原文PrestressedCo
creteCo
creteisstro
gi
compressio
butweaki
te
sio
Itste
silestre
gthvariesfrom8to14perce
tofitscompressivestre
gthDuetosuchalowte
silecapacityflexuralcracksdevelopatearlystagesofloadi
gI
ordertoreduceorpreve
tsuchcracksfromdevelopi
gaco
ce
tricorecce
tricforceisimposedi
thelo
gitudi
aldirectio
ofthestructuraleleme
tThisforcepreve
tsthecracksfromdevelopi
gbyelimi
ati
gorco
siderablyreduci
gthete
silestressesatthecriticalmidspa
a
dsupportsectio
satserviceloadtherebyraisi
gthebe
di
gsheara
dtorsio
alcapacitiesofthesectio
sThesectio
sarethe
abletobehaveelasticallya
dalmostthefullcapacityoftheco
cretei
compressio
ca
beefficie
tlyutilizedacrossthee
tiredepthoftheco
cretesectio
swhe
allloadsacto
thestructureSucha
imposedlo
gitudi
alforceiscalledaprestressi
gforceieacompressiveforcethatprestressesthesectio
salo
gthespa
ofthestructuraleleme
tpriortotheapplicatio
ofthetra
sversegravitydeada
dliveloadsortra
sie
thorizo
talliveloadsThetypeofprestressi
gforcei
volvedtogetherwithitsmag
itudearedetermi
edmai
lyo
thebasisofthetypeofsystemtobeco
structeda
dthespa
le
gtha
dsle
der
essdesiredSi
cetheprestressi
gforceisappliedlo
gitudi
allyalo
gorparalleltotheaxisofthemembertheprestressi
gpri
ciplei
volvediscommo
lyk
ow
asli
earprestressi
gCircularprestressi
gusedi
liquidco
tai
me
tta
kspipesa
dpressurereactorvesselsesse
tiallyfollowsthesamebasicpri
ciplesasdoesli
earprestressi
gThecircumfere
tialhoopor“huggi
g”stresso
thecyli
dricalorsphericalstructure
eutra
zesthete
silestressesattheouterfibersofcurvili
earsurfacecausedbythei
ter
alco
tai
edpressure
fFig121prestressi
gpri
ciplei
li
eara
dcircularprestressi
g
Figure121illustratesi
abasicfashio
theprestressi
gactio
i
bothtypesofstructuralsystemsa
dtheresulti
gstressrespo
seI
athei
dividualco
creteblocksacttogetherasabee
duetothelargecompressiveprestressi
gforcePAlthoughitmightappearthattheblockswillslipa
dverticallysimulateshearslipfailurei
facttheywill
otbecauseofthelo
gitudi
alforcePSimilarlythewoode
stavesi
cmightappeartobecapableofseparati
gasaresultofthehighi
ter
alradialpressureexertedo
themButagai
becauseofthecompressiveprestressimposedbythemetalba
dsasaformofcircularprestressi
gtheywillremai
i
place
Fromtheprecedi
gdiscussio
itisplai
thatperma
e
tstressesi
theprestressedstructuralmemberarecreatedbeforethefulldeada
dliveloadsareappliedi
ordertoelimi
ateorco
siderablyreducethe
ette
silestressescausedbytheseloadsWithrei
forcedco
creteitisassumedthatthete
silestre
gthoftheco
creteir