Tính toán thiết kế kháng chấn nhà nhiều tầng

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DIEN BAN KHOA HOC CONG NGH^

^TINH T O A N THIET KE KHANG C H A N

N H A N H I E U T A N G

I. NHlN CHUNG V^ T A C HAI CUA DQNG DAT
DOi v d i LOAI N H A N A Y

Trong xdy dung d nudc ta, d l i vdi nhOmg ngdi nhd
nhilu ting (tir 5 ting trd xuing) vide dp dgng kit c l u
gach Id khd p h i biln. Bdi le, sir dung vdt lidu gach
dope sdn xult rdng rdi d t i t cd cdc dja phuong, d l cd,
gid thdnh ha vd thi cdng dom gidn.

Nhung khii xdy gach cd nhupc dilm Id dp dai bin
kdm (so vdi b§ tdng cIt thdp hoac thdp), khd nang
chdng kdo, chIng trupt ( d t ) thIp, r i t bit Igi khi phdi
chju Igc ddng dIt n i m ngang; trong nhumg vung cd
d p ddng dIt Idn d l bj nurt thdm chf sup.dl, xdc suit
phd hoai cao.

Khi xdy ra ddng dIt, vj trf bi phd hoai ciia nhd nhilu
ting chu ylu tai noi lidn kit giQa c l u kidn bd tdng cIt
th^p vd khIi xdy gach, cdn bdn thdn kit c l u sdn vd
m&\ chl bj t i n thuomg tuomg d l i nhp.

Kit qud dilu tra ting quan mdt s i trdn ddng dIt d
trong nude vd d ngodi nudc da chl ra quy ludt phd hoai
do ddng ddt ddi vdi cdc ngdi nhd gach nhilu ting nhu
sau:

1. Phd hoai cua khol xdy

KhIi xdy tudng ciia kit d u hdn hpp (b§ tdng cdt
th^p vd gach dd) Id c l u kidn chu y l u chju Iuc ddng
dIt. Khi c6 ddng ddt phdt sinh, khIi xdy tudng song

"*r

a. Vk nut tren twdng ngan§

N G U Y t N H 6 N G H i t P

song vdi phuemg cua Ige ddng dIt thudng bj phd hoai
do cudng dd umg suit kdo chfnh khdng du md bj d t
(trupt), tao ra v l t nuft nghidng. Do tdc ddng qua lai ciia
Iuc ddng dIt, v l t nurt nghieng theo hai phuong tao
thdnh vdt nurt dang giao thoa (xem hinh 1 dudi day),

Quy ludt Chung ciia v l t nurt nghidng ndy trong nhd
nhilu ting Id "dudi nang, tren nhe", "hai ben nang, d
giOra nhe".

Trong nhd cd tudng dpc chju Iuc, khi Iuc ddng dIt
tdc ddng theo phuomg true giao vdi tudng dpc, do
tudng doc chju tdc ddng ciia uln vd d t , tai cdc mdng
tudng giQa cQa, d cdc tilt didn trdn dudi Id cira vd tai
g i n sdn sinh ra v l t nijrt nim ngang kdo ddi.

2. Phd hoai cua gdc tirdng

Trong qud trinh ddng dIt, cdc gdc tudng nhd Id cdc
khdu y l u . Tai noi gdc nhd, do d mdp, sg rdng budc
theo hai phuomg dpc vd ngang tuomg dli Idng ldo vd
lai ludn ludn chju Iuc ddng dIt tQ hai phuong Idm cho
Qng suit tdp trung; vi vdy ddy Id noi thudng nhay cdm
nhit d l i vdi s u t i n thuong (xem hinh 2).

Trong hinh 2 md td nhCimg vf du v l su phd hoai ddi

a. Pha hoai ciia gdc tifdng nha gach

&. Phi hoai^Mgd&nhi phia tnfdc — ^ ^ 
Hinh 2.- Phd hoai cua gdc tudng

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T I N H T O A N T H I E T KE K H A N G C H A N . . .

vdi cdc gdc nhd gach.

