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Data-driven modeling of optimal intensity measure of soil-nailed wall structures
Massoumeh Bayat,Mahdi Bayat,Mahmoud Bayat 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.86 No.1
This article examines the seismic vulnerability of soil nail wall structures. Detailed information regarding finite element modeling has been provided. The fragility function evaluates the relationship between ground motion intensities and the probability of surpassing a specific level of damage. The use of incremental dynamic analysis (IDA) has been applied to the soil nail wall against low to severe ground motions. In the nonlinear dynamic analysis of the soil nail wall, a set of twenty seismic ground motions with varying PGA ranges are used. The numerical results demonstrate that the soil-nailed wall reaction is extremely sensitive to earthquake ground vibrations under different intensity measures (IM). In addition, the analytical fragility curve is provided for various intensity values.
Nonlinear vibration of oscillatory systems using semi-analytical approach
Bayat, Mahmoud,Bayat, Mahdi,Pakar, Iman Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.4
In this paper, He's Variational Approach (VA) is used to solve high nonlinear vibration equations. The proposed approach leads us to high accurate solution compared with other numerical methods. It has been established that this method works very well for whole range of initial amplitudes. The method is sufficient for both linear and nonlinear engineering problems. The accuracy of this method is shown graphically and the results tabulated and results compared with numerical solutions.
Nonlinear frequency analysis of beams resting on elastic foundation using max-min approach
Bayat, Mahmoud,Bayat, Mahdi,Kia, Mehdi,Ahmadi, Hamid Reza,Pakar, Iman Techno-Press 2018 Geomechanics & engineering Vol.16 No.4
In this paper, nonlinear vibration of Euler-Bernoulli beams resting on linear elastic foundation is studied. It has been tried to prepare a semi-analytical solution for whole domain of vibration. Only one iteration lead us to high accurate solution. The effects of linear elastic foundation on the response of the beam vibration are considered and studied. The effects of important parameters on the ratio of nonlinear to linear frequency of the system are studied. The results are compared with numerical solution using Runge-Kutta $4^{th}$ technique. It has been shown that the Max-Min approach can be easily extended in nonlinear partial differential equations.
Forced nonlinear vibration by means of two approximate analytical solutions
Bayat, Mahmoud,Bayat, Mahdi,Pakar, Iman Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.6
In this paper, two approximate analytical methods have been applied to forced nonlinear vibration problems to assess a high accurate analytical solution. Variational Iteration Method (VIM) and Perturbation Method (PM) are proposed and their applications are presented. The main objective of this paper is to introduce an alternative method, which do not require small parameters and avoid linearization and physically unrealistic assumptions. Some patterns are illustrated and compared with numerical solutions to show their accuracy. The results show the proposed methods are very efficient and simple and also very accurate for solving nonlinear vibration equations.
Accurate analytical solutions for nonlinear oscillators with discontinuous
Bayat, Mahdi,Bayat, Mahmoud,Pakar, Iman Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.2
In this study, three approximate analytical methods have been proposed to prepare an accurate analytical solution for nonlinear oscillators with fractional potential. The basic idea of the approaches and their applications to nonlinear discontinuous equations have been completely presented and discussed. Some patterns are also presented to show the accuracy of the methods. Comparisons between Energy Balance Method (EBM), Variational Iteration Method (VIM) and Hamiltonian Approach (HA) shows that the proposed approaches are very close together and could be easily extend to conservative nonlinear vibrations.
An accurate novel method for solving nonlinear mechanical systems
Bayat, Mahdi,Pakar, Iman,Bayat, Mahmoud Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.3
This paper attempts to investigate the nonlinear dynamic analysis of strong nonlinear problems by proposing a new analytical method called Hamiltonian Approach (HA). Two different cases are studied to show the accuracy and efficiency of the method. This approach prepares us to obtain the nonlinear frequency of the nonlinear systems with the first order of the solution with a high accuracy. Finally, to verify the results we present some comparisons between the results of Hamiltonian approach and numerical solutions using Runge-Kutta's [RK] algorithm. This approach has a powerful concept and the high accuracy, so it can be apply to any conservative nonlinear problems without any limitations.
Analytical solution for nonlinear vibration of an eccentrically reinforced cylindrical shell
Mahmoud Bayat,Iman Pakar,Mahdi Bayat 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.5
In this study we have considered the governing nonlinear equation of an eccentrically reinforced cylindrical shell. A new analytical method called He’s Variational Approach (VA) is used to obtain the natural frequency of the nonlinear equation. This analytical representation gives excellent approximations to the numerical solution for the whole range of the oscillation amplitude, reducing the respective error of angular frequency in comparison with the variation approach method. It has been proved that the variational approach is very effective, convenient and does not require any linearization or small perturbation. Additionally it has been demonstrated that the variational approach is adequately accurate to nonlinear problems in physics and engineering.
Mahmoud Bayat,Mahdi Bayat 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.16 No.5
In this study, the performances of the SMRF building equipped with energy dissipating devices are studied. Three types of these structures with different heights are considered. The Added Damping and Stiffness (ADAS) devices are used as energy dissipating devices in these structures. The behavior of these structures with ADAS devices subjected to near source ground motions are investigated. Three SMRF buildings with five, ten and fifteen-story, with ADAS devices were chosen. The nonlinear time history analysis was used by applying the near source ground motions with PERFORM 3D.V4 and conclusions are drawn upon an energy criterion. The effect of PGA variation and height of the frames are also considered based on the energy criterion.
Mahdi Bayat,Mahmoud Bayat,Iman Pakar 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.1
In this paper we have considered the vibration of parametrically excited oscillator with strong cubic positive nonlinearity of complex variable in nonlinear dynamic systems with forcing based on Mathieu-Duffing equation. A new analytical approach called homotopy perturbation has been utilized to obtain the analytical solution for the problem. Runge-Kutta's algorithm is also presented as our numerical solution. Some comparisons between the results obtained by the homotopy perturbation method and Runge-Kutta algorithm are shown to show the accuracy of the proposed method. In has been indicated that the homotopy perturbation shows an excellent approximations comparing the numerical one.
Forced nonlinear vibration by means of two approximate analytical solutions
Mahmoud Bayat,Mahdi Bayat,Iman Pakar 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.6
In this paper, two approximate analytical methods have been applied to forced nonlinear vibration problems to assess a high accurate analytical solution. Variational Iteration Method (VIM) and Perturbation Method (PM) are proposed and their applications are presented. The main objective of this paper is to introduce an alternative method, which do not require small parameters and avoid linearization and physically unrealistic assumptions. Some patterns are illustrated and compared with numerical solutions to show their accuracy. The results show the proposed methods are very efficient and simple and also very accurate for solving nonlinear vibration equations.