K H A O SAT - THI£T Kt XAY DU-NG
DONG LU'C HOC PHA HUY DAY CHUYfeN CUA KHUNG NHliu T A N G BE TONG C 6 T THEP LIEN K H 6 |
TS. CAO DUY KHOI Vi$n KHCN Xay di^png
Tdm tit: Dw6i nhOng tic ddng dSc bi^t nhw sup dd (phi hOy) day chuyin, cic hi$u (mg dgng ddng vai trd quan trong, nhwng c/jua dwoc nghi6n cOu chi tiit ddi v6i khung nhiiu ting. Bdi twgng nghien C(PU cOa bai bao nay li h$ khung nhieu ting be tdng cdt thep (BTCT) liin khdi cd mdt cdt ting 1 bi phi hOy ddt ng0t Di dinh gii hi$u O'ng ddng, gii trj h§ sd ddng Kav dWQc tinh toin bing phwong phip tinh tuyin tinh vi ddng tuyin tinh cho khung vdi sd ting thay ddi.
1. Gidi thif u
Syp d l (phd huy) ddy chuyen Id hidn tu-png mdt hodc mdt vdi d u ki^n ehju lye b| phd huy, din tdi cdc clu kidn edn lgi bj qud tai vd tilp tyc bj phd huy, kit qui Id todn bd hodc mdt phin cdng trinh (vdi quy md Idn so vdi hu* hgi ban diu) syp d l .
Theo cdc tdi lidu hu'dng ddn thilt k l ehing syp do ddy ehuyin cua IWy vd Nga [6,7,12,14], mdt trong nhdng dgng hy hong pho biln trong tinh todn chlng phd hijy ddy chuyen Id edt ehju lyc cOa mdt ting bj phd huy ddt ngdt, Idm phdt sinh tai trpng ddng trong khung ehju lyc cua nhd. Cdc chuyen vj vd biln dgng cua kit d u cd thi rit Idn. Nhu vdy, gia thilt "bien dgng nho" thdng thu-dng cua ca hpc kit elu c6 the khdng thich hp'p de dp dyng.
Ve nguydn tic, cin giai quylt bdi tPdn ddng cd ke din phi tuyln hinh hpc vd ea phi tuyln vdt li^u. Dli vdi khung mOt ting, Mutoka K.N. [3], Rastorguev B.S., Plotnhikov A.I. [4] dd giai quylt dupe bdi todn ndy vd du-a ra Idi giai dan gidn dp dyng trong thye t l . Tuy nhien, khung nhilu ting cd the dng xd khde khung mdt ting.
D l nghien edu dng xy eua khung nhilu ting ehju phd hOy day chuyin, cd the bit diu td gia thilt bai todn Id tuyln tinh. Ddy Id mye tieu cua bai bdo ndy.
2. Cdc gia thiet v4 du> lif u ddu vao a. TiitrQng
Kha ndng chlng phd huy day chuyen cua khung cd the dyp'c ddnh gid bing tinh todn doi vdi to hpp tai
trpng dde bidt, bao gom tai trpng thudng xuyen vd tai trpng tgm thdi ddi hgn vdi hd s l dd tin cdy cua tai trpng bing 1 [6,7,10]:
?0=r/(^7T+^l?/n-D//) 0 ) Trong dd: ^77,^^7-0^" '^^i lu'Ot Id gid trj tieu chuin
ciJa tai trpng thudng xuydn vd tai trpng tgm thdi dai hgn;
/f- h§ s l dd tin edy cua tai trpng,;? = 1;
ijji - hd s l eho tai trpng dai hgn trong to hpp dac biet, ipi = 0,95.
Gia trj edc tdi trpng thudng xuydn vd tgm thdi ddi han ed thi lly theo Tidu chuan SNiP 2.01.07-85* "Tai trpng vd tdc ddng" [8], cd ke den nhdng hidu chinh doi vdi nhd eao ting du'pc lipt ke trong [1].
