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Structural Engineering and Mechanics Volume 85, Number 4, February25 2023 , pages 531-543 DOI: https://doi.org/10.12989/sem.2023.85.4.531 |
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Residual capacity assessment of in-service concrete box-girder bridges considering traffic growth and structural deterioration |
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Yuanyuan Liu, Junyong Zhou, Jianxu Su and Junping Zhang
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| Abstract | ||
| The existing concrete bridges are time-varying working systems, where the maintenance strategy should be planned according to the time-varying performance of the bridge. This work proposes a time-dependent residual capacity assessment procedure, which considers the non-stationary bridge load effects under growing traffic and non-stationary structural deterioration owing to material degradations. Lifetime bridge load effects under traffic growth are predicated by the nonstationary peaks-over-threshold (POT) method using time-dependent generalized Pareto distribution (GPD) models. The nonstationary structural resistance owing to material degradation is modeled by incorporating the Gamma deterioration process and field inspection data. A three-span continuous box-girder bridge is illustrated as an example to demonstrate the application of the proposed procedure, and the time-varying reliability indexes of the bridge girder are calculated. The accuracy of the proposed non-stationary POT method is verified through numerical examples, where the shape parameter of the time-varying GPD model is constant but the threshold and scale parameters are polynomial functions increasing with time. The case study illustrates that the residual flexural capacities show a degradation trend from a slow decrease to an accelerated decrease under traffic growth and material degradation. The reliability index for the mid-span cross-section reduces from 4.91 to 4.55 after being in service for 100 years, and the value is from 4.96 to 4.75 for the mid-support cross-section. The studied bridge shows no safety risk under traffic growth and structural deterioration owing to its high design safety reserve. However, applying the proposed numerical approach to analyze the degradation of residual bearing capacity for bridge structures with low safety reserves is of great significance for management and maintenance. | ||
| Key Words | ||
| concrete bridge; peaks-over-threshold method; residual capacity assessment; resistance deterioration; timedependent reliability; traffic growth | ||
| Address | ||
| Yuanyuan Liu: School of Civil Engineering, Guangzhou University, 230 West Waihuan Road, Guangzhou, Guangdong 510006, China; Research Centre for Wind Engineering and Engineering Vibration, Guangzhou University, 230 West Waihuan Road, Guangzhou, Guangdong 510006, China Junyong Zhou: School of Civil Engineering, Guangzhou University, 230 West Waihuan Road, Guangzhou, Guangdong 510006, China Jianxu Su, Junping Zhang: Earthquake Engineering Research & Test Center, Guangzhou University, 230 West Waihuan Road, Guangzhou, Guangdong 510006, China | ||