Nghien cufu anh hUofng cua do lech tam trong tmh toan cot nha cao tang
Studying the effect of eccentricity in calculating multi-storey building column
Ngay nh$n bai: 23/01/2017 Ngay sCra bai: 18/02/2017 Ngay chap nhan dang: 4/03/2017
T6MTAT
Trong b^i bao nay, anh hifdng do l?ch tam cua cot bien, cpt goc khong dong tryc do thay doi tiet di^n d^n noi lUc tinh toan cua cot duac lam ro thong qua viec so sanh leet qua Ichi bo qua va ke den do lech tam nay khi phan tich npi lUc cot cua 12 cong trinh thifc te vdi chieu cao khac nhau. Diia tren ket qua phan tich, CO the thay rang viec hb qua d6 lech tam nay khi thilc hien tinh toan noi lUc cho c6ng trinh nhif hien nay trong qua trinh thiet ke ket cau nha cao tang cho ket qua tinh toan co do sai so 16n, mat an toan cho cong trinh.
Tii khoa: dp lech tdm, cot goc, cot bien
ABSTRACT
In this paper, the eccentricily effect of misalignment edge and corner column because of changing section on column factor internal forces is verified by comparing results between ignoring and t a b n g into account this eccentricity from analyzing column internal forces of 12 real various height buildings. According to analyzed results, it is said that ignoring this eccentricity, when calculating building internal forces by currently multi-stor)' design process, gave large error, and unsafe to building.
Key word: eccentricity, comer cohinin, edge column
KS. Bui Minh Tan
Trung tam Tu van va Kiem dinh Xay dung Vinh Long Nguyin Huy Gia
Sd X.iy dilng Thanh pho Ho Chi Minh
Bui Minh Tan, Nguyen Huy Gia
IBATVANDS
Trong he ket cau chju lue cong t r i n h , cot ddng vai t r d rat quan trong . Cdt IS cau kien thSng diJTig chiu lUe chinh. eo nhiem vu truyen tai trgng tir h& san dam xuong nen m d n g . Khi thiet k€ eau ki^n eot cho cdng trinh nhieu tang bang be t d n g cdt thep, de tiet kiem vat lieu va sif phan bd d o cLfng hop ly cho cdng trinh theo phuang diJng, ky sU thiet ke thudng giam dan tiet dien cot theo chieu cao cdng t r i n h . Dan den eae cot bien va cdt gdc khdng eon ddng true, lam xuat hien d o leeh tam hinh hoe vh lam gia tang ndi lUc trong cdt. Tuy nhien, trong thUc te thiet ke, ky sU t h u d n g bo qua su lech t a m d o khdng d o n g truc nay khi md hinh tinh toan cdng trinh bang c^c phan m e m hiiu han, Vi&c bd qua nay thudng la cam tinh va chua cd eo sd, lam cho ket qua tinh toan thieu do tin cay, gay mat an toan cho cdng trinh. Do d d , viec khao sat sai so ket q u ^ ndi luc khi khdng ke d o lech tam nay la het siJc can thiet.
2 C ( J s d L y T H U Y g T
2.1 £)6 lech true cot trin vd di/di dnh hUdng tdi gid tri noi lUc cda c6t:
Do sU ddng truc eua cot lam gia tang m o m e n t ndi Idc cho cdt tai tang dang xet.
Vdi: N - luc dpc truyen t d cdt tren cho cdt diidi e - do lech truc cot tren va cdt dUdi Ta ed: M2 = N X e la moment ptiat smh d o leeh true M l - moment trong cdt khi khong xet do lech truc V a y : M o m e n t t d n g tac dung len cot tang dang xet M = M l + M 2 . Tuy nhien, khdng chi thanh phan moment theo phdong lech tryc thay ddi, ma edn dan den sU thay doi eac gia tri ndi lUc khac (lUc doc P, luc cat V2 va V3 theo phuong 2 va 3, m o m e n t M2 va M3 xoay quanh truc 2 va 3, vdi 1 -2-3 la he truc toa dd phan td) cua cac phan tir cot va dam vi ma tran luc tai nut cho ca he da thay doi.
