MQT SO PHI/OIVG PHAP LOC D I T L I E U VA xCf LY SO LIEU QUAN T R A C SO LIEU DO
CHUYEN VI CAU CAN THO
HO THI LAN H U O N G fl6 VAN M ^ N H Bl) mon True dia
Tnrdng Dgi hoc Giao thong Van ldi
Tdm tiit: Noi dung hdi hdo da lua chgn dp dung mgt phuong phdp loc nhiiu so lieu do GPS luong ddi dan gian, sau khi logi trir nhieu, so li^u do chuyen vi duac su dung de tinh ra tan so dao dgng rieng. Id mgt dai luang hen quan mat ihiei den do ciing ciia cdu, dua vdo gid tri Idn so dao dong rieng ndy di ddnh gid linh trgng "sue khde " ciia cong trinh cdu.
Summary: The article choosed a simple interference filler method on GPS measurement data; Using displacement data to calculate the natural-vibration frequency ofthe bridge which IS a relevant quantity lo bridge hardness Using these natural-vibralion frequency lo evaluate Bridge Health.
[. D A T V A N D E
Cau Can Tha la cau day vang c6 nhjp chinh 550m - dai nhat Dong Nam A. Day la cau quan trpng nam tren true dudng chinh noi giua TP. Ho Chi Minh va dong bang song CCi'u Long, he thong SHM (Structural Health Monitoring) dugc thi cong bdi nha thau NTT Data - Nhat ban va da dugc dua vao sir dung.
Trong he thong SHM, GPS dong vai tro quan trgng, xac dinh chuyen vi tai cac diem dac trung cua cau nhu dinh cac tru thap, giua nhjp chinh ciia cau, cac tru cd goi di dpn^ . toan cau CO 9 may thu GPS va 1 tram base dugc dat 6 ngoai khu vyc cau.
Hien tai, he thong quan trae cau Can tha co day dii man hinh true quan va dCi' lieu online dugc cung cap cho nha quan ly. Tuy nhien he thong phan mem mdi chi dirng lai d ngudng cung cap dii lieu do (chuyln vi, gia toe, ung suat, bien dang, lyc cang, lugng mua, nhiet do, van tic va hudng gio...) va khi cac gia trj nay vuot gia tri gidi han thilt kl se co canh bao, chua c6 he thong phan mem danh gia cac so lieu do dinh ky nham phat hien hu hong sdm va len ke hoach duy tu, bao dudng.
Npi dung bai bao da lya chpn mpt phuang phap Ipc nhieu s6 lieu do GPS tuang doi dan gian, sau khi loai trir nhieu, s l lieu do chuyen vi dugc sir dung de linh ra tan so dao dpng rieng, la mpt dai lugng lien quan mat thiet den dp ciing cua cau, dua vao gia tri tan so dao dpng rieng nay de danh gia tinh trang "sire khoe" chung va tir do xac dinh cac tdn thuang cue bg thdng qua cac so lieu do khac.
Tap chi KHOA HQC GIAO THONG VAN TAI S6 47 - 08/2015 4 7
II. NOI DUNG BAI BAO 2.1. Co" SO'ly thuyet
2.1.1. Loc nhiiu bdng phuang phdp ctia so die lieu
Mpt day s l lieu {x,, X2 x/j} moi gia tri tpa dp ung vdi mgt s6 dilm quan trae; Chia day tri do thanh nhilu doan, m6i doan ung vdi 1 cua sl co kich thudc cd s, xac dinh gia trj rms ciia tirng cua so theo cong thuc sau:
EtT".)'
(1)
Trong do: x, la tri do thir j ; i la s6 thir tu ciia ciia s6; x, la gia trj trung binh a cua so thir i;
s la kich thuoc cira so. Khi rms ciia cira s6 thir i co gia trj Ion bit thucmg thi trong cua s& do xuat hien gia tri dj thuimg. Thuat toan nay dugc sii: dung de loc dit lieu tho truoc khi dua vao tinh toan so lieu.
