DIEN DAN KHOA HOC CONG NGHE
PHAN TICH CONG TRINH BE TONG COT THEP CHIU s y p 0 6 DAY CHUYEN
PROGRESSIVE COLLAPSE ANALYSIS OF CONCRETE BUILDING T S . PHAM THANH B I N H
KS. LE QUANG HUY, KS. VU TRQNG QUANG Hpc vi6n KTQS
"nin tat: Sup (I6 dSy chuyen 1^ cd chg phd hoai ket cau nguy hiem, gay ra bdi si/c6 bat thudng nhi/n5, bom dan...TDT htf hdng cue bd tai cdu kien trpng yeu trong he k^ clu dan den xuit hten nhiTng hi/ hdng tai cdc ciu ki^n Idi6ng tn/c ti^p chfu tdc dJiHig t^ttnidng. Cu^' cung xdy ra sup do todn bo hoac phdn idn he ket cau. Sup do ddy chuydn cd ddc di^m quan trwQ U he qud tHi hikig k)n hOn r^ nh^u so w)i h i / 1 ^ cgc bd ban dau. V4n ah nghiSn ciJu cdng trinh chdng lai sup do ddy chuylin (6 duac d^ cdp d ^ trong rit nh^u tiaj chu^ mfdc ngodi [1,2,3,4,5,6,7], tuy nhien 6 Vigt Nam mdi chl dCmg d titf B$u chuygn khdo [4]. Dd ddnh gid dUdc khd ndng sup dd ddy chuy^, trong bdi bdo phdn tich hg khung bg tdng cdt th^, sJ (bjng pNJdng phdp ' d u ^ ddn tdi ttiay th^' (Alternate path rr^thod) hjdn theo tigu chu^n My UFC [5]. Nhdm tdc gid sil (kiVQ (^uong phdp phdn t'ch ffnh tuy^n thh - phUdng phdp ddn ^ , cd dd tin cdy chip nh|n <i\sac, la phUdng phdp thi/dng (hfdc cdc k$ su k^ clu sJ dung hign nay dl [^dn tich sup dd ddy chuydn. K^ qud phdn tich cho thiy h$ k^t clu khdng dii khd ndng phdn phdi lai tii trpng tif clu ki$n trong y^u, du bdo sup do ddy chuyin xdy ra.
T&khoa: Khung tie tdng c^t Mp, phUtUig phdp diJffng din IM thay thd
1.Gi<^i thieu
Bu6i s ^ g ngdy 16 t h ^ g 5 nam 1968, bk Ivy Hodge, cir ddn sdng tai tSng 18 t6a nhd 22 ting Ronan Point d Newham, phfa ddng Ludn Ddn, ddnh (tigm trong b4p. Que diem Qdy ra vu no ga ldm vdng tim tuiffng panel BTCT d gdn g6c cua tba nhd. Todn bd cdc sdn phia trdn do mdt di gdi tua t^i tdng 18 b|
dd SMp xudng. dnh hudng cua cdc sdn SMP d6 phfa trdn gdy ra hieu ijmg sup do theo ddy chuyen. Ket gua Id: todn bd nhjp phfa gdc nhd b| sup d6 tir trdn xudng duia. Bd Hodge sdng sdt nhung 4 nguOi chit.
Sif c6 todn nhd Ronan Point l ^ n g phdi 1 trong cdc thdm hpa cdng trinh \dn trong nhOng ndm gin dfiy. Tuy nhidn nd lai gdy shock t}di mOc dd sgp d^ cua nd hodn todn khdng tucmg xOng vdf sir kien gdy ra.
D^ng F^d ho£u ndy, tir hu hdng ndy d4n hu hdng khdc dupc gpi Id "sup 66 ddy chuydn" vd cdng ddng ky Iht^t. cdc ca quan quan 19 quyet tdm thay d6i thuc tiln Ihidt kd cdng trlnh d l r>gdn ngiia nhUng ttidm hpa tuong tf xdy ra.