Tai trpng trdn dupe coi Id chit mdt cdeh ddt ngpt vdi todn b0 gid trj Idn cdc dam khung [2,3.12,14]. Nhu' vgy. nd Id tai trpng tdc dyng dpng (mdt dgng cua tai trpng ddng).
D l ddnh gid dnh hu'dng cua tai trpng dpng, cd the dung hd so ddng cho tai trpng K(jv=qi/q<i, trong dd q, vd qa lan lupt Id gid trj tai trpng tTnh vd tai trpng ddng gdy ra cOng m0t chuyin vj (trong tnjdng hpp ndy ehuyin vj du'dc tinh todn tgi dilm A tren hinh 1) eho kit d u . b. V$tli$u
Do vide ehit tai mdt cdch ddt ngdt, toe dd bien dgng rit cao, bd tdng vd d t thdp cd thi ed kha ndng ehju lye (cu'dng dO) trong tinh huong ndy Idn hon so vdi tinh hulng thdng thu-dng. Dilu ndy du'pc ke din bing hd s l cung d ddng eho be tdng ybd vd eho d t thdp Ysd. <Ju'dC nhdn vdi cudng dd dde tru-ng cua be tdng vd d t thdp. Theo Popov N.N., Rastorguev B.S.
vd Zabegaev A.V. [5] va nhieu nghidn cdu khac tren thi gidi thi hd s l ndy phy thudc vdo tic dd bien dang cua mlu thI nghidm. Trong edc hydng din thilt k l chlng phd huy ddy chuyin cua M^ [12,14] thi hd so ndy dM^c lly bing 1,25. Cdn theo tdi lidu cua Nga [6,7,10] hd s6 ndy khdng dype the hidn rO. Thilt k l chlng phd huy ddy chuyen theo cdc quan diem khdc
T^p chi KHCN Xiy di/ng - so 3/2012 13
K H A O SAT - THltT K^ XAY DLTNG nhau se dupe phdn tich cy the hon vd trinh bay trong mdt bdi bdo khdc.
Trong bdi bdo ndy su dyng hd so cung d dpng bing 1,25. Ngodi ra, d l tim hilu dng xu cua khung nhilu ting bd 01 edt ehju lye va chiu tai trpng ddng.
cd thi bit diu td gia thilt vdt lidu Idm vide hodn todn ddn hoi. Dilu nay cho phep don gian hda tinh todn, nhung vdn ed the nhdn thdc du'pc nhdng dilm dae bidl trong dng xd eOa khung nhieu ting de tgp trung triln khai cdc nghien cdu sdu hon cd k l din nhdng dde diem trong dng xd cua vdt lieu nhu hidu dng ndt do qua tai ddt ngdt vd suy giam dd cdng elu kidn trong giai dogn idm vide phi tuyln cua vdt lieu.
t-. Md hinh tinh toin
Md hinh tinh todn dupe sd dyng d l nghidn cdu qud trinh phd huy ddy chuyin cua hp khung la khung phing 2 nhjp BTCT. Vj tri bd cdt la cdt ting 1 d gida (hinh 1). Kich thudc tilt dipn cdc clu kidn dim vd edt, b l tri edt thdp, vdt lidu su dung cua khung cd thi tham khao trong [2].
^ 4 t
^
X
Hinh 1. M6 hinh tinh toan 3. Phyong phap tinh toan vd phan tich kit qua a. Phwong phip tinh toAn
Cdc phu'ong phdp phdn tich cd thi su dyng d l tinh todn phd huy ddy chuyen Id: tinh tuyln tinh, tinh phi tuyln (bao gIm phi tuyln hinh hpe vd phi tuyln vdt lidu), ddng tuyln tinh vd ddng phi tuyln. Trong dd, phyong phdp ddng phi tuyln cd thi cho kit qua tidm cdn nhlt nhyng rat phdc tgp vd khd dp dung trdn thyc t l . Trong bdi bdo ndy sd dyng phyong phdp tTnh tuyln tinh vd ddng tuyln tinh d l ddnh gid anh hudng cOa tai trpng ddng tdc dyng Idn khung trong trudng hpp bd 01 d t ehju lyc.
