Effect of boundary conditions on modal parameters of the Run Yang Suspension Bridge

Li, Zhijun,Li, Aiqun,Zhang, Jian Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.8

Changes in temperature, loads and boundary conditions may have effects on the dynamic properties of large civil structures. Taking the Run Yang Suspension Bridge as an example, modal properties obtained from ambient vibration tests and from the structural health monitoring system of the bridge are used to identify and evaluate the modal parameter variability. Comparisons of these modal parameters reveal that several low-order modes experience a significant change in frequency from the completion of the bridge to its operation. However, the correlation analysis between measured modal parameters and the temperature shows that temperature has a slight influence on the low-order modal frequencies. Therefore, this paper focuses on the effects of the boundary conditions on the dynamic behaviors of the suspension bridge. An analytical model is proposed to perform a sensitivity analysis on modal parameters of the bridge concerning the stiffness of expansion joints located at two ends of bridge girders. It is concluded that the boundary conditions have a significant influence on the low-order modal parameters of the suspension bridge. In addition, the influence of vehicle load on modal parameters is also investigated based on the proposed model.

Effect of boundary conditions on modal parameters of the Run Yang Suspension Bridge

Zhijun Li,Aiqun Li,Jian Zhang 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.8

Changes in temperature, loads and boundary conditions may have effects on the dynamic properties of large civil structures. Taking the Run Yang Suspension Bridge as an example, modal properties obtained from ambient vibration tests and from the structural health monitoring system of the bridge are used to identify and evaluate the modal parameter variability. Comparisons of these modal parameters reveal that several low-order modes experience a significant change in frequency from the completion of the bridge to its operation. However, the correlation analysis between measured modal parameters and the temperature shows that temperature has a slight influence on the low-order modal frequencies. Therefore, this paper focuses on the effects of the boundary conditions on the dynamic behaviors of the suspension bridge. An analytical model is proposed to perform a sensitivity analysis on modal parameters of the bridge concerning the stiffness of expansion joints located at two ends of bridge girders. It is concluded that the boundary conditions have a significant influence on the low-order modal parameters of the suspension bridge. In addition, the influence of vehicle load on modal parameters is also investigated based on the proposed model.

New eremophilane-type sesquiterpenes from an Antarctic deepsea derived fungus, Penicillium sp. PR19 N-1

Aiqun Lin,Guangwei Wu,Qian Qun Gu,Tian-Jiao Zhu,De-Hai Li 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.7

Chemical investigation of an Antarctic deepseaderived fungus Penicillium sp. PR19 N-1 yielded fivenew eremophilane-type sesquiterpenes 1–5 and a new rarelactam-type eremophilane 6, together with three knowncompounds 7–9. The structures of these diverse sesquiterpeneswere determined by extensive NMR and massspectroscopic analyses. Compounds 1, 2, 4–6, 8 and 9 wereevaluated for their cytotoxities against HL-60 and A-549human cancer cell lines, and 5 was the most active one withIC50 value of 5.2 lM against the A-549 cells.

New eremophilane-type sesquiterpenes from an Antarctic deep-sea derived fungus, Penicillium sp. PR19 N-1

Lin, Aiqun,Wu, Guangwei,Gu, Qianqun,Zhu, Tianjiao,Li, Dehai 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.7

Chemical investigation of an Antarctic deep-sea derived fungus Penicillium sp. PR 19 N-1 yielded five new eremophilane-type sesquiterpenes 1-5 and a new rare lactam-type eremophilane 6, together with three known compounds 7-9. The structures of these diverse sesquiterpenes were determined by extensive NMR and mass spectroscopic analyses. Compounds 1, 2, 4-6, 8 and 9 were evaluated for their cytotoxities against HL-60 and A-549 human cancer cell lines, and 5 was the most active one with $IC_{50}$ value of $5.2{\mu}M$ against the A-549 cells.

Study of the structural damage identification method based on multi-mode information fusion

Liu, Tao,Li, AiQun,Ding, YouLiang,Zhao, DaLiang Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.3

Due to structural complicacy, structural health monitoring for civil engineering needs more accurate and effectual methods of damage identification. This study aims to import multi-source information fusion (MSIF) into structural damage diagnosis to improve the validity of damage detection. Firstly, the essential theory and applied mathematic methods of MSIF are introduced. And then, the structural damage identification method based on multi-mode information fusion is put forward. Later, on the basis of a numerical simulation of a concrete continuous box beam bridge, it is obviously indicated that the improved modal strain energy method based on multi-mode information fusion has nicer sensitivity to structural initial damage and favorable robusticity to noise. Compared with the classical modal strain energy method, this damage identification method needs much less modal information to detect structural initial damage. When the noise intensity is less than or equal to 10%, this method can identify structural initial damage well and truly. In a word, this structural damage identification method based on multi-mode information fusion has better effects of structural damage identification and good practicability to actual structures.