3. Phd hoai cua gian clu thang

Op cUng mdt bIng ciia khIi xdy tudng cua gian
d u thang tuemg d l i Idn; do dd, Iuc ddng dIt dupe
phdn phii tdi dd nhilu; ddng thdi gian c l u thang
thudng dupc b l cue d dang thodng md, tai ting dinh
trdng trai ndn dd cumg khdng gian kem; ban than gian
d u thang lai Id noi xung y l u ; vi vdy ndi chung, gian
d u thang thudng bj phd hoai nang. Su phd hoai ciia
nd bilu hien chii y l u d v l t nurt nghieng vd v l t nut dao
thoa tai tudng ngang.

Gian thang mdy cung tuomg tu nhu tinh trang ciia
gian d u thang; su phd hoai sinh ra nhilu d g i n Id cira.
4. Pha hoai tai noi lien k i t ciia tudng doc vd 
tudng ngang

Tai noi lien kit giQa tudng dpc vd tudng ngang, do
CO do cUng Idn ndn chju Iuc dpng dIt Idn, Ung suit tap
trung, ngodi ra, do nhumg nguyen nhdn v l mat thi
cdng nhu xdy khdng bit md tdt giQa tudng ngang vd
tudng dpc, thudng hay xult hien hien tupng tudng dpc
vdng ra ngodi hoac sup do; dac trung ciia v l t nOt Id
"rdng tren, hep dudi"

5. Phd hoai cua kit clu phu

Kit d u phu ciia nhd nhu tudng ddn mdi, mdi dua,
Ing khdi g i n vdo tudng nhd, mdng trang trf, thdp
chudng, cdc c l u kidn thdi d i u nhud vdng, ban cdng...
cung nhu cdc gian nhd d i u Ien trdn dinh mdi nhu gian
che mua, gian c l u thang mdy Idn mdi d i u cd tilt didn
nhd, dp cumg thay doi ddt ngdt, lien kit y l u , thilu g i n
bd vdi xung quanh, dudi tdc ddng ciia Iuc ddng dIt,
hidu Qng phd hoai rdt ro ndt: nhQng bd phdn nhd Ien
khdi kit d u chinh ciia nhd chju dnh hudng ciia dang
dao ddng cao, biln dang ddng Iuc Idn hom rit nhilu so
vdi biln dang ciia kit c l u chfnh ben dudi; do dd ton
thuomg ddng d|t nghidm trpng hom ben dudi rit nhilu.
Khi c6 ddng dU, nhQng kit c l u phu ndi trdn bi phd

g-ssJWWw

x_

a. Pha hoai ciia tUdng don mai cua 
mot nha gach nhieu ting

hoai sdm nhit, xdc suit t i n thuomg cung Idri nhit,
nhilu trudng hpp h l u nhu chl mdi ddng dIt d p 6 \k 
da cd t h i bj phd hoai, dac bidt Id cdc I n g khdi nhd ISn
khdi mdi, cdc tudng ddn mdi cao; d i n cap 7 thi ph^
hoai mdt cdch pho biln vd khi da d i n cdp 8, cap 9 thi
h l u nhu bj phd hoai hodn todn (xem hinh 3 dudi day).

6. Phd hoai cua tudng hdi vd dinh thu hdi

Tudng hdi ciia mdi nhd d i e thudng bj phd hoai
nhilu vi khIi xay tudng d day khd cao; n l u cdng them
vdi tinh trang khdng cd neo lidn k i t giQa vi kdo vd x^
g l hoac doan g l i ciia xd g l Ien tudng hdi qud ngdn;
khi cd ddng dIt, xd g l dly, kdo tudng thu hIi hoac xk 
g l rut ra khdi tudng hdi Idm cho nd Idm viec nhu mot
thanh cdng son khd cao, gay ra su phd hoai ciia tudng
hdi vd dinh thu hdi.