14
Sd dyng phu-ong phdp tinh todn ddng cho h^
thanh vdi khli lupng phdn bo deu trong [5], vdi edc gia thilt ve du lipu ddu vdo ndu trong mye 2, tdc gia dd tinh todn dupe chuyin vj, bien dang, cung nhu- npi lyc phdt sinh trong khung trdn hinh 1 cho cdc trudng hpp sd ting khae nhau. Kit qua thu dupe hodn toSn tuang dong vdi cdc tinh todn bang ehupng trinh nhu LIRA 9.6, SAP 2000 ver.12 [2]. Vi khudn kho bdi bao cd hgn, tdc gia khdng di sdu trinh bdy cdc phuong trinh dpng lyc hpc phdc tgp, md ehT tap trung phdn tieh eac kit qua thu dupe.
b. Phan tich kit qui
Phdn tieh cdc kit qua thu duoc theo tinh todn tinh tuyln tinh vd dpng tuyln tinh. cd thi nhdn thiy nhdng dilm ddng ehu y sau:
* Hd sd ddng trong giai do^n lim vi$c din hdi cOa v$t ii$u Kav=2, khdng phu thudc vio sd ting
Dieu ndy cd nghTa id vdi eCing mdt gid trj tai trpng theo cdng thdc (1), tai trpng ddng, khi chit ddt ngpt todn bd gid trj gdy ra chuyin vj gap 2 lln so vdi chuyin vj gdy ra bdi tai trpng tTnh. Do vdt lidu Idm vl§c ddn hdi, tT so 2 cQng ddng vdi cdc gid tri npi lyc dpng vd tTnh tuong dng.
Nhu vdy, trong giai doan Idm vide dan hoi eua v&t lidu, thay vl giai bdi todn d$ng phdc tgp ta cd thi giai bdi todn tTnh tuyln tinh dan gian, vd sau dd nhSn chuyin vj hode ede gid tri npi lyc thu dupe Idn 2 lan se thu dupe kit qua cho trudng hpp ddng tuyln tinh.
Kit qua tren phd hop vdi cdc hudng din cua MJ [12,14]. Vi du, trong [12] neu dp dung phuong phdp tTnh tuyln tinh thi tai trpng Id 2(DL+0,25LL), trong 36 DL - tTnh tai, LL - hogt tai. Cdn trong trudng hpp tinli todn ddng tuyln tfnh thi tai trpng dp dyng \i DL+0.25LL, chat ddt ngdt. Trong [14] to hpp tai trpng hoi khdc: 2(1.2DL+0.5LL)+0.2W (W - tai trpng gid) cho trudng hpp tTnh tuyln tinh, vS 1.2DL+0.5LL+0.2W trong trudng hpp ddng tuyln tinh, Cdc hudng din cua Nga [6,7,10] khdng cd ydu clu cy the doi vdi vide tinh todn ddng.
Dd thiy, khi ddt gia thilt tuyln tinh hinh hpc vd v$t lidu, ta cd Idi giai cho bdi todn ddng lyc hpc phd hOy ddy chuyin khd don gian: giai bdi todn tTnh vd nhdn kit qua vdi 2. Tuy nhidn, se rat hao phi neu thilt k l clu kidn theo phuong phdp tuyln tinh. D l bdi toan gin vdi thyc te hon, d n xem )^dt sy Idm vide eua dim a bang
Tap chi KHCN Xay di/ng - sd 3/2012
K H A O SAT - T H I £ T Kfe XAY Og-NG
thdi sau gidi hgn (hinh thdnh khdp deo, phdn phli lai' khd ndng phdn phli lgi ndi lye cOa kit clu. Nhung ndi lye, d t thdp eua hd dim sieu tTnh hda thdnh he vin d l tren hy vpng se ed dip trinh bay trong mdt bdi day treo sau khi be tdng vOng ndn bj vd). bdo hay cdng b6 khde.
