A cylindrical shell model for nonlocal buckling behavior of CNTs embedded in an elastic foundation under the simultaneous effects of magnetic field, temperature change, and number of walls

Timesli, Abdelaziz Techno-Press 2021 Advances in nano research Vol.11 No.6

This model is proposed to describe the buckling behavior of Carbon Nanotubes (CNTs) embedded in an elastic medium taking into account the combined effects of the magnetic field, the temperature, the nonlocal parameter, the number of walls. Using Eringen's nonlocal elasticity theory, thin cylindrical shell theory and Van der Waal force (VdW) interactions, we develop a system of partial differential equations governing the buckling response of CNTs embedded on Winkler, Pasternak, and Kerr foundations in a thermal-magnetic environment. The pre-buckling stresses are obtained by applying airy's stress function and an adjacent equilibrium criterion. To estimate the nonlocal critical buckling load of CNTs under the simultaneous effects of the magnetic field, the temperature change, and the number of walls, an optimization technique is proposed. Furthermore, analytical formulas are developed to obtain the buckling behavior of SWCNTs embedded in an elastic medium without taking into account the effects of the nonlocal parameter. These formulas take into account VdW interactions between adjacent tubes and the effect of terms involving differences in tube radii generally neglected in the derived expressions of the critical buckling load published in the literature. Most scientific research on modeling the effects of magnetic fields is based on beam theories, this motivation pushes me to develop a cylindrical shell model for studying the effect of the magnetic field on the static behavior of CNTs. The results show that the magnetic field has significant effects on the static behavior of CNTs and can lead to slow buckling. On the other hand, thermal effects reduce the critical buckling load. The findings in this work can help us design of CNTs for various applications (e.g. structural, electrical, mechanical and biological applications) in a thermal and magnetic environment.

Large deflection behavior and stability of slender bars under self weight

Goncalves, Paulo B.,Jurjo, Daniel Leonardo B.R.,Magluta, Carlos,Roitman, Ney,Pamplona, Djenane Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.24 No.6

In this paper the buckling and post-buckling behavior of slender bars under self-weight are studied. In order to study the post-buckling behavior of the bar, a geometrically exact formulation for the non-linear analysis of uni-directional structural elements is presented, considering arbitrary load distribution and boundary conditions. From this formulation one obtains a set of first-order coupled nonlinear equations which, together with the boundary conditions at the bar ends, form a two-point boundary value problem. This problem is solved by the simultaneous use of the Runge-Kutta integration scheme and the Newton-Raphson method. By virtue of a continuation algorithm, accurate solutions can be obtained for a variety of stability problems exhibiting either limit point or bifurcational-type buckling. Using this formulation, a detailed parametric analysis is conducted in order to study the buckling and post-buckling behavior of slender bars under self-weight, including the influence of boundary conditions on the stability and large deflection behavior of the bar. In order to evaluate the quality and accuracy of the results, an experimental analysis was conducted considering a clamped-free thin-walled metal bar. As this kind of structure presents a high index of slenderness, its answers could be affected by the introduction of conventional sensors. In this paper, an experimental methodology was developed, allowing the measurement of static or dynamic displacements without making contact with the structure, using digital image processing techniques. The proposed experimental procedure can be used to a wide class of problems involving large deflections and deformations. The experimental buckling and post-buckling behavior compared favorably with the theoretical and numerical results.

Finite Element Analysis of Buckling Behavior for Cold-Formed Steel Hat Purlins with Openings

Fatimah De’nan,Kok Keong Choong,Jin Ying Ling,Nor Salwani Hashim 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.4

In urban building design, introducing openings in the webs of structural members allows the fl exible installation of ductwork and piping. This study investigated the eff ects of the shape, location, and spacing of web openings on the buckling behavior of cold-formed steel hat purlins. Eigenvalue analysis shows that the existence of web openings reduced the buckling moment of a section by up to 24%. The shape and location of the web openings also aff ected the buckling behavior. In particular, the buckling moment decrease when the web opening was located at mid-span. It was found that, the buckling moment increase when the web opening spacing increases. The section with diamond web openings shows the highest buckling moment and the section with elongated circle openings shows the smallest buckling moment compared to other web opening shapes. The results of this study should provide guidance on hat purlins with openings design to meet structural performance requirements.

