The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
Jongsup Park - One of the best experts on this subject based on the ideXlab platform.
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inelastic lateral buckling resistance of Stepped i Beam with compact section and continuous bracing
Ksce Journal of Civil Engineering, 2019Co-Authors: Luis Aristeo Asistores, Shane Alolod, Jongsup ParkAbstract:Continuous multispan Beams in bridges experiences high negative moment at interior supports and the top flanges of these Beams are laterally braced due to the concrete slab or steel deck above it. The negative moment can be resisted by increasing the cross sections of the Beams at the supports. An earlier study on the elastic lateral torsional buckling of Stepped Beam with continuous lateral bracing was conducted to propose new design equations. The main focus of this study is to continue the previous research considering the inelastic buckling of Stepped Beams. ABAQUS, a finite element method program was used to conduct the buckling analysis of the Beams. A total of five different load cases were used in the analysis. The effects of the residual stress and geometric imperfection were also considered for the inelastic buckling strength. Results showed that the inelastic buckling strength exceeds the plastic moment of the section and it is not needed to focus on the inelastic range when computing the lateral torsional buckling strength.
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a numerical study on inelastic lateral torsional buckling strength of doubly Stepped and singly symmetric i Beam subjected to uniform moment
Journal of the Korea Academia Industrial Cooperation Society, 2013Co-Authors: Yi Seul Park, Jongsup ParkAbstract:Abstract The cross-sections of continuous multi-span Beams are sometimes suddenly increased or Stepped at the interior supports of continuous Beams to resist high negative moments. This paper investigates inelastic lateral-torsional buckling of monosymmetric Stepped I-Beams subjected to pure bending. A three-dimensional finite-element program ABAQUS and a regression program were used to analytically develop new design equation. The flange thickness ratio, flange width ratio and Stepped length ratio were considered as parameters of this study. The combined effects of residual stresses and geometric imperfection on inelastic lateral-torsional buckling of Beams are considered. The proposed solution can be easily used to calculation for inelastic lateral torsional buckling strengths of monosymmetric Beams with doubly Stepped cross sections and to develop new design equations for inelastic lateral-torsional buckling resistances of Stepped Beams. Key Words : Beam design, Doubly Stepped Beam, Inelastic buckling, Monosymmetric Beam
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moment gradient factor for lateral torsional buckling strength of monosymmetric Stepped i Beam subjected to uniform moment
Journal of the Korean Society of Hazard Mitigation, 2010Co-Authors: Kathleen Mae Gelera, Jongsup ParkAbstract:Stepped I-Beams having increased moment of inertia at one end (singly Stepped Beam) or both ends (doubly Stepped Beams) can often be seen in construction of bridges due to material economy and easy fabrication of the section. This paper presents the results of the parametric study of lateral torsional buckling of monosymmetric Stepped I-Beams with constant depth subjected to uniform moment. Design recommendations were made based on the finite element results of the models having different combinations of monosymmetric ratio, Stepped length ratio, flange thickness ratio and flange width ratio. The proposed approximation is acceptable based on the parameters given having mostly conservative results. The proposed equation can be further used to extend the study to different loading conditions.
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a study on moment gradient factor for inelastic lateral torsional buckling of Stepped i Beam subjected to uniformly distributed load and end moment
Journal of Korean Society of Hazard Mitigation, 2009Co-Authors: Jimin Son, Jongsup ParkAbstract:This paper investigates inelastic lateral-torsional buckling of Stepped Beams subjected to uniformly distributed load and end moments. A three-dimensional finite-element program ABAQUS (2007) and a regression program MINITAB(2006) were used to analytically develop new design equation for singly and doubly Stepped Beams with simple boundary condition. The flanges of the smaller cross-section in the Stepped Beams were fixed at 30.48 by 2.54 cm, whereas the width and thickness of the flanges of the larger cross-section varied. The web thickness and height of the Beams were kept at 1.65 cm and 88.9 cm, respectively. The ratios of the flange thickness, flange width, and Stepped length of Beam are considered with analytical parameters. Two groups of 27 cases and 36 cases, respectively, were analyzed for doubly and singly Stepped Beams in the inelastic buckling range. The combined effects of residual stresses and geometrical imperfection on inelastic lateral-torsional buckling of Beams are considered. The distributions of residual stress of the cross-section is same as shown in Pi and Trahair (1995) and the initial geometric imperfection of the Beam is set by central displacement equal to 0.1% of the unbraced length of Beam. The comparisons between results from proposed equations and the results from finite element analyses were presented in this paper. The maximum differences of two results are of 13% for the doubly Stepped Beam and 10% for the singly Stepped Beam. The proposed equations definitely improve current design methods for the inelastic lateral-torsional buckling problem and increase efficiency in building and bridge design.
