DIEW D A N KHOA H O C C n u i i > i « u ^
OE XUAT KET C A U D A M C H O G I A O T H O N G N O N G T H O N T R E N OUCiNO C A P B VA C
SUGGESTIONS FOR A BRIDGE STRUCTURE ON TYPES B AND C RURAL ROAD NETWORK
T J ^ A i i t - I U f ' " " "'^^°- ^"'*= *=' " ^ °"<" '=• SHQG TP HCM rs>. v u HONG NGHIEP - Tn/dng Bai hoc GTVT TPHCM
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i™ load tHkidion factor and d i s M M S Z i r n r t c L a r T M S , ! ! ^ tMwort including selecting cross section, posed to choose matt paramelHsTSn rt l i u S T ^ m ^ 2 ™ ^ " " ^ ™ ^'^•''*- 5°™ ^«^=^'*s P™"
*; Ihan I beam in tenns rt nMetlals S s ^ S L ^ ^ ^ ' ° " * " " " * °°^" ' " ^ ^ '= " • « ™ ™ -
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1. Gidl THIEU CHUNG
He thing cd sft ha ting ft cac vung ndng thdn v i n a>n Chua phat then kip d i dap ung vdl nhu c i u thue L °^'i '^" " " " "'"3 "^'^ "*l°"9 "^m gin day Nha nuftc da va dang ttiuc hien mdt s i dff an i l thien mang luoi duong ket ndi den cac khu vuc ndng thdn Tuy nhien, he thdng dudng giad thdng ndng thdn ft dong bang song Cffu Long v i n con t i n tai nhiiu han che do mat dd kenh rach day dac va n i n d i t y i u Rit nhieu cau khi lam tff tre, g i hoae cay dffa v i n cdn Pha, Sff dung. Mot sd loai cau xay dung eho vung nay b cau dan thep. cau dan bailey tan dung tff oac o i u nniJi ;^?-" " ™"^ "" '*' '™"9 ""? <:W y^" did nguCT dl ho, xe tho so hay xe may Cac loai c i u nay lam han che ve kha nang Uep can bra cac phuong tien
b Ehjona c j p C i n j i cat ncang cau 4m Hmh 1. Mil cAl ngang cau ciia dddng giao ihdng nong thdn
mmm:m/^xiisi=^i,
van tai den vung nay
Mat dp cua sdng, kenh, rach tren vijng ding bind Sdng Cuu Ldng la kha day dac. N i u xem xet mat dd cua cau tren mat do km duftng, thi sd luong c i u "nhip vua va nho tff 5m den 30m c i n cd s i luong rit idn d i cai thien Oft sft ha tang cua vung nay Hien tai, c i u chd giad thdng ndng thdn ft day chii y i u la c i u d i m BTCT DUL nhip gian ddn mat cat chff I cd chiiu diu nhip nhp tff 12m den 15m nhff Hinh 1 tren duftng c i p B va C "
Cac loai dam nay cd mat c i t chff I h i t dien nho duoc thiet ke theo 22TCN 18-79='. nay da khdng cdn hieu luc. Dd dd, de phat t n i n ket c i u c i u che giad thdno ndng thdn ft ddng bang sdng Cffu Ldng ddi hdi mdt dang ket cau kmh te va phu hop v a diiu kien ciia vung, Gan day mdt sd nghien cuu da d i xuit mdt s i dang ket cau cau mdi chd c i u cd chiiu dai nhd va trung bmh Mdt trong sd cac dang k i t c i u mra nay cd the phu hop v « cau giao thdng ndng thdn la cau d i m uet dien T-kep (Double-T) K i t c i u nay cd t h i cd ud diem la nhe hdn va thi cong d i dang hon dd viec thi ceng ban mat cau nhanh hdn va khdng c i n van khucn. Do dd, so sanh va danh gia thiit k i k i t c i u dam T-kep Sd vfti ket cau dam I cho c i u chiiu dai nhip nhd va trung binh la c i n thiit. Tff do nhim Ida chdn ket cau cau phu hop cho cau giao thdng ndng thdn dac biet la duong cap B va C ft khu vffc ding bino
Sdng Cyu Ldng ^ 2. Bt XUAT K 6 T C A U PHU HOP
2.1 Chiiu dai nhip
Chiiu dai k i t c i u c i u nhip vffa va nhd dang gian dra, va CO chieu dai tu 5m d i n 33m la r i t p h i bien ft
DJ XUAT K^T cAu nAM CHO GIAQ THONG...
