## About

MGroup is a numerical simulation lab situated in the Institute of Static Analysis and Seismic Research lab of the Civil Engineering school at the National Technical University of Athens. MGroup is involved in a vast array of research subjects, all revolving around numerical simulations, including:

- Material modeling
- Multiscale analysis
- Uncertainty quantification
- Optimum design
- Machine learning and artificial intelligence
- Accelerated computing and HPC

## Code

MGroup is a proponent of the open-source philosophy and has all of its codes available to the public. Feel free to check out our repository in GitHub

## Lectures

MGroup is actively participating in lecturing, both in the university curriculum and as independent seminars, as shown below:

- Static analysis of structures (statically determinate and indeterminate)
- Structural analysis using FEM
- Stochastic mechanics
- Non-linear and stochastic FEM
- Algorithms and computational methods
- Software engineering and architecture

## Publications

MGroup is active on research with a presence on both international journals and conferences. A list of journal publications sorted by year can be found below.

- Giovanis, D., Papadopoulos V. and Stavroulakis, G., “An Adaptive spectral Galerkin stochastic finite element method using variability response functions”,
*International Journal for Numerical Methods in Engineering*, 104(3), pp. 185–208, 2015. - Giovanis, D. and Papadopoulos V., “Spectral representation-based neural network assisted stochastic structural mechanics”,
*Engineering Structures*, 84, pp. 382-394, 2015. - Papadopoulos, V. and Kokkinos, O., “Transient response of stochastic finite element systems using Dynamic Variability Response Functions”,
*Structural Safety*, 52 (PA), pp. 100-112, 2015. - Papadopoulos, V. and Tavlaki, M., “The impact of interfacial properties on the macroscopic performance of carbon nanotube composites. A FE2-based multiscale study”,
*Composite Structures*, 136, pp. 582-682, 2016. - Fragiadakis M., Giovanis, D. and Papadopoulos, V., “Epistemic uncertainty assessment using Incremental Dynamic Analysis and Neural Networks”,
*Bulletin of Earthquake Engineering*, 14(2), pp. 529-547, 2016. - Kokkinos, O. and Papadopoulos, V., “Robust design with Variability Response Functions; an alternative approach”,
*Structural Safety*, 59, pp. 1-8, 2016. - Papadopoulos, V. and Kalogeris, I., “A Galerkin-based formulation of the probability density evolution method for general stochastic finite element systems”,
*Computational Mechanics*, 57, pp. 701-716, 2016. - Savvas, D., Stefanou, G., Papadopoulos, V. and Papadrakakis, M., “Effect of waviness and orientation of carbon nanotubes on random apparent material properties and RVE size of CNT reinforced composites”,
*Composite Structures*, 152, pp. 870-882, 2016. - Papadopoulos, V., Seventekidis, D. and Sotiropoulos, G., “Stochastic Multiscale modeling of Graphene reinforced composites”,
*Eng. Structures*, 145, pp. 176-189, 2017. - Stavroulakis, G., Giovanis D., Papadopoulos, V. and Papadrakakis, M., “A GPU domain decomposition solution for spectral stochastic finite element method”,
*Comp. Meth. Appl. Mech. Eng*, pp. 327, 392-410, 2017. - Giovanis, D., Papadimitriou, I., Papadopoulos, V. and Straub, D., “Bayesian updating with subset simulation using artificial neural networks”,
*Computer Methods in Applied Mechanics and Engineering*, 319, pp. 124-145, 2017. - Papadopoulos, V. and Kalogeris, I., “Limit analysis of stochastic structures in the framework of the Probability Density Evolution Method”,
*Engineering Structures*, 160, pp. 304-313, 2018. - Papadopoulos, V., Soimoiris, G., Giovanis, D. and Papadrakakis, M., “A neural network-based surrogate model for carbon nanotubes with geometric nonlinearities”,
*Comp. Methds in Appl. Mech and Engineering*, 328, pp. 411-430, 2018. - Papadopoulos, V. and Impraimakis, M., “Multiscale modeling of carbon nanotube reinforced concrete”,
*Comp. Structures*, 182, pp. 251-260, 2017. - Manitaras, T., Papadopoulos, V. and Papadrakakis, M., “Dynamic variability response functions for stochastic wave propagation in soils”,
*Soil Dynamics and Earthquake Engineering*, 97, pp. 60-73, 2017. - Fajardo, K.M., Papadopoulos, V., Halldorsson, B. and Papageorgiou, A., “Earthquake response of liquid storage tanks, accounting for rocking excitation, caused by basin induced surface waves”,
*Earthquake Engineering and Structural Dynamics*(submitted).

