KEl i-AU - UUNe N G H E XAY DU'NG
PHAN TiCH DONG LLfC KHUNG THEP CO HE GIANG C H 6 N G O A N TR^N c a s a K^T QUA THi NGHIEM G I A N G
P G S . T S . N G U Y E N T | £ N C H l / a N G , T h S . P H A M T H U H I ^ N TrucPng dai hpe T h u y Ip'i
Tdm tat: Khi tinh toan kit ciu co cac giing chdng oan phai can cw vao d$c tinh cua cac giing dwgc xac dinh bing thi nghi$m. Bai bao phan tich kit ciu khung thep co he giing chong oin theo md hinh giing /d dan - deo tai bin vai bin bg s6 li$u liy tif kit qua thi nghiem: li/c chay lan nhit, Iwc chay nho nhit, Iyc chay trung binh va Iyc chay tinh toan theo d$c trwng v$t lieu. Kit qua nghien cwu cho thiy sy phan tan cua kit qua thi nghidm khong lam thay doi nhiiu den kit qua tinh toan kit ciu. Ket qua nghien cwu co the dugc dOn^ l^m can cw di xiy dwng md hinh tinh toan cua thanh giing chong oin khi kit ciu chiu tac dgng cua dgng dit.
Jir khda: khung thep, giing chong oin, chju d0ng dit 1. D | i t v a n d e
Hg khung gidng chong oan (Buckling Restrained Braced Frames - BRBF) giup tieu tdn nang lugng d u g c SLP dyng ngdy cdng n h i l u trong nhG'ng nam gan day tren khap t h i gidi, (Sabelli et al. 2003, Uang va Nakashima 2003) [7] dac biet la tgi cdc nudc thudng xuyen xdy ra dpng dat nhu: Nhgt Ban, Dai Loan, My, Canada,... Hg khung BRBF khde vdi cdc hg khung
Tllm biin A572 Cr 50 Q Tim In ^ / , 5 ; ;
thdng t h u d n g vl thanh g i l n g chong oan BRB cd t h i lam vigc t u o n g d u o n g trong ca 2 tnj'dng hgp chju keo vd chju nen. Thanh gidng BRB d u g c nghien cG'u trong pham vi bdi bdo d u g c gpi la "sandwiched BRB"
(hinh 1), viec t h i l t k l da loai trilF su" dung cac vgt ligu kem lien k i t trong qua trinh san xuat va tdng cdc l y a chpn t h i l t k l lien k i t 6 ca 2 dau tam thep loi. Hai bp phdn giong nhau d u g c lien k i t b l n g each hdn vdo 1 thep ehu' U va sau dd d u g c lap day bdng be tdng hogc vu'a. Khdng giong nhu cdc thanh giang BRB thdng thudng s u dyng I6i thep duge bpc ben ngoai thep hpp, "sandwnehed BRB" cd 1 tam thep duge kgp giu'a 2 thanh phan bao bpe duge sG- dyng d i n cudng dp chju keo cao n h i t t u o n g duong bu long A490 trong qua trinh san xuat. Mpt t i m 161 thep co the thay t h i 1 t i m bj hdng va d u g c kgp bang cdc t i m bao v g se khong bj phd hoai trong s u i t trgn dpng dat xdy ra ( n l u co). V fu6ng su' dyng tam thep nhdm tieu hao nang lugng dpng dat dd d u g c k i l m tra vdi nhieu i>ng dyng khac nhau (Chou vd W u 2007, Chou et al.
2008) [1], [2].
^ l
Phdn ni\ Ph^ diuy^
Mflt ciil A-A MBl ciit a-B Uat ciit C-C Hinh 1. ciu tao cOa thanh giing BRB
Tap chi KHCN Xay dyng - so 2/2015 15
Ktl CAU - CONG NGHE X A Y DLTNG
S u dyng he thong gidng chong odn la mpt giai phdp hign dai va higu qud de tang kha nang khdng chan cho cdng trinh. Khi tfnh todn cdc k i t cau cd hg thong giang chdng oan phdi m6 hinh hda s y Idm viec cGa g i l n g tren co s d cae k i t qud thi nghigm. V i n de can xem xet la each xdy dyng md hinh tinh toan cua thanh gidng chIng oan ti> so ligu thi nghigm.
