Crack either width of joint concrete (Cw) is adopted as the evaluation index for lateral connections.The inspection data for ten bridges are selected as clustering samples for condition evaluation; these samples should possibly cover every bridge condition. They are listed in Table 1.Table 1Field data for bridge durability evaluation.The calculated fuzzy equivalence matrix based on fuzzy clustering theory is listed in Table 2.Table 2Fuzzy equivalence matrix for durability evaluation index system.Different thresholds �� are adopted for clustering analysis; its dynamic process is listed in Table 3.Table 3Dynamic clustering results using different thresholds.Firstly, we determined the effective classification quantity (3, 4, 5, and 6), and F-statistics analysis is used to determine the best classification.

The calculation results of F0.05 and F are listed in Table 4.Table 4F-statistics calculation results for each program.As can be seen from Table 4, when �� = 0.9684, the gap between F and F0.05 is the largest. Therefore, four categories are the best classification; the detailed results are 2, 4, 5, 3, 6, 9, 1, 8, and 7, 10.The durability condition can be determined combined with service time of bridge; the year of opening for each bridge are listed in Table 5.Table 5Opening data for bridge.As can be seen from Table 5, the service time for 2, 4, 5 is the shortest; therefore, its condition is ��very good��. Similarly, 3, 6, 9 is ��good,�� 1, 8 is ��ordinary,�� and 7, 10 is ��poor.��4.3.

Engineering VerificationTen samples for durability evaluation are classified into four categories, and their conditions are determined through service time. The clustering results can be treated as database for assessment; the average value corresponding to each index is regarded as the center of this category as shown in Table 6, and the other bridges can be evaluated based on approaching principle through calculation of fuzzy nearness.Table 6Category center for durability evaluation.Nanping Bridge was built in 2005; there are totally eight spans, and they are simply supported T-beam bridges. Its overview is shown in Figure 3. The inspection data are listed in Table 7.Figure 3Overview of Nanping Bridge.Table 7Field data for durability evaluation of Nanping Bridge.The calculation results of fuzzy nearness between field data of Nanping Bridge and category center for durability evaluation are listed in Table 8.

Table 8Fuzzy nearness between field data and category center of Nanping Bridge.As shown in Table 8, the fuzzy nearness between field data Drug_discovery and ��poor�� is the largest. Therefore, the durability of Nanping Bridge can be evaluated as ��poor��, and it needs enhancement of the conservation and maintenance. This bridge bears heavy traffic load through investigation and analysis of the traffic (Figure 4), and the evaluation result is consistent with the actual situation.