he thdng ddm si€u tinh

Ddi v6i kdt cdu ddm n6i chung, khi ndng chiu udn vd chiu cit li hai dac

tlmg co bin nhdt, vi vhy pham vi nghiOn crfu du-o c gidi han ld giii guydt b)ito6n co bin nhdt trong d6i vdi kdt cdu nhip ddm h6p BTDUL tl6 li d6nh gi6

DTC theo tlidu ki6n cudng tl6 chiu uon vi chiu cdr cfra kdr ceu nhip ddm hdpBTDUL phn hqp v6i didu ki0n cta ViCt Nam, sau d6 ph6t tridn ddn dd giii

quydt c6c bai to6n cdn lai.

3 Muc ti€u vir cr{c n6i dung, pharn vi nghidn cfu

Muc deu cira dd tdi li nghiOn crfu tinh todn DTC cira kdt ct{u nhip ddmhOp BTDUL theo didu ki€n crrdng 116 chiu udn vi chiu c6t vdi nhtrng n6i dung

v) pham vi nghidn criu cu lhe llhu sau:

- Nghi0n cfu quy ludt phan phdi cira c5c BCB dac fiung vd kich rhudc

hinh hoc, cudng d0 cira bC tdng cfra m6t sd kdt cdu nhip BTDUL dn xay dmg

6 Vict Nam, ker hqp v6i vi€c kh6o sdt cdc kdt qua nghi€n crfu tr€n thd gi6i vdphan phoi thdng kC cia rirrg luc do tiii trong gay ra do tii trong, dAc fimg

cudng d6 ciia cdt th6p v.v x6c dinh h€ sd bidn sai gdn dring sit dung dd tinh

ro6n DTC cia kdt cdu nhip BTDUL.

- Tham khio c6c c6ng trinh nghidn crlu tr0n thd gidi vd linh vu.c DTC ddnkidn nghi thang didm d6nh gi6 DTC ddi vdi kdt cdu nhip BTDUL.

- Thidt lep b)i to6n didn hinh vd d6nh gi6 DTC theo him bidu dien trangth6i chiu udn vd chiu cat ciia kdt cdu nhip ddm h6p BTDUL.

- Xay dung thuAt to6n giii quydt bdi to6n d6 dar ra ve ldp phdn mdm

chuycn dung dd tinh to6n DTC chiu udn, chiu c6t ddi vdi kdt cifu nhip ddmhdp BTDtJL

- Tinh to6n DTC ciia m0t s0 kdt cdu nhip ddm hdp BTDUL de xAy drrng

6 Viet Nam.

6

- Kh6o s6t dQ nhay cria c6c BCB ddi v6i DTC dd ddnh gi6 mrlc dd 6nhhrr&ng cria cr4c BCB ddi v6i DTC chiu u6n cira cira mQt s6 k6t cdu nhip ddmhop BTDUL.

Vdi muc tieu trcn noi dung han 6n duo c trinh biry gdm phdn m6 ddu vi 5chuong sau: Chuong 1: Tdng quan

Chudng 2: Phdn tich lua chon phrrong ph6p d6nh gi5 DTC diii vdi kdt c{u

nhip ddm hoP BTDUL.

Chuong 3: Nghien crlu phan ph6i x6c sudt cira c6c bidn co trin vi dd xudtthang ttidm ddnh gi6 DTC cia k6t cdu nhip ddm hOp BTDLIL.

Chdcrng 4: XSc.dinh DTC chiu udn vi chiu cit cia kdt cdu nhip ddm hOp

STDIJL.

Chudng 5: Tinh to6n DTC vi khio s6t dd nhay cira mdt s6 BCB ddi v6i

DTC cira kdt cdu nhip ddm hdp BTDUL.

4 Phuong ph6p nghi€n cftu

Dd dinh gi6 DTC cira kdt cdu nhip ddm hOp B'T!UL, tudc h€t cdn xfc l{p rnO hinh bii tordn DTC theo didu kien cdamg d0 chiu udn vd chiu cit; xdc

tlinh c6c dac tnmg phan phdi xdc sudi v) h€ s0 bidh sai cira cdc dai ludng ngiunhi€n; xdc dinh hdm bidu di6n trang thdi chiu udn vi chiu c6t cira kdt cd'u nhip

ddm hdp BTDUL; ph6t tridn c6c phrrdng phdp phan tich DTC d6i vdi KCCT

vi xay ddng thuat to6n dd phan tich DTC cria kdt ct'u nhip ddm hdp BTDULv.v , d6ng thdi nghi€n cfu 6nh huorg phAn t6n cira c6c ydu td ngdu nhi€n ddi vdi DTC chiu u6n v) ritrg dung kdt qui nghidn crlu dd d6nh gi6 DTC ddi vdi

mot s6 k6t cdu nhip ddm hop BTDTIL de xey dung 6 ViCt Nam

7

Chuong I

TONG QUAN r.t TiNH HiNH xAv lur.lc cAu rAu sop nt roNG DV{NG Lu c

0 vIEr N,ln'r

Theo dac tlidm cong nghq xay d{ng, kdt cdu nhip ddm hop BTDUL 6 Vi€t Nam gdm c6 c6c loai sau: kdt cdu nhip c6 MCN dang hinh hop BTDULdric hAng, kdt cdu nhip c6 MCN dang hinh hOp BTDUL dric duiy, kdt cdu nhip

c6 MCN dang hinh hop BTDUL dfc tr€n ddn gi6o cd dinh, kdt cdu nhip

BTDUL ddm ban r6ng, kdt cdu nhip BTDTIL ddm bin drc v.v

Ndi dung cria muc rtiy phdn tich dac didm c61u tao cira m6t sd dang kdt

cdu nhip cdu BTDLIL di duoc xay dung 6 Viet Nam hicn nay dd ldm co sd luachon loai hinh kdt cdu nhip BTDttL tinh todn DTC cta luan 6n

CdNG THEO PHTTO\C PHAP DUC HANG

' Dang kdt cdu nhip ddm h0p cdu BTDUL thi cdng theo phtrong ph6p thic

hdng xudt hiCn trong thi cong cdu bC tOng cdt th6p du fng lrrc khoing nhfng

ndm 50-60 thdk1i trrr6c vd ngly mOt phdt tddn manh vd chi€u siu vi di€n rOngtr€n thd gidi Nhfrng cdu BTDUL khdu dO l6n da drro c thi cdng theo phucrng phdp hing nhu: cdu Medway 6 Anh nhip 152m, cdu Avtozavog 6 M6t-xcd-va