7. Pha hoai cua sdn

Trong ddng dIt, bdn than sdn bj ton thuong rit
nhd. Do tfnh todn khIi chinh t h i ciia san panen lip
ghep tuomg d l i kdm cdng them tinh trang nhdi khe
panen khdng chat, khi cd ddng dIt d p cao, cdc sdn

bj kdo rdi nhau ra, cdc d i m gdc vdo tirdng cung nhir
cdc d i m c l u thang, do khdng cd bidn phdp neo chSt
vdi tudng ndn thudng cd hidn tupng d i u dim rut ra
khdi tudng hoac dudi ddy d i m xult hidn cdc khe nuft
thing dOng tao ndn bdi Igc xung kfch dpc do nhd bj
rung Ien trong qud trinh ddng dIt.

8. v l chit iuong thi cong

Chit lupmg thi cdng t i t hay x l u cd quan hd rit Idn
d i n khd nang khdng chin ciia nhd. NhQng khilm
khuylt ciia thi cdng phdn dnh rit ro rdng trong tdc hai
cua dpng dIt d l i vdi nhd. Cung trong mdt dilu kign
dja chit, dja hinh, ciing mdt thilt k l kit c l u cua nlid
vd cdng trinh nhung n l u chit lupmg thi cdng khdc
nliau thi mQc dd nghidm trpng cua t i n thuong do ddng
dIt da chdnh Idch nhau r i t nhilu. Qua dilu tra tdc hai
cua ddng dIt, ngudi ta da phdt hidn nhumg v i n d l chu
y l u v l chit lupng thi cdng d l gdy ndn ton thuong do
ddng dIt bao gIm: khi xdy tudng khdng cd lidn kit
giQa tudng trong vd tudng ngodi md chl cd bit m6
dUng, vj trf tudng khdng thing hoac khIi xdy tudng
nghidng veo, chilu ddi g l i gdc Idn tudng ciia cdc clu
kipn due s i n khdng du, sd hidu vtira xdy tudng thIp,
d p phii ciia vQa khdng dung hodc d l nudc tiiy tien
vdo trong vOa, trdn thdm chit hda ddo vdo vQa;

b. Pha hoai cua ong khdi nho 
J Ien khdi mai.

Hinli 3.- Pha hoai ciia cac kdt ciu phu

Hinti 4: Susup do cua tUdng doc ngodi khdng lien ket tdt vdi cdc 
tudng ngang ben trong.

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T I N H T O A N THIET KE KHANG C H A N . . .

phuomg phdp xdy khdng thda ddng nhu diing khIi xdy
tudng Idm khudn due cdt hodc diing vQa vdi xdy
tudng...

Hinh 4 dudi ddy bilu thj mdt ngdi nhd, chl vi giQa
tudng trong vd tudng ngodi chl bit md diTng md khdng
lidn kit t i t ndn da gdy ra sg sup d l ciia tudng ngodi.

I L T I N H T O A N K H A N G CHAN

1. Lire c i t (trirort) dpng d I t tai cdc t i n g vd sir
phdn p h i i cua nd gii?a cdc k h I i xdy tirdng

Lgc d t (trupt) ddng dIt song song vdi phuemg cua
Iuc ddng dIt tdc ddng tai ting l l u thU j (tfnh tU ting
ddy trd Idn) bIng ting Ige ddng dIt tai chit dilm ciia
cdc ting bdn trdn ting dd (xem hinh 5 dudi ddy):

e,=Z^

(1)

i=j

Trong bilu thOe: Qj: Lgc ddng ddt tai ting thU j

Pj: Luc ddng dIt tac ddng tai chit dilm i, tfnh theo
bilu thiirc (15a) trong bdi ddng d s i tap chf thdng
trude.

n: S l chit tflm.