- Schillinger, D. and Papadopoulos, V., “Accurate Estimation of Evolutionary Power Spectra for Strongly Narrow-Band Random Fields”,
*Computer Methods in Applied Mechanics and Engineering*, 199 (17-20), pp. 947-960, 2010. - Schillinger, D., Papadopoulos, V., Papadrakakis, M. and Bishoff, M. “Buckling Analysis of Imperfect I-Section Beam-Columns with Stochastic Shell Finite Elements”,
*Computational Mechanics*, 46|(3), pp. 495-510, 2010. - Papadopoulos, V., Stefanou, G. and Papadrakakis, M. “Buckling load variability of cylindrical shells with stochastic imperfections”,
*International Journal for Reliability and Safety*, 5 (2), 191-208, 2011. - Papadopoulos, V. and Kokkinos, O., “Variability response functions for stochastic systems under dynamic excitations”,
*Probabilistic Engineering Mechanics*, 28 , pp. 176-184, (2012). - Papadopoulos, V., Giovanis, D., Lagaros, N. and Papadrakakis, M., “Accelerated subset simulation for reliability analysis using neural networks”,
*Computer Methods in Appied. Mechanics and Engineering,*223-224 , pp. 70-80 (2012). - Savvas, D., Papadopoulos, V. and Papadrakakis, M. “The effect of interfacial shear strength on damping behavior of carbon nanotube reinforced composites”,
*International Journal of Solids and Structures*, 49(26), 3823-3937, 2012. - Papadopoulos, V., Soimiris, G. and Papadrakakis, M. “Buckling analysis of I-section portal frames with stochastic imperfections”,
*Engineering Structures*, 47 , pp. 54-66 2013. - Papadopoulos, V. and Lagaros, N. “Performance-Based Optimum Design of Structures with Vulnerability Objectives”,
*International Journal for Reliability and Safety*, 7 (1) , pp. 75-94, 2013. - Vryzides, I., Stefanou, G., Papadopoulos V., “Stochastic stability analysis of steel tubes with random initial imperfections,
*Finite Elements in Analysis and Design*, - Savvas, D. and Papadopoulos V., “Nonlinear multiscale homogenization of carbon nanotube reinforced composites with interfacial slippage”,
*J. Multiscale Computational Engineering*, 12 (4), pp. 271-289, 2014*.* - Stavroulakis, G., Giovanis, D.G., Papadrakakis, M. and Papadopoulos, V. “A new perspective on the solution of uncertainty quantification and reliability analysis of large-scale problems”,
*Computer Methods in Applied Mechanics and Engineering*, 276, pp. 627-658 2014.