Vtet nam. Ket cau cau dam gian don nhi/dSm ban dac, ban rong, dam cau mat cat chu'T b^ng BTCT thuiong van con daac sCr dyng. Cau dam ban dac va r6ng blng BTCT thutiTig co chieu dai kmh t§ khong qua 6m va chieu cao mat cat dam len den 0,35m. C§u d i m gian don bang BTCT Ihuting mat cat dang chu'T co chiiu dai nhip len den 24m va chieu cao mat cSt dam t h u ^ g lay tCf 1/8-1/20 chieu cao d i m K§t hop vcfi cong nghe duUng iLfc (DIA), ket cau dam ban rang co chi§u dai nhip kinh te len den 24m va cd chilu cao mat c i t nhjp len d§n 1,05m. C l u d i m BTCT DUL mat cat dang chQ T va I CO chilu dai nhip kinh t l tC/ 24 m d i n 33 m Chilu cao cua d i m 133m len d i n 1,85m bao g i m chilli cao dim la 1,65m va chilu cao ban mat c l u 0,2m. G i n day nhlt, la SL; phat then cua c l u d i m gian don tilt dien dang Super-T Chilu dai nhip cua dang cau nay cd the len den 45m vdi chilu cao d i m cd the len d i n 1,95m, Ngoai kit c l u BTCT, kit c l u lien hop giua dim thep va ban mat c l u blng BTCT cung duCTc phat then d Viet Nam nhung s6 Iutmg con han c h l do cac nhucc diem cita kit c l u nay
Do nhu c l u phat triln ba ting giao thdng nong thon, nen viec lua chon mpt kit c l u nhip c l u phu hop vdiyeu c a u v l tai trong, kha nang thi cong la dilu c l n thilt. Mpt s6 nghien ciru da chi ra ring, k i t c l u d i m mat c i t chij" I hay T thutmg kinh t l hon so vdi cac kit c l u dam c l u khac nhu d i m ban, d i m ban rong ya dim h6p(3). Tuy nhien do co uu diem v l thi cong, l i p dung, van chuyen nen cac kit c l u c l u khac van duoc sCr dung. Tren^thl gidi, mot s6 k i t c l u c l u m6\ cung duoc ph^t then. D§m ban rdng (spread slab beam) duac phat tnen boi T X D 0 T ( 3 ) cd chilu dai nhip len \6\
15,2m. D^ng dam ban rpng dircrc d l xult nhu la mot ck\ tien cua d i m ban va d i m ban ring nen co kha nang canh tranh vcri kit c l u d i m mat cat chD I hay T dac biet khi kit c l u nhip ngln khoang tCr 15m diri 24m. Mot dang kit c l u nua la d i m T-kep ph^t trien bdi NEXT('*' cijng co nhilu un diem hon so vdi kit c l u dam mat cat chu' I hay T khi chilu dai nhip tCr khoang 15 den 24m Uu diem cua dang d i m nay la co the tilt kiem van khuon khi do ban mat c l u va thi cong an to^n hon bcfi co ban canh, cd the thay doi chilu rong cau va cau ch6o.
Viec lua chpn loai kit c l u va chilu dai nhip cho k i t cau cau GTNT khong chi phu thuoc vao dilu kien ihi cong ma con vao viec kit hop vdi kit c l u mo try c l u , Khi chieu dai nhtp lang lam gtam s i tru nhung lai lam tang kich thudc mo try va tang s6 coc va chilu dai coc cung nhu tang chieu cao mat c i t d i m . K i t c l u m l tru Ion la dieu bat loi cho nhOng vung nong thon co n l n dat yeu nhu dong bang song Cuu Long Oe giam ki'ch thuoc mo tru thi chieu dai nhip cua c l u giao thong nong thon cap B va C thuong cd chilu dai nhip ngln tu 12 den 15m Chilu dai nay cung phu hop vdi chilu rong cua kenh, rach. Khi kit hop vdi kit c l u BTCT DUL, ket cau dam c l u T-kep cd chilu dai d i m tC/12m den 15m se cq chilu cao nhd co the lam giam tTnh tai dam va dan den lam giam ki'ch thudc m l tru. K i t hop vdl hoat tai khdng Idn ( 0,6HL93) va kha nang thi cdng
nhanh thi m l try deo la k i t c l u dudi thich hop cho c l u giao thong nong thon.