2.2 Phdn mem phdn tCfhOu han"' (PTHH) ETABS
ETABS'" la phan m e m PTHH thUOng mai rat manh me, duoc sd dung rat phd bien tai Viet Nam va tren the gidi, dUOc phat tnen neng diing cho viec phan tich va thiet ke cac cdng trinh dan dung bdi hang phan mem Computers and Structures inc., California, USA Vdi chu'c nang Insert Point, viec khai bao sU khong ddng true rat de dang bSng ETABS
Vl t r i khai bao nut lien ket phan tir eiia mat eat trong ETABS nhU hinh H I ,
3 MO HiNH PHAN TiCH, KET QUA VA NHAN XET 3.1 Mo hinh
Sd dung phan mem ETABS de m d hinh tinh toan cho 12 cdng trinh nha nhteu tang be tdng cdt thep thuc te, da duoc thiet ke va dUa vao SLf dung trong 2 trudng hop cd xet ua khdng xet tdi d o lech tam do lech truc cua cdt gay ra Dimg chc/c nang insert point cua ETABS de khai bao tinh chat lech true cho cdt Cac thdng sd co ban ciia cac cong trinh dUOc cho trong b a n g T !
eOSBniFlST 03.2017
STT
1 2 3 4 5 6 7 8 9 10 11 12
Bang T l . T h o n g
^ - . j O f e l O A - ^ T Cuc Thue huyen Vung Liem-Vlnh Long
Nha lam viee Trung tam vien thdng VTnh Long Nha dieu hanh s a n x u a t e d n g t y d i e n l U c Vinh Long Tru 56 lam viec Cue Thue tinh Vinh Long Tru sd lam viee Dai phat thanh va Truyen hinh Vinh Long T r u s d i a m viec Cdng an tinh Tra Vinh
Nha cong vu TPHCIW
Trudng dai hoc Van hda nghe thuat quan ddi Cd s6 hgc vien tU phap tai TPHCIVl Khu can hd cao tang Asiana Living Trudng Dai hoc cong nghe TPHCM-Khdi 2 Tru sd Eximbank-Chi nhanh Phu My Hung
so cac con M a hieu CTI CT2 CT3 CT4 CT5 CT6 CT7 CT8 CT9 CT10 CT11 CTI 2
a trinh
So hieu cot k h i c sit C d t g o c
C67 C67 C3 CIS C26 C41 C3 C31 C l C32 C22 Cl
Cot bien C68
C8 C4 C16 C27 C27 C2 C34 C2 C28 C19 C14
Kidithifdicdn) H 17.4 19.8 31.5 30.3 37.3 39.3 36.6 38.4 61.8 45 59 52.6
L 29.4
25 38 61.8
30 94.1 69.6 49.5 48.8 5 1 J 51 39.2
B 15.6 11.8 17.6 27 2 2 5 17.8 26.4 22.5 19 18 15 25.45
V a t l i ^ B e t d n q B15 B20 830 B22.5 B30 B25 B22.5 B22.5 B30 B25 830 B25
1 2 3 Hinii HI Diem nut lien ket tren net dien
Vl du Cdng tnnh Tru sd lam viec Dai phat thanh ua Truyen hinh Vinh Long (CT51 eho trong hinh H2, H3, va H4
3.2 Ket qud
Ket qua sai sd ndi lUc ciia 2 tru'dng hop tai chan cdng trinh thu duoc tdviec phan tich m d h i n h bang ETABS duoc cho trong b a n g T 2 v a T 3
3.3 Nhdn xet
3.3.1 061 vdi luc doc P {hinh H5)
- Sai sd Ion nhat cua cdt gdc va cot gdc bien la nhd duoi 10%, cdt gdc Idn hon cdt bien (9 4% so vdi 1 0%).