C ^ d$ SUP 66 ddy chuydn dupc dinh nghTa bdng ti Id giQa di^n tfch tiodc thl tich cua vung bj sup 66 vdi phd hoai ban diu. €>6\ vdf tda nhd Ronan Point, ti 1^
dd bdng 20. €>d Id su syp 66 ddy chuydn thieu cdn xdng. Mdt gdc cua tda nhd 22 tdng sgp 66 trdn pham vi todn b^ chi4u cao do mdt vu n6 khd binh thudng. Ti 1$ sgp d6 rd rdng Id ktidng tutfng jojmg vdi tdc nhdn gdy syp d6.
Ida nhd h&ih chfnh Udn bang Murrah dthanh ph6 Oklahoma bi phd huy do bom vdo ngdy 19 thdng 4 ndm 1995. Qua bom dut;*: d§t trong mdt chile xe tai d ting him cua tda nhd (Ei phd huy 3 t^t. Sy mit gdi ''%/a khien cho spp 66 dim dniyln, ddn tdi &fp 66 cdc
bOt ndm trdn dim chuyin vd phin sdn diAte dd true
tilp bdi cdc cdt dd.
Tham hpa tda nhd Murrah ro rdng Id syp d l ddy chuydn. Sgp d l cua phin Idn cdng trlnh gdy ra bdf phd ho^i cue bd m|t phin nhd (vdl cpt). Vy syp d l cung cd ddu hidu cua ddy chuydn: phd ho^i cdt, dim, sup d l kdt cdu phfa trdn. Nhung sup d l nhd Murrah khdng thidu cdn xijmg gidng nhu vu tda nhd Ronan Point. Syp nhd Murrah rd Id ldn, nhong nguydn nhdn ciia nd, tdc ddng cua qua bom cung Idn, Idn du d l cd t h l phd ho^i trdn di^n rpng nhiiu tda nhd dd thj.
Hai tda thdp WTC1 vd WTC2 syp d l vdo ngdy 11 thdng 9 nam 2001: chiec mdy bay Boeing 767 ddm vdo tda thdp vdi toe dd cao; gdy ra hu hdng kdt ciu tai vung bj dam, ehdy Idn trong tda nhd; kit cau d gin vj trf bj ddm, mdt kha ndng chju tai trpng thing dumg vd bi syp d l todn bd tCrtrdn xudng dudi. Bdy cung chfnh Id sup d l day chuydn, nhung Id syp do cdn xCmg, cd nghla Id vu syp do Idn \ ^ tdc nhdn gdy syp d l (va ch^m, chdy) cung Idn.
Tir nhufng thdm hpa syp do Idn trong ijch sCr trdn cd thl hieu syp d l ddy ehuyin la syp d l cua todn bd hoac mdt phin Idn cija ket ciu gdy ra t}di su cd hodc hu hdng d mdt bd phdn tuwg doi nh6 cua nd. GSA vd UFC [3, 5] dua ra djnh nghTa nhu sau: Syp d l ddy chuydn Id tlnh hulng khi md su phd hoai cue b | cua eiu ki$n ehfnh ddn din su syp d l mang hidu iimg ddy chuydn cija cac cdu kidn Idn cdn, tir dd ddn den su syp d l todn bd hodc mOt phin Idn h$ kit eiu.
Sugia tdng tham hpa (^ng trlnh da ehl ra ring vi|c ngdn ngUa vd gidm nhe syp d l ddy chuydn phdi dupc dua ra nhu mdt ydu ciu ddi vdf vide thiit k l cdng trlnh. Cd rdt nhiiu phucmg phdp da dupc dd xudt d l gidm nhe syp d l ddy chuyin vd nhiiu tidu chuln cdng trinh, hudng ddn cung da d i edp din vdn d i ndy.