Matjaž Skrinar - One of the best experts on this subject based on the ideXlab platform.
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computational analysis of multi Stepped Beams and Beams with linearly varying heights implementing closed form finite element formulation for multi cracked Beam elements
International Journal of Solids and Structures, 2013Co-Authors: Matjaž SkrinarAbstract:Abstract The model where the cracks are represented by means of internal hinges endowed with rotational springs has been shown to enable simple and effective representation of transversely-cracked slender Euler–Bernoulli Beams subjected to small deflections. It, namely, provides reliable results when compared to detailed 2D and 3D models even if the basic linear moment–rotation constitutive law is adopted. This paper extends the utilisation of this model as it presents the derivation of a closed-form stiffness matrix and a load vector for slender multi-Stepped Beams and Beams with linearly-varying heights. The principle of virtual work allows for the simple inclusion of an arbitrary number of transverse cracks. The derived at matrix and vector define an ‘exact’ finite element for the utilised simplified computational model. The presented element can be implemented for analysing multi-cracked Beams by using just one finite element per structural Beam member. The presented expressions for a Stepped-Beam are not exclusively limited to this kind of height variation, as by proper discretisation an arbitrary variation of a cross-section’s height can be adequately modelled. The accurate displacement functions presented for both types of considered Beams complete the derivations. All the presented expressions can be easily utilised for achieving computationally-efficient and truthful analyses.
M Attar - One of the best experts on this subject based on the ideXlab platform.
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a transfer matrix method for free vibration analysis and crack identification of Stepped Beams with multiple edge cracks and different boundary conditions
International Journal of Mechanical Sciences, 2012Co-Authors: M AttarAbstract:Abstract This paper illustrates an analytical approach to investigating natural frequencies and mode shapes of a Stepped Beam with an arbitrary number of transverse cracks and general form of boundary conditions. A new method to solve the inverse problem of determining the location and depth of multiple cracks is also presented. Based on the Euler–Bernoulli Beam theory, the Stepped cracked Beam is modeled as an assembly of uniform sub-segments connected by massless rotational springs representing local flexibility induced by the non-propagating edge cracks. A simple transfer matrix method is utilized to obtain the general form of characteristic equation for the cracked Beam, which is a function of frequency, the locations and sizes of the cracks, boundary conditions, geometrical and physical parameters of the Beam. The proposed method is then used to form a system of 2N equations in order to identify N cracks exploiting 2N measured natural frequencies of the damaged Beam. Various numerical examples for both direct and inverse problem are provided to validate the present approach. The results are in good agreement with those obtained by finite element and experimental methods.
Chang Shu - One of the best experts on this subject based on the ideXlab platform.
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optimization of a piezoelectric wind energy harvester with a Stepped Beam
Journal of Mechanical Science and Technology, 2020Co-Authors: Jiantao Zhang, Zhou Fang, Chang ShuAbstract:A galloping-based piezoelectric energy harvester using the Stepped cantilever Beam is proposed and investigated. Transverse galloping is induced with the square cross sectioned bluff body. When the wind speed exceeds the critical wind speed, the self-excited oscillation of the harvester occurs and more output power is generated. To obtain the optimal design of the energy harvester, the sequential quadratic programming (SQP) and the evolution strategy (ES) are employed to determine the optimal solution. The finite element method is used to calculate the output voltage of the harvester. After optimization, the output voltage of the optimal harvester is significantly improved in comparison with that of the initial one. Two prototype harvesters based on the initial and optimal dimensions were fabricated and measured experimentally. An open-circuit rms voltage of 36 V and an output power of 0.52 mW were obtained at the wind speed of 14 m/s for the optimal harvester. They are about 8.3 times and 4.73 times of that of the initial harvester. The validity of the optimal design is verified with the experimental results.
