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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 [r]
(1)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 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 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 phdi chju Igc ddng dIt n i m ngang; nhumg vung cd d p ddng dIt Idn d l bj nurt thdm chf sup.dl, xdc suit phd hoai cao
Khi xdy 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 nude vd d ngodi nudc da chl quy ludt phd hoai 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 N G H i t P
song vdi phuemg cua Ige ddng dIt thudng bj phd hoai cudng dd umg suit kdo chfnh khdng du md bj d t (trupt), tao 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 dudi day),
Quy ludt Chung ciia v l t nurt nghidng ndy nhd nhilu ting Id "dudi nang, tren nhe", "hai ben nang, d giOra nhe"
Trong nhd cd tudng dpc chju Iuc, Iuc ddng dIt tdc ddng theo phuomg true giao vdi tudng dpc, 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 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, 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 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
(2)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; 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 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, CO cUng Idn ndn chju Iuc dpng dIt Idn, Ung suit tap trung, ngodi ra, 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 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; 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 \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 thi ph^ hoai mdt cdch biln vd da d i n cdp 8, cap thi h l u nhu bj phd hoai hodn todn (xem hinh 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 khdi tudng hdi Idm cho nd Idm viec nhu mot cdng son khd cao, gay 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, cd ddng dIt d p cao, cdc sdn bj kdo rdi ra, cdc d i m gdc vdo tirdng cung nhir cdc d i m c l u thang, khdng cd bidn phdp neo chSt vdi tudng ndn thudng cd hidn tupng d i u dim rut khdi tudng hoac dudi ddy d i m xult hidn cdc khe nuft thing dOng tao ndn bdi Igc xung kfch dpc nhd bj rung Ien 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 tdc hai cua dpng dIt d l i vdi nhd Cung 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 ddng dIt da chdnh Idch 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 ddng dIt bao gIm: xdy tudng khdng cd lidn kit giQa tudng 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 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 cua tUdng doc ngodi khdng lien ket tdt vdi cdc tudng ngang ben
(3)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 dudi ddy bilu thj mdt ngdi nhd, chl vi giQa tudng vd tudng ngodi chl bit md diTng md khdng lidn kit t i t ndn da gdy 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 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) 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), 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 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 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 bdng dudi ddy thi sdn ciTng 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 hidn tupng xoln; dd, ta cd chuyin vj nim ngang ciia nhOng tudng ngang Id bdng (xem hinh dudi ddy)
Bang : 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 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:
ã/ f ^ f
f.-Mô-t-(ij
Qn
Qj2
^Jm
Qj^
A I
^ ^ A ^ ^
A ~~S~ ji"
A ^ ^
(3)
Q / = i _
Trong dd: Qjn,: Luc cdt (trupt) ddng ddt bOc tudng gach thU m chiu dung
A: Chuyin vj n i m ngang ciia dinh nhQng bUc tudng ngang
a,„: Chuyin vj sinh tai tfnh ciia bUc tudng gach thU m cd dom vj Igc nim ngang Q = tdc ddng Idn
Buc tircmg ngang thirm
Hinh 7: Sd dd chju lUc cua bUc tUdng ngang thUm
(4)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 — + +
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$t d t ngang ciia biit; tudng ngang thur m cd tdc ddng cOa don vj Igc =
1, bdng # dd i id hd sd khdng ddng ddu
•^Jm
ci^a phdn phii Qng suit trupt, Aj„ Id didn tfch ciia tilt didn tudng ngang
G|n,: Md dun Ige trupt cua khIi xdy gach, cd quan hd vdi s l hidu ciia gach vd vOa
Dem bilu thQe (6) t h i vdo bilu thOc (5) vd gid thilt chilu cao cdc ting bdng nhau, s l hidu ciia gach vd vQa xdy cdc bde tudng ngang gidng (tile Id md dun Ige trupt Gj^ gilng nhau), ta thu dupc:
1
m=\ 8j„
Qj2=—^-pxe,-^,2ey
/n=l O jm
3^ im ^jm
Sj.i:
— x p =k Q
\S jm
m=\ Sj^
(4)
Trong dd: k.^ = 1
5 f — (5)
V^ dupe gpi Id he s l phdn phii Ige cat (trupt) ddng dIt giQa cdc ting
TQ bilu thOc (5), ta cd t h i thIy muln xdc djnh dupc kn, ta phdi tfnh chuyin vj ngang h^ tai tfnh tudng ngang cd dom vj Ige ndm ngang Q = tdc ddng tai dinh cdc bute tudng ngang Khi tfnh todn j ^ , ndi Chung ngudi ta chl xdt d i n biln dang trupt
TU mdn sQe b i n vdt lidu ta cd:
•jm
G,_ ^^ G,A jm jm (6)
Trong dd:
Y|n,: LTng biln trupt ciJa bOc tudng ngang thiT m
N G U d i X A Y D I / N G S T H A N G 2011
1r -.AJUL jm
y "
m=l
(7)
jm
Trong dd:
A^: Didn tfch tilt didn ngang thu hpp ciia buPc tudng ngang thur m ciia t i n g thi]r j (xem hinh 8)
^ Aj„ : Ting dipn tfch ndm ngang thu hpp cua
cdc bOc tudng ngang Di thudn tidn ta vilt k^ hi$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: 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 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