Su phdt triln biln dgng deo trong kit d u BTCT * D^m cua mdi ting lam vi$c khic nhau: chuyin vj liln khli cho phdp giam ddng ke anh hudng eOa tai (do t^i diim giao giO-a cgt giwa vi dim), ngi Iwc giim trpng ddng (nghTa Id hd s6 Kd«<2), ding thdi tdn dyng din tCedLfdilen trSn.
—•— 1) Tort-ng hgp bd c^l tAng 1 - * - 3) Jniirng hpp M c^t ting 10
9 10 11 12 13 14 IS 16 17 IS ] S o t h u r t v ' d i a t a n g
- • - 2 ) Tru&ng hop bfl cW ting 5
——4) Truing hofp bd cftt ting 15 Hinh 2. Gii tii mo men u6n d dau dam tr&n c0t bj bo, phu thu^ vio vj tn dam De dd hinh dung, tren hinh 2 dua mdt vi dy tinh
todn tTnh tuyln tinh eho khung phing 2 nhjp, 20 ting vdi edt gida bj bo lln lupl d ting 1, ting 5, ting 10 vd ting 15. Ta thiy trong trudng hpp edt gida ting 1 bj bo, gid trj md men tgi diu dim trdn edt bj bd giam din: md men d dim tang 1 Id 460 kNm, nhung din ting 19 ehi cdn ed 150 kNm. Khi bo cpt d cdc ting khde, ta thu dupe buc tranh tuang ty.
Dieu ndy cho thay: trong trudng hpp phd huy cd tinh chit ddy chuyen, edc dim sd dgt din trgng thai gidi han khdng ddng thdi.
* Ddi vdi khung thip ting (1-10 ting), gii trj md men udn trong dim ting 1 thay ddi khdng ding ki khi bd cdt ting 1. Theo s6 ting ting din, gii trj md men udn trong dim ting 1 cOng ting nhanh. cd thi gip 3 lin so vdi glA tri md men udn trong dim khung 1 ting (hinh 3).
Cd thi thiy, khung dudi 10 ting ed dng xd khd gilng vdi khung 1 ting. Dilu ndy cd the eho phdp xem xdt bdi toan phd huy day ehuyin cOa khung thip tang nhu cua khung 1 ting, tuong ty nhu gia thiet dupe dp dyng trong m0t s6 nghien cuu [3,4].
Sddng
-•—1) MO men fWi - • - 2 ) M6 men il^ng
Hinh 3. Sl/ thay d6i gii td md men udn (t^i dau dim trSn c^t bi bd) theo s6 ting ting din
Tap chi KHCN Xiy di/ng - s6 3/2012 15
K H A O SAT - THltT K^ XAY DU-NG
Tuy nhidn, khung n h i l u t i n g lai dng x u khdng giong vdi khung 1 t i n g . Khdng ehi thay doi v l gia tri md men trong d i m tang 1, ban than cac d i m cua mdt khung cdng Idm vide khdng g i l n g nhau nhu da nhgn xdt d tren.
Cde k i t qua dupe trinh bdy cho t h i y , n l u gia thiet bdi todn Id t u y l n tinh, ddng lyc hpc qud trinh phd huy ddy ehuyin trong khung n h i l u t i n g ed phdn biet khd ro ret vdi khung mdt t i n g .
Bdi todn ddng t u y l n tinh ed t h i dupe giai q u y l t don gian hon b i n g each dp dyng hp so ddng Kdv=2.
C i n xem xdt khd ndng Idm vide cua e l u kidn d i m sau trgng thdi gidi han d l giam t h i l u anh hudng eua tai trpng ddng vd tdn dyng kha ndng phdn p h l i lgi ndi lye cDa k i t d u BTCT lien k h l i .