De lam sang td van de ndy, bai bdo se khao sat bdng s6 k i t e l u khung thep cd hg gidng chong odn theo md hinh giang la ddn - deo tdi ben vdi b i n bp s6 ligu lay tG* k i t qua thi nghigm: Iyc chay Ion nhat, Iyc chay nhd nhat, Iyc chay trung binh vd Iyc chay tinh todn theo dgc tn^ng vgt ligu. Cdc k i t qud thi nghigm thanh giang chong oan duge thyc hign tai Dgi hpe Qu6c gia Dal Logn ndm 2010.
2. L y a c h o n mo h i n h
S y lam viec cua thanh gidng BRB co the dugc md hinh hda bdng nhieu each khac nhau, v i dy nhu: m6 hinh dan deo ly tuong, m6 hinh tai ben, mo hinh 3 dogn thing, mo hinh poly, hay md hinh hdm mu. Tnang do, md hinh ddn deo ly tueang tuong doi don gidn trong tinh toan vd xdc djnh cac th6ng so; tuy nhien mo hinh ndy chi phu hgp vdi phdn tich tmh k i t cau.
Tren co so cdc k i t qud thi nghigm thanh giang BRB (hinh 2) - thyc hign tgi Dgi hpe Quoc gia Dai Loan (Chou va Chen 2010) [2], quan sat s y lam vigc cua thanh gidng vd dgc tinh cua vgt ligu tdc gia k i l n ' nghj s u dyng dgng mo hinh 2 dogn thang ddn deo tdi ben - tuong doi don gidn, phdn dnh gan nhat s y lam vigc cua thanh gidng, tang dp chfnh xac khi tfnh todn de m6 hlhh hda BRB.
Md hinh 2 dogn t h i n g dan - deo tdi ben dug^
xac djnh tu" 5 diem (hinh 3), trong do cdc diem 1,3,5 Id CO djnh; cdc d i l m 2, 4 d u g c thay doi theo cac phuong dn. Diem 3 la d i l m cd tpa dp (0,0); diem'1,5 ldn lugt Id cdc diem cd toa dp ldn nhat (theo. gid trj tuyet doi) khi thanh giang chju nen, keo. Gid trj cy thS la: diem 1 (-56.46; -1723.50) va d i l m 5 (55.41;
1566.71). Trong phgm vi bai bao, tdc gia tdp tmng nghien cG'u cdch xac djnh tpa dp cdc d i l m 2, 4 sao cho hgp ly- n h i t d y a tren k i t qud thf nghidm thanh gidng BRB. Cdc gia trf d l xac djnh md hinh tinh toan thanh giang d u g e de xuat theo 4 each (hinh 4). Tren CO s d d u d n g cong tre, xdc djnh tru6c cdc dfnh tgo thdnh dudng cong, 4 phuong an k i l n nghj nhu sau:
- Phuong an 1: lay d u d n g bao ngodi cGa dudhg con^ tre theo thf nghigm;
- Phuong dn 2: fflwn chdy deo dugc xdc djnh la diem nam giua 2 diem chay dec cGa phuong an 1 vd 3;
- Phuong an 3: d i l m chay deo d u g c xdc i^nh t^
diem bat dau s y thay doi dp cong theo thf nghigm;
- Phuong an 4: d i l m chay deo d u g c xac c^nh theo \'if thuyet tren co so' cac dgc tinh vgt ligu vd kicii thudc g i l n g .
Biln dang {%)
-30 0 30 Chuyin vj dpc true (mm) Hinh 2. Kit qua thi nghi$m BRB
e ^ /© -<s
-30 0 30
Chuyen vj dpc trye (mm).
Hinh 3. M6 hinh hoa BRB si> dijng 5 diSm Bien d^ng (%)
- 2 - 1 0 1 2
— PAl - ^ PA2
^
1 1 -
— _ P A 3 P "
16
J -1000
-2000
-60" -30 0 30 60 Chuyin vi dcjc Iryc (mm) Hinh 4. CSc phuang an de xuat m6 hinh hda BRB
T^p Chi KHCN Xay di/ng -s6 2/201i
Ke.