- Papadrakakis, M. and Papadopoulos, V. “A computationally efficient method for the limit analysis of space frames”,
*Journal of Computational Mechanics*, 16(2), pp. 132-141, 1995. - Papadrakakis, M., Papadopoulos, V. and Lagaros, N. “Structural reliability analysis of elastoplastic structures using neural networks and Monte Carlo simulation”,
*Computer Methods in Applied Mechanics and Engineering*, 136, pp. 145-163,1996. - Papadrakakis, M. and Papadopoulos, V. “Robust and efficient solution techniques for the stochastic finite element analysis of space frames”,
*Computer Methods in Applied Mechanics and Engineering*, 134, pp. 325-340, 1996. - Papadopoulos, V. and Papadrakakis, M. “Stochastic finite element-based reliability analysis of space frames”,
*Probabilistic**Engineering**Mechanics*, 13 (1), pp. 53 – 65, 1998. - Papadopoulos, V. and Papadrakakis, M. “Finite element analysis of cylindrical panels with random initial imperfections”,
*Journal of Engineering Mechanics*130, (8), pp. 867-876, 2004. - Papadopoulos, V. and Papadrakakis, M. “The effect of material and thickness imperfections on the buckling load of shells with random initial imperfections”,
*Computer Methods in Applied Mechanics and Engineering*, 194, (12-16), pp. 1405-1426, 2005. - Papadopoulos, V., Deodatis, G. and Papadrakakis, M. “Flexibility-based upper bounds on the response variability of simple beams”,
*Computer Methods in Applied Mechanics and Engineering*, 194, (12-16), pp. 1385-1404, 2005. - Papadopoulos, V. and Deodatis, G. “Response variability of stochastic frame structures using evolutionary field theory”,
*Computer Methods in Applied Mechanics and Engineering*, 195 (9-12), pp. 1050-1074, 2006. - Papadopoulos, V., Papadrakakis, M. and Deodatis, G. “Analysis of mean response and response variability of stochastic finite element systems”,
*Computer Methods in Applied Mechanics and Engineering,*195 (41-43), pp. 5454-5471, 2006. - Lagaros, N. and Papadopoulos, V. “Optimum design of shell structures with random geometric, material and thickness imperfections”,
*International Journal of Solids and Structures*, 43 (22-23), pp. 6948-6964, 2006. - Papadopoulos, V and Inglessis, P. “The effect of imperfect boundary conditions on the buckling analysis of cylindrical shells with random geometric material and thickness imperfections”,
*International Journal of Solids and Structures*, 44 (18-19), pp. 6299-6317, 2007. - Papadrakakis, M., Papadopoulos, V., Lagaros, N., Oliver, J., Huespe, A.E. and Sánchez, P. “Vulnerability analysis of large concrete dams using the Continuum Strong Discontinuity Approach and neural networks”,
*Structural Safety*, 30 (3), pp. 217-235, 2008. - Moschonas, I.F., Kappos, A.J., Panetsos, P., Papadopoulos, V., Makarios T. and Thanopoulos, P. “Seismic fragility curves for greek bridges: methodology and case studies”,
*Bulletin of Earthquake Engineering*, 7(2), pp. 439-468, 2009. - Papadopoulos, V. Charmpis, D.C. and Papadrakakis, M. “A computationally efficient method for the buckling analysis of shells with stochastic imperfections”,
*Computational Mechanics*, 43 (5), pp. 687-700, 2009. - Papadopoulos, V., Stefanou, G. and Papadrakakis, M. “Buckling analysis of imperfect shells with stochastic non-Gaussian material and thickness properties”,
*International Journal of Solids and Structur**es,*46(14-15), pp. 2800-2808, 2009. - Papadopoulos, V. and Lagaros, N. “Vulnerability-based robust design optimization of imperfect shell structures”,
*Structural Safety*, 31(6), pp. 475-482, 2009.

## The team

#### Vissarion Papadopoulos

Vissarion is an associate professor at the school of Civil Engineering of the National Technical University of Athens and founding member of the group. He is active in the field of material design, stochastic processes, computational mechanics and optimization

#### George Stavroulakis

George is a senior researcher, software architect and founding member of the group. He is active in the field of high performance and accelerated computing, domain decomposition and algorithms.

#### Odysseas Kokkinos

Odysseas is a senior researcher and he is active on stochastic processes and optimization

#### Dimitris Giovanis

Dimitris is a senior researcher and he is active on stochastic processes, machine learning and artificial neural networks

#### Dimitris Tsapetis

Dimitris is a doctoral student at the school of Civil Engineering of the National Technical University of Athens. Dimitris is active in isogeometric analysis and computational mechanics

#### Maria Tavlaki

Maria is a doctoral student at the school of Civil Engineering of the National Technical University of Athens. Maria is active on multiscale analysis, optimization and computational mechanics

#### Serafeim Bakalakos

Serafeim is a doctoral student at the school of Civil Engineering of the National Technical University of Athens. Serafeim is active on X-FEM, optimization and numerical algorithms

#### George Soimiris

George is a doctoral student at the school of Civil Engineering of the National Technical University of Athens. George is active on non-linear analysis, surrogate modelling and numerical algorithms

#### Gerasimos Sotiropoulos

Gerasimos is a doctoral student at the school of Civil Engineering of the National Technical University of Athens. Gerasimos is active on multiscale analysis, computational mechanics and HPC

#### Yannis Kalogeris

Yannis is a doctoral student at the school of Civil Engineering of the National Technical University of Athens. Yannis is active on stochastic mechanics and processes

## Advisory

#### Manolis Papadrakakis

The MGroup is advised by emeritus professor Papadrakakis, founding member of the group, with a long-standing career and contribution in the field of computational mechanics and HPC