- Sai sd trung binh cdt goc va cdt bien la kha nhd (duoi 3'^.o), edt gdc Ion hon cot bien (2 4% so vdi 0 5%)
- Mile do phan tan ket qua tinh toan dd sai sd cua cot gdc va cdt bien kha nhd - dudi 3%, cdt goc Ion hon cdt bien (2.6''o so vdi 0 3%), cho thay ket qua co dd tin eay rat cao
H-inhH2 Mo hinli 3D trong ETABS
I' Xet do lech true HinhH3 \1atbSrgb6triColQ6vaC27
03.2017 iSDn¥iWi» 61
I
(a) Xet dd lech true (b) Khdng xet Hinh H4. Mat diitig (6t C27 - lliay doi tiet dien tai tang 4
B^ng T2. Sai s6 noi life chan cong trinh khi xet den va khong x^t den 6b i6ch tSm khong flong true ciia cot goc
- Mac d6 phan tan k i t quS tinh toan dd sal so kha 16n, cot goc Icrn hon cot bien (15.3% so vdi 17.6%), cho thay ket quS co dp hn cSy cao.
3.3.4 D^i vdi moment iW2 (hinh H8)
- Sal so ldn nhat c i a cot goc va cot goc blen la I6n, cot goc nh6 hon c 6 t b l e n ( 7 1 . 8 % s o v a i 8 9 . 1 % ) . _, ^ , ™ ^ • ; , -
' - Sai so trung binh c6t goc va cot bien la hoi ifln di/fli 30%, co g i i tr|
x a p x i n h a u { 2 5 . 5 % s o v d i 3 1 . 8 % ) . _ - M * do phan tan ket quS t i n h toan d p sai so kha Ion, cot goc lOn
hon cat h i S n J 1 j j % so vOI 27.8%), cho thay kel q u i co do t m cay cao.
Cong trinh CTI CT2 CT3 CT4 CT5 CT6 CT7 CT8 CT9 CTIO
cm
CTI 2 Chi^u
cao m 17.4 19.8 31.5 30.3 37 3 39.3 36.6 38.4 61 8 45 59 52.6
C6tg6c(%) So hieu
C67 C67 C3 C15 C26 C41 C3 C31 Cl C32 C22 Cl Gid tri max Trung b'inh Oolechchudn
Pi
3.7 1.6 4.2 1.2 0,5 3.0 1.1 2.0 1.1 0 7 9.4 0.2 9.4 2.4 2.S
|V2|
46.5 14.4 47.4 54.7 20.0 48,1 8,2 29.0 10.4 0.5 16.9 38.1 54.7 27.5 18.5
|V3|
20,2 51,6 48.2 33,0 28.8 34.4 9,2 37.1 121 0,1 23.8 25.2 5J.fi 27.0 75.3
|M2|
18,4 71.8 32,6 23.4 12,2 32-7 21.0 45.6 8.7 0 1 32,7 6.7 71.8 2S.S 19.6
|M3|
46.9 84.1 26.1 24.3 2.3 7 4 0 2.2 14.8 5.9 0.6 92.5 21 3 92.S 32.9 33.4 3.3.2 Doi voi lUc cSt V2 (hinh H6)
- Sai sd [dn nhat cua cdt goc va edt goc bien la Idn, cdt gdc nhd hon cdt bien (54 7% so vdi 98.7%)
- Sai sd trung binh cdt goc va cdt bien la hoi Idn dodi 30%, cd gia tri xap xi nhau (27 8% so vdi 27.7%)
- IWirc dd phan tan ket qua tinh to^n dd sai sd kha Idn, cdt goc Idn hOn cdt bien (18.5% so vdi 37.6%), cho thay ket gua ed do tin cay cao.