파형 강판 웨브를 갖는 보의 매개변수 해석 연구

박근우,이서행,유정한 한국공간구조학회 2018 한국공간구조학회지 Vol.18 No.1

The purpose of this study was to analyze some parameters’ effects on buckling behavior of Sinusoidal Corrugated Web using finite element analysis program. Studying buckling behavior is one of the most important things to design sinusoidal corrugated web girders and predict the shear performance. In this paper, Four parameters of Sinusoidal Corrugated Web, which are thickness(tw), height(hw), wave height(a3) and wave length(w), were selected for buckling behavior analysis. Via buckling analysis, it is shown that tw, hw and a3 have influence on shear buckling stress, Initial stiffness and reduced strength after buckling.

Experiments and analysis of the post-buckling behaviors of aluminum alloy double layer space grids applying ball joints

Hiyama, Yujiro,Ishikawa, Koichiro,Kato, Shiro,Okubo, Shoji Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.9 No.3

This study discusses on the experimental and analytical results of the global buckling tests, carried out on aluminum alloy double layer space grids composed of tubular members, ball joints and connecting bolts at the member ends, with the purpose of demonstrating the effectiveness of a simplified analysis method using an equivalent slenderness ratio for the members. Because very few experiments have been carried out on this type of aluminum space grids, the buckling behavior is investigated experimentally over the post buckling regions using several space grid specimen with various values for the member slenderness ratio. The observed behavior duping the experiments is compared with the analytically obtained results. The comparison is made based on two different schemes; one on the plastic hinge method considering a bending moment-axial force interaction for members and the other on a method using an equivalent slenderness ratio. It is confirmed that the equivalent slenderness method can be effectively applied, even in the post buckling regions, once the effects of the rotational rigidity at the ball joints are appropriately evaluated, because the rigidity controls the buckling behavior. The effectiveness of the equivalent slenderness method will be widely utilized for estimation of the ultimate strength, even in post buckling regions for large span aluminum space grids composed of an extreme large number of nodes and members.

Seismic behavior factors of buckling-restrained braced frames

Kim, Jinkoo,Park, Junhee,Kim, Sang-Dae Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.3

The seismic behavior of a framed structure with chevron-type buckling restrained braces was investigated and their behavior factors, such as overstrength, ductility, and response modification factors, were evaluated. Two types of structures, building frame systems and dual systems, with 4, 8, 12, and 16 stories were designed per the IBC 2003, the AISC LRFD and the AISC Seismic Provisions. Nonlinear static pushover analyses using two different loading patterns and incremental dynamic analysis using 20 earthquake records were carried out to compute behavior factors. Time history analyses were also conducted with another 20 earthquakes to obtain dynamic responses. According to the analysis results, the response modification factors turned out to be larger than what is proposed in the provision in low-rise structures, and a little smaller than the code-values in the medium-rise structures. The dual systems, even though designed with smaller seismic load, showed superior static and dynamic performances.

Behavior of three-tube buckling-restrained brace with circumference pre-stress in core tube

Yang Li,Haiyan Qu,Shaowen Xiao,Peijun Wang,Yang You,Shuqing Hu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.2

The behavior of a new Three-Tube Buckling-Restrained Brace (TTBRB) with circumference pre-stress (σθ,pre) in core tube are investigated through a verified finite element model. The TTBRB is composed of one core tube and two restraining tubes. The core tube is in the middle to provide the axial stiffness, to carry the axial load and to dissipate the earthquake energy. The two restraining tubes are at inside and outside of the core tube, respectively, to restrain the global and local buckling of the core tube. Based on the yield criteria of fringe fiber, a design method for restraining tubes is proposed. The applicability of the proposed design equations are verified by TTBRBs with different radius-thickness ratios, with different gap widths between core tube and restraining tubs, and with different levels of σθ,pre. The outer and inner tubes will restrain the deformation of the core tube in radius direction, which causes circumference stress (σθ) in the core tube. Together with the σθ,pre in the core tube that is applied through interference fit of the three tubes, the yield strength of the core tube in the axial direction is improved from 160 MPa to 235 MPa. Effects of gap width between the core tube and restraining tubes, and σθ,pre on hysteretic behavior of TTBRBs are presented. Analysis results showed that the gap width and the σθ,pre can significantly affect the hysteretic behavior of a TTBRB.

