Papers by Keyword: Existing Bridges

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Authors: Josef Vican, Jaroslav Odrobinak, Peter Kotes
Abstract: In the frame of global European standardization and in consequence of new knowledge related to existing bridges, the need for revision of the service handbook "Determination of load-carrying capacity of railway bridges" grown up. The paper presents general concepts and basic assumptions for determining the railway bridge load-carrying capacity. In contrast to design of a new bridge, additional data related to existing bridge condition and behavior like information from regular inspections and real state of degradation can be taken into account. Based on these data together with the remaining lifetime, a modification of reliability levels for existing bridges based on the mathematic theory of probability can be adopted in the evaluation process. Special attention is also paid to the specific features of determination of load caring capacity of steel-concrete composite bridges in exploitation. Recommendation and allowances for global analysis of existing composite steel and concrete superstructures for the purpose of the load-carrying capacity estimation are discussed as well.
Authors: Chun Sheng Cai, Wei Zhang, Lu Deng, Miao Xia
Abstract: This paper summarizes the recent work by the first author’s research group related to the performance evaluation of existing bridges under vehicle dynamic effects. Based on the data from short-term monitoring of existing bridges, a framework to estimate the extreme structure responses from the live load in a mean recurrence interval is developed in the first part. The Gumbel distribution of the extreme values was derived from an extreme value theory and Monte Carlo Simulation. In the second part, a framework of fatigue damage and reliability assessment for existing bridges is presented to include the effects of the progressively deteriorated road conditions and random dynamic vehicle loads in bridge’s life cycle. The random effects of vehicle speed and type, road profiles, and stress ranges are included. Studies have shown that the vehicle-induced dynamic allowance IM value prescribed by the AASHTO LRFD code may be underestimated under poor road surface conditions (RSCs) of some existing bridges. In addition, multiple dynamic stress ranges induced by vehicles cannot be included in the maximum displacement-based dynamic allowance IM values. In the third part of this paper, the reliability indices of a selected group of prestressed concrete girder bridges are calculated by modeling the IM explicitly as a random variable for different RSCs. Nevertheless, a reliability based dynamic amplification factor on stress ranges (DAFS) for fatigue design is proposed to include the fatigue damages from multiple stress range cycles due to each vehicle passage at varied vehicle speeds under various road conditions in the bridge’s life cycle.
Authors: Guo Jun Liu, Yong Qing Yang, Fan Guo
Abstract: This paper makes an in-depth research on Assessment Methods of Load-bearing Capacity of Highway Bridge (Ministry of Communications of The People’s Republic of China, 1988) and makes a conclusion on assessment methods. Combined with current bridge inspection technology, it points out the limitations and shortcomings of the methods, and proposes the direction of assessment of existing bridge load-bearing capacity.
Authors: Jun Deng, Jian Li, Xiao Yue Fang
Abstract: The assessment of the risk probability and risk consequence of existing long-span bridges has become a focus in both research and engineering applications. In this paper, a process to assess the risk consequence of existing long-span bridges is developed. The analytic hierarchy process was combined with the fuzzy synthesis. In accordance with the features of existing long-span bridges, risk consequences are classified and the model of the risk consequence is simulated. A bridge as the example is evaluated by this process and the results show that the risk consequence of the bridge is negligible. Combining the risk probability and risk consequence gives the comprehensive risk of this bridge is negligible.
Authors: Hua Jian Zhou, Xin Quan Wang, Shi Min Zhang, Juan Liao, Ying Sheng Huang, Rong Geng Lin
Abstract: Aiming at the defect happened in existing bridges, a side-excitation way is adopted. Here, the mutual interfere phenomenon between transverse-and longitudinal-wave will appear, which certainly will be influence the reflection the information from fault position. Meanwhile, considering the responses of displacement are too lower, the velocities are used as test data so as to reduce the influence of noise. In the paper, the eigencurves with significant distinctions is suggested, the feasibility of the proposed method is demonstrated by a concrete item.
Authors: Xin Quan Wang, Shi Min Zhang, Juan Liao, Ying Sheng Huang, Xian Kai Wang
Abstract: Aiming at the defect happened in existing bridges, a side-excitation way is adopted. Here, the mutual interfere phenomenon between P-wave and S-wave will appear, which certainly will be influence the reflection of the information from fault position. In the paper, considering that the multi-resolution and local features within time-frequency of signal can be appeared by wavelet transform, a defect diagnosing method which utilize eigencurves of acceleration responses is presented, a group typical eigencurves which fit for reinforced concrete piles are given.
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