2.1.2. Phicffng phdp tinh tinh lan sS dao dpng rieng tie ket qua do chuyen vi Chu ky dao dong rieng cua ket cau gian don c6 the tinh theo cong thirc:
f (0 \ K (2)
Trong do: T la chu ky dao dong rieng, tinh bang (s), voi tin so tuong Ullg f (hz); M la khoi luong thu gon; K la dac trung do cirng ket cau. Thirc t6 viec phan tich dao dong rieng ciia ket ciu ciu la bai toan tong hop khi do phuong trinh dao dong ca ban viet theo phuong phap vi phan cua dao dgng:
Mu{t)+Cu(t) + Ku(t) = F(t) (3)
Vdi M, C, K lan lugt la ma tran khoi lugng, ma tran lyc can va ma tran dp cung; u(t) la vector chuyen vj, la ham cua bien thdi gian lien tuc t; F(t) la vector ngoai lyc tac dung
Tir cdng thirc (2) dl dang nhan thiy khoi lupng M ciia ket ciu la gia trj bit biln theo thdi gian nhung dp cirng K ciia ket cau a gia trj thay doi, co the xac djnh dugc sy thay doi nay thong qua tSn s l dao dgng rieng f hogc chu ky dao dpng rieng T.
So lieu do GPS la sd lieu do chuyen vj lien tuc theo thdi gian, dya vao phep biln dii Fourier de phan tich cac dao dgng thu dugc. I'hep bien doi Fourier cho phep anh xa mgt tin hieu mien thdi gian x(t). y(t), z(t) sang tin hieu miln tan so.
Thay vi sir dung cac tin hieu hinh sin theo toan hgc, chiing ta co the sir dyng cac ham so mu vdi ca tan so dieu hoa duong va tan so dieu hoa am nhu cong thiirc Euler (4).
48
Tap chi KHOA HO C GIAO THONG VAN TAI So 47 - 08/2015Sine V(.™ Sian,il
M ;'\ ;"; \ i\
\i \l \j \ M /
0 o ; 0 1 0 r. OR 1
Puwor S p o c i m m of j Si
lime (s) Freouency (Hi)
Hinh I. Chuyin tir mien thdi gian sang mien tdn so
Cong thirc Euler: e""' = sincot + jcosrot (4) Phat trien ly thuyet neu tren, phep biln dii Fourier thuan cho phep chuyln dii mpt tin hi^u
tir mien thdi gian sang mien tan so theo cong thuc (5). Phep bien doi Fourier nghich chuyln dii miln tin sl tiing phSn trd l^i miln thdi gian ban dau (6):
f(t) = ^J_>(ja)y"do) (5)
f{so,)=\y(xy
'dt (6)Trong do: f(t) la ham chuyln vi theo phuang x, y hoac z theo thdi gian t; F(iw) la ham phi nang lugng xet trong mien tan so.
Trong cac phep nghien ciru tin hieu cua minh Fourier chi ra rang khi xet cac trj do rdi rac trong khoang thdi gian ngan co the coi chiing nhu nhiJng tin hieu lien tuc va co thi bieu diln cac tin hieu rdi rac nay dudi dang (7) khi anh xa. tir mien thdi gian sang miln tin s6 va (8) khi anh xa tii miln tan so ve mien thdi gian. D6i vdi cac trj do quan trie cau, tin sl cai dat phai luong thfch vdi vdi tan so dao dong cua cau, doi vdi cac ket cau mem deo, thong thudng tin so cai dat tir IOH2 ^ 20Hz. vi the co the sir dung phep bien doi nay dl giai quylt bai toan tinh chuyen tir mien thdi gian sang mien tan so.
x[n]-—rx(eJ'')eJ""'dM (7)
Xe^-^
= Z4n]'
(8)Trong do: x[nl la ham chuyen vi theo phuang x. y hoac z theo thdi gian t; X(e'") la ham pho nang lugng xet trong mien tan so,
Trong cac gia trj tan so tinh toan mau khi sir dung de linh tan so ciia ket cau se co mgt gia tri tin sl dao dpng bing vdi tin sd dao dgng rieng ciia ket cau cau xuat hien hien tugng cong hudng (f = fo), liic nay ham xet se dat pho nang lugng eye dai va quan sat dugc rat ro rang tren mien tan so. Tir gia trj do ma chiing ta co the su dung cac phep loc de npi suy ra tan so dao dpng rieng cua ket cau
2.2. Tinh toan so lieu thyc nghiem cau Can Tho'
So li?u dugc tinh thyc nghiem la so li$u do chuyen vi giira nhjp cau can tha bang GPS- RTK. Giua nhip chinh ciu Cin Tho lap dat hai tram rover GPS. mgt tram GPS_519501 ve phia Tap chi KHOA HQC GIAO THONG VAN TAI S6 47 - 08/2015
thugng luu va tram GPS_519502 vl phia ha luu song Hau. Sl lieu su dung d& tinh toan trong khoang thdi gian tir OhO'OO" ngay 01/12/2104 den 01h0r02" ngay 01/12/2014.
