Since the recent arising of advanced nano-technologies, as well as of innovative engineering design approaches, nanoporous materials have been extensively studied in the last two decades, leading to a considerable worldwide research interest in both industrial and academic domains. Generally characterised by high specific surface area, uniform pore size and rich surface chemistry, nanoporous materials have allowed for the development of challenging ultra-high performance devices with tailorable properties, finding widespread application in several technical fields, including civil and environmental engineering, petroleum and chemical industries, aeronautics and biomechanics. In order to fulfil to these promising applications, one of the most fundamental research aspect consists in characterising and predicting the strength properties of these materials, as dependent on the size of voids. Since the current lack of an exhaustive benchmarking evidence, as well as of a comprehensive theoretical modelling, the central purpose of the present thesis consisted in: • investigating strength properties of in-silico nanoporous samples via Molecular Dynamics computations. In detail, a parametric analysis with respect to the void radius and for different porosity levels has been carried out, by considering different loading paths with a wide range of triaxiality scenarios. As a result, the influence of void-size effects on the computed strength properties has been clearly quantified, also highlighting the dependence of the predicted material strength domain on the three stress invariants; • establishing engineering-oriented theoretical models able to predict macroscopic strength properties of nanoporous materials, by properly accounting for void-size effects. To this end, theoretical approaches based on both non-linear homogeniza- tion techniques and kinematic limit-analysis strategies have been proposed. As a result, closed-form macroscopic strength criteria have been derived, allowing for a consistent description of void-size effects and taking into account different local plastic behaviours.