This study synthesizes the use of chemicals to prevent one of common concrete durability problems, alkali-silica reaction (ASR), and can help researchers (i) identify widely used potential chemicals and evaluate these chemical solutions to prevent ASR with proper understanding of mechanisms, and (ii) to identify the research gaps in order to develop guidelines and implementation plan on the use of these chemicals for future research.

n this paper, armchair rectangular monolayer graphene nanoplates were analyzed based on the assumption of orthotropic properties with different boundary conditions. For this purpose, the nonlocal elasticity and Kirchhoff theories were applied to analyze the small-scale effects on the armchair monolayer graphene nanoplates and obtain the static equation of the graphene nanoplates, respectively. As there were no readily accurate answers to the analyses of all the problems associated with nanoplates of different boundary and geometrical conditions, numerical methods were employed for obtaining approximate responses. One of the capable approaches to the analyses of the differential equations governing these types of plates is the meshless method. In this research, the Discrete Least Squares Meshless (DLSM) method was employed for the static analysis of rectangular nanoplates with different boundary conditions besides assessing the effect of nonlocal coefficient amount on the nanoplate deflection. According to the results of this investigation, it could be concluded that the method utilized here was suitable for solving the problems of nano-dimensions compared to the analytical and Galerkin meshless methods.

In this paper, a smoothed weighted function with the compact support is suggested to improve the numerical accuracy of blending elements for the extended finite element method (XFEM) applied to the crack problem. Such a weight function consists of the shape functions used for the meshless method, reflecting the characteristics of the enriched bases inside the blending element. The effectiveness of this weight function is validated through the numerical examples.

The use of elastic elements in actuators can be effective in improving their performance. The present paper examines the different layouts of the elastic element in actuators, choosing the appropriate design, and then designing a series elastic actuator for use in an active knee orthosis. For this purpose, the design elements of actuators were extracted using the knee data for walking. In the next step, considering the effect of the spring stiffness on the energy consumption and actuator’s peak power, its optimum amount for gait was calculated. Afterwards, the effect of adding the spring has been shown at an optimal value. Since the human knee in a gait cycle involves position and force control, designing an efficient controller to track the force and position of the knee during the gait cycle is the next section of this study. Due to the specific application of this actuator, its volume and size are important for the user. For this reason, it is necessary to design and construct an actuator with a suitable size and weight, with good output. For this purpose, a lightweight and low volume actuator was fabricated.

Failure analyses require more and more reliable and robust approaches to structural response prediction. This represents a quite complex task to be accomplished especially when dealing with historical or ancient constructions in seismic geographic areas. The paper is aimed at providing approaches to the analysis of buildings alternative to simplified methods usually adopted in professional practice, which do typically involve drastic simplifications of the fabric. The approach allows developing full holonomic non-linear analyses for forecasting the behavior of structural panels present in the structural system, and it results in higher reliability and flexibility than ordinary procedures that are generally adopted in commercial software and are typically based on gross simplifications of the real structure. The presented method allows taking into account the real geometry of the masonry building under analysis, also including a number of elements such as architraves, tendons or reinforcements possibly incorporated into the walls. Besides the consistent improved reliability in performing structural analyses under quasi-static loads, the main potential of the approach is related to the possibility of developing its extension for performing dynamic analyses quite easily.

This paper presents a numerical investigation on the flexural performance of a novel cementitious reinforced GEM-TECH material using finite element method. A discrete nonlinear FE model using the commercial software ANSYS was employed to model a steel-reinforced GEM-TECH beam. Element SOLID65 was used to model the cementitious material while LINK180 element was used to model the reinforcing bars and stirrups. For model validation, FEA results and crack plots were compared to those obtained from the experimental results of five reinforced GEM-TECH beams: three beams designed with target density of 1810 kg/m3 and two beams with target density of 1600 kg/m3. Both load-deflection plots and the failure mode crack plots predicted by the FE model were in good agreement with the experimental results.

In the present paper, the theory of generalized photo-thermoelasticity under fractional order derivative was used to study the coupled of thermal, plasma, and elastic waves on unbounded semiconductor medium with a cylindrical hole during the photo-thermoelastic process. The bounding surface of the cavity was traction free and loaded thermally by exponentially decaying pulse boundary heat flux. The medium was considered to be a semiconductor medium homogeneous, and isotropic. In addition, the elastic and thermal properties were considered without neglecting the coupling between the waves due to thermal, plasma and elastic conditions. Laplace transform techniques were used to obtain the exact solution of the problem in the transformed domain by the eigenvalue approach and the inversion of Laplace transforms were carried out numerically. The results were displayed graphically to estimate the effect of the thermal relaxation time and the fractional order parameters on the plasma, thermal and elastic waves.

In this paper, the edgewise and flatwise compressive behaviour of an innovative sandwich panel, mainly developed for quick assembly of post-disaster housing as well as load bearing panels for pre-fabricated modular construction and semi-permanent buildings, is investigated experimentally and by finite element modelling. The panel is composed of two 3-D high-density polyethylene (HDPE) sheets as the skins, filled with high-density Polyurethane (PU) foam as the core. HDPE sheets manufactured with a studded surface considerably enhance the stress distribution and buckling performance of the sandwich panel. Material characterisation tests and flatwise compression and edgewise compression experiments were performed in accordance with ASTM standards to evaluate the compressive strength and the load-carrying behaviour of the sandwich panels. A finite element analysis and validation were also conducted to model the compressive behaviour of sandwich structures. Results demonstrate that the developed sandwich panel exhibits very good compressive performance.