Nga nhip 148m, cdu Houston 6 Texas (M!) nhip 229m, cdu Hirosima nhip236m vi cdu Hamana nhip 240m 6 Nhat BiiLn, cdu Schotwien 0 Ao,nhip

250m, cdu Gateway i! Australia 260m (1986); cdu Ha MOn (1997) 6 Trung

Qudc c6 nhip 270m vi cdu Rafsundet 298m vi Stolmisundet 30lm cila Na Uy [59l 174] v.v

Dric hdng li cdng ngh€ thi cong kdt cdu nhip BTDUL bing phrrong ph6p

d(c be tong c6c khdi ddm lien tidp nhau theo kidu ddi xfhg (tU tru ra hai phia)ho4c khOng tldi xfng (td md ra) C6c khcii be rong dfc hing dr,r.c dd rai ch6

ren da gi6o di dong (goi li xe dric) Cic thao tdc cong nghd tir khi di chuydn

xe thlc h6ng v)o vi tri mdi cho ddn khi cing k6o xong DUL dudc goi le mot

chu ki dfc hdng

Qud trinh thi cong dric hang thuong durrc ti6n hinh ti m6i tru ra ddi xrlngttdu 2 phia theo doc tim cdu Ndu li cdu ddm thi b€n tr0n dinh tru phii tl6t cdcgdi k€ t4m bang bc tong cdi th6p (BTCI), trcn d6 s6 t16c ddt ddm ben tr€n tru

rdi k6o cdng c6c cdt th6p thanh du fng luc thlng dfng tam thdi hodc le b6 cdtth6p DUL dd licn kdt cfng tam thdi kdt cdu nhip v6i tru nham tlim bio dnilinh chdng lat trong sudt qu6 trinh thi cong hdng Doan ddm 6 s6t mfi crianhip bicn c6 thd drroc 16p gh6p hay dfc tai ch6 tren di gi5o cd dinh

Sau khi thi cdng xong cdc cdnh hring thi phii hqp long rheo trinh tq dud c

du kidn tinh to6n k! lrrdng Tru6c hdt c6 thd hgp long trong nhip bi€n, n6i

do4n thi cong trcn de gido cd dinh v6i mdt cdnh hang d6 duo.c thi cong h6ng.Cfing c6 thd ndi ting cdp c6nh hSng dd tao ra kdt cdu ddm hing sieu tinh vfing

chac, th6o c6c gi6 dO vd c6c gdi k0 tam rdi kO ddm l6n gdi Tidp theo d6 sE

' hqp long dd ndi cdc ddm tinh tlinh n6i tr€n vdi nhau thinh h€ ddm si€u frnh c5

s6 bac sicu tinh tang ddn sau m6i ldn hgp long

Khoing 10 ndm tr6 lai ddy, hdng loat cdu BTDUL dric hing dA du.c thidt

k6 xay drrng 6 Vici Nam gdn 50 cdu v6i khoing hon 9000m chidu dii.

Chidu ddi kdt cau nhip chinh cfra cdu BTDUL dfc h5ng duoc dSnh gi6 ln

' kinh td nhdt trong khoing ti 70 m tldn 150 m Thuc td c6c cdu bc tong cdt

th6p du ung luc licn tuc dfc hang da du-d c thidt kd ve xay dmg tai Viet Nam

cho ddn thdi didm hi€n nay ddu c6 chidu dii nhip chinh nam trong khoeng tir

60 m tldn 130 m: 60m; 6lm; 63m; 64m; 80m; 85m; 90m; 100m; 102m; 105m;

120m; 130m Cdc cdu BTDUL drlc hAng nhidu nhip 6 Viet Nam ddu duoc

thidt kd nhip chinh bing nhau nhu: cdu Phir Ddng (7x100m); ceu Cau Leu

(3x78m); cdu Vin Ddn (3x90m) v.v

1.1.2 DANG xlr cnu Nnp oAu Hop eE r6Nc DIJ(NC LW Tr{I

c6uc ruro PHI-]()NC PHAP DUC DAY

D4ng kdt cdu nhip ddm hdp BTDUL dric ddy ln dang kdt cdu nhip ddmhQp thi cong theo phudng ph6p thic c6c kh6i ddm tr0n bd sau d6 ddy k6t cdunhip ra vi tri thi6t kd Cdng ngh€ dfc (l6p) vt ddy tlrroc tidn hhnh timg dot li€ntidp nhau dd ddy ct nhtng kdt ca'u nhip c6 chidu dii rdt lon' Cong nghc thic6ng ney c6 nhidu uu tlidm nhu: cong trudng gon, tap trung, t6 chfc thi c0ngdon gi6n, cOng nghi0p ho6 cao it Anh huong ddn giao th6ng bcn du6i, ph hqpcho thi cong cdu vuqt trong thinh phd, noi mdt bang thi cong hep, st dung it

dAn gi6o, tohn bo vi€c thi c6ng nhu dric, l6p ddm, ddy ddm duoc thuc hien trcn

bd dim bio chdt ludng cdng trinh vi an toin cho ngudi lao ddng v.v." [59]'C6ng nghc thi cong dem hop ddc ddy theo chu kj'duo.c ring dung c6 hi6u qui kinh tC d6i vdi nhring ciiu c<i chidu dli nhip tir 40-80m Nhmg trong thrrc td

khdu do nhip tir 40 ddn 60m li chidu ddi l! tudng nhai thuong dudc thidt kd

xay dLmS [3q1

Thdi gian qua, nginh GTVT da fng dung cong nghd thi cOng rtric ttdyKdt cdu nhip ddm hop BTDUL khdu dO nhip 40m vd 42m DEn nay cdng ngh€thi cOng ddm hop theo phuong ph6p dfc ddy dd drroc 6p dung thinh c0ng 6

c6c c6ng trinh xey dung cdu Hiiin Lrrong, cdu Met, cdu Qu6n Hiu, cdu Sio

Phong, ciiu Hir Nha v.v

I.I.3 DANG T6T CAU NHIP DAM HOP BE TONC DU LNG LI-IC THI coNc eANc cAc PHUoNG PHAP KHAC

Ngoii c5c cOng nghe thi cOng dam hdp BTDTIL theo phudng ph6p thichdng, <hic tldy theo chu ki' nhu trinh biy 6 trcn, 6 Vict Nam dn tfug dungnhidu cdng nghO thi cdng ddm hdp BTDUL dang khdc nhu cdng ngh€ thi cOng

bing phuong phrip tldy din gi6o cli dong thi cong ddm hop tren din gi6o c6dinh che tao dirm BTD{.IL bAn r6ng v.v

l0

COng ngh6 thi c6ng ddm h6p BTDUL theo phuchg ph6p ildy bing din

, :i$ido di dong, ld loai hinh cdng ngh€ thi cdng m6i, budc ddu d6 duoc ring dung

thi cdng 6 Drr 6n cdu Thanh Tri vi c6c nhip ddn cdu Bai Ch6y Hi€n nay,

KHCN GTVT dA hoin thicn thidt kd cong ngh€ n)y tld nhi thdu trong

,.

