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Amir M. Yousefi,Asraf Uzzaman,James B.P. Lim,G. Charles Clifton,Ben Young 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.3
In cold-formed stainless steel lipped channel-sections, use of web openings for service purposes are becoming increasingly popular. Web openings, however, result in the sections becoming more susceptible to web crippling. This paper presents a finite element investigation into the web crippling strength of cold-formed stainless steel lipped channel-sections with circular web openings under the interior-two-flange (ITF) loading condition. The cases of web openings located centred and offset to the bearing plates are considered in this study. In order to take into account the influence of the circular web openings, a parametric study involving 2,220 finite element analyses was performed, covering duplex EN1.4462, austenitic EN1.4404 and ferritic EN1.4003 stainless steel grades. From the results of the parametric study, strength reduction factor equations are proposed. The strengths obtained from reduction factor equations are first compared to the strengths calculated from the equations recently proposed for cold-formed carbon steel lipped channel-sections. It is demonstrated that the strength reduction factor equations proposed for cold-formed carbon steel are unconservative for the stainless steel grades by up to 17%. New coefficients for web crippling strength reduction factor equations are then proposed that can be applied to all three stainless steel grades.
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James B.P. Lim,Amir M. Yousefi,Asraf Uzzaman,Ying Lian,G. Charles Clifton,Ben Young 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.3
In cold-formed stainless steel lipped channel-sections, web openings are becoming increasingly popular. Such openings, however, result in the sections becoming more susceptible to web crippling, especially under concentrated loads applied near the web opening. This paper presents the results of a finite element parametric study into the effect of circular web openings on the web crippling strength of cold-formed stainless steel lipped channelsections for the interior-one-flange (IOF) loading condition. This involves a bearing load applied to the top flange of a length of member, away from the end supports. The cases of web openings located centred beneath the bearing load (i.e. beneath the bearing plate delivering the load) and offset to the bearing plate, are considered. Three grades of stainless steel are considered: duplex EN1.4462, austenitic EN1.4404 and ferretic EN1.4003. In total, 2218 finite element models were analyzed. From the results of the parametric study, strength reduction factors for load bearing capacity are determined, where these reduction factors are applied to the bearing capacity calculated for a web without openings, to take account the influence of the web openings. The strength reduction factors are first compared to equations recently proposed for cold-formed carbon steel lipped channel-sections. It is shown that for the case of the duplex grade, the strength reduction factor equations for cold-formed carbon steel are conservative but only by 2%. However, for the cases of the austentic and ferritic grades, the cold-formed carbon steel equations are around 9% conservative. New strength reduction factor equations are proposed for all three stainless steel grades.
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CORRELATION STRUCTURE ANALYSIS : CHINA AND THE U.S STOCK MARKETS
Soo Yong Kim,Hee Yun Choi,Mohammad Haizad bin Mohd Tarik,Asraf Hanafi bin Mohd Hairudin 국제과학영재학회 2011 APEC Youth Scientist Journal Vol.3 No.-
We conducted an empirical investigation regarding the correlation between stocks. Specifically, we use methods of random matrix theory (RMT), which originated from the need to understand the interactions between the constituent elements of complex interacting systems, to analyze the correlation matrix C of returns. To analyze correlation between stocks, we used data from Shanghai Stock Exchange (SSE) and Standard and Poor’s 500 (S&P 500). These data are grouped according to sector. The analysis is conducted by using MATLAB. Firstly, we compute a price matrix; return matrix and correlation matrix using time series. Next, we tried to obtain the eigenvalues and eigenvectors. Then, we plotted the graph of p( ) i.e. density of eigenvalues of correlation matrix. From the graph, we discover some important information such as the correlation between stocks.
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Yaohui Chi,Krishanu Roy,Boshan Chen,Zhiyuan Fang,Asraf Uzzaman,G. Beulah Gnana Ananthi,James B.P. Lim 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.2
Recently, a new generation of cold-formed steel (CFS) channel section with edge-stiffened web holes has been developed by industry in New Zealand. However, no research has been reported in the literature to investigate the axial capacity of back-to-back channels with edge-stiffened web holes. This paper presents a total of 73 new results comprising 29 compression tests and 44 finite element analyses (FEA) on axial capacity of such back-to-back CFS channels. The results show that for back-to-back channels with seven edge-stiffened holes, the axial capacity increased by 19.2%, compared to plain channels without web holes. A non-linear finite element (FE) model was developed and validated against the test results. The validated FE model was used to conduct a parametric study involving 44 FE models. Finely, the tests results were compared with the design strengths calculated from the AISI and AS/NZ standards and from the proposed design equations of Moen and Schafer. From the comparison results, it was found that the AISI and AS/NZ design strengths are only 9% conservative to the test results for plain channels without web holes. While Moen and Schafer equations are conservative by 13% and 47% for axial capacity of CFS back-to-back channels with un-stiffened and edge-stiffened web holes, respectively.
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