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modeling and nonlinear analysis of Stepped Beam energy harvesting from galloping vibrations
Journal of Sound and Vibration, 2020Co-Authors: Jiantao Zhang, Xiaobo Zhang, Chang Shu, Zhou Fang, Yiwen NingAbstract:Abstract This paper presents a nonlinear distributed-parameter model for harvesting energy from galloping oscillation. The Stepped Beam structure is beneficial to increase the stress and strain of the piezoelectric elements, thereby enhancing the power generation. The finite element analysis is used to verify the feasibility and effectiveness of the developed harvester. A nonlinear distributed-parameter model for the piezoelectric energy harvester with a Stepped Beam is developed. The instantaneous fluid force in the transverse direction is analyzed. Based on Euler-Bernoulli Beam theory, a distributed-parameter model for undamped free vibration is derived, which can be used for the modal analysis. The electromechanical coupling model is established by using the piezoelectric effect theory. The forced vibration subjected to the galloping excitation load is analyzed by using the mode superposition method. The state vector and the fourth order Runge-Kutta algorithm are used to seek the numerical solution. The effects of the electrical load resistance, length, width and thickness of the piezoelectric Beam, exposure area and mass of the bluff body on the output power are investigated. In order to find the optimal design of the energy harvester, optimization design is performed based on the established theoretical model. The particle swarm optimization algorithm is employed to search the optimal solution in multidimensional space. Finally, experimental work was carried out, the electrical output characteristics of the energy harvester prototypes were measured. The simulation results are validated with the experimental data. It is demonstrated that the optimal configuration of the energy harvester can improve the output power from galloping phenomenon effectively.
Jiantao Zhang - One of the best experts on this subject based on the ideXlab platform.
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optimization of a piezoelectric wind energy harvester with a Stepped Beam
Journal of Mechanical Science and Technology, 2020Co-Authors: Jiantao Zhang, Zhou Fang, Chang ShuAbstract:A galloping-based piezoelectric energy harvester using the Stepped cantilever Beam is proposed and investigated. Transverse galloping is induced with the square cross sectioned bluff body. When the wind speed exceeds the critical wind speed, the self-excited oscillation of the harvester occurs and more output power is generated. To obtain the optimal design of the energy harvester, the sequential quadratic programming (SQP) and the evolution strategy (ES) are employed to determine the optimal solution. The finite element method is used to calculate the output voltage of the harvester. After optimization, the output voltage of the optimal harvester is significantly improved in comparison with that of the initial one. Two prototype harvesters based on the initial and optimal dimensions were fabricated and measured experimentally. An open-circuit rms voltage of 36 V and an output power of 0.52 mW were obtained at the wind speed of 14 m/s for the optimal harvester. They are about 8.3 times and 4.73 times of that of the initial harvester. The validity of the optimal design is verified with the experimental results.
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modeling and nonlinear analysis of Stepped Beam energy harvesting from galloping vibrations
Journal of Sound and Vibration, 2020Co-Authors: Jiantao Zhang, Xiaobo Zhang, Chang Shu, Zhou Fang, Yiwen NingAbstract:Abstract This paper presents a nonlinear distributed-parameter model for harvesting energy from galloping oscillation. The Stepped Beam structure is beneficial to increase the stress and strain of the piezoelectric elements, thereby enhancing the power generation. The finite element analysis is used to verify the feasibility and effectiveness of the developed harvester. A nonlinear distributed-parameter model for the piezoelectric energy harvester with a Stepped Beam is developed. The instantaneous fluid force in the transverse direction is analyzed. Based on Euler-Bernoulli Beam theory, a distributed-parameter model for undamped free vibration is derived, which can be used for the modal analysis. The electromechanical coupling model is established by using the piezoelectric effect theory. The forced vibration subjected to the galloping excitation load is analyzed by using the mode superposition method. The state vector and the fourth order Runge-Kutta algorithm are used to seek the numerical solution. The effects of the electrical load resistance, length, width and thickness of the piezoelectric Beam, exposure area and mass of the bluff body on the output power are investigated. In order to find the optimal design of the energy harvester, optimization design is performed based on the established theoretical model. The particle swarm optimization algorithm is employed to search the optimal solution in multidimensional space. Finally, experimental work was carried out, the electrical output characteristics of the energy harvester prototypes were measured. The simulation results are validated with the experimental data. It is demonstrated that the optimal configuration of the energy harvester can improve the output power from galloping phenomenon effectively.