NGUdi XAY DUNG s 6 THANG 1 ft 2 - 2017
PHAN TICH C 6 N G T R I N H BE T 6 N G COT THEP..,
0-
Theo [2,3,5] c6 hai nhdm phuong ph4p d l giSm thilu Mi& nSng sup d l ddy chuyin cho cdng trtnh. Nh6m phuang phdp tryc Sep: duftng d§n t i i thay t h l (AP), 0 . gia tSnp c u ^ g dd cue t)d (ELR). Nh6m phuong pttAp thilt kd gidn tilp: Uen kit luc (TF). Bdi l>do ndy tdp tmng nghidn cOu phuong phdp AP. Day Id cdch tiip can khdng phy thudc vdo nguydn nhan gay s^ co, duijt stjr dyng phi biln 6i phdn tfch sup d l ddy (Ty^ - chuyin. Phuong phdp ndy dua trdn co sd lo^i bd cdu kidn bj hu hdng, cdc cau kien kit cdu cdn lai phdi d u ^
thilt k l sao cho du kha nang chju lyc v6i tdi trpng da (7\i]
d^t vdo vd gia tdng Idn hd ket clu. Cd nhilu cdch d l ^ ^ ^ phdn tlch AP dupc d l xuit trong cdc hudng ddn. Od Id
fTnh tuyin tlnh, ddng tuyin tTnh, tTnh vd ddng phi tuyin. NhQng th$p k^ gdn ddy, nhidu nghidn curu xdc djnh khd ndng syp d l ddy chuyin bdng md phdng mdy tlnh vd cung cd nhung ddnh gid uu vd n h u ^ dilm cua mdl phuong phdp (Marjanishvili, 2004), (Mc Kay, 2008). Vide phdn tlch phi tuyin phOc t?p dem lai nhDng kit clu sdt vd< thyc t l hon, nhung tit hon Id kit tvfp chlit che phdn tlch ffnh vd ddng d l cdc thu dune cdc kit qud tit nhit. d ddy nhdm tdc gid sir dyng phuong phdp tTnh tuyin tlnh (LSP) - don gIdn vd dd tin cliy tit, hidn nay duyc siir dyng khd phi biln khi phdn tlch cdng trinh chju syp d l day chuyin.
2. Phirong phdp phin tfch tinh tuyen tfnh AP Trinh ty thyc hidn dui?o chl rd trong [5] nhu sau:
- Xdy dyng m l hlnh diy du, tiln hdnh phdn tlch tuyin tlnh vd b l tri d t thdp cho cdc clu kidn hd kit cdu;
- Xdc djnh khd ndng chiu lyc cua clu kidn trong hd kit clu;
- Xdc djnh hd s l tl Id gioa khd ndng chju lyc ban d i u vdl n i l lyc nguy h i l m n h i t (DCR) theo cdng thUc [51:
DCR = Qup / <3ct Trong d d :
Q<x - Khd ndng chju lyc cua t i l t didn khi tlnh vdi tdc ddng lyc
QUF • Ndi lyc Idn n h i t x u i t hidn trong c l u kidn duOi tdc ddng lyc
- Xdy dyng cdc md hinh mdi tuong Ung vdi tUng vj trf io^i bd cdt (tutmg) theo quy djnh, cd thay dli tdi trpng thoo [5]. Phdn tlch tuyin tlnh hd kit clu vd xdc djnh ndi lyc nguy hilm nhit dli vdi mdi clu kidn trong hd;
- K i l m tra d i l u kidn chdng syp d l ddy c h u y i n theo [5].
