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Dynamic increase factor for progressive collapse analysis of semi-rigid steel frames
Yan Fei Zhu,Chang Hong Chen,Yao Yao,Leon M. Keer,Ying Huang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.2
An empirical and efficient method is presented for calculating the dynamic increase factor to amplify the applied loads on the affected bays of a steel frame structure with semi-rigid connections. The nonlinear static alternate path analysis is used to evaluate the dynamic responses. First, the polynomial models of the extended end plate and the top and seat connection are modified, and the proposed polynomial model of the flush end plate connection shows good agreement as compared with experimental results. Next, a beam model with nonlinear spring elements and plastic hinges is utilized to incorporate the combined effect of connection flexibility and material nonlinearity. A new step-by-step analysis procedure is established to obtain quickly the dynamic increase factor based on a combination of the pushdown analysis and nonlinear dynamic analysis. Finally, the modified dynamic increase factor equation, defined as a function of the maximum ratio value of energy demand to energy capacity of an affected beam, is derived by curve fitting data points generated by the different analysis cases with different column removal scenarios and five types of semi-rigid connections.
Component-based model for posttensioned steel connections against progressive collapse
Yan Fei Zhu,Chang Hong Chen,Ying Huang,Zhaohui Huang,Yao Yao,Leon M. Keer 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.4
A component-based method for the estimation of the posttensioned (PT) steel frame against progressive collapse is proposed and presented in the current paper. A mechanical model of PT steel connections is developed and benchmarked with experimental data of a PT beam-column substructure from literature. The developd mechanical models of four PT connections are able to capture the initial elastic stiffness, decompression load, and residual stiffness under lateral loading. Then, analysis of a reduced-scale three-storey two-bay PT steel frame is carried out with sufficient accuracy by incorporating the proposed joint model into the frame analysis. The proposed method is then applied to assessing progressive collapse of a one-storey two-bay PT frame under middle column removal scenario, and is verified against existing experimental and ANSYS finite element results. Three resistance mechanism for progressive collapse of the PT frame are evaluated, which consists of angle flexural mechanism, beam compression arching action and strand tensile catenary action. Finally, parameter analyses of the PT frames are conducted to investigate the effects of the connection details on the behavior and resistance of progressive collapse. The proposed model can be used to predict the quasi-static behavior of PT frames under monotonic vertical loading conditions with satisfactory accuracy.
Yan, Changzeng,Xue, Xiaolan,Zhang, Wenjun,Li, Xiaojie,Liu, Juan,Yang, Songyuan,Hu, Yi,Chen, Renpeng,Yan, Yaping,Zhu, Guoyin,Kang, Zhenhui,Kang, Dae Joon,Liu, Jie,Jin, Zhong unknown 2017 Nano energy Vol.39 No.-
<P><B>Abstract</B></P> <P>To produce hydrogen and oxygen from photocatalytic overall splitting of pure water provides a promising green route to directly convert solar energy to clean fuel. However, the design and fabrication of high-efficiency photocatalyst is challenging. Here we present that by connecting different nanostructures together in a rational fashion, components that cannot individually split water into H<SUB>2</SUB> and O<SUB>2</SUB> can work together as efficient photocatalyst with high solar-to-hydrogen (STH) energy conversion efficiency and avoid the use of any sacrificial reagent. Specifically, Te/SnS<SUB>2</SUB>/Ag artificial nanoleaves (ANLs) consist of ultrathin SnS<SUB>2</SUB> nanoplates grown on Te nanowires and decorated with numerous Ag nanoparticles. The appropriate band structure of Te/SnS<SUB>2</SUB> p-n junctions and the surface plasmon resonance of Ag nanoparticles synergistically enhance the quantum yield and separation efficiency of electron-hole pairs. As a result, Te/SnS<SUB>2</SUB>/Ag ANLs enable visible-light driven overall water-splitting without any sacrificial reagent and exhibit high H<SUB>2</SUB> and O<SUB>2</SUB> production rates of 332.4 and 166.2μmolh<SUP>−1</SUP>, respectively. Well-preserved structure after long-term measurement indicates its high stability. It represents a feasible approach for direct H<SUB>2</SUB> production from only sunlight, pure water, and rationally-designed ANL photocatalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Te/SnS<SUB>2</SUB>/Ag ANLs heterostructure is prepared to catalyze overall water splitting. </LI> <LI> The catalyst show impressive H<SUB>2</SUB> and O<SUB>2</SUB> production rate under visible light. </LI> <LI> The structure and efficiency of catalyst shows no degradation after 10 days. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Effects of Aluminum Nanoparticles on Thermal Decomposition of Ammonium Perchlorate
Zhu, Yan-Li,Huang, Hao,Ren, Hui,Jiao, Qing-Jie Korean Chemical Society 2013 대한화학회지 Vol.57 No.1
The effects of aluminum nanoparticles (AlNs) on the thermal decomposition of ammonia perchlorate (AP) were investigated by DSC, TG-DSC and DSC-TG-MS-FTIR. Addition of AlNs resulted in an increase in the temperature of the first exothermic peak of AP and a decrease in the second. The processing of non-isothermal data at various heating rates with and without AlNs was performed using Netzsch Thermokinetics. The dependence of the activation energy calculated by Friedman's isoconversional method on the conversion degree indicated the decomposition process can be divided into three steps. They were C1/D1/D1 for neat AP, determined by Multivariate Non-linear Regression, and changed to C1/D1/F2 after addition of AlNs into AP. The isothermal curves showed that the thermal stability of AP in the low temperature stage was improved in the presence of AlNs.
