A novel artificial bee colony (ABC) algorithm to detect structural damage via modal and frequency analyses is proposed (named as TCABC algorithm). Compared to the standard ABC algorithm, tabu search method and chaotic search method are adopted in the proposed algorithm to enhance the exploration and exploitation ability. The tabu search method uses a memory function to avoid the solution being trapped in a local minimum, which increases the exploitation ability. Chaotic search method generates more searching points for finding the global minimum, which increases the exploration ability. Additionally, the first roulette wheel selection is replaced by the tournament selection to enhance the global searching ability of the TCABC algorithm. Several explicit test functions and an implicit damage detection function are employed to check the numerical results obtained from ABC and TCABC algorithms. Afterward, the damage detection accuracy of the TCABC algorithm is verified under different circumstances, and several recommendations are given for using the TCABC algorithm to detect structural damages under actual conditions. Finally, an experimental study is applied to examine the performance of TCABC algorithm for damage detection. The results show the following: (1) compared to traditional ABC algorithm, TCABC algorithm performs better; (2) fewer groups lead to faster convergence as demonstrated by both algorithms used in the same damage situation; (3) TCABC algorithm can infer the locations and extents of the damage when the groupings are inaccurate; (4) the accuracy of the field test data profoundly affects the precision of the damage detection results. In other words, stronger noises result in worse identification results; (5) whether or not the noises exist, the more data are measured, the more accurate the results can be achieved; (6) the TCABC algorithm can efficiently detect structural damage in the experimental study.

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Steel-concrete composite beam cable-stayed bridge is a complicated system consisting of a composite beam, tower, and stayed cables. And the composite beam is composed of a steel beam, bridge deck and connectors, which has a different mechanical behavior from the general beam structure. In a word, the steel-concrete composite beam cable-stayed bridge is characterized by specific mechanical behavior and has many influencing factors. Thus, its safety analysis often cannot be easily implemented. This paper aims to study the component reliability of the steel-concrete composite beam based on the stochastic finite element method (SFEM) and the recognition of main failure modes in the system reliability of the cable-stayed bridge. For the component reliability of the steel-concrete composite beam, a nonlinear element model with 10 degrees of freedom (DOF) is adopted, which can consider the particular longitudinal slip effect between the steel and concrete. And the direct differential method (DDM) is used to deduce the response gradient of the element model. Meanwhile, the tower and the composite beam are considered as beam-column members to establish their limit state functions in the form of interaction equations. For the recognition of main failure modes in the system reliability, this paper proposes the concept of uniformity of the reliability index and the refinement strategy to improve theβ-unzipping method, which can identify the main failure modes or neglect the unnecessary non-main failure modes. Finally, a certain steel-concrete composite beam cable-stayed bridge is used to verify the effectiveness of the proposed method.

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