3. Thl} nghllm s l
Cdng trtnh khdo sdt cd hd kit clu chju lyc Id hd khung BTCT 9 ting vdi chft: ndng chlnh Id vdn phdng Idm vide. Kich thudc mdt bdng 16x18m. Ting 1 cao 3,6m, tir ting 2-9 eao 3,3m. Todn bd cdc ting cd m^t bdng kit clu gilng nhau (hlnh 1). Tilt didn cdt 500x500mm, dim 250x600mm, chilu ddy sdn 150mm. Cdc thdng s l v l vdt lidu duoc t h l hidn trong
bdng 1. _ ^ Khi tiln hdnh phdn llch AP, ta xdc dinh vi tri loai bd ^
cdt trong md hlnh tlnh todn cua cdng trtnh, vd kilm tra
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^feii m ' bll
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Mull 1. Mit bing Hi ciu
X
Bdng 1. TTidng s6viv$t ll$u BITANG
cip dt bin (B) Ci/dng dt chju n6nRk Clidng dt chju k^Re, Htsts, Mtdun din htl E
B20 11,6 0,9 0,590 27000
(Mpa) (Mpa)
(Mpa)
THtP LD9ltll«p Ciidno dt chju kio, nin R„R„
Ci/Ong dt chju kio clt dai R „ H i s t On
Mil 365 290 0,416
(Mpa) (Mpa)
md hlnh vdl tUng vj tri dd. Theo [5] ta c d ode v| tri sau:
- Lo^il bd odt g i n giQa e?nh n g i n C5 t^i t i n g 1 - Loai bd cdt g i n giQa c^nh ddi C2 t^i t i n g 1 - Loai bd cdt gdo Cl ting 1
- Loai bd cdt glQa C6 t i n g 1 - Lo?ii bd cdt tang 5, 9
Cdo vj tri dd iSa)c chl ra trdn hlnh 2.
Kit qud phdn tfch hd ting thl cho thiy hd s l DCR nhu sau:
®
5^%
(^
^\^
®H>fe-B-Hfc-=-Hfer
' % - - * — %
®
^ter
®
• *
Hlnh 2. CSc (n*l5/ldp M c^( j i , j /
NOUdi X A Y D I / N G S 6 T H A N G 1 » 2 . 2017
DUiinuiaue J^
l l n M i K f r n aPHAN T i C H C O N G THJNH BE T 6 N G COT THER..
eOi
Cl C2 C3 C5 C6 C7 C9 CIO 1^1
Bang 2.
TANG1 N (KN) 1830.2 2914,0 2914.0 2514,6 3807.4 3807.4 2501.6 3270.2 3270,2
N , (KN) 5601.537 5601 537 5601.537 5601.537 5601.537 5601.537 5601.537 5601.537 5601.537
DCR 0.33 0,52 0,52 0.45 0.66 o.es 0.45 0.58 0.58
K4t qua H'nft to^ l>4 s6 OCR liNSS
N (KN) 1003.9 1580,1 1580.1 1366,6 2062.6 2062.6 1351,9 1794,2 1794.2
N , (KN) 4999.514 4999.514 4999.514 4999,514 4999,514 4999.514 4999.514 4999,514 4999,514
DCR 0.20 0.32 0.32 0.27 0.41 0.41
T A N S ! N (KN) 163,2 281.2 281.2 238,8 433.8 433.8 0.271240.1 0,36 326,6 0,36 326.6
N , (KN) 4999,514 4999,514 4999.514 4999,514 4999,514 4999,514 4999,514 4999,514 4999,514
DCR 0,03 0.06 0.06 0.05 0.09 0.09 0.05 0.07 0,07 K i t qua phdn ti'ch AP trong cac mji£mg hop k>ai bo d t t i n g 1 dMC t h l hi#n trong b & i g 3.
Bdng 2.Hds6 DCR cdc tn/img hap bd cOt tai ting 1
IIIIIIIIIIIK' (^
Cl C2 C3 a C6 C7 C9 CIO C11
Cl
-
2,585 1,853 2,355 2,592 2,446 1,595 2,021 2,028
C5 1,674 1,958 1,828
-
2,860 2,421 2,534 2,204 2,050
C2 1,923
-
2,595 1,756 3,174 2,601 1,532 2,019 2,032
06 1,319 2,445 1,978 2,099
-
2,962 1,742 3,192 2,225 Bdng 4.H0s6 DCR trudng hfip l>6c^tC6tai ting 5,9
i4i Cl cz C3 CS C6 C7 C9 CIO CII
TANGI HC6TS 1^6743 2.11283 1,93093 1,82084 1,46383 2.67S22 1,69962 2^0165 2.19501
ucen 1.19909 1.91147 1.8709 1.65177 2.36866 2.53136 1.62289 2.15965 2.13162
TANCS BiCST?
