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Buckling Analysis of Steel H Column with Thermal Gradient Along the Flanges
Wei-bin Yuan,Pei-jun Ge,Yue-ting Shen,Shan-shan Cheng,Nan-ting Yu 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.2
This paper presents an analytical study about the axial compression buckling of H-section columns with one side of the flanges exposed to fire. The fire-induced thermal gradient along the flanges is obtained by using simplified Fourier heat conduction equation. The pre-buckling stress and bowing effect due to the non-uniform temperature distribution through the cross-section is considered. The analysis is accomplished by using the Rayleigh–Ritz method. The analytical solution is validated by finite element analysis using ANSYS. Finally, the parametric study is performed for different sections including different values of length, thickness ratio and width-to-height ratio.
Wei-bin Yuan,Yue-ting Shen,Nan-ting Yu,Zhao-shui Bao 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.5
This paper presents an analytical approach to predict the critical load of global buckling with locally buckled channel-section columns under axial compressive loads. The eff ect of local deformation before global buckling is considered. The analysis is performed by using the Rayleigh–Ritz method. The analytical solution is validated by using the nonlinear fi nite element analysis method. Parametric study is also performed for diff erent sections including diff erent values of slenderness ratio, height-thickness ratio and width-height ratio. The comparison between the present approach and those taken from Chinese and American standards demonstrates that the present model provides a good approach for predicting the critical loads of steel columns involving local and global buckling interaction.
Nonlinear Bending of Box Section Beams of Finite Length Under Uniformly Distributed Loading
Wei-bin Yuan,Zhao-shui Bao,Nan-ting Yu,Shuang-shuang Zhu,Li-ping Wu 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.2
In this paper, the bending response of box-section beams of finite length is investigated by using energy methods. The basic assumptions used in the present study are that the total strain energy of a box-section beam subjected to uniformly distributed loading can be simplified into a two-stage analysis process. One is the local bending response of the webs and flanges behaving as plates; the other is the overall bending response of the beam with a deformed cross-section. Analytical solutions for both static and dynamic instabilities of box section beams of finite length subjected to transverse uniformly distributed loading are derived by applying the minimum potential energy principle. To validate the analytical solutions developed, geometric nonlinear finite element analyses are also conducted. Good agreement between the present solutions and the FEA results is demonstrated. Finally, the effects of beam length on the limit critical uniformly distributed load are also discussed.
Nonlinear Instability of Angle Section Beams under Uniformly Distributed Loads
Wei-bin Yuan,Wei Zhang,Jie Xu,Nan-ting Yu 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.2
This paper presents a study on the flattening behavior of angle-section beams of finite length subjected to uniformly distributed transverse loads. Analytical solutions for static instabilities of angle-section beams when they are bent about their weak axis are derived using energy methods. The basic assumptions used in the present study are that the total strain energy of an angle-section beam subjected to a uniformly distributed load can be simplified into a two-stage process. One is the bending response of the two legs behaving as the plate; the other is the bending response as a beam with flattened section. The nonlinear instability is derived by applying the minimum potential energy principle and the corresponding static critical moments associated with the section flattening-induced buckling are determined. To validate the analytical solution developed, nonlinear finite element analyses are also conducted. Good agreement between the present solution and the FEA results is demonstrated.
Deflection of Castellated Beams Subjected to Uniformly Distributed Transverse Loading
Wei-bin Yuan,Nan-ting Yu,Zhao-shui Bao,Li-ping Wu 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.3
This paper presents an analytical solution for determining the deflection of castellated/cellular beams with hexagonal/circular web openings, subjected to a uniformly distributed transverse load. The solution is derived using the principle of minimum potential energy. To validate the derived analytical solution, three-dimensional linear finite element analysis is performed using four-node shell elements built-in ANSYS software. Good agreement between the finite element result and the present analytical solution is demonstrated.
The effects of grooves on wind characteristics of tall cylinder buildings
Wei-bin Yuan,Nan-ting Yu,Zhao Wang 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.26 No.2
For most full-scale tall buildings the Reynolds number of a flow field around a circular cylinder under strong wind is usually greater than 2107, which is difficult to achieve in most wind tunnel tests. To explore the wind characteristics of tall cylindrical buildings with equidirectional grooves from subcritical to transcritical flow (6.6104 Re 3.3105 and 9.9106 Re 7.2107), wind tunnel tests and full-scale large eddy simulations were carried out. The results showed that the rectangular-grooves narrow the wake width due to the downstream movement of the separation point and the deeper grooves cause smaller mean and fluctuating pressure while the peak pressure is little affected. Furthermore, the grooves lead to lower frequency of vortex shedding but the Strouhal number remains at the range from 0.15 to 0.35. The drag coefficient of the cylinders with grooves was found to be 2~3 times as large as that of smooth cylinders.
The effects of grooves on wind characteristics of tall cylinder buildings
Yuan, Wei-bin,Yu, Nan-ting,Wang, Zhao Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.26 No.2
For most full-scale tall buildings the Reynolds number of a flow field around a circular cylinder under strong wind is usually greater than $2{\times}10^7$, which is difficult to achieve in most wind tunnel tests. To explore the wind characteristics of tall cylindrical buildings with equidirectional grooves from subcritical to transcritical flow ($6.6{\times}10^4{\leq}Re{\leq}3.3{\times}10^5$ and $9.9{\times}10^6{\leq}Re{\leq}7.2{\times}10^7$), wind tunnel tests and full-scale large eddy simulations were carried out. The results showed that the rectangular-grooves narrow the wake width due to the downstream movement of the separation point and the deeper grooves cause smaller mean and fluctuating pressure while the peak pressure is little affected. Furthermore, the grooves lead to lower frequency of vortex shedding but the Strouhal number remains at the range from 0.15 to 0.35. The drag coefficient of the cylinders with grooves was found to be 2~3 times as large as that of smooth cylinders.
Cai, Bin,Wang, Mu-Yong,Liao, Kai,Xu, Yan-Song,Wei, Wei-Yuan,Zhuang, Yuan,Zhang, Sen Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.20
Background: Studies have shown the existence of gender- and age-related differences in the incidence and anatomic distribution of colorectal cancers. The purposes of this study were to analyze the distribution characteristics of colorectal cancer patients regarding gender, age, location and tumor size in the course of colonoscopy. Materials and Methods: All colorectal cancer patients who underwent colonoscopy in the First Affiliated Hospital of Guangxi Medical University from 2003 to 2012 were included in our retrospective study. Demographic information (age and gender) and colonoscopy report information (tumor size and location) were collected and analyzed. To compare the gender differences in tumor location and tumor size, as well as the size differences in tumor location, the chi-square test was used. Results: A total of 3, 369 colorectal cancer patients (2, 007 men vs 1, 362 women) were included in our study. Statistical analysis showed there was no gender difference in the anatomic distribution of the tumors (p>0.05). However, there was a gender difference in tumor size (p<0.05). In addition, our study found there was a significant difference in tumor size between rectal and colon tumors (p<0.001). Conclusions: There was no gender difference in the anatomic distribution of colorectal tumors. In addition, tumors observed in men were larger than in women.