Abstract
A probabilistic approach is used to create a preliminary inspection evaluation form (PIEF) for scour potential at bridge sites. In Taiwan, the risk of pier scour is often evaluated using a two-step procedure. First, a bridge is visually inspected based on a PIEF. An advanced scour risk analysis is conducted for a bridge with a high PIEF score. Because a PIEF can quickly evaluate scour potential, it can be used to build a maintenance sequence for a group of bridges. However, a PIEF is often created based on only engineers’ experience; the accuracy and reliability of PIEFs have not been examined systematically. Thus, a probabilistic-based PIEF is constructed by establishing a close correlation between the PIEF score and scour potential via Taguchi method. The scour potential is evaluated by Bayesian network (BN) that incorporates experts’ judgments and results of reliability analyses. For example, the conditional probabilities (CP) in the proposed BN are calculated based on an existing PIEF and results of a stability-based reliability analysis. Thus, the proposed PIEF implicitly considers the probabilistic characteristics in the scour potential, which will provide an efficient and accurate evaluation of scour potential and assist in establishing maintenance priorities of existing bridges in Taiwan.
Highlights
The scour potential at bridge sites in Taiwan has drawn much attention in recent years, especially after Typhoon Morakot in 2009
A probabilistic method is used to evaluate the scour potential at the bridge sites, the results are converted into a preliminary inspection evaluation form (PIEF), which is popularly used by practicing engineers
The established Bayesian network (BN) is used for the reliability analysis, and the correlation between the two is analyzed
Summary
The scour potential at bridge sites in Taiwan has drawn much attention in recent years, especially after Typhoon Morakot in 2009. Because scour potential evaluation involves many uncertainties, a probabilistic approach is often adopted. A preliminary inspection evaluation form (PIEF) can efficiently evaluate the scour potential of a bridge. The PIEF is a visual inspection process that is generally used in Taiwan as the first step of a bridge scour risk evaluation. If the overall assessment score from the PIEF does not meet a predefined standard, the evaluation should proceed to an advanced investigation to ensure the safety of bridges. Several scouring assessment measures using the approach of PIEF have been proposed. Evaluation of Scour Risk and River Stability at Bridge Sites (CAESAR). Each evaluated item is divided into three to five levels, and another weight (b in Table 1) is assigned to each level. The overall assessment score of an inspected bridge is the sum of
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