1.52451 1.52451 1,2283 1,31163
-
1.8138 1.0752 1.98565 1.37409
ucsn 1,23012 1,17005 1,05963 1,05963 1.56945 1,01259 1,38948 1.38948 1,32574
T«N69 B6C6T5
0.1594 0.30132 0.24306 0.25561 0.11271 0.38554 0.21069 0.37251 0.27438
BiC6T9 0,3349 0^3443 0,27631 0,27631
0.19636 0.43026 0.43026 0.25836
vdf nd CO he sd DCR ldn nhat so vdf cdc cpt lan can, c d nguy ccr h u hai cao nh^t. N h u vay, khi xdy ra s u c6, s i / phd ho^i cue b^
cac cdu kien ehju luc thdng dumg phia trong mat bdng gay ra s u gia tdng mdc cf$
h u hai v d nguy c o syp 66 day chuydn cao hon so vdi phd hoai cdc cau ki#n ngodi t»en.
Tir cac kdt q u a phan tfch trdn, ta ti4n hdnh khao sdt ktid nang chdng l^i sgp 66 ( ^ y chuydn khi loai b d cdt giOd C6 d cdc tdng 5,9 cua tda nhd. Kdt qua k i l m tra didu kien t ^ ^ i g sup do ddy ehuydn thdng q u a he sd DCR dupc trinh bdy trong bdng 4 . Nhan thdy rdng, trong tnidng hpp l o ^ b d edt giOa d cde t ^ g trdn, m$c di^ h ^ so DCR cd gidm di (so sdnh bdng s6 li^u bdng 3 vd bdng 4 eua cde cot tdng 1) vd gidm d\
khong ddng d4u, giam nhidu n h i t d c $ t CIO, dieu ki$n I d i m tra cdng trinh chdng dupc sup 66 ddy chuydn DCR<1 [5] chi thda man ddi vdt tdng 9 edn cdc t ^ g 1 vd t i n g 5 vdn ktidng ttida man.
4. K e t l u a n v d Id4n n g h j
Bdi bdo phdn tfch fTnh tuydn tfnh kha ndng ch6ng lai sup do ddy c h u y i n cOa cdng trinh nhd khung BTCT 9 tdng theo hudng ddn UFC [5]. K i t qud nghidn cuu eho thdy:
- Cdng trinh khdng d u khd ndng chong l^i syp d d ddy chuydn;
- Kidn nghj t i l n hdnh phdn tfch tlnh phi t u y i n v d p h ^ tich d$ng d l c d cdi nhin sdu hon v l cdng trinh chju sup dd ddy c h u y l n . Q
TU 9da than) idiao:
1. Amencan Concrete Institute (ACI 318-02) Building code requiremans for s&iM^ural concrete. November 1,2001.
2. American Society of Civil Engineers / Stnjcbral Englne^ing Institme (ASCE/SB 41-13).
3. General S^vces Administration attemate path analysis &
design for pro^essive coBapse resist^ce (GSA), OCTOBER 24, 2013.
4. Sw iS5 dfty chuyk cua cAng trinti - GS. TSKH Nguyen Van Khang. Nhd u j ^ b ^ xdy diAig. 2012
5. Umfied FaciBties Criteria (UFC 4-023-03) design ot budd- ings to resist progressive collapse . 14 July 2009 Including Ctiange2-1June2013.
6. Untied F^ities Criteria (UFC 3-301-01}.
7. PacoMen/iauHM no sauufte MOHo/iHTHbix JKHJIUX aoaKMM OT nporpeccMpy»mero odpyuieHun . MocKsa.
2005.
Tif bdng 2, nhdn thdy so vdi so dd ban ddu. hp s d DCR tdng idn tir 100-300%, d i l u kidn DCR<1 [5]
khdng thda man. Do d d cdng trlnh cd nguy co sup d d ddy c h u y i n cao. Trong ba md hlnh kiai bd cdt C l , C5, 0 2 thi cd< C6 ndm trong d bdn cd ciing cdc cdt dd c d h$ s l DCR Idrt n h i t , c d nguy ccr h u hai cao nhdt. EJdi vdf m d hlnh k)9i bd cdt giuB C6 thl cdt CIO g i n n h i t