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Object-Oriented Comodeling Methodology for Development of Domain Specific DEVS Models
Published in Gabriel A. Wainer, Pieter J. Mosterman, Discrete-Event Modeling and Simulation, 2018
Dynamic loading means that a dynamically linked library loads and unloads at run-time on request. The request to load such a dynamically linked library may be made implicitly at compile-time, or explicitly by the application at run-time.
Modal Identification of a Soil-subway System with Emphasis on Scattering of Seismic Waves Induced by Uniform and Non-uniform Support Excitations
Published in Journal of Earthquake Engineering, 2022
Mohsen Isari, Majid Damadipour, Abbasali Taghavi Ghalesari, Seyyed Kazem Razavi, Reza Tarinejad
In this study, an empirical modal analysis (EMA) approach composed of FRFM-SVD and wavelet transform methods was proposed to identify modal parameters of linear structural systems subjected to arbitrary dynamic loading (e.g. earthquake ground excitations) based on input-output records. The application of this method is limited to structural systems in an elastic situation to use this algorithm. The linear dynamic analysis of a soil-Daikai subway system was carried out using FLAC software. The fundamental assumption in the linear structural analysis is the linearity of the structural response. Therefore, the linear seismic responses of this soil-subway system under Kobe earthquake excitation were used to identify modal parameters (such as damping ratios and natural frequencies) based on the proposed approach. Further, scattering of seismic waves induced by this underground structure was investigated by applying soil–structure interaction effects as well as soil layering effects using coherence function-based random vibration method.
Inverse problem techniques for multiple crack detection in 2D elastic continua based on extended finite element concepts
Published in Inverse Problems in Science and Engineering, 2021
There are several methods to overcome the ill-posedness, amongst which, the regularization techniques are very popular. The main idea of regularization is to include additional constraints to make the problem solvable or stable. There are several regularization methods such as, Tikhonov methods [41], truncated singular value decomposition methods (TSVD) [42], total variation methods [43] and etc. In this respect, Liu et al. [44] proposed a dynamic load identification scheme based on Gegenbauer polynomial expansion theory with Tikhnov regularization for stochastic structures. The authors also proposed a new shpae function method that was combined with interval analysis to determine the dynamic loading on stochastic structures [45]. They employed TSVD regularization technique to solve the inherent ill-posed inverse problem. In this paper, we use a modified version of Tikhonov regularization to identify the stiffness matrix of a cracked body from its displacement responses in the time domain. The objective is to find the closest stiffness matrix to that of the uncracked body. The identified matrix is then compared to the uncracked body stiffness matrix to find the locations of the flaws. The method requires no iterative solution and correctly captures multiple cracks in the presence of high levels of noise.
Finite element analysis of the axial dynamic response and efficiency of pile groups
Published in International Journal of Geotechnical Engineering, 2021
Ossama Salem Ali, Mohamed Sherif Aggour
The use of the finite element method in the study of a single pile under dynamic loading was undertaken by many researchers such as Wu and Finn (1997), Manna and Baidya (2009), Giannakos, Gerolymos, and Gazetas (2012) and Ali, Aggour, and McCuen (2017). In addition, the finite element method was used in modelling of piers subjected to dynamic loading and was studied by Chen et al. (2009) and Halabian, Naeemifor, and Hashemolhosseini (2012). In the study of a group of piles, Petrash, Bounds, and Wong (2011) used the computer program DYNA 5 that is based on the Novak plain strain approach. Kouroussis et al. (2013) used a three-dimensional (3-D) finite element to model dynamic pile–soil–pile interaction in time domain, and Ali (2015) used the ANSYS computer program in the determination of the response of a group of piles under dynamic loading.