6p dung xAy dung cdu Nam O TP Di Ndng vi m6r sd cOng rrinh khdc

' Theo cdc 86o crio kidm tra chdr ludng aldi vdi mor sei c6c Kdt cdu nhip

:ddm hop BTDIIL dric hAng tli xdy.lung d Viet Nam [60], t6U, t621, t631,

:[64],

t651, t661, t671, [68] de xudt hi€n cdc ddu hicu it nhidu 6nh huong ddn

f itrflt t,rqng vi thdi han khai th6c cria cong rrinh nhrr hicn tr,rong ntt trong c6c

"(foang ddm, nril bd mat ddm, dong nddc trong cdc khoang ddm v.v Mu6n

&nh gi6 duoc mrlc dd inh hu&ng tir nhfrng ddu hi€u hu h6ng n6i trdn ctra c6ng

uinh khi khai thdc vi drr b6o thdi han phuc vu cira n6 cdn phii tidn hdnh kidm

' ti"a, d6ntr gi6 theo cdc phuong ph6p chdn doSn vi c6c ticu chudn hicn hinh

[6],

't81,1361,

t711

I.2 DO TIN CAY CUA KET CAU CONG TRINH

1.2.1 KHAI NIEM VE DO TIN CAY CUA KET CAU CONG TRINH

Dd d6nh gi6 chdt ludng hodc khri nang chiu luc cua KCCT drr6i t6c d6ngngAu nhi€n trong qud trinh thidt kd, thi cong v) tdc dong ciia c6c td hop trii

trong khai thric, cing nhu inh huong cira moi truong v.v tai thiri didm nhdt

dinh theo c6c chi ti€u li tucrng ddt ra, ngudi ta dua ra kh6i ni6m DTC dd so

s6nh.

' Nhu vay, c6 thd dinh ngfra DTCcia

KCCT ld tdp hop cic tinh thdt cia

d1i tltdng thtc hi?n cr.it thtic ndng cho tnf4c, bdo todn cdt tham sd trong thoi

han khai thtic, tuong ing vcri qui dinh cfia qui trinh vd dtdu ki€n st dung, btiodudng kj thuQt, sfta thia btio qutin vd ndng luc l*u thbng [126] N6i cSch'kh6c OtC thd t ien khri ning tl6p ring tlutrc y€u cdu chiu luc (hodc y€u cdu ldmvi€c an toin) ciia KCCT theo qui dinh cira ti€u chudn, tai thdi didm cu rhd.

1l

;Toy thuO" vio f nghia vd tlidu kiOn khai th6c cfia KCCT, md DTC c6 thd

rhi qua c6c tinh chdt hoac khi nang nhrr: khi nang chiu luc, tinh b€n lAu

han khai th6c hay tudi tho), khi nang sira chfra, khi nang duy tu; bao

:lf,".'T uuJru'uow

d6 cia

: iiffecf D6i vdi c6c cong tdnh cdu n6i chung, khi ndng chiu luc hay khi ndng

': I :,chiu :^i;,'.rii tii nira nd thrrhno cira n6 thudng drrnn du-d c quan nrrrn ftm tam nhdt trong thidr kd nh4'i fr nn rh;dr lzd^;-^ -L,,;-^-^ cing nhrr trong kidm

r.i{.-, , .,tra tl6nh gid chllt lugng

dung cira c6c td hqp tei trong vd tAc d6ng nhu: chiu udn, chiu c6t, chi

' ': tliirh chung, dn dinh cuc b6, bidn dang, chiu

chiu udn, chiu c5t, chiu k6o, dn

m6i, chiu nrlt vi tudi tho thg v.v v.v

:Trlc l), khii ning chiu I iu luc cira kdt cilu nhip BTDUL drro c kidm tra, d6nh gid

bing cr4c chi sd DTC cira bd pha! hoAc chi sd DTC cira h€ thdng

] I.2.2 CAC DINH NGHIA VA THUAT NGU

Cdc khdi nhi€m co bin vd DTC c6 m6r i nghja quan trong, dac biCr tlong

giai rloan ddu nghidn crlu vi rlng dung li rhuydr ndy trong c6c nginh kinh td

-h! thu4t ViCc tap hqp, hC thcing cdc khdi ni6m co bin cira khoa hoc vd DTC ld cdn thidt, nhim dim b6o su thdng nhdt vd quan tlidm ctra linh vuc khoa hoc

'ndy vd tr6nh nhfrng

hidu ldm rrong trao ddi chuy€n m6n Theo [34], hC th6ngc6c khdi nidm vd DTC n6i chung c6 thd tluo c chia thlnh bdn nh6m sau: C4ckhdi ni€m vd tldi tuong nghi€n crfu; Cdc kh6i ni€m vd rrang th6i cira tldi tuong;

Cic khdi niem vd tinh ch{r cfia d6i turng; Cdc dac rung cira DTC Trong ludn

r4n chi lua chon rrich din m6t sd khdi ni6m, dinh nghia v) rhuat ngi cd ben

,,.n!dt lien quan d€'n DTC cia KCCT da du.c dinh nghia trong ti€u chudn

'l

ISO2394-1998 vi trinh biy trong cdc tii li6u 1341, t401, IgZl, tl23l,11261.

12

tudng ky thuat (ddi tuong): ld d6i tudng duoc xem x6t, nghien crlu,

, phan tich ve tht nghiOm trong qu6 trinh thi6t kq chd tao, sii dung v), s&a chfra, gia cddng v.v nhAm muc dich d6m bio hi€u qui cric' :' , Kdt cdu c0ng trinh (KCCT): l} su kdt hqp c6 td chrlc cdc bd phAn li€n

:kdf cfra cOng trinh xdy dmg, tluoc thidt kd kien cd vdng chdc vI tldp rlng drroc

'mgc ticu sft dung khai th6c

:'., H€ thting kdt cdu: ld c6c b6 phriLn chiu luc cira KCCI v] dang cdu trricI,'md c6c bd phdn niy li€n kdt vdi nhau

I :: ,,, Thdi han khai thdc - l) thdi han khai th6c licn ruc crla KCCT kd tt khi :,:bitddu sil dung hodc sau khi srla chta phuc hdi hoiLn to)n chrlc ning cria cong::tririh, ddn khi kdt cdu xudt hi6n trang th6i gidi han

Thdi han khai thric cdn lai ti thdi han khai thiic ten ruc cta KCCT ti

thdi tlidm kidm tra tinh trang ky thuar cira n6 ddn khi xu{t hien trang th6i gidi

Trang thdi lhm vi6c - li trang th6i cira dfii trrong, trong d6 gid tri cira tdtcdc tham sd, dac tnmg cho khi ndng thuc hien chrlc ning cho trudc, thoe man

YOu cdu cira ti€u chudn ky thuat.'