Dudi tdc ddng ciia Igc ddng dIt ngang cua ntid (tOc
Id Iuc ddng dIt thing gdc vdi phuemg ciia chilu ddi
nhd; cdn Ige ddng dIt song song vdi phuemg ciia
chilu dpc nhd gpi Id Ige ddng dIt dpc ciia nhd), do dd
cumg tudng ngang cua nhd gach nhilu ting Idn hom
rdt nhilu so vdi dd cQng ciia tudng dpc ndn quy pharri
thilt k l khdng chin thudng quy djnh todn bd Ige d t
(trupt) ddng dIt theo phuemg ngang cua nhd do tudng
ngang chju hit. Nhumg tudng ngang ndi d ddy Id chl
tudng ngang cd t h i chju Ige ddng dIt dupe tUc tudng
ngang khdng chin. Quy pham quy djnh chilu ddy cua
tudng ngang khdng chin khdng dupc nhd hom 22cm.

Cdn vide phdn phii Igc d t (trupt) ddng dIt tai cdc
tdng Ign nhtimg bOc tudng ngang tuy thudc vdo dd
cUng ciia sdn d l xdc djnh.

•^fPn

Qj

TffT?

Qo

Hinli 5: Lffc dt (tnAft) ddng dit

(1) Sin cUng tifc 
sin bS tdng cit thdp 
due tai chd hoic sdn 
lip ghdp xong dd Ilin 
khil

Khi khodng cdch giOa
cdc bUc tudng ngang
phil hpp vdi cdc quy djnh
trong bdng 1 dudi ddy thi
sdn ciTng trong mdt
phing ciia nd cd t h i
xem nhu d i m lidn tgc
cQng tuydt d l i tga trdn
nhtimg g l i tga ddn hdi
(tite cdc bOe tudng ngang vd gid thilt Id trung tdm dd
cdng vd trung tdm khIi lupng ciia nhd Id triing hpp md
khdng sinh ra hidn tupng xoln; khi dd, ta cd chuyin vj
nim ngang ciia nhOng tudng ngang Id bdng nhau
(xem hinh 6 dudi ddy).

Bang 1 : Khoang each cue dai gida cac bde tudng

ngang ehiu iuc (m)

Phan loai san

Be tong cot thep due tai ch6 
Be tong cot thep lap ghep

Gd

Cdp ddng dat thiet ke

7 
25 
20 
12

8 
20 
16 
8

g 
12 
9 
4

ff

4

(c)

Hinh 6: Tinh toin

phan phdi li/c cit (tn/dt) 
dong dit giOa san cdng

cua cac tang

Nhu vdy, can cQ vdo gid thilt ndi trdn ta cd ting Iuc
d t (trupt) ddng dIt do nhQng bOc tudng ngang khdng
chin tai ting thU j chju dung phdi bIng ting Igc d t
(trupt) ddng dIt d ting dd.

Qn +Qj2 + +Qj. + +Qjs=Qj (2) 
Ta ddt:

•/. f ^ f

f.-M«-t-(ij

Qn

Qj2

^Jm

Qj^

A I

^ ^

A

^ ^

A

~~S~

ji"

A

^ ^

(3)

Q / = i _

Trong dd: Qjn,: Luc cdt (trupt) ddng ddt do bOc
tudng gach thU m chiu dung

A: Chuyin vj
n i m ngang ciia
dinh nhQng bUc
tudng ngang.

a,„: Chuyin vj
sinh ra tai tfnh ciia
bUc tudng gach
thU m khi cd dom vj
Igc nim ngang Q
= 1 tdc ddng Idn

Buc tircmg 
ngang thirm

Hinh 7: Sd dd chju lUc cua bUc tUdng 
ngang thUm

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tfnh ciia bOe tudng gach thur m dd (xem hinh 7).

Mang bilu thQe (3) t h i vdo bilu thOe (2). ta cd:

A A
— + +

+ +

Ta rut ra:

A =

1

1 ^'

-18,.

n=\ jm

Mang bilu thQe tren t h i vdo bilu thUe (3), ta thu
dupc Iuc d t (trupt) ddng dIt phdn phii cho cdc bOc
tudng ngang chiu dung nhu sau:

T I N H T O A N T H I E T K J K H A N G C H A N . . .

cd dom vj Ige tdc ddng.

h,„,: Chilu cao ciia bOc tudng ngang thQ m cOa
ting l l u thur j .