2.2 Kfch thi/(?c mat c^t d i m
Tieu chuan cho c l u giao thong nong thon;", chia dutftig ra lam 4 d p A, B, C va D. Trong dd, d p A, B va C la choxe 6 to chay qua. B I rpng mat d u ^ g tli thieu cho d p B va C l l n luot la 3,0m va 3,5m. Chilu rdng n l n du©ng t l i thieu l l n lutrt la 4,0m va 5,0m. Do dd, b l rdng c l u d l xult l l n luot la 4m va 5m Trong do, tdng b l rong hai gd lan can 1^ 0,5m
DOI vdi k i t c l u c l u giao thdng nong thdn, tai trpng thudng nhd hon, chieu day ban mat c l u va chilu rpng sudn d i m cd thegiani khi khoang each d i m chu giam. Tuy_ nhien, d l xuat cac kfch thudc phu hpp vdi k i t d u c l u giao thdng ndng thdn thi chua dupc quy dinh chat che. Trong Tieu chuan TCN 272-05'«, chilu rdng tdi thieu cua sudn d i m d l i vdi k i t d u BTCT DUL canp trudc 1^ 165mm, chilu rdng cua sudn dim d l i ydi ket d u d u BTCT thudng t6i thieu la 125min.
Chilu rpng sudn d i m , ngo^i de dam bao kha nang chju luc d t , luc x o l n va du chilu day bao vk c6t th6p, cdn phai dam bao cho viec thi cdng dupc d l d^ng. Khi sit dung_klt d u d i m T-kep'^', chilu day sudn t l i thilu 95mm v i n 6km bao k i t cau BTCT DUL cang trudc c6 kha nang thi cong dupc. Do do, chilu rdng sudn dim cho k i t d u d u giao thdng nong thdn dupc d l xuat nho nhlt nen lly \k 125mm.
rQ=4=
1 u u \p
b Dircmg cAp C, mat cSi ngang cau 4m Hinti 2: D6 xuat mSt cSt ngang cau dung dkm T-kep Theo Tieu chuan 22TCN 272-05'=', khoang c^ch giija hai sudn dam \\J 1100mm d i n 4900mm v^ chilu day tdi thieu cua ban mat c l u la 175mm. Chilu d^y tli thieu cua ban canh d i m T-kep dd trudc dupc quy dinh la 50rnm. Khi d u sCrdung d i m T-kep, ngoai phln bin mat cau do trudc, cdn phai k i t hop vdi ban mat c l u d l tai chd de dam bao kha nang chiu luc. Khi dd, tong chieu day cua ban mat d u cdn phai thda man dilu kien trong Dieu 5 14.1.5 l a va Dilu 9.7.2 4 theo cdc cdng thdc (1) va (2).
