Numerical and Experimental Study of Five-Layer Non-Symmetrical Paperboard Panel Stiffness

This paper concerns the analysis of five-layer corrugated paperboard subjected to a four-point bending test. The segment of paperboard was tested to determine the bending stiffness. The investigations were conducted experimentally and numerically. The non-damaging tests of bending were carried out in an elastic range of samples. The detailed layers of paperboard were modelled as an orthotropic material. The simulation of flexure was based on a finite element method using Ansys® software. Several material properties and thicknesses of papers in the samples were taken into account to analyse the influence on general stiffness. Two different discrete models based on two geometries of paperboard were considered in this study to validate the experimental stiffness. The present analysis shows the possibility of numerical modelling to achieve a good correlation with experimental results. Moreover, the results of numerical estimations indicate that modelling of the perfect structure gives a lower bending stiffness and some corrections of geometry should be implemented. The discrepancy in stiffness between both methods ranged from 3.04 to 32.88% depending on the analysed variant.

Nonlinear modelling of the seismic response of masonry structures: Calibration strategies

In this paper, a simple and practitioners-friendly calibration strategy to consistently link target panel-scale mechanical properties (that can be found in national standards) to model material-scale mechanical properties is presented. Simple masonry panel geometries, with various boundary conditions, are utilized to test numerical models and calibrate their mechanical properties. The calibration is successfully conducted through five different numerical models (most of them available in commercial software packages) suitable for nonlinear modelling of masonry structures, using nonlinear static analyses. Firstly, the panel stiffness calibration is performed, focusing the attention to the shear stiffness. Secondly, the panel strength calibration is conducted for several axial load ratios by attempts using as reference the target panel strength deduced by well-known analytical strength criteria. The results in terms of panel strength for the five different models show that this calibration strategy appears effective in obtaining model properties coherent with Italian National Standard and Eurocode. Open issues remain for the calibration of the post-peak response of masonry panels, which still appears highly conventional in the standards.

Mechanical Behavior of the Reinforced Retaining Wall Subjected to Static Load

To study the mechanical behavior and influence factors of the reinforced retaining wall under the static load, numerical simulation of the reinforced retaining wall is conducted by finite element analysis, and its mechanical behavior and influencing methods are studied in accordance with relevant theories. The results showed that the properties of back fill, reinforced spacing, reinforced stiffness, reinforced length, and panel stiffness all affect the mechanical behavior of retaining walls. According to the example calculations of different wall heights, the distribution of panel horizontal displacement and maximum tensile stress are analyzed. The gravel with good gradation has better durability and can reduce the amount of reinforcing steel; with the decrease of the reinforcement spacing, the deformation of the wall panel will become smaller, and the reinforcement effect will be improved; the length of reinforcement is not the longer the better, and the deformation of wall panel can be minimized at the suitable length; the larger the elastic modulus of the wall panel, the smaller the deformation of the wall panel will be.

Numerical Assessment of Lateral Deflection Equation of Single-Storey Light-Frame Wood Shearwalls

Based on the decomposition of the deflection into bending, panel shear, nail slip, and base rotation terms, the nonlinear four-term equation specified by the Canadian wood design code provides an estimate of the total lateral deflection of light-frame wood shear walls. This paper reports the creation of a numerical procedure for separating the responses for each term using a detailed nonlinear finite element modeling (FEM) that simulates individual components of shear walls. Since sheathing panel stiffness is not considered in computations of the bending term, the study reveals that bending deformation results calculated using the equation are more conservative than the FEM results. The nail slip term does not reflect the real nail base connection properties. A new equilibrium equation for determining the lateral deflection due to base rotation is presented. The equation is generally conservative because of the omission of some practical considerations.

Transverse fastening reinforcement of sandwich panels with upcycled bottle caps core

This work describes the use of transverse reinforcement in eco-friendly sandwich panels made from aluminium skins and a core of upcycled bottle caps. The Design of Experiments technique identifies the effect of the position of the metal rivets on the panel. The results show a moderate increase in strength and a significant enhancement of the sandwich panel stiffness when the rivets are placed on the upper skin, with a remarkable improvement in terms of the core shear modulus. The use of metal rivets has also increased the specific mechanical strength and stiffness of the panels, which highlights the effectiveness of the transverse reinforcement in bottle caps panels.

Cross-Laminated Secondary Timber: Experimental Testing and Modelling the Effect of Defects and Reduced Feedstock Properties

The construction industry creates significant volumes of waste timber, much of which has residual quality and value that dissipates in conventional waste management. This research explored the novel concept of reusing secondary timber as feedstock for cross-laminated timber (CLT). If cross-laminated secondary timber (CLST) can replace conventional CLT, structural steel and reinforced concrete in some applications, this constitutes upcycling to displace materials of greater environmental impacts. The fabrication process and mechanical properties of CLST were tested in small-scale laboratory experiments, which showed no significant difference between the compression stiffness and strength of CLST and a control. Finite element modelling suggested that typical minor defects in secondary timber have only a small effect on CLST panel stiffness in compression and bending. Mechanically Jointed Beams Theory calculations to examine the potential impacts of secondary timber ageing on CLST panels found that this has little effect on compression stiffness if only the crosswise lamellae are replaced. Since use of secondary timber to make CLST has a more significant effect on bending stiffness, effective combinations of primary and secondary timber and their appropriate structural applications are proposed. The article concludes with open research questions to advance this concept towards commercial application.

Influence of Nonsymmetric Steel Sandwich Panel Joints on Response and Fatigue Strength of Passenger Ship Deck Structures

Present paper investigates the factors contributing to the stress response of steel sandwich panel deck joints when applied into the hull girder of modern passenger vessel. The emphasis is put on the fatigue analysis, which is the critical design criterion in application of these structures to ships. Two types of joints are considered, i.e., a symmetrical and a nonsymmetrical prismatic joint with respect to the geometrical midplane of the sandwich panel. Stiffness properties are derived for the joints in order to enable the modeling of sandwich structures as part of the hull girder finite element model. The influence of sandwich joints to hull girder response is studied. Notch stress analysis is used for the fatigue strength estimation. The applicability of notch stress method for steel sandwich panels is validated with experiments. The investigation shows that the fatigue strength of steel sandwich panels does not depend only on local stress concentration factors at details, but also on the global stiffness of the structural hull girder system, the sandwich panels, and thus the joint response must be taken into account.

The Effect of Perforation on the Dynamics of a Flexible Panel

Introduction of holes into plate-like structures is commonly found as one of the practical noise control measures to reduce sound radiation. However, perforation also reduces the panel stiffness and hence increases its vibration. The discussion on this effect is lacking and hence this paper discusses the dynamics of a perforated panel from the results obtained from Finite Element (FE) model. Different hole geometries and arrangement are simulated to investigate their effect on the plate mobility. In general, it is found that increasing the perforation ratio increases the plate mobility. For a fixed perforation ratio, the mobility increases at high frequency (above 1 kHz) for a smaller hole density in the plate. The plate with holes concentrated at the middle shows the largest increase of vibration around the plate centre compared to those uniformly distributed or away from the middle and concentrated at the plate edges. This is because as the hole separation becomes smaller, the reduction of the global stiffness around the mid area of the plate becomes greater. This also corresponds to the finding here that the mobility is greater at the vicinity of the hole. Different conditions of the plate edges are found to give consistent trend of the effect of perforation.