Trang thdi khOng c6 khri ning chiu luc - li trang rh6i cia rldi tuong,trong d6 chi cdn mOt tham sd dac rrrng cho ndng lrrc llm vi€c cfra n6, khdng

' thoi man theo y€u cdu cira tli li€u ti€u chuzln k! rhuat Thuc chdt, day le hangthdi khi bo phan hoac toin bO KCCT gap su c6

13

,tffiiflfra"e tmi girfi han (TTGH): liL m6c m) n6u vuot qu6 thi KCCT krong

rlng tidp c6c ycu cdu thi6r kd de ddt ra

TTGH cudng d0 (TTGH cuc han): lh trang thdi sap dd hoac 6 trangtoin bQ KCCT gap su cd

,r,.'."-,, TTGH khai th6c: lh m6c mi ndu vuot qua m6t didu ki6n nio dd thi

hodc b0 phAn KCCT kh6ng cdn d6p ring duoc y€u cdu khai thdc dd ra

':|i" Chi sd DTC cria bd phAn: li chi

sd DTC dac tnng cho b6 pban KCCT

: mi theo d6 KCCT d6 tlat <tuoc DTC qui dinh.

' Chi sd DTC thinh phdn: li chi sd DTC thanh phdn tlon 16 cia KCCT,

'trong d6 chi c6 mor dang su cai don le duy nhdt

r.hoqc m6i bO ph4n KCCT

Biin sri co bin IBCB): ln mOt phdn rrong rap hgp cdc bi6n s6 dAc trung

,eho cdc dai ludng vat l! mi€u tri cfc t6c ddng vi nhfng inh huong cfia mOi

.,trudng, nhlmg tinh chdt co hoc ctra vet licu vi cdc ddc tntng hinh hoc cria

'a5gcr

Him bidu di€n trang thri (Him trang thdi): ln him G cria cric BCB'biCu di6n trang th5i chiu luc cira KCCT: Ndu G6l , n .Xn) = 0 tuong fng

vrfi TTGH; neu G > 0 lI trang th6i ldm vi6c an toin; ndu G < 0 lA trang th6i

.1Am uie" n Ong an toln (l)m vicc c6 su cO.

: Chi sd DTC p: l) chi s6 dac trung cho xiic suAt su cd P' , dddc xdc dinh

nhu sau: B = Q t(Pt), trong d6 /'/ lb him nghich d6o cira hdm phan phdi

chuA"n ho5

14

,',' io

"ohai

dang su cd tr0 len hodc ld DTC ciia mot KCCT c6 hai b0 phan k6t

cdu tr& l€n'

' Tic along thuimg xuydn: th t^c dong licn tuc trong sudt khoing thdi

l' f.igi- dung *" x6t vi theo d6, su bidn thiOn cfra cuatng do ctng vdi thdi gian li

-il 'r{t nh6 so vdi gi6 tri trung binh

't ' T6c tl6ng ngiu nhi0n: li tdc dOng md rn6i khi xiy ra trong khoang thdi

' t'-,gian dang *"m x6t sc c6 mot gi6 tri inh hrr6ng rieng bict d6i v6i KCCT'

' :"1 T6c rtOng tinh: ld tdc ddng khong tao ra rihtng inh huong ddng kd nio

' tldi vdi KCCT cing nhrr c6c b0 phan KCCT'

' I : : Tic atong along: ld tdc dong c6 thd tao ra nhfrng inh huong ddng kd ddi

I "idi KCCT cing nhu cdc bd phan KCCT

! Dac trrrng th6ng k€ ciia vit li€u: ld quy luat phan phfii thdng k€ vd c6c

- rinh chdt vat licu alltdc x6c tlinh trong qu6 trinh sin xudl vat licu theo cdc ticu

chudn cri li€n quan

' odlvdtrfrc{ucONcrnixn

Od oarn brio cho KCCT lim viec an todn (iim vi€c khdng su cO thi fng

:' lq do tii trong t6c dong lcn KCCT gay ra phii ludn nh6 hon srlc kh6ng'

l,::l.Trong tinh to6n kdt ctu theo cdc TTGH th0ng thudng chi sil dung c6c gi6 tri

; trung binh cira cdc dai ludng nhu kich thudc hinh hoc, crrdng dd cira vat licu,

: ,.rrlng luc do tii trong gey ra t(nh to6n v.v ' md khdng xem x6t d6n bin chdtngau nhien cira c6c dai luong niy Vi vay, dd dim bio didu ki6n an to)n cho

KCCT, trong cdc bidu thric rdt dinh tinh to6n KCCT n6i chung thudng dua vio

: c6c h€ sd di6u chinh duoc goi li: h0 sei tii trong, h€ sd vd vAt li€u' h€ sd ttidu

I kien lam vi€c cita KCCT v.v Cic h€ sti n6i trdn ducrc lua chon tt cdc kdt qui

'' nghicn cf'u thrtc td hodc dr kinh nghi€m xdy dmg, quan li khai th6c conguinh Nhung trong thuc td, cic tham s6 nhrr tii trong, t6c d0ng' kich thudc

l5

,ftnh hgc, cudng d0 cfia vat licu v.v , ddu li c6c DLNN ncn v6i cec tinh to6n,:;$01g thudng nhu trcn, khong rhd xfc dinh dtroc DTC (lrrong du trt an toen)

cia KCCT trong thuc td le bao nhieu Vi vay, fiong qu6 trinh khai th6c c6 thd

.ryit tricn trang thSi chiu lrrc cira kdt cdu tai thdi didm nio d6 mI tdc dong cila

, ,,,lirg hlc do tii trgng gAy ra l6n hon khi nang chiu luc (sr1c kh6ng) cua KCCT.: C6c trang th6i chiu h,tc n6i tr€n li nguyen nhdn ddn ddn c6c srr cd, hrr h6ng,c{ia cong trinh t1231.