(Dieu 5 14.1,5.1a)
(Oieu 9 7 2.4)
(1)
NGUdl XAY OlTNG S d THANG 7 & 8 • 2016
. ^ ' ° " g * • 'w la chiiu day ban canh d i m . s la chiiu rdng cd hieu ciia canh d i m , (, la chiiu day suftn d i m , t, la chieu rdng cua vuit dudt ciSnh d i m . N i u chiiu day tdl thiiu cua sudn d i m la 125 mm va chiiu rdng cua VUdt la 40 mm, thi chiiu day cua ban mat c i u thee Cdng thuc (1) la tff 45 mm d i n 235 mm. Dua vad cdng thiic (2), chieu day ban canh d i m cd t h i thay dd'i tff 60mm den 270 mm. Hon nua, khi tinh tdan he s i phan bo ngang, yeu c i u d i ap dung cdng thuc trdng Tieu chuan", chieu day t i i thiiu ciia ban mat c i u l la ^110mm Bci vdl k i t c i u c i u d i m mat c i t chff I da' trien khai trdng thuc te che c i u giao thdng ndng thdn nhff trdng Hinh 1, chiiu day ban mat c i u la 100mm khi khdang each dam c h i la 650mm. Chiiu day ban m^at dam T.kep khoang 100mm"', bao g i m phin canh do trudc khoang 50mm va phin be tdng mat c i u d i sau khdang 50mm. Vi vay d i xuit chiiu day ban ciSnh dam be tdng do tru«ic la 50mm. Cdn phin be tdng dd t?i chd cua ban mat cau t i i thiiu la 60mm. Nhff vay tdng chieu day tdi thiiu cua ban mat c i u cho c i u giao Ihong ndng thdn sff dung dim T.kep la 110mm. Chiiu day thuc te con phu thupc vao hoat tai cho phep va khoing each giOa 2 suftn d i m de dam bad kha nang chiu luc cua ban mat cau. Dira vao phan tich tren mat cat ngang c4u sff dung d i m T-kep dffdc d i xuit dung chd cau^giad thdng ndng thdn dudng c i p B va C nhff dudc the hien treng Hinh 2.
2.3. Hoat tai
Tieu chuan™ cung yeu c i u tai trong truc thiit k i la 2j5 tan va t i l trpng true vuot tai la 6 t i n Trong khi dd ong tai trdng cua xe tai khdng duoc neu rd. Trong Phu luc c ciua tieu chuin™ va thdng s i ky thuat ciia n h i sin xuat thl xe thudng dung trong giad thdng ndng thdn cd tai trprig Idn nhat la 9,28 t i n , tai trong truc Id^
nhat la 6,17 tan. Chidu dai truc co sd thee nha san xuat nhd hon 3,23m. Trdng khi dd, chiiu dai truc cd sd theo xo thiet ke trong tieu chuin™ la 6,5m. Do dd niu Sff dung tai trdng thuc t i d i thiit k i thi se gay b i t la hdn chd cau. IHay ndi cich khic n i u c i u an toan vdi tai trpng thffe te thi an toan vra tai trong thiit k i
Tff nam 2005, Tieu chuan thiit k i c i u 22TCN 272-
? 9 T r i > ^ / ? „ ' ' " " ' ' * ^ ' ^ ' '^'"" »'''*' '^^ =^° ' « " ^ u i n 22TCN 18.79 vra dinh nghia ve xe t i i thiit k i va triit K f ^ ^ " ' ? ^ " "'''"' ^^ ™"9 •:*" ^i'P B va C du ,0T?-.T S ° ' " " ^ " '°"^ ""*! ' * " "" •'"^o "eu chuin 22TCI^ 272-05. Xe tai thiet ke trong tieu chuin 272TCN 272.05 cung khac vdi xe tai thiit k i trono tieu chuin chd 22TCN 18-79 va khic vdl xe tai thuc t i dang khai thic trcng Phu luc C nhu trong Bing 1 Khoang each giQa cac truc xe ciia xe t i l thiit k i la 4,3m nhd hon khoang each true xe thiit k i trong tieu chuan TCVN 10380-2014. Tuy nhien, khoang cich truc xe cua xe tai thiet ke trong tieu chuan mra idn hon so veu xe dang luu hinh nhff trong Bang 1 Trong tieu chuan hien hanh'=' cijng cho phep d i i vra dudng c i p V hdac thip hdn va d u ^ g giad thdng ndng thdn hdat tai thiet ke duec phep bing xe t i i thiit k i trong tieu chuan nhan vra 0,5 heac 0,65 Sff dung xe tai thiit k i xe hai truc thiit ke trong Tieu chuan 22TCN 272-05 v i