Buckling-restrained steel plate shear walls using recycled aggregate concrete: Experimental and analytical study

Muwang Wei,Jianhe Xie,Weicai Liu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.2

To meet the demands of the sustainable development of construction, the combination of precast structures and recycled aggregate concrete made from construction and demolition waste is being promoted as a promising green construction technology. In this study, a new prefabricated member, a buckling-restrained steel plate shear wall with a cover plate made of recycled aggregate concrete (PBRW), was developed and experimentally studied. Eight specimens were tested to study the effect of the cover plate with different recycled aggregate substitution ratios and various bolt arrangements on the seismic behavior of this shear wall system. Based on the high-order buckling in the inner steel plate, a theoretical method was proposed to predict the shear resistance of PBRWs. The test results indicated that the PBRWs exhibited high shear strength, an adequate initial stiffness, a favorable energy absorption capacity, and a stable hysteresis curve. A full replacement of recycled aggregate with natural aggregate had almost no adverse impact on the seismic behavior of the PBRWs. The wall with an insufficient number of bolts (bolt arrangement of 3×2) imposed weaker lateral constraints on the inner plate, resulting in a reduction in the seismic behavior.

Seismic behavior factors of buckling-restrained braced frames

김진구,박준희,김상대 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.2

The seismic behavior of a framed structure with chevron-type buckling restrained braces was investigated and their behavior factors, such as overstrength, ductility, and response modification factors, were evaluated. Two types of structures, building frame systems and dual systems, with 4, 8, 12, and 16 stories were designed per the IBC 2003, the AISC LRFD and the AISC Seismic Provisions. Nonlinear static pushover analyses using two different loading patterns and incremental dynamic analysis using 20 earthquake records were carried out to compute behavior factors. Time history analyses were also conducted with another 20 earthquakes to obtain dynamic responses. According to the analysis results, the response modification factors turned out to be larger than what is proposed in the provision in low-rise structures, and a little smaller than the code-values in the medium-rise structures. The dual systems, even though designed with smaller seismic load, showed superior static and dynamic performances.

Ultimate behavior of long-span steel arch bridges

Cheng, Jin,Jiang, Jian-Jing,Xiao, Ru-Cheng,Xiang, Hai-Fan Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.14 No.3

Because of the increasing span of arch bridges, ultimate capacity analysis recently becomes more focused both on design and construction. This paper investigates the static and ultimate behavior of a long-span steel arch bridge up to failure and evaluates the overall safety of the bridge. The example bridge is a long-span steel arch bridge with a 550 m-long central span under construction in Shanghai, China. This will be the longest central span of any arch bridge in the world. Ultimate behavior of the example bridge is investigated using three methods. Comparisons of the accuracy and reliability of the three methods are given. The effects of material nonlinearity of individual bridge element and distribution pattern of live load and initial lateral deflection of main arch ribs as well as yield stresses of material and changes of temperature on the ultimate load-carrying capacity of the bridge have been studied. The results show that the distribution pattern of live load and yield stresses of material have important effects on bridge behavior. The critical load analyses based on the linear buckling method and geometrically nonlinear buckling method considerably overestimate the load-carrying capacity of the bridge. The ultimate load-carrying capacity analysis and overall safety evaluation of a long-span steel arch bridge should be based on the geometrically and materially nonlinear buckling method. Finally, the in-plane failure mechanism of long-span steel arch bridges is explained by tracing the spread of plastic zones.