This special issue contains selected papers first presented in a short format at ACSM20 (Advances in Coupled Systems Mechanics) held at the Global Education Center for Engineers (GECE) in Seoul, Korea, August 25~29, 2020. ACSM20 was regrouped with 11 other International Conferences, all placed within the framework of The 2020 World Congress on Advances in Civil, Environmental, & Materials Research (ACEM20)/The 2020 Structures Congress (Structures20).

This study is aimed to develop a damping model to accurately predict vibration amplitude reduction for any size of structure. It is developed in the framework of multi-scale analysis, where different sources of energy dissipation at captured at material-scales (e.g.,scale of representative volume element). In particular, we illustrate details for concrete structures, where one needs different failure mechanisms like plasticity, damage and viscosity to represent different sources of dissipation are reproduce the typical hysteresis loops of concrete with both residual deformation and change of initial elastic response. The final step in proposed approach is to account for structure heterogeneities by allowing for variability of elasticity limit, which produces the same exponential (rather than linear decay) of vibration amplitudes, just as in the case of Rayleigh damping. However, contrary to Rayleigh damping calibration that can be done only on a single structure (and for a chosen frequency), the proposed approach can be adapted to any structure size and full interval of frequencies of interest. The price to pay is in terms of nonlinear analysis, which is here rendered very efficient by hybrid-stress formulation to uncouple different damage mechanisms and by using linear evolution equations for internal variables representing such mechanisms. The details illustrated for 1D and 3D concrete model can be easily adapted to other materials, such as steel, soils etc.

Breakwaters are used for the protection of harbors and beaches against wave action. This paper focuses on the analysis of the stability of the caisson-type breakwater under Flip-through wave impacts using a coupled Fluid-Porous model. The fluid hydrodynamic is described by the Volume-averaged Reynolds-Averaged Navier-Stokes (VARANS) equation with k-ε model. The flow in the porous medium and armour layer is simulated by the extended Forchheimerlaw. The developed model is used to estimate the influence of the thickness of armour layer and angle of wave return wall. Thus, a new relation of the overtopping discharge with the thickness of armour layer and angle of wave return wall is established, which can be used to design the structure of breakwater according to the limited value of overtopping wave discharge.

In this paper, we discuss about the notable locking-free techniques of several simple plate bending finite elements for the Reissner-Mindlin plate bending theory. The brief background for Reissner-Mindlin plate theory is presented, in which stress and strain derivation are given along with one-field and two-field variational approaches. Afterwards, we classify several efficient robust techniques in a cluster of main categories to present sequentially, which are all able to overcome the locking phenomenon in thick plate bending problems. Only selective algorithms are programmed to conduct numerical simulations. The corresponding results are compared between these elements to show their performances.

The presentation deals with an investigation on the static and dynamic behavior of a five floors reinforced concrete building supported by a shallow foundation system, called SNSF (Spider Net System Footing). The present study concentrates on the linear static under permanent and life vertical loads and on the free vibrations of the upper structure and the foundations. The study based on performing 3D solid finite elements includes the soil underneath (one layer of 2 m and an additional layer of 9 m). Several aspects are investigated like: the structural analysis of the SNSF foundation compared to a simpler raft foundation and the soil-foundation interaction of the soil and the structure-foundation system on the first frequencies and modes of vibration.

This paper investigates an alternative way to the Raleigh formula to catch con- tributions of damping effects. Nowadays, thanks to the power of new software and effi- cient computational methods, there exist possibility to implement new analysis of damping through multiscale approach. The corresponding homogenization of a representative elemen-tal volume of concrete is used to calculate the effective properties of the composite, since energy dissipation properties such as viscoelasticity are not taken into account. At the end of this work, these methodologies are incorporated into a column of a building subject to seismic action. More precisely, with concrete as a composite material (aggregate+cement), we can use homogenization methods to calculate its effective properties by using the classical approach of a representative elemental volume. This can help to take into account properties of energy dissipation, such as produced by viscoelasticity. Finally, for illustration, the pro- posed methodology is applied to structural analysis of a column under the most unfavorable conditions in a building subject to earthquake action.