ok XUAT KJT cAu DAM C H O GIAO THAM,^
mot so xe t i i dang khai thic tren dudng giao thdng ndng thong trong Bang 1 de tinh tdan mdmen tai mat cat giffa nhip va trinh bay trcng Hinh 3. K i t q u i chi ra rang, trcng khdang chieu dai nhip d i xuit che c i u giac thdng ndng thdn, tff 12 d i n 15m, xe t i i thiit k i van chiem up the se vdi xe hai truc thiit k i , N i u nhan vra he sd 0,5 hoac 0,65 thi t i i trcng ciia xe tai thiit k i cho dffdng giao thdng ndng thdn thee tieu chuin 22TCN 272-05 lan Iffdt la 16,25 t i n va 21,125 t i n Tii trong true thiet ke tuong ung l i n iuot la 7,25 t i n va 9,425 tan. Vdl he sd nay tai trdng xe tai thiit k i va t i i trpng true thiet ke cho cau tren duOng giao thdng ndng thdn la lon hdn sd vdi tai trong thffe t i tren duOng giad thdng ndng thdn nhu trong Bing 1. Sd sanh vra t i i trpng khai thic tren dudng giad thong ndng thdn xe tai thiet ke cho cau tren dudng giad thdng ndng thdn duoc de xuat la xe t i i thiet k i trong tieu chuan 22TCN 272-05 nhan va he sd 0,45 Vdi he s i 0,45 tnng tai trong xe thiet ke ia 14,625 t i n , t i i trang truc la 6 975 tan, Gia tn niy l i phii hop vdi yeu c i u cua xe tai thiit ke cho cau tren dutmg giag thdng ndng thdn c i p B va C trong tieu chuan TCVN 10380-2014
Bang 1 Thong s6ky thual cua mot so xe tii Irong thiet ke ciu giao thong nong thon
Loai xe I T5i ,f„nn |
Ten
Tandem Mitsubistii Canter Giaiphona T-IOSI YJ Hoamai HD3450A 4x4
Ky higu
Tandem Mitsubishi T4081 YJ HD3450A
True 1 True 1 ^ " " 0 iai sau " " " f l
11,2 55 2,375 3,11
14,ib 11,2 4,(iS5 57 6,17
33,13 224
8,075 9,28
1 Chieil 1 tm cd SQ (m) 43
3,23
- 1 1
— —-•
— -^
- - I - UI.93
"• ~- Tandem -"- - 0.65HI.93
— - a.5111,93 - • - 0,45HL93
—•—Mirsubjshi
— — " 1 4 0 8 1 VJ
• HD3450A
Hinh 3 So sanh momen do cac hoat ta, gay ra tai mSt cSt giffa dam 2.4 He s6 phan bd ngang
, Trong ti'nh toan thill k l , anh hudng cua hoat tai ien dam duoc the hien thong qua viec tinh toan he sd phan bo ngang va he so lan xe, Ddi vc^ dudng giao thong nong then cap B va C, chilu rong cau tuunq uTig VOI 1 lan xe Oo dd, viec xac dmh he s6 lan xe tneo quy dmh trong Tieu chuan hien hanh la 1 2 He
J'^M^^iJ^^L^^I'^SOTHANG 7 & 8 . 2016
D i XUAT K ^ CAU D ^ C H O GIAQ T H O N G . sd phan bo ngang cua hoat tai cd the chia ra lam hai
loai la he sd phan bd ngang cho mdmen va cho lut cat. Viec tinh toan he sd phan bd ngang ddi vdi d i m T-kep trong IVluc 4.6 2.2.2 trong tieu chuan hien hanh cua Viet Nam, cung gidng nhu Tieu chuan AASHTO LRFD 2017'" cua My, co the xac dinh theo md hinh (/) trong Hinh 4. Khi sif dung md hinh (/), viec xac djnh khoang each giiJa tim d i m gap nhilu khd khan. Odi vdi mat cat ngang cau nhu Hinh 2 gdm 2 d i m T-kep, viec lua chpn khoang giiJa 2 tim dam hay khoang each giUa hai sudn dam de ti'nh he so phan bd ngang theo md hinh (i) van chua dugc giai thich mdt each t h i u dao Hon nOa, sau khi do them be tdng mat c l u , c l u sir dung dim T-kep cd the coi nhu mo hinh (k) trong Hinh 4. Khi quan mem theo md hinh (i). khoang each giua 2 tim dim dugc sddung. Cdn khi quan niem theo md hinh (/^, khoang each giija 2 sudn d i m dugc sir dung Do dd, quy tac tfnh toan he sd phan bd ngang theo mo hinh {;) va md hinh (k) cho 2 mat cat ngang cau chi ra trong Bang 2.
