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Nonlinear dynamic analysis of soil nail walls considering different modeling approaches
Mahdi Bayat,Amir Homayoon Kosarieh,Mehran Javanmard 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.6
Soil nailing is one of the most common and important techniques to exchange conventional retaining systems for deep excavation. This approach contains a significant saving in cost and time of construction compared to conventional retaining systems. In this paper, an attempt has been made to evaluate the dynamical response of a deep vertical excavation on ground of 8 m height using soil nail wall. It has been tried to investigate the effects of different modeling approaches on the dynamic response of soil-nailed walls by considering the three behavioral methods; Mohr Coulomb (MC), hardening soil (HS) and hardening soil model with Small-Strain stiffness ensued from small strains (HSS). Nonlinear time history analysis has been implemented to compare the displacements under the sinus excitation with 0.5, 1, and 1.5 Hz with PGA= 0.3 g. Different points along the height of the wall are selected and considered. At the last part of this paper, incremental dynamic analysis (IDA) was implemented to the soil nail wall to consider the effect of the different earthquake records on the response of the wall. The IDA curve is also presented for the considered soil nail wall.
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.
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.
Accurate analytical solutions for nonlinear oscillators with discontinuous
Mahdi Bayat,Mahmoud Bayat,Iman Pakar 국제구조공학회 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
Mahdi Bayat,Iman Pakar,Mahmoud Bayat 국제구조공학회 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.
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.
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.
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.
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.
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.