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Experimental Study on Y-shaped Bridge Under 3-dimentional Earthquake Ground Motions
Yan Lei,Li Qingning 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.6
Based on similar theory and multi-dimensional seismic design theory, a Y-shaped bridge model with the scale ratio of 1:20 was made to conduct the seismic simulation shaking table test in this paper. Failure mode and dynamic responses of Y-shaped bridge under different seismic wave spectrum, different peak accelerations and different seismic excitation directions were studied. The experimental results show that, the piers mostly exhibit bending failure mode and the vertical ground motion has a great influence on the development of cracks in girders. Dynamic responses of the Y-shaped bridge are different and presented different laws when three different seismic waves were applied. Seismic wave is input along the direction of the branch straight girder, which is the most unfavorable earthquake input direction when calculating the peak acceleration at the top of piers. Multi-dimension seismic excitation should be considered when calculating the width of the expansion joint between adjacent girders. The horizontal bidirectional seismic excitation can satisfy the design requirements of strain response at the bottom of pier. The model structure would cause vertical vibration during its horizontal seismic excitation, and vertical seismic excitation exerts more significant influence on the vertical vibration of branch straight girder.
Wind tunnel study of wind structure at a mountainous bridge location
Yan, Lei,Guo, Zhen S.,Zhu, Le D.,Flay, Richard G.J. Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.23 No.3
Wind tunnel tests of a 1/2200-scale mountainous terrain model have been carried out to investigate local wind characteristics at a bridge location in southeast Tibet, China. Flows at five key locations on the bridge at deck level were measured for 26 directions. It was observed that wind characteristics (including mean wind velocity and overall turbulence intensity) vary significantly depending on the approaching wind direction and measurement position. The wind inclination angle measured in the study fluctuated between $-18^{\circ}$ and $+16^{\circ}$ and the ratio of mean wind velocity to reference wind velocity was small when the wind inclination angles were large, especially for positive wind inclination angles. The design standard wind speed and the minimum critical wind speed for flutter rely on the wind inclination angle and should be determined from the results of such tests. The variation of wind speed with wind inclination angles should be of the asymmetry step type. The turbulence characteristics of the wind were found to be similar to real atmospheric flows.
The Influence of Collision Energy on the Reaction H+HS→H2+S
Yanlei Liu,Hongsheng Zhai,Zunlue Zhu,Yufang Liu 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.11
Quasi-classical trajectory calculations have been carried out for the reaction H+HS by using the newest triplet 3A" potential energy surface (PES). The effects of the collision energy and reagent initial rotational excitation are studied. The cross sections and thermal rate constants for the title reaction are calculated. The results indicate that the integral cross sections (ICSs) are sensitive to the collision energy and almost independent to the initial rotational states. The ro-vibrational distributions for the product H2 at different collision energies are presented. The investigations on the vector correlations are also performed. It is found that the collision energies play a postive role on the forward scatter of the product molecules. There is a negative influence on both the alignment and orientation of the product angular momentum for low collision energy at low energy region. Whereas the influence of collision energy is not obvious at high energy region.
Boron and Phosphorus Removal During High Purity Hypereutectic Al–Si Solidification
Yanlei Li,Jian Chen 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.4
Al–Si solvent refining is a promising process for silicon purification, and the key impurity elements are boron and phosphorus. Thermodynamic calculation and experiments in particular temperatures show that boron and phosphorus segregationcoefficients in Al–Si melt decrease with decreasing temperature, and it is not verified in traditional solidification. In orderto character boron and phosphorus removal in Al–Si solidification over a temperature range, high purity hypereutecticAl–Si melts were solidified at relatively low cooling rate. It is found that boron and phosphorus removal rates increase withdecreasing temperature. The tread that the boron and phosphorus segregation coefficients in the Al–Si melt decease withdecreasing temperature is confirmed in solidification over a temperature range. In addition, aluminum content in purifiedsilicon is close to the maximum solid solubility of aluminum in silicon.
Yanlei Wang,Dong-Sheng Li,Fangzhu Du,Zhi Chen 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.3
The CFRP-confined circular concrete-filled steel tubular column is composed of concrete, steel, and CFRP. Its failure mechanics are complex. The most important difficulties are lack of an available method to establish a relationship between a specific damage mechanism and its acoustic emission (AE) characteristic parameter. In this study, AE technique was used to monitor the evolution of damage in CFRP-confined circular concrete-filled steel tubular columns. A fuzzy c-means method was developed to determine the relationship between the AE signal and failure mechanisms. Cluster analysis results indicate that the main AE sources include five types: matrix cracking, debonding, fiber fracture, steel buckling, and concrete crushing. This technology can not only totally separate five types of damage sources, but also make it easier to judge the damage evolution process. Furthermore, typical damage waveforms were analyzed through wavelet analysis based on the cluster results, and the damage modes were determined according to the frequency distribution of AE signals.
Enhancement of Photoluminescence by Ag Localized Surface Plasmon Resonance for Ultraviolet Detection
Yanlei Lyu,Jun Ruan,Mingwei Zhao,Ruijin Hong,Hui Lin,Dawei Zhang,Chunxian Tao 한국광학회 2021 Current Optics and Photonics Vol.5 No.1
For higher sensitivity in ultraviolet (UV) and even vacuum ultraviolet (VUV) detection of siliconbased sensors, a sandwich-structured film sensor based on Ag Localized Surface Plasmon Resonance (LSPR) was designed and fabricated. This film sensor was composed of a Ag nanoparticles (NPs) layer, SiO 2 buffer and fluorescence layer by physical vapour deposition and thermal annealing. By tuning the annealing temperature and adding the SiO 2 layer, the resonance absorption wavelength of Ag NPs matched with the emission wavelength of the fluorescence layer. Due to the strong plasmon resonance coupling and electromagnetic field formed on the surface of Ag NPs, the radiative recombination rate of the luminescent materials and the number of fluorescent molecules in the excited state increased. Therefore, the fluorescent emission intensity of the sandwich-structured film sensor was 1.10–1.58 times at 120–200 nm and 2.17–2.93 times at 240–360 nm that of the single-layer film sensor. A feasible method is provided for improving the detection performance of UV and VUV detectors.