Singh'" cung da sir dung ca 2 md hinh dd ti'nh he so phkn bd ngang. K i t qua chi ra ring, ddi vdi d i m trong sd dung khoang each sudn d i m de tinh to^n theo mo hinh (^k) de ti'nh toan se gay ra gia tri b i t lgi hon. Ddi vdi d i m bien, gia tn he sd phan bd ngang se dutfc ti'nh toan theo ca hai md hinh (/) va md hinh {kj.
Gia tn phin bd ngang Idn hon trong hai md hinh se duge SLf dyng de tfnh anh hudng cua hoat tai. Singh cung ket luan ring, he sd phan bd ngang cho mdmen va luc c i t se chi phdi theo d i m bien trong trudng hgp 1 lan xe. Trudng hpp tfnh toan cua Singh, elu gdm nhilu d i m .
Bang 4. So sarih khdi Iutmg vat lieu lam ciu ctio du6ng cip B dai 15m
UnududiinuthM
•^14a nging
M Ung due tin
r i
dfilBICKi duclln
(0 «,«.«-u„,^'=r;
11 ir X ¥ m
TIlO t l /
1 2 3 4
vat lita Bg t6ng dam Be teng mat du ThSp Dt/L ioai 12.7mm Thgp cSc ioai
fidnvj m^
m^
tSn tSh
Kh6i tiring D i m I
r.o
8,7 0.618 2 452
Dkn T.kflp 80 53 0.474 2.012
Hinh 4: C^c mo hmh dS tinh he s6 ph&n bo ngang cho dim T-gh6p B a n g 2 . Tinii to^n he s6 phan bo ngang cho 1 lan xe Mfi
hinh Ma hlnh (0 M6 hinh [k)
D^m trong Mfimen Quy tac aan b^y
'^l430oJ UJ \j7j
Lut: c i t QuytaciJflnb^y
0,36 + ^^ 7 6 0 0
D^m mn Mdmen Quy tac a6n \iiy Quy t i c flbn biy
Lire tk Quy tac
Ouy t k iJbn biy
Mdtc^l dl^n hinh
Ma hinh [k]
MO hinh [i]
Mb hinh [k]
m hinh {/•) B a n g 3.
Chi^u m nhlpL
(m) 12 13 14 15 1 2 - 1 5
12 13 14 15 1 2 - 1 5
Tinh toan he Khoang each glij'a cdc d i m S(mm)
110D
2000
1250
2500
so phan bo ngang cho 1 ian xe H$ so ph3n b6 ngang cho Dim trong Mbmen
0,337 0 328 0.320 0 313 0 388 0 36'1 0.354 0 345 0 337 0 460
Li/c cat
0.505
0 388
0 524
0 460
Dim ngod!
Mbmen
0 409
0 388
0 340
0 460 Life ck
0.409
0.340
D.460
ffll NGUdl XAY DUNG SO THANG 7 & 8 • 2016
Trong khi k i t c l u e l u ndng thdn tren dudng d p B va C thudng chi cd 2 d i m T-kep. Do dd, n l u theo kit luan cua Singh thi vi_$c ti'nh toan he s6 phan b l ngang chi c l n tfnh cho d i m bien. Tuy nhien, Singh cung chua chi rd tfnh theo md hinh nao, Hon nua, h§ so phan bd ngang tfnh cho d i m bien cdn phu thudc vko vi tri cua b^nh xe ddi vdi d i m bi^n. Do dd, n l u dinh hinh dugc k i t c l u thi cd the g\km dugc khdi lugng tfnh toan. Bkng 3 \\k\ ke he sd phkn bo ngang duoc tinh todn theo quy tic tr9ng Bang 2. K i t qu§ chi ra ring h§
s6 phan bd ngang eho luc elt ludn bj chl phdi bdi md hinh (/O tinh theo d i m trong. Trong khi dd, he sd phSn bd ngang cho mdmen ludn bj chi phdi bdi md hinh (/) tfnh theo dim bien. Bang 4 chl Net ke mot sd khli lugng khi c l u sir dyng d i m I vk theo d i m T-kep. K i t qua chi ra ring clu sir dung d i m T-k^p tilt kiem hdn v l mat vat lieu. Ngo&i ra trong qu^ trinh thl cdng khdng tdn v^n khudn de d6 bd tdng mat cau tai ehd d i n din tilt kiem thdi gian v^ vat lieu thi cdng.