TAI LigU THAM K H A O
1 AnMA30B B.O. ConpoTManeHMe nporpeccMpyiou4eMy paapyiijeHMio: pacneTHbie M KOHcrpyKTHSHbie MeponpHSTMa IBecmHUK i4Hi^l4CK UM. B. A. Ky^epenKo
«l^ccnedoeaHUfi no meopuu coopyxeHuu», Ws 1 (XXVI) 2009, cmp. 179-193, UHMl^CKuM. B. A. KyiepeHKO.
I.. KAO 3yi)i KXOl)^. «/]iiHaMMKa nporpeccMpyioi^ero paspytueHiifl MOHoniiTHbix MHoroarajKHux KapKacoB».
^ucc. Ha coucKauue y^enou cmenenu KaHdudama mexHU<iecKux uayK. MocKea, MTCV, 2010, 193 c.
3. MYTOKA K.H. «)KMByHecTb MHOroaraxcHbix KapKacHbix 3Kene3o5eTOHHbix rpa)KAaHCKMx 3flaHnCi npw ocodbix B03Aei^cTBiinx». JJucc. Ha coucKanue cmenenu K.m.H.
MocKBa, Mrcy, 2006, 185 c.
4. nJlOTHMKOB A.M., PACTOPrVEB B.C. Pacnei HeCyil4ltX KOHCTpyKMHI! MOHOnHTHblX }Kene3o6eTOHHbix 3AaHMM Ha nporpeccMpyioujee paapymeHHe c yneTOM flMHaMMMecKMX 3(t34)eKTOB.// C6opHUK Hay^Hbix mpydoe
I'lHcmumyma cmpoumenbcmea u apxumeKmyphi MrCV. M..MrCy. 20O8. cmp. 127-135.
5. n o n O B H.H.. PACTOPrVEB B.C.. SABEfAEB A B . AwHaMMMecKMf^ pacnex KOHCTpyKywH Ha KpaTKOBpeMeHHbte M cneuVianbMbie HarpysKH. M., Bbictnan uiKona, 1992, 319 c.
u. PeKOMeHflaLiMM no aamHxe MOHonMTHbix jKMnbix 3p,ami\
OT nporpeccMpyiomero oSpyLueHvin. MHt/WTSn, M, 2005. 44 c.
7. PeKOMeHflauMM no aau^Mre BbicoTHbix SAaHtiii OT nporpeccMpyuufero oOpyiueHMfl n/n MHUl^Tdn, M, 2006. 10c.
8 CHwri 2.01.07-85*. HarpysKM li BoaAeCiCTBKfl. - M:
ToccmpoQ Poccuu, rvn Linn, 2003. - 42 c.
9. CHMn 52-01-2003. BeroHHbie 11 iKeneaoSeToHHbie KOHCipyKUMM. OcHOBHbie nonOMceHHR. M.: orvn ann, 2004. - 24 c.
10. CTO-008-02495342-2009. nPEflOTBPAmEHME n p o r p E C C M p y w i M E r o OBpyiUEHMfl )KEJlE30GET0HHblX MOHOJlMTHblX KOHCTPVKUHl^
3flAHHPI. flpoeKmupoeaHue u paciem.
11. THXOHOB H.H, ApMiipoBaHMe aneMeHTOB MOHonHTHbix jKenesodeTOHHbix 3p,aHm. dHyn
«Cmpoumenbcmeo». M. 2007. 168 c.
12. Progressive Collapse Analysis and Design Guidelines for New Federal Office Buildings and Major Expansion Projects, prepared by Applied Research Associates for GSA. Washington, B.C., 2003. 119p.
13. MENG-HAO TSAI, BING-HUI LIN. Investigation of progressive collapse resistance and inelastic response for an earthquake-resistant RC building subjected to column failure. Engineering structures, Ns30 (2008).
pp.3619-3628.
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Ngay nh$n bai:27/9/2012.
16 T^p chi KHCN Xiy dtjDg - s6 3/2012