I C A H i u y n i j i3. T i n h t o a n kef cau vdn cac t h d n g s o khac n h a u c u a m o h i n h t h a n h g i a n g B R B
Cdch xdc djnh cu the tpa dp cac d i l m 2, 4 theo 4 phuong dn nhu sau:
" Phwang dn 1:
TCr k i t qua thi nghidm thanh gidng thu d u g c Id 1 tap hgp r i t n h i l u diem tgo thdnh dud'ng cong trd, tac gia d l xuat tpa dp d i l m 2, 4 d y a tren vigc xdc djnh d u o n g bao ngodi cua d u o n g cong tre. NghTa la tpa dp d i l m 2 se la giao d u o n g bao ngodi cua d u d n g cong vd d u d n g thang x u i t phdt tu' d i l m 3 - v d i gid t h i l t ta trong giai dogn tJ Ig cua vat ligu; t u o n g t y xdc djnh diem 4 trong giai dogn keo cua vgt lieu. Gid tn cy t h i Id: diem 2 (-7.15;-1476.8), diem 4 (7.02;
1445.29).
* Phwang dn 2:
Vj trf cDa diem chay deo d u g c xdc djnh Id gia trj taing binh v l Iyc dpc va b i l n dgng dpc tn^c cOa 2 phuong dn 1 v d 3. Tat nhien cac diem 4 ndy deu nam tren mpt d u o n g Uiang - cd goc Id diem (0.0) trong giai dogn ti Ig cGa vgt ligu. Gid trj cy t h i la: d i l m 2 (- 6.31 ;-1298.73), diem 4 (6.22; 1279.53).
' Phwcmg an 3:
D i l m 4 - d i l m chay deo d u g c xde djnh la d i l m bdt dhu cd s y thay ddi dp cong tG' hinh ve t h i hign moi quan hg Iyc dpc - bien dang dpc tnjc cua thanh gidng khi thanh BRB chju keo. Dong thdi diem 4 ndm trdn d u d n g thang t u y l n tinh xuat phdt tO d i l m 0.
D i l m 2 d u g c xdc djnh t u o n g t y , G'ng v d i tardng hgp thanh gidng chju nen. Gid tq cy the la: diem 2 (-6.46;- 1120.7), diem 4 (5.98; 1113.79).
* Phwang an 4:
Diem 2 va 4 trong p h u o n g dn ndy d u g c xdc djnh theo quan d i l m ly t h u y l t tinh toan thanh giang BRB, nham nghidn c u u xem cd hay khong s y khac nhau gii>a vigc md hinh hda thanh giang theo quan diem ly thuylt so v d i k i t qud thf nghiem t h y c t l .
- Cud'ng dp chay deo: P^ = F^A;
F - C h u y i n -^j tgi diem chay deo: A =—^L.
trong dd:
Fy' gid'i hgn chay cua vgt ligu Fy = 367 MPa;
. A - t i l t dign thanh g i l n g A = 150x22 (mmxmm);
£s - md dun dan hoi; Es = 2.03x10^ MPa;
l-y - c h i l u ddi tinh todn thanh giang BRB; Ly - 2800 m m .
Gia trj cy the la: diem 2 (-5.06;-1211.1), diem 4 (5.06; 1211.1).
M6 hinh tfnh toan d u g c l y a chpn Id khung thep 1 tang (hinh 5): cdt, dam si> dung k i t c l u thep cd chieu cao 3.76 m, chieu rdng 3.18 m vd su' dyng phan mem SAP 2000 de phan tich dpng Iyc k i t cau.
6x25
o X
r— eo
H370
H605x230x11x17
<?>/
V
6x25 (370x1 H370
3180
Hinh 5. Md hInh khung th4p 1 ting Khi md hinh khung tren phan mem SAP2000, cpt, dam d u g c md hinh hda bang phan t u thanh; trong dd thanh giang BRB md hinh hda bang cac phan ti> 'link"
v o i chieu ddi l-y = 0.66 L - d y a tren cdc nghien c u u triFdc dd; khung d u g c lien k i t ngdm d chan cpt, cac nut khung deu Id lien k i t cu'ng.
So ligu dpng d i t si> dyng d l nghien ci>u d u g c l l y theo gian do gia toe cDa trgn dpng dat Northridge xay ra ngay 17/1/1994 tai My. VOng ddng dat d u g c ghi ti>
4 d i l m tgi Los Angeles vd 1 diem tai Castaic - Old Ridge Route (CAST 360). Hg khung d u g c phan tich dpng Iyc d u o i tdc dpng cua so lieu dpng dat CAST 360 nhu hinh 6 - md ta moi lien hg giua thdi gian va gia toe d u g c ghi tiJ tam c h i n .