Hay ndi each kh^c c l u d i m T-kdp cd hieu qua kmh t l va thdi gian thi cdng hon so vdi c l u d i m I dang duge Sp dung trong giao thdng ndng thon.
4. KET LUAN
Cd rit nhilu kit c l u e l u cd th4 ap dung cho c l u giao thdng ndng thdn, noi hoat tai cd tai trong nhd (0.6HL93). Chieu dai cua c l u thudng 1^ nhip vda va nhd (I5m). Vdi dudng c^p B va cap C. cau cho giao thdng nong thon su dung kit cau c l u dim (Xem tiep trang 75)
UONG NUCtC NHd NGUON....
90.000 me duoc phong tang va truy tang danh hieu vinh du Nha nudc - Ba me Viet Nam anh himg Ddn nay gan 6.000 me cdn s i n g d i u ducic cac co quan, dan vi nhan^cham sdc, phung dudng suit ddi,
Dao nghia cua dan toc ddi hoi Dang, Nha nudc va nhan dan ta phai tilp tuc lam t i t hdn niia cdng tac
"DSn on dap nghTa" d l i vdi nhung ngudi, nhung gia dinh cd cong vdi nudc. Myc tiSu va nhiem vu giai doan 2016-2020 1^: "Tiep tue thud hien Nghf quyet Tmng uang 5 khda XI ve chmh sach xa hdi. Lam tdt chinh saeh uu dai ngudf cd cdng". Dai hpi XII ciia Dang cung da d l ra chu truong: "Bao dam an sinh xa hoi, nang cao phuc lot xa hoi; thuc hien tdt chfnh sach ngudi CO edng". Dai hoi XII ciia Dang cung da d l ra chu truong "Bao dam an sinh xa hpi lam t i t chfnh s^ch ngudi cd cdng. De thi/c hien thing Icri muc tieu va nhigm vu tr^n. trong thdj gian tdi, cac d p uy, chfnh quyln, MTTQ. doan th^ chfnh tn c l n t i l p tuc ddng vign c^n bd, dang vien. cong chdc, vien chdc, cac doanh nghiep va mpi ngudi dan quan tam, giup dd nhilu hon nua cho gia dinh thuong bmh, liet sy, nhijng ngudi cd cong vdi nudc bSng nhilu viec lam that thilt thuc va vdi ca t i m Idng, sa tri an sku s i c d l i vdi thuong binh, gia dlnh liet sy, cac gia dlnh chinh skch. Cac ckp. eke nganh thudng xuyen quan tam lanh daa chi dao lam tdt hon niJa chinh sach cua Nha nudc d l i vdi thuong, benh binh, gia dinh Net sy va ngudi CO cdng vdi each mang. Tilp tuc ra soat, thyc hiSn day^du chfnh sach vdi phuong cham tuyet d l i khdng de lot, d l sdt va giai quylt nhanh, dut diem nhijng trudng hop ngudi that su cd cdng nhung chua duoc hudng c h l dp, chfnh sach ciia Dang va Nha nudc. Tang cudng thanh tra, kiem tra, ra soat, phat hign va nghigm tn theo phap lu§t nhi}ng trudng hpp
lam gia h i so de hudng chfnh sach thuong bmh, Net sy, ngudi cd cdng vdi nudc. Mat tran Td qudc va cac to chdc doan the dpng vign, doan vien, hoi vien c^c t^ng Idp nhan dan. keu gpi cac doanh nghiep, cac ca nhan va cac nha hao tam trong va ngoai tinh ung hd phat trien Quy "Din on dap nghTa", phung dudng cac me Viet Nam anh hung,_tang nha tinh nghTa, cham sdc sue khoe, giup dd, hd trg true t i l p vat chit, dpng vign tinh t h i n cho cac gia dinh chfnh sach, con Net sy, thuong binh gap nhieu khd khan trong cudc sdng.