Bdng T3. Sai so no! life chan cong trinh khi xet den va khong xet den do lech tam khong dong true cua cot blen
Cdng trinh CTI CT2 CT3 CT4 CTS CT6 CT7 CTS CT9 CTIO C T l l CT12
Chieu cao
m 17.4 198 31 5 30.3 37 3 39 3 36 6 38 4 61.8 45 59 52 6
Cdt Bien (%) Sdhieu
C68 C8 C4 C16 C27 C27 C2 C34 C2 C28 C19 C14 Gid tri max Trung binh Dd lich chuan
|P|
0 0 0 8 0,9 0 3 OS 0 1 0 0 0 7 0,4 0 7 1 0 0 6 1.0 0.5 0.3
|V2|
90,0 12.4 76.3 3 5 0 9 1 0 4 9 7.5 28-1 0 6 8.5 98 7 98.7 27.7 37.6
|V3|
26 3 107 139 27.8 50-3 46 3 40 5 41 2 26 3 0 5 56 0 135 56.0 29.4 17.6
|M2|
23.6 70 4 137 20 5 22 1 43 5 89 1 25 3 6 9 1 6 58 8 5 7 89.7 3J.8 27.8
|M3|
841 92-4 10-5 1 4 2.0 1 8 3 1 22-8 26.8 0 8 8 1 23 7 92.4 23.1 31.9 3.3.3 D o i v d i liic cat V3 (hinh H7)
- Sai sd Ion nhat ciia cdt gdc va cdt gdc bien la Idn, c cdt bien (51 6% so vdi 56 0%)
- Sai sd trung binh cdt gdc va cdt bien la hoi Ion doc xap xi nhau (27 0% so vdi 29 4%)
HinhHS.Saiso'lgcdocP
Hmh H6 Sai so life cat V2 3.3.5 Doi vdri moment M3 {hinh H9)
- Sai sd Idn nhat cua cdt gdc va cdt gdc bien la Idn, edt goc nhd hon cdt bien (92 5% so vdi 92 4%)
- Sai sd trung bmh cdt gdc va cot bien la hoi Idn dUdi 30%, cd gia tn xap xi nhau (32 9% so vOi 23 1%)
- Mdc d d phan tan ket qua tinh toan dd sai sd kha Idn, edt goc Idn hon cot bien (33.4%sovOi 31 9%|, eho thay ket qua cd dd tin cay cao.
5 2 iSEiniKilffi'V 03.2017
hinliH7.Sais6li/CtatV3
- Sai sd ddi vdi li/e doc rat nho, khdng dang ke va d d tin eay ciia ket qu3 rat eao (do phan tan < 3%)
- Sai so doi vdi life e3t va momen cho ca 2 phu'dng la t u o n g d o i ldn (khoSng 30%) va do phan tan k^t qua tfnh toan cOng kha ldn (17% -^
37.6%), cho thay d p tin cay cOa ket qua khdng cao.
Td dd cho thgy, thanh phan ndi lire m o m e n t va life c i t ket qua sai so Idn khi khdng ke den do lech tam nay trong viee phan tich noi lire cho eau k i f n coL Do do, Bdi bdo de xuat: chung ta phai keden do lech tam ndy khi tinh todn
4.2 Kien nghi
Trong khudn kho eua Bai bao da dUa ra dUOe m o t so ket luan quan trong, tuy nhien van cdn nhieu han che can du'pc nghien euu va phat trien them nhUsau:
- Sd lifOng cac cong trinh khao sat ehi/a di/pc nhieu (12 edng trinh) Can khao sat nhieu mau hon de thu dUoc ket qua ehi'nh xac.
- Cac thanh phan noi life duoc phan tich rieng le tif nhieu to hop tai trong khac nhau, chUa hoan toan phii hgp vdi viee thiet ke cau kien nen lech tam xien n h d cdt.
TAI UEU THAM K H A O
[1] Chu Quoc T i l i n g , Ptitfong phap Phan tiJ hifu han. Ha Noi, ^ h a xual ban Khoa hoc va Ky thuat, 1997-
[2] Q l Computer & Structures, Elabs 9 7.4 Tutorial, Cahfomi
Hinh H9,5ai so moment M3 4 K^T LUAN VA KIEN NGHI 4.T Ket luan
Trong Bai bao nay, bang phuong phap PTHH duoc tien hanh voi phan mem ETABS, tac gia da tien hanh linh toan cac thanh phan ndi iuc cdt gdc, va cdt bien eua 12 cdng trinh nhieu tang thUc te, vdi chieu eao khac nhau, da duoc thiet ke va dua vao sii dung eho 2 IrUdng hop- khdng ke den dd lech tam do cdt leeh true va cd ke den Qua ket qua phan tich, Tac gia rut ra mdt sd ket luan nho sau:
03.2017 iSBniEieii 6 3