:: , Kh6c v6i vicc tinh to6n KCCT theo phuong ph6p tdt alinh th6ng thudng,

rrong tinh lo6n DTC c6c dai lddng nhu tii trong, tiic dong, kich thddc hinhhgc, cudng do cia vat licu v.v , duoc xem x6t dfng bin chdt ngiu nhi€n crla

ln6 DTC ld x6c sudt lhm vi€c an todn cira KCCT drroc x6c dinh theo cdc

thuYdi xdc sudi vir l1i thuYei DTC

'phudng ph6p todn hoc cira 1!

Nhu vay, so vdi c6c phrrong ph6p tinh todn, ddnh gi6 khi nang chiu luc

'ata KCCT thOng thuong, vicc ti-nh tofn DTC dfii vdi KCCT sE dim bAo srr

chinh xric hon phdn dnh dring khA ndng chiu luc ri ban chAr ngdu nhi6n cuasrlc kh6ng cira KCCT cfrng nhrr cric ydu td tdc ddng trong ftuc td v.v

r3 TiNH HiNH NGHIEN C(fu I1NG DUNG Li THUYOT DO TIN

TRONG NTI6C

_ Li thuydt DTC ld khoa hoc nghi€n crlu qu6 trinh thay ddi c6c chi tieu

ch{t luong cira sin phdm theo thdi gian, thidt lap nhtng quy luAt xudt hiCn huh6ng cira san phdm vd nhfng phuong ph6p dr.r bdo chfng, tim kidm nhfrng

Phuong phdp dd nang cao DTC ciia sin phdm khi thidt kd vi chd tao chringctng nhu c6c bi0n phdp dd duy tri DTC trong bio quin vb khai th6c s6n phdm

'

Ban ddu li thuydt DTC drro c rlng dung trong kt thuat dicn trl, chd tao mdy vi

ky thuat hdng khdng Sau d6 duoc irng dung vlLo mot s6 nglnh kh6c, trong d6

I c6 KCCT Do tldi tuong ctra lj thuydt DTC ddi vdi KCCT ld c6c cdng trinh

xay dung c6 ddc thi riOng nhu viec x6c dinh cdc dac tnmg hu h6rrg khdng don

16

:F'i

, ""igien, ;;,jts vi6c kidm tra thi nghiem san phZirn kh6 khin, mdi li€n h0 gita c6c ydu td ' 'h cdc phudng trinh vi phan li6n tuc _hoic duoc rdi rac h6a theo phrrcrng ph6p: i: phdn tft htu h4n, cho n€n li thuydt DTC ddi vdi KCCT tr& thenh mot nh6nh

:.Jr.ar.

:,iieng va phSt tridn theo mdt hrrong khdc t161 Lf thuydt DTC dA du.c fng dung trong tinh todn ddi voi KCCT tir deu thd kj' XX Ban ddu sft dung lf

jluyd, DTC dc xdc dinh h€ sfi an tod,n trong thidt k6 KCCT theo tridr ly rhidr

,.:.':'kd rlng sudt cho ph6p ([ISCP)

Nam 1953 t6c gi6 Streletcki N S., dd sil dung lf thuydt DTC dd lam cd sd

j:iql

':'cria phuong ph6p luan xay dung hidt li thidr kd KCCT theo TTGH Vio nhtng

, rram 1960 1970, Bolotin V V [120] d6 cOng bd nhtng cOng rrinh nghidn crirr,md sau ndy duoc coi nhu ndn m6ng cira ly thuydt DTC ddi vdi KCCT hi€n dai

' T6c gii Rzhanicin A R [27] di nghi€n crtu anh huong cia su thay ddi ddng.1.thdi tii trong vi srlc kh6ng de'n tudi tho cflng nhu DTC cira KCCT theo c6c so

I :'dd don girin khOng ddi h6i

nhfrng tinh torin qu6 phrlc tap Rzhanicin A R

:

l clng li ngudi di drra ra khrii ni6m xdc sudt bio tlim khOng bi ph6 hoai cfrng

-: nhu cdng thfc tinh x6c su{t niy.

, r:mC, dac biet ld trong nhfrng nam 1970 ddn nay Hing loat c6c c6ng trinh

nghien crtu cua Bolotin V V [120], I-6-xi-lev-xki [123], Trircov V.P [133],

' Iu-ma-sev V M

[135] v.v vd DTC ddi v6i kdt cAu BTCT

' .; ' O phuong Tiy, nhidu nhd khoa hoc cfrng c6ng bfi nhfrng nghi€n crlu vd ly'' thuygt DTC KCCT nhu cic cdng rrinh cira Hasofer vi Lind

t891, 11001

:-,1 Rackwitz vi Fiesler [109], Christensen P T v] Bake M J t871, v.v Nhfrng

;'i ttstrien criu niy tAp trung veo tfuh DTC cria KCCT theo phuong ph6p x6c sudt' 'nham fng dung trong rhuc rC Day li phuong ph6p dir d6 chinh x6c vi ph6nj.i:- dnh duo c bin chdt xdc sudt nhung kh6ng qud phrlc tap

' :

i; t.ont ddnh giri DTC ddi v6i KCCT, Uj ban Li6n hi€p vd an toln kdt c{u l:li.(Joint Committee on Structural Safery) da phdn ra 3 mfc d6 cld 6p dung MrlcFI:'

i.::t:

I i'

ir€fisi;+

:t':rili: :i

i .:Ci,3 la mfc dd chinh x6c nhdt, trong d6 xem xet t6c d6ng vd srlc kh6ng cia

,, liccT li c6c qud trinh ngdu nhi€n kh6ng dung Mrlc tlo 2 xem x6t t6c ilong vdsrlc khdng ctra KCCT nhu cdc DLNN hay cdn tluo c goi li phrrong phdp x6c

,,iu{t Trong d6, c6c DLNN rinh hucrng tldn DTC cia KCCT c6 thd dac tnmg

, biag sd, khdng tuong quan v6i nhau Mrlc d0 1 dfnh giri c6c t6c d0ng vi c6cphin rlng cria kdt cdu qua c6c h€ s6 DTC hay cdn duoc goi li phrrong ph6p

,,b{p.xdc sudt vd ddy ld co s& dd xAy dung c6c tidu chudn d6nh gi6 c6ng rrinhhiPn naY.

- I.3.I TiNH HiNH NGHISN cIfu fNG DUNG Lv THUYgT Do TIN cAY TRoNc TTNH T0AN CONG TRINH TnEn rtln cIoI

,,r Nhu da trinh biy 6 tren, viec rlllg dung li thuydr DTC trong rinh to6n ddi

.r,:iqi KCCI vi xAy drmg hC rh6ng ri€u chudn xdy dung tlang duo c nhidu qu6ct.,,.:gia, td chrlc qudc td vd nhidu nh) khoa hoc rrCn thd gi6i quan tam nghien cfu.

