Vo
l.
17
NO.3 Joumal
of
Southwest Jiaotong University (English Edition)
Ju
l.
2009
Ar
ticle
ID:
1005-2429
(2009)
03
-0
207 -05
Lifetime Reliability Analysis
of
Flexural Cracking
for Prestressed Concrete Bridge
TONG
Yu-qiang
(童育强)
1
*,
XIANG
Tian-yu
(向天宇
)2
，
DU
Bin
(杜斌)
2 ,
YUAN
Xin-peng
(袁新朋)
2,
ZHAO
Ren-da
(赵人达
)2
1.
Chin
α
High
四
Jay
Planning and Design 1nstitute , Beijing 100010, China
2.
Dep
α
rtment
of
Bridge Engineering ,
South
印刷
Ji
ω
tong
University , Chengdu
61
ω
131
，
China
Abs
位
act
Time-dependant
reliability
is
analyzed
for
the
flexural
cracking
of
prestressed
concrete
bridges
und
巳
:r
service
limit
state.
The
limit
state
function
and
random
variables
缸
'e
derived
from
Chines
巳
highway
bridge
design
specifications.
For
deterioration
of
structural
performances
,
chloride-induced
reinforcement
corrosion
is
emphasized.
Through
integrating
丑
Ist
order
reliab
出
ty
method
(FORM)
and
time
discretized
approach
,
the
time-variant
reliability
is
evaluated.
For
illustrative
propose
，也巳
reliability
of
a
typical
simply
supported
prestressed
concrete
beam
is
exemplified.
Key words
Prestressed
concrete
bridge; Reliability;
Service
limit
state;
Fl
exural
cracking
Introduction
For concrete bridges , perfonnance deterioration
with time due to aggressive environment is an inevita-
ble phenomenon
, and this deterioration process may
lead to time-dependant reduction
of
structural reliabili-
ty. Thus
, how to evaluate whether bridges can meet
structural performance requirement during its service
life is a critical topic for structural rational design and
safety assessmen
t.
There are many causes for structural performance
degradation
，
e.
忌，
reinforcement corrosion , fatigue ,
thaw-freeze , alkali-silica reaction , and carbonation.
Of
all these reasons , the chloride-induced reinforce-
ment corrosion has
been
identified as the major
one
[1].
Practically , those parameters related to struc-
Received
S
巳
p.
4,
2008;
revision
accepted
Nov.
11
,
2008
Biography
TONG
Yu-qiang
(1979
-),
enginee
r.
His
re-
search
interest
is
in
structural
behavior
of
bridg
巳
*
Corresponding
autho
r.
T
巳1.
: +
86-13671193686;
E-mail:
njsq1418@126.
com
tural chloride-induced deterioration process , such as
diffusion coefficient
, steel corrosion rate , have ran-
dom nature. Therefore
,
it
is more logical to include
those uncertainties in analysis and design. Unlike
deterrninistic analysis
, which is just a point estimate ,
the reliability evaluation includes the stochastic infor-
mation
, and provides a more rational criterion for the
likely consequence
of
decisions[2]. A significant
amount
of
researches have been performed on the
time-variant reliability
of
concrete structures under
chloride-induced corrosion
[3-7].
However, they are
mainly focused
on
reinforced concrete structures. As
for prestressed concrete bridges
, to the best knowl-
edge
of
authors , little literatures is available. Further-
more
, unlike reinforced concrete bridges , the key fac-
tor for design
of
prestressed concrete bridges is the
service limit state rather than the ultimate limit state.
In this paper
, we intend to investigate the time-
dependant reliability
of
prestressed concrete bridges
under service limit state.
For
all the performance re-
quirements under service limit state
, the flexural
cracking resistance is mainly concemed. The typical
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