Bridges, Tunnels and other Transportation Structures
Full Session with Abstracts
Dan Frangopol, ScD, PE, Dist M ASCE, F SEI, F EMI
Professor of Civil Engineering, The Fazlur R. Khan Endowed Chair in Structural Engineering and Architecture
Lehigh University
David Yang, PhD, AMASCE
Postdoctoral Research Associate
Lehigh University
Bridges are subjected to deterioration in their service life due to environmental stressors (e.g.
corrosion) and long-term effects (e.g. fatigue). Structural deterioration can compromise the
functionality, serviceability, and safety of bridges. Therefore, timely inspection and repair
actions are extremely important to ensure adequate life-cycle performance of bridges and
mitigate their life-cycle failure risks. Since inspection/repair actions bring in additional
expenditures to the total life-cycle cost of bridges, optimized planning is needed to
simultaneously minimize the life-cycle maintenance cost due to inspection/repair as well as the
life-cycle failure risk.
Compared to prescriptive inspection plans, risk-based inspection (RBI) planning provides a
quantitative tool for life-cycle management of deteriorating structures and has been widely used
to improve structural longevity and reduce life-cycle cost (Frangopol & Soliman 2016). In
general, for a deteriorating structure, RBI planning optimizes its inspection times and the repair
criterion based on the inspection results. Conventionally, both the obtained inspection times and
the repair criterion are data-independent or rigid, meaning neither of them varies depending on
the data obtained from inspections. Recently, adaptive RBI planning methods have been
proposed to adaptively update the inspection times and/or the repair criterion based on the
available information drawn from inspections and repair histories (Yang & Frangopol 2018).
Specifically, based on the available information at the time of an inspection, future inspection
and/or repair actions are planned based on the total cost (i.e. maintenance cost and failure risk) in
the remaining service life of the structure.
In this study, the aforementioned rigid and adaptive RBI planning methods are compared using a
fatigue-sensitive bridge detail. In particular, the differences in (a) the inspection times, (b) total
life-cycle cost, (c) value of information, and (d) computational effort are investigated for results
obtained using different RBI planning methods. Based on this comparison, the advantages and
disadvantages of different RBI planning methods are summarized.