Papers by Ioannis Mitseas
Journal of physics. Conference series, Jun 1, 2024
Journal of physics. Conference series, Jun 1, 2024
Earthquake engineering and structural dynamics/Earthquake engineering & structural dynamics, May 28, 2024
A novel, practical, and computationally efficient probabilistic methodology for the stochastic ge... more A novel, practical, and computationally efficient probabilistic methodology for the stochastic generation of suites of fully non-stationary artificial accelerograms is presented. The proposed methodology ensures that the produced ground motion suites match a given target spectral mean and target variability for the whole period range of interest. This is achieved by first producing an ensemble of random target spectra with the given mean and variability and then using them to generate artificial, target spectrum-compatible, acceleration time-histories with spectral representation techniques. Spectral correlation can also be assumed for the generated ground motion spectra. Based on the same backbone, two different formulations are proposed for generating spectrum-compatible acceleration time-histories of the non-stationary kind. The distinction between these two variants lies in the techniques employed for modeling the temporal and spectral modulation, focusing on the site-compatibility of the produced records. The first approach uses past-recorded seismic accelerograms as seed records, and the second proposes and uses a new, probabilistic time-frequency modulating function. The outcome of the proposed methodology is suites containing site-compatible ground motion time-histories whose spectral mean and variability match those obtained from any of the usually employed target spectra used in the earthquake engineering practice. An online tool implementing the proposed methodology is also freely provided.
COMPDYN Proceedings, Dec 31, 2022
Mechanical Systems and Signal Processing, Apr 1, 2023
Mechanical Systems and Signal Processing
International Journal of Non-Linear Mechanics
ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part A: Civil Engineering, 2021
An approximate analytical technique for determining the survival probability and first-passage pr... more An approximate analytical technique for determining the survival probability and first-passage probability density function (PDF) of nonlinear multi-degree-of-freedom (MDOF) structural systems subject to an evolutionary stochastic excitation vector is developed. The proposed technique can be construed as a two-stage approach. First, relying on statistical linearization and utilizing a dimension reduction approach the nonlinear n-degree-of-freedom system is decoupled and cast into (n) effective single-degree-of-freedom (SDOF) linear time-varying (LTV) oscillators corresponding to each and every DOF of the original MDOF system. Second, utilizing the effective SDOF LTV oscillator time-varying stiffness and damping elements in conjunction with a stochastic averaging treatment of the problem, the MDOF system survival probability and first-passage PDF are efficiently determined. Applications regarding MDOF structural systems exhibiting highly nonlinear behavior subject to stochastic excit...
An efficient nonlinear stochastic dynamics methodology has been developed for estimating the peak... more An efficient nonlinear stochastic dynamics methodology has been developed for estimating the peak inelastic response of hysteretic multi-degree-offreedom (MDOF) structural systems subject to seismic excitations specified via a given uniform hazard spectrum (UHS), without the need of undertaking computationally demanding non-linear response time-history analysis (NRHA). The proposed methodology initiates by solving a series of inverse stochastic dynamics problems for the determination of input power spectra compatible in a stochastic sense with a given elastic response UHS of specified damping ratio. Relying on statistical linearization and utilizing an efficient decoupling approach the nonlinear N-degree-of-freedom system is decoupled and cast into (N) effective linear singledegree-of-freedom (SDOF) oscillators with effective linear properties (ELPs): natural frequency and damping ratio. Subsequently, each DOF is subject to a stochastic process compatible with the UHS adjusted to th...
Computers & Structures, 2019
Mechanical Systems and Signal Processing, 2019
This is a repository copy of Modal decomposition method for response spectrum based analysis of n... more This is a repository copy of Modal decomposition method for response spectrum based analysis of nonlinear and non-classically damped systems.
Structural Safety, 2018
This paper proposes a novel computationally economical stochastic dynamics framework to estimate ... more This paper proposes a novel computationally economical stochastic dynamics framework to estimate the peak inelastic response of yielding structures modelled as nonlinear multi degreeof-freedom (DOF) systems subject to a given linear response spectrum defined for different damping ratios. This is accomplished without undertaking nonlinear response history analyses (RHA) or, to this effect, constructing an ensemble of spectrally matched seismic accelerograms. The proposed approach relies on statistical linearization and enforces pertinent statistical conditions to decompose the inelastic d-DOF system into d linear single DOF oscillators with effective linear properties (ELPs): natural frequency and damping ratio. Each such oscillator is subject to a different stationary random process compatible with the excitation response spectrum with damping ratio equal to the oscillator effective critical damping ratio. This equality is achieved through a small number of iterations to a pre-specified tolerance, while peak inelastic response estimates for all DOFs of interest are obtained by utilization of the excitation response spectrum in conjunction with the ELPs. The applicability of the proposed framework is numerically illustrated using a 3-storey Bouc-Wen hysteretic frame structure exposed to the Eurocode 8 elastic response spectrum. Nonlinear RHA involving a large ensemble of non-stationary Eurocode 8 spectrum compatible accelerograms is conducted to assess the accuracy of the proposed approach in a Monte Carlo-based context. It is found that the novel feature of iterative matching between the excitation response spectrum damping ratio and the ELP damping ratio reduces drastically the error of the estimates (i.e., by an order of magnitude) obtained by non-iterative application of the framework.
Strojniški vestnik - Journal of Mechanical Engineering, 2016
Vulnerability, Uncertainty, and Risk, 2014
Computers & Structures, 2021
Uploads
Papers by Ioannis Mitseas