T9P chi KHCN Xay dung - so 2/2015 17
K^T cAU - CONG NGHE XAY DU'NG
tt/fff""*^
_1 I L_
20 30 40 Thdi gian (giay) Hinh 6. S6 lieu dgng dit CAST360
Biln dgng (%) - 2 - 1 0 1
-30 0 30 Chuyin vj dpc trye (mm)
Hinh 7. Kit qui n^i li/c thanh giing twang irng v6fi 4 phifang in
U 01 i^iflfi It*"" •«
-3
0 10 20 30 40 50 60 Thdi gian (giay)
Hinh 8. Chuyen vj cua khung khi xet phuvng an 1
0 10 20 30 40 50 60 TM\ gian (giay)
Hinh 9. Chuy4n vj ctJa khung khf xet phuung Sn 2
Tap chi KHCN Xay dung - s6 2/2015
K^T CAU - C 6 N G N G H E X A Y DU'NG
^ 2
0 10 20 30 40 50 60 TTidi gian (gidy)
Hinh 10. Chuyen vj cua khung khi x4t phwang an 3
IT
10 50 60
2.
20 30 40 Thdi gian (gidy) Hinh 11. Chuyen vj cua khung khi xit phwang an 4 4. L y a c h p n cac t h o n g so cua m d h i n h t i n h toan
cua t h a n h giang c h o n g oan BRB
K i t qua tinh phdn tfch trye t i l p dpng lye k i t c l u d u d i tac dyng eua dpng d i t CAST 360 cho t h i y s y khac nhau khdng n h i l u giua cae phuong an cua md hinh g i l n g . V i dy npi Iyc thanh g i l n g tuong G'ng v d i 4 phuong an d u g c the hign tren hinh 7. S y chdch I0ch giu-a cae gia trj tuygt doi Idn nhat eua chuyen vj nGt khung theo 4 phuong an da de xuat, t u o n g G'ng la: 2.24%, 2.28%, 2.61%, 2.27% (hinh 8-11).
5. K i t ludn
Tren eo sd cdc so iigu tu' k i t qua thi nghigm thanh giang chong oan, bdi bdo dd lya chpn md h1nh dan - deo tai ben v d i bon bd so lieu khde nhau d l khao sat dpng lye k i t cau khung thep bang phuong phap tieh phdn trye t i l p . Cdc so iieu d u g c lya chpn t u o n g iJng v d i cdc gid trj Iyc chay Id'n nhat, Iyc chdy nhd n h i t , Iyc chdy trung binh vd Iyc chay tinh todn theo dgc trung vgt iigu. Ket qud nghien ciJu cho thay s y phdn tdn cua k i t qua thf nghigm khdng lam thay doi nhieu d i n k i t qua tfnh todn k i t cau. Ket qua nghien c u u co t h i dwac dung Idm cdn cG' d l xdy d y n g m6 hinh tfnh todn eua thanh giang chdng oan khi k i t e l u chju tac dpng cua dpng dat.
Earthquake Engineering and Structural Dynamics, 36:
2083-2097.
CHOU C-C, WENG C-Y. CHEN J-H (2008). "Seismic design and behavior of post-tensioned connections including effects of a composite slab". Engineering Stnjctures. 30: 3014-3023.
4.
T A I Lieu THAM K H A O
1. CHOU C-C, WU C-C (2007). "Performance evaluation of steel re^duced flange plate moment connections', T^p Chi KHCN Xay dyng - s6 2/2015
CHOU C-C, CHEN S-Y (2010). "Subassemblage Tests and Rnite Element Analyses of Sandwiched Buckling-Restrained Braces", Engineerrig Stmctures, 32, 2108-2121.
CHOU C-C, UANG C-M (2002). "Cyclic peri^ormance of a type of steel beam to steel-encased reinforced concrete column moment connection", Journal of Constructional Steel Research 58: 637-663.
SAP (2000). "Structural Analysis Program".
TSAI K-C, HSIAO P-C (2008) "Pseudo-dynamic test of a full-scale CFT/BRB frame—Part II: Seismic performance of buckiing-restrained braces and connections". Earthquake Engineering & Structural Dynamics 37: 1099-1115.
UANG C-M, NAKASHIMA M (2003). Steel buckiing- restrained braced frames. In Earthquake Engineering fnam Engineering Seismology to Performance-based Engineering (Chapter 16). Bozorgnia Y; Bertero V-V (eds), CRC Press LLC: Boca Raton, FL, 16-1-16-37.
Ngay nhan bai: 14/4/2015.
Ngay nh$n bai sij'a lincuoi: 19/5/2015.
19 7.