Kinetics of thermal decomposition of ε-hexanitrohexaazaisowurtzitane by TG-DSC-MS-FTIR
Yan-Li Zhu,Ming-Xin Shan,Zhi-Xia Xiao,Jing-Si Wang,Qing-Jie Jiao 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.6
Thermal decomposition of ε-hexanitrohexaazaisowurtzitane (HNIW) was studied by thermogravimetrydifferential scanning calorimetry-mass spectrometry-Fourier transform infrared spectroscopy (TG-DSC-MS-FTIR) simultaneous analysis. It has been shown that there is a crystal transition point for ε-HNIW, and only a single decomposition process has been observed for HNIW. The kinetic parameters of thermal decomposition of HNIW were obtained by Kissinger and Flynn-Wall-Ozawa methods, indicating that HNIW has the higher reactivity compared to the other nitramines. The HNIW decomposition mechanism demonstrated by the non-isothermal kinetics conformed to Avrami-Erofeev equation with the factor of nucleus growth of n=1/3 and the conversion degree of α from 0.1 to 0.7. The MS and FTIR analyses indicated that the thermal decomposition of HNIW favors N-N bond cleavage over C-N bond cleavage as the rate determining step.
Comparison of the Nutritional Composition of Bullfrog Meat from Different Parts of the Animal
Yanli Zhu,Min Bao,Chong Chen,Xiaoli Yang,Wenliang Yan,Fazheng Ren,Pengjie Wang,Pengcheng Wen 한국축산식품학회 2021 한국축산식품학회지 Vol.41 No.6
The objective of this study was to evaluate the nutritional content of bullfrog meat from different parts of the animal, including fore-chest, thigh and calf. Bullfrog meat was found to be a rich source of proteins, essential amino acids and minerals, but with a low fat content, compared with other aquatic meat products. There was no significant difference (p>0.05) between thigh and calf in mineral content (K, P, Na, Mg, Ca, Zn, Fe, Cu, and Mn), but the contents of K, P, and Mg were higher in thigh and calf than in the fore-chest (p<0.05). The salt-soluble, water-soluble and insoluble protein bands in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) electrophoresis, from fore-chest, thigh and calf were similar, with the most abundant bands being 35 kDa (salt-soluble protein), 35-48 kDa (water-soluble protein) and 48 kDa (insoluble protein). The results showed that the insoluble protein content in the fore-chest meat was higher than that in the thigh meat and calf meat, but the salt-soluble protein fraction was the most abundant in thigh meat. These results showed that the nutrients in different parts of bullfrog meat were different.
Zhu, Fei-Yan,Jeong, Sungwoo,Lim, Hyoung Jun,Yun, Gun Jin Elsevier 2018 Composite structures Vol.195 No.-
<P><B>Abstract</B></P> <P>This paper presents a probabilistic multiscale approach to model the random spatial distribution of local elastic properties arising from the heterogeneous waviness and orientation of CNT fillers within a 3D microscale continuum representative volume element (RVE) of a CNT-reinforced polymer matrix. The proposed direction-sensitive 3D Karhunen-Loève expansion (KLE) provides the basis to simulate stochastic variations in the CNT orientations rather than assuming a perfect alignment. Computational homogenization analyses are carried out to investigate the effects of the statistical parameters of random CNT waviness on the microscale continuum RVE size. The proposed probabilistic multiscale modelling framework allows to consider the uncertainty associated with the use of CNT nanocomposites for various applications.</P>