DiFrereNTIAL SHRINKAGE -
9n Composite members using pre casT
pre-sttessed units,
in situ cast Concrete, a tonsi d erable porticn tetal shrinkoge
uill hove ateady taken place in the
preCcoat prestreasel beam,
belote the Casting and harclening et the in-situ concrete.
Due to fhigh watr cement raHas usecd in the in-situ
Concrele, there wil be a Conside roble Shrinkaqe o this
Part in the compoelte section.
herefore differential shrin kage between the Pre cast
Sttesses in both.
andd in situ cast units result in
he magnitute of oieretral, shrinkaqe is indluebee
the eñvironmental
by Composition o Concrete and
Conditions to whrch the Composite member is exposed.
Estimation et stesses due te Dfferential Shrinkoge-
Assumptiens
)Jhe shrinkage is unfom over the în-situ port of the
Section
n)he elect of cree and increase in mduwus of
etasthicity
uith oge and the domponent e shrin koge which is
Common to both the unts is hegligible.
, Methocd o Computing Stresses
First in situ slab is allowed te unalergo ull
differential shrinkage ¬cs.
is applied through the
h e n tensile dorce of Nsh
Ceniroid at both ends fill it reaches the length o
precast etement.
Nour uniform tensite sttength o Ees X E is incduced
in tn-sittt Conctetc and Nsh =
¬es* Ec A
Where, A= 4rea in-situ tonretc secdion
Ee Modul et elasticity e in-stu toxrek.
Ecs/ Ses/2
Cast in situ
slab Area -A:
Precast elemert
unit length
Nsh
Nsh
eesEA
|<-
19 A
Direct Bercing
Sttess Stress
9n Composite members using pre casT
pre-sttessed units,
in situ cast Concrete, a tonsi d erable porticn tetal shrinkoge
uill hove ateady taken place in the
preCcoat prestreasel beam,
belote the Casting and harclening et the in-situ concrete.
Due to fhigh watr cement raHas usecd in the in-situ
Concrele, there wil be a Conside roble Shrinkaqe o this
Part in the compoelte section.
herefore differential shrin kage between the Pre cast
Sttesses in both.
andd in situ cast units result in
he magnitute of oieretral, shrinkaqe is indluebee
the eñvironmental
by Composition o Concrete and
Conditions to whrch the Composite member is exposed.
Estimation et stesses due te Dfferential Shrinkoge-
Assumptiens
)Jhe shrinkage is unfom over the în-situ port of the
Section
n)he elect of cree and increase in mduwus of
etasthicity
uith oge and the domponent e shrin koge which is
Common to both the unts is hegligible.
, Methocd o Computing Stresses
First in situ slab is allowed te unalergo ull
differential shrinkage ¬cs.
is applied through the
h e n tensile dorce of Nsh
Ceniroid at both ends fill it reaches the length o
precast etement.
Nour uniform tensite sttength o Ees X E is incduced
in tn-sittt Conctetc and Nsh =
¬es* Ec A
Where, A= 4rea in-situ tonretc secdion
Ee Modul et elasticity e in-stu toxrek.
Ecs/ Ses/2
Cast in situ
slab Area -A:
Precast elemert
unit length
Nsh
Nsh
eesEA
|<-
19 A
Direct Bercing
Sttess Stress