2.2.1. Loc du lieu so lieu do
Hinh 2. DH lieu theo phuong v tl udc khi loc Hinh 3 Du lieu theo phuang v sau khi lgc
Hinh 4. Dir liiu theo phuong z trudc khi lgc Hinh 5. Dir tiiu theo phuang y sau khi loc Trong thdi gian xet, theo p h u a n g true x khong phat hien d u p c gia tri di t h u d n g , true y tim va lgc dugc cac gia tri di thudng tii' giay 250 den giay 253 va tir giay 3500 den giay 3700, true z tim va loc dupc cac gia tri di thudng trong viing tir giay 500 den giay 600 viing tii'giay 1300 den 1600, vimg tir giay 3600 den giay 3750.
2.2.2. Tinh tdn so dao dpng rieng cua cdu tic so lieu GPS-RTK
Sau khi Ipc hd cac gia tri dj thudng tu chuli kit qua do GPS-RTK, tiln hanh tinh tin sl dao dpng cho 2 diem do giCfa nhip chinh cau Can Tha.
Trong hinh 6 va 7 la ket qua ciia tan so dao dpng diem giua nhjp chinh GPS_51950I theo phuang X, de dang nhan bilt dugc tin so dao dgng rieng ia x = 0.1365 Hz tuong ung vdi pho nang lugng y = 0.03523.
Hinh 6. Chuyen vi cua diem GPS_5t950!
trong mien thdi gian.
Hinh 7. Tdn so dao dong ciia diim lim nhip chinh
50 Tap chi KHOA HQC GIAO THONG VAN TAI So 47 - 08/2015
Bang I, Trich so lieu tdn so dao dong vd pho ndng It^ong dao ddng tirong ung
STT 1 2 3 4
ZE
67 8 9
Pho nang luvng 0.03417926 0.03297566 0.02262080 0.02530846 0.03522737 0.03335753 0.03158893 0.02803783 0.02359548
T i n s6 dao d6ng (Hz) 0.027300027 0.054600055 0 081900082 0.109200109 0.136500137
STT 28 29 30 31
h2
Pho nSng liryng 0.02505344 0.02397985 0.02240749 0.02153014 0.02689155
Tan so dao dong (Hz) 0.764400764 0.791700792 0.819000819 0.846300846 0.873600874 n 1618001M 1 TinsodaodOngrieasHnQnoonnoni 0.191100191
0.218400218 0.245700246
34 35 36
0.02404937 0.02584577 0 02872967
0.928200928 0.955500956 0.982800983 Tien hanh lam tuang tu vdi cac dii lieu cac phuang con lai ta thu dugc ket qua tinh loan thyc nghiem tan so dao dpng rieng ciia diem giira nhjp chinh GPS_519501 theo cac phuang (bang 2) va GPS_519502 (bang 3).
Bdng 2. Kel qud linh todn I hue nghiem cho diem GPS_519501
STT (11 1 2 3
Phirong dao d$ng (2)
X V z
Tan so dao d^ng riSng tinh toan
(Hz) (3) 0.1365 0.1638 0.2184
Pho nang liroTig (m") (4) 0.00350 0 03061 0.07577
Tan so (tao dong rieng t h i l t k l (Hz)
(5) 0.1766 0.2178 0.2847
Ty 56 (%) (6) = (3)/(5)
77.29%
75.21%
7 6 7 1 % Bang 3. Kit qud tinh loan thuc nghiem cho diem GPS_519502
STT ( 0
1 2 3
P h u o n g dao d9ng
(2) X V z
T a n so dao d6ng r i e n g t i n h toan (Hz)
(3) 0 1365 0 1638 0.1092
Ph6 nang l u o n g
(4) 0.04639 0-03085 0 07577
Tan so dao dong rieng thiet
k^ (Hz) (5) 0.1766 0.2178 0.2847
Ty s5 {%) (6) = (3)/(5) 77.29%
75.21%
38.35%
III. KET LUAN VA KIEN NGHI
Bai bao da nghien cuu ap dung phuong phap cira so dfi' lieu de lgc nhieu cho so lieu do GPS cau Can Tha va phuang phap tinh chuyen dii lieu do chuyen vi tir mien thdi gian sang pho nang lugng trong mien tan so de tinh ra tan so dao dgng rieng ciia ket cau cau Can tha va c6 mot so kit luan nhu sau-
- Phuang phap ciia so Ipc dir lieu don gian, de hieu, de thuc hien tuy nhien chi xac djnh dugc cac nhieu di thudng xuat hien trong thdi gian ngan, neu nhieu la c6 dinh (vi du sai so do phan xa tin hi?u tir mpt vat co djnh tai khu vyc do) hoac nhieu xuit hien trong thdi gian dai thi can tinh toan kich thudc cira sd cho phii hgp hoac chpn phuong phap khac phii hgp ban.