•tjn,: iJng suit trupt tren m$t d t ngang ciia biit;
tudng ngang thur m khi cd tdc ddng cOa don vj Igc 0 =

1, bdng # trong dd i id hd sd khdng ddng ddu

•^Jm

ci^a phdn phii Qng suit trupt, Aj„ Id didn tfch ciia tilt
didn tudng ngang.

G|n,: Md dun Ige trupt cua khIi xdy gach, cd quan
hd vdi s l hidu ciia gach vd vOa.

Dem bilu thQe (6) t h i vdo bilu thOc (5) vd gid thilt
chilu cao cdc ting bdng nhau, s l hidu ciia gach vd
vQa xdy cdc bde tudng ngang gidng nhau (tile Id md
dun Ige trupt Gj^ gilng nhau), ta thu dupc:

1

m=\ 8j„

Qj2=—^-pxe,-^,2ey

/n=l O jm

3^ im ^jm

Sj.i:

— x p =k Q

\S jm

m=\ Sj^

(4)

Trong dd: k.^ =

1 5. f —

(5)

V^ dupe gpi Id he s l phdn phii Ige cat (trupt) ddng 
dIt giQa cdc ting.

TQ bilu thOc (5), ta cd t h i thIy muln xdc djnh
dupc kn, ta phdi tfnh ra chuyin vj ngang h^ tai tfnh 
tudng ngang khi cd dom vj Ige ndm ngang Q = 1 tdc
ddng tai dinh cdc bute tudng ngang. Khi tfnh todn j ^ ,
ndi Chung ngudi ta chl xdt d i n biln dang trupt.

TU mdn sQe b i n vdt lidu ta cd:

•jm

G,_ ^^ G,A jm jm (6)

Trong dd:

Y|n,: LTng biln trupt ciJa bOc tudng ngang thiT m khi

N G U d i X A Y D I / N G S 6 T H A N G 8 2011

1r -.AJUL 
jm

y "

m=l

(7)

jm

Trong dd:

A^: Didn tfch tilt didn ngang thu hpp ciia buPc
tudng ngang thur m ciia t i n g thi]r j (xem hinh 8)

^ Aj„ : Ting dipn tfch ndm ngang thu hpp cua

cdc bOc tudng ngang. Di thudn tidn ta vilt k^ hi$u 
bdng Aj.

^ N ^ ^

Ajm

Hinli 8:
D/e/J tich

nim ngang 
cua tudng 
ngang nhi

Bilu thire (7) trdn ddy gidi thfch ring: khi thda man
cdc dilu kidn ndi trdn thi Ige trupt ddng dIt phdn phii
cho cdc bOc tudng ngang chju dgng dupe phdn phdi
theo ty Id vdi didn tfch tilt didn ngang.

(2) Sin mim tifc sin gd

Vi dd cQng ciia sdn mIm tuomg d l i nhd, ndn khi
phdn phii Ige d t (trupt) ddng dIt, ta cd t h i xem sdn
nhu mdt d i m dom tga trdn cdc bOe tudng ngang (xem
hinh 9). Nhu vdy hd s l phdn phii k:^ cua bOe tudng
ngang thQ m chju Igc d t (trupt) Qi^, = kjn^Q, cd thi
xdc djnh dupe can cU vdo ty s l giua trpng lupng kit
c l u ciia ting dd md bOc tudng ngang thU m phdi gdnh
chju vdi ting trpng luemg cua k i t c l u tai ting j dd, t<K 
Id ty s l giQa trpng lupng ciia phin didn tfch chju tdi
(tute mdt nira cua hai didn tfch liln k l hai bdn cOa buic
tudng thU m) trdn ting trpng lupng k i t c l u ciia ting

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