Trong nhfrng ndm gdn tlAy, mOr sfi c0ng trinh nghi0n cfu didn hjnh vd vi€c

.,.:.fng dqng lf thuydt DTC trong phan tich d6nh gi6 vd xdy dr;ng hC thdng tiCu

'

chudn thidt kd ddi vdi KCCT nhu:

1 Nam 1992, tdc giA Chirkov V P [134] d6 c6 nhiing tap hqp vC c6c dac

.!1mg ciia cric DLNN dnh huong tldn khi nang khai th6c crla cdu BTCT T6c

1.1$i6 cfing da dua ra phudng ph6p thay thd ng6u nhi6n liCn tuc tld xay dung hlLrn

,r.nat dQ xdc sudt ddng thdi cria c6c DLNN ve tinh DTC cfra kdt cdu BTCT chiu

, ,,;$9o, chiu n6n, chiu udn v.v

, ,., 2 Nam 1996, cdc tdc gi| B6n-da-ren-cd V M., I-0-x!lev-xki L I,

-Chirkov V P tll9l, d6 nghi€n crtu tltj xudt bidu rhric x6c dinh rhdi han khai

th6c cria kdt cA'u nhip cdu BTCT theo su rhay ddi cudng dO cira be t0ng:

n,l ti I

( 1.1)

trong d6: T,.",- Thdi han khai th6c cia kdt cdu nhip cdu BTCT (nlm);

N=2.106 - sd luong chu k! tii trong co bin cho ttdn khi phd huj (nam);

l8

t.'i:i:i.r, n, - sd luong chu ki' di trong trong mot nam;

i/- he s6 tuong rhg vdi DTC cho tru<ic:

:: : /, - hC sd bi6n sai vd cudng tl6 cria bC t6ng;

a ,' 4 - hd sd, phu thuoc vlo mfc d6 rlng sudt trong be t6ng, do tinh tii vtrhoal tii gAy ra:

rz - chi sd dudng cong khi ndng chiu tei cia be lOng

" ': - Nam 2001, t6c gia l-o-xi-lev-xki L.I., t1231 dE dd xudt phudng ph6p

; r rhuc hanh ilSnh gi6 DTC cira kdt cdu nhip BTDUL Trdn cos6 phan tich li

, '::thuydt chung trong tinh to6n DTC tldi v6i cric cdng rrinh cdu, rric gii dd xu{t

dro hinh tl6nh gi6 trang th6i fng su6lt vi clua ra giii phdp quin l1i, khai th6c <ldi:.,.r::vdi kdt cdu nhip BTCT gdm nhrmg noi dung sau: Khio s6t thu thap sd [eu

,:' 166nt 1a dd xdy dung ngan hlrng dtr fieu tldi vdi kdt c{u nhip BTCT, xem x6t

hd so thidt kd, ridu chudn dzinh giri vi thrrc hdnh rinh rodn, phan tich DTC theo

i thdi gian.

, ,, 3 Nam 1989, ti4c gii Iu-ma-sev V M tl35l tl6 tld xu6't phuong phrip

'

ildnh gi6 khll ndng chiu tAi cira k€i ctlu nhip ddm BTDUL ddn gien m6t cit

ngang hinh chf T TrCn co s& nguy€n li tinh to6n d6nh gi6 khi ndng chiu tii

l.i vi dO lech chudn mdmen kh6ng udn vd sfc khfng c6t cria mdt cit ngang dCm,, ', ddng thdi dd kidn nghi so dd khdi sir dung tld tinh ro6n DTC chiu u6n vi chiu

c6t cfa cdc mat car ngang ddm h)nh chf T theo phuong ph6p m0 ph6ng thuc

" i nghiem Monte:Carlo vdi 18 bidn co bin (BCB) dac tnmg

cho cudng tl6 cria

: :r vat lieu b€ rong, cdp DUL, cdt th6p vi kich rhudc hinh hoc cfra mdt cdr ngangdam dCu ruan theo quy ludt phan phoi chuiin.

4 Allen D E (1992) Canada [82], t831, t1101 dd khio srtr phdn tich dd.: ixSc

ldp chi sd DTC trong tl6nh gi6 DTC rl6i v6i cdu BTCT Trong tt6, vi€c lua

ii'cho n chi sd DTC B drra tr€n kdt qui kidm tra, ddnh gi6 khri ning chiu luc cria

i " c6c bQ phan cira hc thdng k6t cdu nhip cdu BTCT rheo cdp tii trong T6c gii

i1,

:t,.

.::, cho ring, khi chi s6 DTC bidn ddi vdi gi6 tri ap4,25, thi c6c b0 phdn KCCT' " bi hu h6ng (su c0) dot ngot, cdn canh b6o sila chffa dd duy tri khA ndng chiu

' ' lrrc cria kdt cdu nhip BTCT, vi khi chi sd DTC thay ddi ktoeng /F0,5, thi bo

phan KCCT bi hu h6ng dl{n ddn mdt khi nang chiu luc

: ,, 5 Nam 2001, c6c tdc gi6 Sherif El-Taw l, Ayman M Okeil, tl09l,

Trudng Dai hoc Xdy drmg Florida M! da cdng bd cdng trinh nghi€n crlir tl6nhiia khi ndng chiu udn cria kdt ca'u nhip ddm drrn gidn hinh chir T clrroc boc

Eng cuitng bang sdi cdc bon thOng qua chi s6 DTC B Kdt qui nghidn criu cho

" thlty, chi sd DTC cfia ciic ddm tdng theo ti le boc soi c6c bon dgc theo ddm.Phdn l6n cdc chi s6 DTC chiu udn cira cdc mat cit ngang ddm c6 boc soi c{cbon l6n hon chi sd DTC muc ti€u Ticu chudn thi6t kd cdu AASHTO LRFD

