Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Civil and Environmental Engineering | en_US |
| dc.contributor.advisor | Xia, Yong (CEE) | en_US |
| dc.creator | Shan, Yushi | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/13570 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Global temperature behavior of long-span cable-stayed bridges | en_US |
| dcterms.abstract | Varying temperatures significantly affect behavior of long-span cable-stayed bridges due to their large scale and high indeterminacy. However, existing studies remain limited. Physics-based approaches are constrained in a divide-and-conquer strategy, while data-based approaches are hindered by sparse sensor data. This PhD thesis aims to comprehensively investigate the global temperature behavior of long-span cable-stayed bridges by integrating numerical simulation and field monitoring. The Qingzhou Bridge, a navigation channel bridge of the Hong Kong–Zhuhai–Macao Bridge, is used as the testbed. | en_US |
| dcterms.abstract | First, a physics-based unified analysis approach is developed to obtain detailed temperature distribution and temperature-induced responses by integrating heat-transfer analysis and structural analysis. A global 3D finite element (FE) model of the Qingzhou Bridge is established. The heat-transfer analysis is then conducted to obtain the temperature field of the entire bridge based on real-time environmental conditions, with thermal boundary conditions carefully determined. Subsequently, the same global 3D FE model of the bridge is automatically transferred for structural analysis, with the temperature results converted to thermal loads and thermal elements changed to structural elements. The simulated results show a good agreement with the measurements in four different seasons, verifying the effectiveness of the proposed methods. Furthermore, the unified analysis approach is employed to calculate and separate temperature-induced responses from typhoon-induced responses during Typhoon Higos. The typhoon-induced quasi-static and dynamic deflection responses align well with the wind tunnel test results. Additionally, the temperature-induced response constitutes a dominant proportion of the total quasi-static recordings, both on a typical sunny day and during the typhoon period, whereas the typhoon induces substantial dynamic responses. | en_US |
| dcterms.abstract | A data-based approach is then explored by leveraging graph neural network (GNN) and long short-term memory (LSTM). A GNN-LSTM-based temperature prediction model is developed to enhance the accuracy of numerical simulations while preserving full-field information. First, the calculated temperature results of the girder section based on an FE model serve as training data to learn the heat-transfer mechanism. Real measurements are then used as input to reconstruct the temperature field. The average discrepancy between the predictions and measurements over one year is reduced by more than half compared to the simulation results. Besides, the proposed model demonstrates strong generalization ability by compensating for numerical errors across all four seasons. The temperature calculated by the GNN-LSTM technique is then used to obtain the temperature-induced responses. The discrepancy of the responses is reduced by over one third compared to the simulation results. Thus, the model effectively bridges the gap between numerical simulation and field measurement, enabling a more accurate investigation of the temperature behavior of long-span bridges. | en_US |
| dcterms.abstract | Finally, yearly temperature and response measurements are further analyzed to reveal the long-term temperature effects, with the focus on the temperature and structural responses of the girder. Based on statistical correlation analyses, the total longitudinal displacement is mainly dominated by the effective girder temperature, and the stress of the girder is primarily governed by the vertical temperature difference. Moreover, the mid-span deflection shows a positive correlation with the effective girder temperature, and the natural frequencies exhibit a negative correlation, with an annual variation of approximately 1%. | en_US |
| dcterms.extent | xxvi, 196 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2025 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.LCSH | Cable-stayed bridges | en_US |
| dcterms.LCSH | Temperature | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.accessRights | open access | en_US |
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