AN INVESTIGATION INTO RELIABILITY
BASED METHODS TO INCLUDE RISK OF
FAILURE IN LIFE CYCLE COST ANALYSIS OF
REINFORCED CONCRETE BRIDGE
REHABILITATION
A thesis submitted in fulfillment of the requirements
for the degree of Master of Engineering
Weiqi Zhu
School of Civil, Environmental and Chemical Engineering
Science, Engineering and Technology Portfolio
RMIT University
July, 2008
II
DECLARATION
I certify that except where due acknowledgement has been made, this work is that
of myself alone. The content of the thesis is the result of work that has been carried
out since the official commencement date of the approved research program under
the supervision of Associate Professor Sujeeva Setunge of the School of Civil,
Environmental and Chemical Engineering, RMIT. This work has not been
submitted previously, in whole or part, to qualify for any other academic award.
Any editorial work, paid or unpaid, carried out by a third party is acknowledged.
Name: Weiqi Zhu
Sign:
Date:
III
ABSTRACT
Reliability based life cycle cost analysis is becoming an important consideration
for decision-making in relation to bridge design, maintenance and rehabilitation.
An optimal solution should ensure reliability during service life while minimizing
the life cycle cost. Risk of failure is an important component in whole of life cycle
cost for both new and existing structures.
Research work presented here aimed to develop a methodology for evaluation of
the risk of failure of reinforced concrete bridges to assist in decision making on
rehabilitation. Methodology proposed here combines fault tree analysis and
probabilistic time-dependent reliability analysis to achieve qualitative and
quantitative assessment of the risk of failure. Various uncertainties are considered
including the degradation of resistance due to initiation of a particular distress
mechanism, increasing load effects, changes in resistance as a result of
rehabilitation, environmental variables, material properties and model errors. It
was shown that the proposed methodology has the ability to provide users two
alternative approaches for qualitative or quantitative assessment of the risk of
failure depending on availability of detailed data. This work will assist the
managers of bridge infrastructures in making decisions in relation to optimization
of rehabilitation options for aging bridges.
IV
ACKNOWLEDGEMENT
First of all, I would like to express my deep sense of appreciation to my
supervisor Associate Professor Sujeeva Setunge for her consistent support and
warm-hearted guidance for my research. This work would not have been
completed without her patience and understanding.
I would like to extend my gratitude to CRC research team comprising of QDMR,
BCC, RMIT and QUT. Thanks in particular to Dr. Rebecca Gravina and Dr.
Srikanth Venkatesan, who helped me kindly during several stages of this research.
QDMR is greatly appreciated for providing data and materials for case study of
this research.
Finally a special thanks goes to my parents, who have given sustainable financial
support and great encouragement to ensure the completion of my research.
V
LIST OF PUBLICATIONS
Zhu, W, Setunge, S, Gravina, R & Venkatsan, S (2007), ‘Use of fault tree analysis in risk
assessment of reinforced concrete bridges exposed to aggressive environments’, in Proceedings of
the 4th International Structural Engineering and Construction Conference, Melbourne, pp.
387-393.
Zhu, W, Setunge, S, Gravina, R & Venkatsan, S (2007), ‘Use of fault tree analysis in risk
assessment of reinforced concrete bridges exposed to aggressive environments’, Concrete in
Australia, vol. 34, no. 1, pp. 50-54.
Zhu, W, Setunge, S, Gravina, R & Venkatsan, S (2008), ‘Estimation of residual capacity and
time-dependent reliability of reinforced concrete bridges after initiation of a deterioration
mechanism and subsequent rehabilitation’, Australian Structural Engineering Conference.
Melbourne (Accepted for publication).