6 Nam 1998, cdc gi6 Casas J., R., Aparicio A., C., Ramos Gonzalo,

Tnrdng Dai hoc k! thuAt Catalunya, Barcelona, Tdy Ban Nha [84] dd dua vdo

lf thuydt DTC dd xay drrng phuong phdp tl6nh gi6, phan loai cdu BTCT phuc

vu cho viqc qudn lyi cdu tr€n cdc tuydn qudc 16 6 Tdy Ban Nha Kdiquii nghicn

crlu niy dd kidn nghi phrtong phr{p t(nh to6n phan loai ciic dang cdu BTCT trcn

'qudc

16 drra vio chi s6 DTC dd phuc vu cho cong tic quin lj cdng trinh cdu

7 CAc t6c gii Faber M H thuoc Licn hicp cdc vidn nghi€n cfu congnghe thdnh phd Zurich Thuy S/ vi Sorensen J.D., Truong Dai hoc Aaiborg,Dan Mach [90], ndm 2OO2 da cong bd b6o c6o kdt qui nghiOn crfu cira minh

vd van dd dinh lAp cric ti€u chudn du tren co sd l1y' thuydt DTC Trong d6, dn dd

; ' c{p ddn nhidu vdn dd nhu; m6i li€n hc gifia DTC vi h€ sd an toirn; C:ic vd'n ddcdn phii giii quydt trong vicc dinh lap fieu chudn; Li thuydt toi rru vi viec xi4c

dinh chi sd DTC muc ti€u; Kidn nghi cdc nOi dung co bin trong vi€c dinh ltrpti€u chuiin

g Vd vidc d6nh giri rui ro doi voi KCCT, nam 2000 cdc tdc gia Mark G

Stewart, Val D.V (Australia), Rosowsky D V (My) [98] da dd xudt thang

didm dua tr€n co sd so lf thuydr DTC ddi v6i kdt cdu xiy dung Trong d6, dd

chuiin, chi sd DTC muc ti6u, x6c dinh tudi tho tdi m du ircn cd s& tlidu kien

; Sinh tC xd hOi Kdt qui nghi€n crlu dd kidn nghi bidu thfc tinh rofn thiet hai

: kinh td do c6c hu h6ng gAy ra nhrr sau:

M

fiong d6: P1i- lit xic suai hrr h6ng ddi vdi theo TTGH l; Cri - gi6 tri qui ddi

fhiet hai do hu h6ng theo trang th6i gi6i han l; M - l) sd truong hqp hrr h6ng

10 Nam 2004, tdc gii Nowak A S., Truong dai hoc Nebraska, Lincoln

My t1031 de ffinh biy phrrong ph6p xic dinh chi sd DTC 1"r,," cira h€ ddm

don giin drra trdn co s6 c6c chi sd DTC Br;,a", cira c6c ddm trong kdt cdu nhip

Tren co sd lf thuydt DTC vd phucmg ph6p phan tich KCCT cdu theo TTGH,

, rdc gie de dd xudt bidu thfc tinh to6n chi s6 DTC theo quy ludt phan ph6i x6c

sudt cia ciic DLNN dac tnmg cho srlc kh6ng R vd fn! luc do tdi trong gAy ra S

nhu sau:

- Ndu tdt ci c6c DLNN dac tnmg cho srlc kh6ng R vd rlng luc do tii rong

gAy ra S dliu tuan theo quy luAt phAn phdi chudn thi chi sd DTC x6c dinh theobidu thrlc:

us- u\

tJ = :=:==:::

' It

vdR + or

,_ .r trong d6, ltn, tts - li gi6 tri trung binh cria sfc kh6ng R vd tlng luc do tai

, , fiqng gay ra S; dR, os - li dd lCch chudn cira kh6ng R vi rlng lrrc do tii trorrg

' gay ra S.

- Ndu cdc DLNN ddc trung cho srlc kh6ng R v) ring luc S do tii tro ng

, gay ra ddu tu6n theo quy luAt phan phtii loga chudn thi chi sd DTC x6c dinh

(1.3)

lnR-lnS

21

(1.4)

i ' lns = ln(ml - 0,5 o2 ns.ln(mJ trong trudng hgp hc sd bidn sai V.=0,20;

ln[V'?* +1] -ln trong trudng hgp h0 sd bi6n sai V*=0,20;

ln[V', +l ] zV2, trong trudng hqp h0 sd bidn sai %=0,20.

i, , Tr€n co sd d6, tdc gii d6 thuc hi€n tinh todn tinh rodn DTC cira m6t sd

i ddm thep li€n hgp khdu dd nhip 12m, l8m, 24m, 30m duoc liCn kdt ddmngang c6 chi€u rdng 1,8m, 2,5m vi 3,0m Kdt qui nghiOn crlu tl6 cho thdy, h€

i ,,, Ngoii ra, trCn thggidi hiCn nay cdn c6 nhfng cdng trinh nghi€n crlu nhu:

- Ciia ciic t:ic gi6 Ditlevsen O., Madsen H.O Khoa COng trinh bidn vd kdt

, .ceu xdy dung thuOc trrrdng Dai hoc Ki rhuat tdng hqp Dan IVIach, ndm 2005

: ,di xutt bAn tap s6ch "Cdc phuong ph:ip DTC d6i vdi kdr ca'u cong trinh" [89].

Trong d6, de cAp vd l1i thuydt chung vd c6c phuong ph6p tiSn ti6n, hi6n tlai

: hi€n nay rrong phan tich, rinh todn DTC d6i vdi KCCT.

I r - Tdc gii Nowak A.S., nIm 1999'dn cOng bd Brio c6o sd 368 thu6c

i , Chudng trinh nghi€n cfu c{p qudc gia cfra M! (National Coperrarive Highway

t Research Program - NCHRP ) vd vi€c dinh ldp tiOu chudn thidt kd cdu theo h€

:

i s6 tii trong vi hQ sd srlc khr4ng (LRFD) t1041.

' - Cric tdc gid Nowak A S., Chan-Hee Park, Casas J.R., n6m 2000 tli trinh

i bdy 86o cdo phan tich vi so sdnh ci4c chi sd DTC muc tiOu tldi vdi c6c ddm

j BTDTJL giiia cdc tieu chuAn: Eurocode, Spanish Noima IAp vi AASHTO

- T6c gi|Poul Linneberg Pedersen Dan Mach, nam 2002 ili c6ng bd

I nghien crlu vd co s& lf thuydt DTC trong thidt kd khdp ndi cdu treo day v6ngLittle Belt [107]

- C6c tic gii Rackwitz R., Streicher H., Tnrdng Dai hoc tdng hop

Munich, CHLB Drlc, nam 2002 dd dd cifp mdi li€n h€ giiia phuong phrlp tdi rru

ho6 vd viec x6c lAp DTC muc tidu trong c6c ti€u chudn tl6nh gid [108]

