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Seismic resistant design of highway bridge with multiple-variable frequency pendulum isolator
Xu Liang,Jianian Wen,Qiang Han,Xiuli Du 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.2
Multiple variable frequency pendulum isolator (MVFPI) has been recently developed as a superior alternative to the traditional friction pendulum bearing (FPB) especially for the seismic isolation in near-fault regions. The MVFPI is characterized by its variable frequency and self-adaptability, which are achieved by piecewise function of sliding surface and shape memory alloy (SMA). The objective of this study is to propose the design algorithm of the MVFPIs in highway bridge as an extension of the direct displacement-based design (DDBD) framework. The nonlinearities of the structural components are taken into account in the design procedure, and the corresponding damage states satisfy the two-stage design philosophy. The accuracy and robustness of the design procedure are verified by an isolated four-span highway bridge through nonlinear time history (NLTH) analyses. The analytical results indicate that the proposed design procedure can predict the profile of deck displacement and amplitude, as well as the damage states of the piers. From statistic aspect, the fragility analyses illustrate that the bridge isolated by MVFPIs exhibits better seismic performance than that of the bridge isolated by FPBs.
Jing Xu,Hairong Liu,Guangyue Su,Meng Ding,Wei Wang,Jincai Lu,Xiuli Bi,Yuqing Zhao 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.1
Background: Panax ginseng Meyer has been used as a nourishing edible herb in East Asia for thousands of years. 25-OH-PPT was first discovered as a natural rare triterpenoid saponin in ginseng stems and leaves by our group. Research found that it showed strong inhibitory effects on a-glucosidase and protein tyrosine phosphatase 1B, and protected cardiocytes (H9c2) through PI3K/Akt pathway. Methods: In the research, in order to optimize the 25-OH-PPT enrichment process, optimal macroporous resins and optimal purification conditions were studied. Meanwhile, the hypoglycemic effect and mechanism of 25-OH-PPT were evaluated by using STZ to establish insulin-dependent diabetic mice and the spontaneous type 2 diabetes DB/DB mice. Results and Conclusion: Research found that 25-OH-PPT can reduce blood glucose and enhance glucose tolerance in STZ model mice. It increases insulin sensitivity by upregulating GLUT4 and AMPK in skeletal muscle, and activating insulin signaling pathways. In DB/DB mice, 25-OH-PPT achieves hypoglycemic effects mainly by activating the insulin signaling pathway. Meanwhile, through the influence of liver inflammatory factors and lipids in serum, it can be seen that 25-OH-PPT has obvious anti-inflammatory and lipid-lowering effects. These results provide new insights into the study of ginseng as a functional food.
Vibration reduction design of the Hangzhou Bay cable-stayed bridges
Liu, Weiqing,Xu, Xiuli,Wang, Rengui,Wang, Zijun,Wu, Xiaolan Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.24 No.3
Hangzhou Bay Bridge spans the Hangzhou Bay and is located at Zhejiang province in the southeast seacoast of China. The total length of the bridge is 36 km. The bridge is composed of bridge approaches made up of multi-span prestressed concrete box girders and two cable-stayed bridges over the north and south navigable spans respectively. The seismic response analysis of the bridge model shows that if the navigable spans are designed as the routine earthquake-resistance system, the displacements and internal forces in pylons, piers and deckes are too large to satisfy the anti-seismic requirement of the structure. Therefore, the seismic reduction design was carried out by using viscous dampers to dissipate the kinetic energy of the structure both longitudinally and transversely. Using the vibration reduction system and aiming at the reasonable optimal goal, the purpose to reduce the seismic responses in south and north navigable spans has been achieved.
Bochuan Tan,Shengtao Zhang,Wenpo Li,Xiuli Zuo,Yujie Qiang,Lihui Xu,Jiangyu Hao,Shijin Chen 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.77 No.-
Phenyl disulfide (PDF), 2,20-dithiodipyridine (DDP), 5,5-dithiobis(1-phenyl-1H-tetrazole) (DPT) werestudied as inhibitors for Cu in H2SO4 via electrochemical methods, surface morphology analysis andtheoretical calculations. Electrochemical experiments show that PDF, DDP and DPT can exhibit excellentcorrosion inhibition performance. Their order of corrosion inhibition is DPT > DDP > PDF. Surfacemorphology analysis supports the electrochemical results. The X-ray photoelectron spectroscopy (XPS)results show that S Cu bonds are detected in PDF, DDP and DPT, and N Cu bonds are detected in DDPand DPT. PDF, DDP and DPT adsorption on the Cu surface obey the Langmuir isotherm model. The resultsof quantum chemical calculations show that DPT has more active reaction sites than DDP and PDF. Molecular dynamics simulation results show that the order of binding energies of the three corrosioninhibitor molecules on the copper surface is DPT > DDP > PDF.
System identification of the suspension tower of Runyang Bridge based on ambient vibration tests
Zhijun Li,Dongming Feng,Maria Q. Feng,Xiuli Xu 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.19 No.5
A series of field vibration tests are conducted on the Runyang Suspension Bridge during both the construction and operational stages. The purpose of this study is devoted to the analysis of the dynamic characteristics of the suspension tower. After the tower was erected, an array of accelerometers was deployed to study the evolution of its modal parameters during the construction process. Dynamic tests were first performed under the freestanding tower condition and then under the tower-cable condition after the superstructure was installed. Based on the identified modal parameters, the effect of the pile-soil-structure interaction on dynamic characteristics of the suspension tower is investigated. Moreover, the stiffness of the pile foundation is successfully identified using a probabilistic finite model updating method. Furthermore, challenges of identifying the dynamic properties of the tower from the coupled responses of the tower-cable system are discussed in detail. It\'s found that compared with the identified results from the freestanding tower, the longitudinal and torsional natural frequencies of the tower in the tower-cable system have changed significantly, while the lateral mode frequencies change slightly. The identified modal results from measurements by the structural health monitoring system further confirmed that the vibrations of the bridge subsystems (i.e., the tower, the suspended deck and the main cable) are strongly coupled with one another.