- Tinh tin s l dao ddng rieng tir ket qua quan trae chuyen vj theo thdi gian thuc theo phuang phap tren la chat che, cho do chinh xac cao.
- Can nghien cuu nhilu phucmg phap Ipc diJ lieu hien dai va chat che hon trong xir ly sd lieu quan trae Men tuc. De danh gia dupc cu the tinh trang cong trinh cau, cin ket hgp voi cac trj
Tap chi KHOA HOC GIAO THONG VAN TAI S6 47 - 08/2015 51
do khac nhu ung suat, gia toe, luc cang cue bg... trong chuli cac dir lieu do tai cac vi tri khac nhau tren ket cau.
Ngay nhan bai iin dau: 5/5/2015 Ngay nhan bai sira: 2/6/2015 Ngay chap nhan dang bai: 11/6/2015
Tui lieu tltuiu khao
[1]. iValker. JS. Fast Fourier Tran.sforms, CRC Press, 1996, Burrus, CS. and T.W. Parks, DFT/FFT and Convolution Algorithms, John Wiley and Sons, New York, 1985.
[2]. Dr.DiincanL MacFarlane, Fast Fourier Transform and MATLAB Implementation (2011).
[3]. Dmh Xudn Vinh (2011), Nghien ciiu phuong phap quan trie, xir ly so li^u va phan tich bien d?ng cong trinh cong nghiep - dan dung trong diSu kien Vi^t Nam, Thu vien Bai hpc Mo - Dja chit [4]. H6 so thi^t kS he th6ng quan trie ket cau cau Can Tha, thang 7/2010*
Phan bi6n: Nguyin Thi Cim Nhung; Trin Quang Hoc
PHirONG PHAP ACN - PCN ...
(Tap theo Irang 46) HI. KET LLIAN VA K I E N NGHI
3.1. Ketluijn
Vdi phuong phap ACN - PCN cho biet mdt may bay cd the sir dung khdng ban che mat dudng neu dong thdi thoa man hai dieu kien sau:
- ACN ciia may bay dugc xac dinh vdi loai mat dudng va cap dat nen da duac cong bo ciia mat dudng la nho hon hoac bang PCN cua mat dudng do.
- Ap lyc bom banh cua may bay khong vupt qua ap lyc toi da cho phep da cong bo cua mat dudng nay,
Giiip cho cac nha quan ly xac djnh chinh sach quan Iy san dudng tir do cd ca sd hao tri, nang cap san bay.
3.2. KiCn nghi
Kien nghi nen thi6t lap cac tieu chuan de quy ch^ hda viec sir dung mat dudng cho mpt may bay co ACN cao han PCN da cong b6 cho mat dudng do.
Ngay nhan bai lan dau: 5/5/2015 Ngay nhan bai su^: 2/6/2015 Ngay chap nhan dang bai: 11/6/2015 Tai lieu tham khao
[1]. Thong tus6 150/5380-6A ban hanh ngay 14/7/2003 v6 cac hudng dan va quy trinh bao du&ng m3t duong san bay ciia cue hang khong lien bang My.
[2]. ThS Nguyen Phit Hdi - Bao cao co so khoa hoc xay dyng tieu chuin vi quy trinh bao duang duy tu
!,an bay dan dung Viet Nam.
[3], Aerodrome Degign Manual International Civil Aviation Organization (ICAO) (1983), Part 3 Pavements, second Edition.
[4]. Advisory Circular of FAA (30/09/2011) Use of Nondestructive Testing in the Evaluation of Airport Pavements, 150/5370-1 IB*
Phan bifn: Phrim Huy Khang; VO Due SJ
5 2 Tap chi KHOA H O C GIAO T H O N G VAN TAI So 47 - 08/2015