Temperature-induced Variations of Measured Modal Frequencies of Steel Box Girder for a Long-span Suspension Bridge

YouLiang Ding,AiQun Li 한국강구조학회 2011 International Journal of Steel Structures Vol.11 No.2

This paper addresses the temperature-induced variations of measured modal frequencies of steel box girder for a suspension bridge using long-tem monitoring data. The output-only modal frequency identification of the bridge is effectively carried out using the Iterative Windowed Curve-fitting Method (IWCM) in the frequency-domain. The daily and seasonal correlations of frequency-temperature are investigated in detail and the analysis results reveal that: (i) the identified modal frequencies using IWCM provide an effective indication for changes of the bridge due to the ambient temperature variations; (ii) temperature is the critical source causing modal variability, and there is an overall decrease in modal frequency with temperature for all the identified modes; (iii) the random variations in measured modal frequencies mainly arise from the identification algorithm due to the nonstationary loadings, which can be effectively eliminated using multi-sample averaging technique; (iv) the daily averaged modal frequencies of vibration modes have remarkable seasonal correlations with the daily averaged temperature and the seasonal correlation models of frequency-temperature are suitable for structural damage warning if future seasonal correlation models deviate from these normal models.

Opportunities, Challenges and Tactics for Communication of Sports Academic Journals in the Era of AI and Multi-Media

Feifei Song,Aiqun Li,Yingya You 아시아건강운동학회 2023 Journal of Asian Society for Health & Exercise Vol.5 No.1

PURPOSE : With the advent of the AI and multi-media in 21st century, the innovation of media technology has brought new opportunities and challenges to the communication of academic journals. RESULTS : The study concluded that AI + multi-media can help sports academic journals realize the efficient production of academic papers, the diversified publication of academic achievements, and the precise distribution of academic ideas. CONCLUSIONS : It is also necessary to pay attention to the challenges, which are the accelerated imbalance in academic publishing ecology, slow enhancment of academic attractiveness, and becoming fomality in academic communication. The authors also puts forward the tactics, such as balancing technical rationality and value rationality, promoting the integration of technology and content, and strengthening the depth of accurate communication.

Study of the structural damage identification method based on multi-mode information fusion

Tao Liu,AiQun Li,YouLiang Ding,DaLiang Zhao 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.3

Due to structural complicacy, structural health monitoring for civil engineering needs more accurate and effectual methods of damage identification. This study aims to import multi-source information fusion (MSIF) into structural damage diagnosis to improve the validity of damage detection. Firstly, the essential theory and applied mathematic methods of MSIF are introduced. And then, the structural damage identification method based on multi-mode information fusion is put forward. Later, on the basis of a numerical simulation of a concrete continuous box beam bridge, it is obviously indicated that the improved modal strain energy method based on multi-mode information fusion has nicer sensitivity to structural initial damage and favorable robusticity to noise. Compared with the classical modal strain energy method, this damage identification method needs much less modal information to detect structural initial damage. When the noise intensity is less than or equal to 10%, this method can identify structural initial damage well and truly. In a word, this structural damage identification method based on multi-mode information fusion has better effects of structural damage identification and good practicability to actual structures.

Structural Response of an Extra-Wide Concrete Self-Anchored Suspension Bridge under Static Vehicle Loads: Testing and Numerical Simulations

Guangpan Zhou,AiQun Li,Jianhui Li,Mingyang Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4

The finite element (FE) analysis by ANSYS software based on field test was used to study the structural performance of an extra-wide concrete self-anchored suspension bridge under static vehicle loads. The longitudinal, transverse and vertical stresses of the extra-wide girder were analyzed, and the changing criteria of girder stresses induced by vehicle loads were presented. Additionally, the effects of the shear lag on extra-wide box girders were investigated. The results showed that the maximum shear lag coefficient was 1.89 at the junction of bottom plate and outer web at the middle of midspan. Moreover, the non-uniformity of cable force is perceptible under eccentric load. Furthermore, an optimization measure for comparable bridges and essential health monitoring locations were outlined.

Assessment on the Progressive Collapse Resistance of a Long-Span Curved Spatial Grid Structure with Main Trusses

Guangpan Zhou,Qianen Song,Aiqun Li,Shungao Shen,Qing Zhou,Bin Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3

The progressive collapse resistance of the terminal building of Zhongchuan Airport in Lanzhou, China was studied, which is a long-span curved spatial grid structure with main trusses. Firstly, the finite element model was built using MSC.Marc software adopting the fiber model based on material. Secondly, an improved method of zoned concept judgment and sensitivity analysis was proposed to determine the key components. Thirdly, the initial failure components were removed individually based on the alternate load path method (AP method). The responses of remaining structure were calculated using nonlinear dynamic analysis method. Lastly, the influences brought by the cross-sectional sizes of grid members were investigated through conducting parametric analysis. According to the results, the proposed selection method can avoid omitting the key components. The structural responses are significant when removing the concrete filled steel tubular (CFST) column SC14 directly supporting the front middle part of the roof, with a maximum vertical displacement of 10 m at cantilever end, which should be focused on for this kind of large-span spatial structure. In addition, the tensile strength and cross-sectional area of the upper and lower chords should be increased by 20% to enhance the progressive collapse resistance of the structure, and the changes of axial compression ratios of the columns supporting the roof have little effects.