- CAc tlc gii Tarek N Kudsi, Chung C Fu, nam 2002 rai HOi nghi qudc

td lAn thf nhdt vd quin lf, sua chfia cdu td chfc tai Barcelona TAy Ban Nha, cl6

cong bd b6o c6o vd co s6 tidp can trong phan tich DTC deii vdi h€ ddm dln

: qui nghien crru n6i tr€n c6 thd tham khio dd xay dung phuong phdp phan tich

' DTC vi tl6 xudt thang didm ddnh gi6 DTC ddi v6i kdt cdu nhip BTDUL 6 Vi€t

I :Nam Tuy nhi€n, dd c6 thd 6p dung <lrroc c6c kdt qui nghicn cfu n6i trcn trong

, di6u kien ddi vdi kdt cdu nhip BTDUL trong tlidu ki€n cira Vi0t Nam, cdn phii

i nghi€n cfu hd thdng h6a cdc kidn thfc lf thuydt hi€n nay, ddng rhdi phdi bd

: sung, phdt tridn c6c phrrong ph6p chung thlnh thuar to6n vi lap chuong tr)nh

tinh dd giAi quydt c6c bli to6n cu thd

1.3.2 riNH HiNH NGHTEN cfu lNc DUNG LV rHUyEr D0 rrN cAy

: TnoNc riNn roAN cONG rRiNH d vr€r NAM

i , Li thuydt DTC dudc quan tam nghiCn crfu 6 ViCt Nam ti ddu nhfng nam

i 1980 Tt m6t sfi cdc nhi khoa hoc drro c d)o tao tt nudc ngoAi tr6 vd, qua cdc

23

khoa hoc, c6c xemina tai c6c Vien nghi€n crlu vi c6c Tlrdng Dai

|.jthuy6t OtC tl6i vdi KCCT drroc 6p dung vio thrrc td xdy dung Vict

tdc gii Nguy6n Vdn Ph6 vi Pham Ngoc Thach [47], ndm 1993 dd

cong trinh nghi€n crfu vd Phuong phrdp tuydn tinh h6a trong bi'i to6n

d6 c6 thd fng dung dd giii c6c bii to6n 1i6n quan ddn vi0c xdc dinh

theo c6c hi,m bidu di6n trang th6i hrr h6ng c6 nhidu BCB bdc cao'iTec gii enan Van Khoi [37], nam 2001 tl6 xudt bin cudn s6ch Co s6

DTC, trong d6 tla dd cAp c6c ndi dung vd lf thuydt co bin cfing nhtl

ph6p chung phan tich, d6nh gi6 DTC ddi v6i KCCT

-'tac gii le XuAn Hui'nh, nam 2000 tl6 c6ng bd kdt qui nghi€n criu ddphuong phdp xdc dinh DTC cira kdt cdu din ddm si0u tinh'

- tac gii Nguydn Vidt Trung vi ddng nghi€p t nhfrng ndm 80 d6 thucthu thap sd lieu thdng k0 ild x6c tlinh phan phdi x6c sudt vd cudng d0 cira

- Narn 2000, t.ong luan van thac st t6c gie Hohng HI dd nghiOn crlu d5nh

c0ng nghc thi cdng b€ tong cho cric cdu 1dn 6 Vi6t Nam giai tloan

1995-B4l Kdl qui nghi€n crlu tl6 x6c dinh tluoc cuong dd chiu n6n cira bdcdc bO phan: cgc khoan nh6i, tru cdu, ddm hdp don giin, ddm thic h5ng

cfra c6c cdu l6n xay drmg trcn QLIA ddu tuan theo quy luat chudn'

g tl6 he s6 bidn sai cira b0 t0ng cira: Ddm hOp tton giin V=11,577o; Ddmh6ng ld V=9,787o

- T6c giri Trdn Drlc Nhidm, nam.1996 di xulft bin giSo trinh Cic phuong

p xdc sudt vh lf thuydt DTC trong tinh todn cong trinh [40], nhdm phuc vu

cong tdc dao teo sau tlai hoc cira Trrrong Dai hoc GTVT, trong d6 cing ddcdp d6n c6c nOi dung vd lf thuydt co bin cfing nhu cdc phudng ph6p chungr(ch ddnh gizi DTC d6i voi KCCT

24

- T6c gii Nguy6n XuAn Chinh, nim 2001 d5 holn thinh luAn 6n tidn s!

thuat vd de tdi nghicn crlu Phuong ph6p tl6nh gi6 DTC cira khung bC tongth6p thidt kd theo tieu chudn Vict Nam

- Tic gih Bii Dfc Chinh, ndm 2002 de hoen thanh luan 6n tidn st kt

vd dd tdi nghidn crfu "Ap dung bdnh hoc cOng trinh vd tin hoc tl6nh gi6c{u nhip don gian cdu b€ tong cait th6p trcn dudng O to" Noi dung co bin

lu4n 6n niy li vi€c xay dung thuat to6n nhdn dang dd cfng (il0 crlng udn,xoin cira hd ddm vlL d6 crlng hinh tru cria bin) cfra kdt c{u nhip BTCT don

theo d0 vdng do khi thri di tinh drt.c xay ddng trCn co s& phuong phep

bii tor4n quy hoach phi tuydn trong ly thuydt nhAn dang co hoc dd xdc

md hinh thrrc trang ctra cdu BTCT Phrrong ph:ip nhAn rlang trang thdi hu

g vi ph6t hiOn vi tri hu h6ng ciia kdt cdu nhip tlon gi6n cdu BTCT dua theo

g quan sd li6u dd vdng (do hodc tinh) khi thit tai tinh li mdt phrrong ph6p

giin v) hi€u qui dd xric dinh m0 hinh thuc trang cira cdu BTCT Ddngxhy dmg m6 hinh ddnh gi6 kdt cdu nhip clon giin cdu BTCT theo phuong

p x6c sudt (mr1c do 2) c6 x6t tldn gi cot thip ad aann gia cdu BTCT theo

didm lf thuydt DTC

- Ngoii ra, cic t6c gih Pham Kh5c Hirng, Phan Y Thuan, cing dA congc6c cong trinh nghiOn cfu fng dung ly thuy6t DTC trong phdn tich, d6nhddi vdi KCCT C6 thd n6i, lti thuydt DTC da du.c nghi€n crtu rlng dung

phan tich, d6nh gi6 KCCT vI giing day trong c6c tnrong dai hoc phd

6 Vict Nam Thdi gian qua, c6 mot sd luan 6n tidn si k! thuat nhu [16], 7l v) luan 6n thac s! nhrr [24] dd nghien crtu ring dung ly thuydt DTC vA li

dr xdc sudt th6ng kc dd danh gi6 DTC ddi vdi KCCT, d6nh gi6 cong nghcicong bc t6ng cho c6c cong trinh cdu l6n 6 viet Nam v.v

25