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Title: System reliability-based bridge assessment using response surface methods
Author: Jo, Sung-Il
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2005
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The objective of the present research was to develop a system reliability-based bridge assessment method for damaged composite bridges. A response surface method was adopted in combination with the nonlinear finite element analyses, which provided a powerful tool for the evaluation of the reliability of a bridge system. Using the method, investigation was made into the effects of corrosion on the reliability of a bridge system. A numerical bridge model used for the present study was developed using an actual composite bridge in the UK. Commercial FE programmes such as ABAQUS and DIANA were used for the development of the model. In order to validate the use of these FE programmes in the present study, simulations on the full-scale bridge test were carried out. Of the three, 40-tonne vehicle loading given in BD 21, the vehicle loading which caused the worst resistance was selected as a reference loading model. In the present study, the failure of the load redistribution system due to punching shear was addressed in detail. It was found that punching shear in the concrete slab may prevent the total collapse of a whole bridge system taking place. This is because the system cannot reach the ultimate state in such a case. It was proposed that such cases be excluded from the evaluation of the failure probability of a whole system. This approach is expected to provide a more rational basis for the evaluation of the reliability of a global bridge system than simply suppressing such failure. The system reliability-based assessment was developed based on the response surface method in combination with the nonlinear finite element analyses. In the present study, reliability analyses were carried out for both intact and damaged bridges. Corrosion on steel girders was simulated by reducing the thickness of the web and the flange. The present study shows that the two-lane loading case governs the total failure probability (reliability) of the present bridge model. In addition, it was found that the traffic loading for the evaluation of load effects has a significant influence on the results. It was also found that the failure of a bridge is most likely to take place due to extremely heavy trucks for the intact state. It seems that this has a close connection to the high uncertainty of the traffic loading. However, the failure is likely to be governed by reduced dimension for severely damaged model. This is because the uncertainty related to the dimension and ultimately the resistance becomes bigger as corrosion proceeds. Results of this research revealed that this assessment methodology is less conservative. This may lead to rational use of a limited resources. It was clearly demonstrated through the reliability analyses that a system reliability-based bridge assessment methodology developed in this research may provide a tool for more rational bridge assessment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available