Ddng thdi, dgng vien, mong mudn cac d i n g chi thuong bmh, gia dinh ligt sy, cac gia dinh cd cdng vdi node vuot len trdn moi khd khan, nd lut h i t sue minh sdng va lam vigc guwig m i u , ddng gdp tinh t h i n , sue Iyc dung xay d i t nudc, lam rang rd truyin thing que huong va gia dinh..
Nam 2016 nay, de thilt thyc chao mimg ky niem 69 nam n^ay Thutfng binh-Ligt sT, Thu tudng Chfnh phu vira ddng y iiy quyln Bd tradng Bd LD-TB vk XH trinh Chu tich nudc xem xet tang qua cho ddi tugng ngudi cd cdng vdi each mang nhan dip ky nidm 69 nam ngay Thuong binh - Liet sT.
Miic qua tang theo phuong an trlnh Chii tich nudc dutfc chia thanh 2 ioai: 400.000 d i n g va 200.000 ddng.
^ Tong kmh phi de tang qua cho ddi tugng ngudi cd cdng vdi each mang nhan djp ky nigm 69 nam ngay Thuong binh - Liet sT nam nay i^ hon 397,7 ty ding.
Khoan kmh phf n^y da diTOC bd tri trong k l hoach Ngan sach Nha nudc nam 2016
Oang, Nha nudc va nhan dan ta ddi ddi nhd on cac anh hiing. Net sT, thuong bmh, ngudi cd cdng vdi nudc da xa than vi su nghiep giai phdng dan tdc, xay dung va bao ve To quocQ
DE XUAT KET C A u D A M C H O . . .
(flip theo trang 68)
T-kdp cd the mang lai kinh t l hon so vdi c l u d i m I khi cd nhip ti/ 12m d i n 15m, Kit hop vdl hoat tai khdng l(in lam va kha nang thi cong nhanh, m l tru deo la kit cku dudi thfch hop cho c l u giao thdng nong thdn Tuy nhien, viec lua chon kich thurffc mat c i t va tfnh toan he sd triet giam tai trong, he sd ph&n b l ngang ciia c l u dam T-kep lai chua dutfc phan ti'ch va d l xult rd rang trang Tieu chuSn TCN 272-05. Ti/ nhung kit qua phan tfch d tren, viec lua chon kich thudc mat c i t d i m cho cau giao thdng ndng thdn d p B va C da duoc d l xult.
He sd tnIt giam hoat tai duoc d l xult la 0,45 thay cho 0.5 hay 0,6 trong Tieu chuan hien hanh cho phii hop vdl tai trong thuc t l dang khai thac tren dudng d p B va C Cach tfnh hg sd phan bd ngang cho mdmen bi chl phdi bdl md hinh (/) iinh theo d i m bien. Trong khi
do, he so phan b l ngang cho lue d t ludn bi chi phdi bdl md hinh (k) tfnh theo d i m trong, Vdi nhi/ng de xult nay, cd the giam_ thieu khdi iuong cdng vigc trong vigc tfnh toan thilt k l d i m T-kep cho d u giao thdng ndng thon ma dam bao ygu d u ky thuat va tfnh kinh t l ciia cdng trinh,•
TAI Uiu THAM KHAO:
1 TCVN 10380-2014 Di/cJng Giao Thong Nong Thon - Yeu Cau Thiet k l . 2014
2 22TCN-1B-79, Quy tnnh thigl ke cau ciing theo trang thai giOi han. 1979,
3 Mary Beth D Huesle, John B Mander, Tei/lik Terzioglu, Dongqi Jiang, and Joel Petersen-Gautfiier Spread Prestressed Concrete Slab Beam Bndges, Report No FHWA/TX-15/0-6722-1, 2015
4 Abhi]eet kumar Singh, Evaluation of Live-Load Oistnbution Factors (LLDFs) of NEXT Beam Bndges. Master !hesis, 2012
5 22TCN 272-05. Tieu chuan Thiet kg Can, 2005, 6 PCI Design Handbook, Precast and Prestressed Concrele, 6tfi Editon, 2004
7 AASHTO LRFD Bndge Design Specifications, Customary U S Units, 7ffi Edition with 2015 and 2016 Intenm Revisions NGt/dl XAY DU>IG Sd THANG 7 & 8 - 2016
