Experimental Behavior of a Full-Scale Housing Section Built with Cold-Formed Steel Shear Wall Panels under Horizontal Monotonic and Cyclic Loading

This paper presents the results of an experimental study on the behavior of the cold- formed steel shear wall panel (CFSSWP) with fibrocement panels as sheathing, when it is subjected in-plane shear deformations and flexural deformation under perpendicular monotonically increasing horizontal loads on the longest plane. A full-scale housing section was built with three walls and a ceiling using commonly used construction details in El Salvador. The strength and stiffness of the experimental specimen tested overcame significantly critical demand imposed by the technical design standards in this country. Additionally, a simplified finite element model was defined with the objective to analyze stresses in the components. The results of the numerical model were similar to the experimental model tested.

See-through reflective optical elements with embedded wavelike films.

The recently proposed optical elements containing semitransparent wavelike films embedded into the transparent material are investigated. Such optical elements do not distort a wave transmitted through them. Novel optical elements can be fabricated using well-known embossing methods. Their possible applications are discussed. The optical elements containing holographic wavelike films can be used for color holography, for augmented reality wearable glasses, as a beam combiner for head-up displays. The optical elements containing diffuse wavelike films can be used as an alternative for tinted car windows, instead of mirror-glass windows in high-rise buildings, for shop-windows, for one-way privacy windows, for printing images on eyeglasses. The scheme of a waveguide display with a single-layer holographic wavelike films is analyzed. The feasibility of the proposed applications is verified by estimation of the optical elements’ parameters and computer simulation, and measurements conducted on an experimental specimen.

THE SEISMIC BEHAVIOR OF BURIED SEABED WALLS IN LIQUEFACTION SOIL

The present study aimed to investigate the seismic behavior of enclosed seawater walls, the buried site of which lies in liquefaction soil. An experimental specimen was manufactured and tested on the seismic table, and a numerical study was also modeled in the ABAQUS software based on the experimental outcomes. In both the experimental and numerical studies, a susceptible liquefaction layer around the root of the wall was considered due to the root lean soil leakage and large lateral pressure, and the soil behind the root caused the failure of the buried section. According to the results, the lateral movement significantly decreased due to the backing effect of this layer on the buried section of the wall. Furthermore, an active wedge was formed from the buried side to the back of the containment, and the braces were overwhelming due to the presence of the locks in the wedge and their movement along with the wedge. The displacement of the crown and foot of the wall decreased with the increased base acceleration and higher frequency of the entrance movement.

Large Deflection of Clamped Curved Beam Under Finite Clamping and Different Combinations of Bending-Stretching

The paper experimentally and theoretically analyses large deflection behaviour of clamped curved beam subjected to finite clamping and combined bending-stretching loads. The experimental specimen is clamped around central location under vertically concave and convex orientations. For each specimen settings, clamping is done by two different torque values. Application of vertical end loads on the clamped concave and convex systems produces two different combinations of bending and in-plane loadings. Large deflection behaviour of the experimental system is modelled theoretically considering geometric nonlinearities coming from combined bending-stretching, non-uniform curvature and asymmetric geometry. Effect of finite clamping is incorporated in the theoretical model through equivalent additional end loads. Due to the involved geometric nonlinearities, analysis is carried out through variational energy principle based incremental Lagrangian approach in curvilinear system and transformed into global frame. The semi-analytical model is successfully validated by comparing with the experimental results. The combined theoretical-experimental study addresses practical complication associated with local deformation at boundaries. In addition, the physically plausible theoretical model may be of interest for simulation of many real world structures with complicating system parameters. Moreover, observations on combined effects of curvature, loading combinations and finite clamping may provide reference for design optimization of equivalent engineering structures.

Analysis of Discharge Characteristics and Fire Risk of Mobile Phone Batteries according to the Concentration of Salt Water

The process of discharging batteries using salt water, when used for the disposal of a lithium-ion (Li-ion) batteries, is likely to cause a fire. However, there is a dearth of studies in the literature on the risk of fire while discharging mobile phone batteries in salt water. In order to investigate the possibility of fire by elucidating the discharge characteristics and the generation of heat, we conducted experiments by varying the concentration of the salt water, number of overlapping batteries, and type of the mobile phone batteries used as experimental specimen. The discharging voltage and the temperature of the batteries were measured, and the fire risk was predicted by analyzing the data. The results of the experiment showed that the higher the salt water concentration, the greater the discharge value of the mobile phone battery and the higher the exothermic temperature. Moreover, the exothermic temperatures of the overlapping batteries were higher than that of the single battery submerged in salt water. The highest exothermic temperature points of the battery occurred at the positive and negative poles.

Discrete Tangent Stiffness Estimation Method for Pseudo Dynamic Test

In pseudo dynamic (PSD) test, researchers have long recognized the importance and potential benefits of utilizing the tangent stiffness of experimental specimen to correct the restoring force and analyze the energy error. However, improving accuracy and efficiency of the instantaneous stiffness estimation still presents a challenge. Based on the theory of discrete curve parameter recognition and the geometrical analysis approach, this paper proposes a discrete tangent stiffness estimation (DTSE) method to estimate the instantaneous tangent stiffness of a single degree of freedom (SDOF) experimental specimen. For different magnitudes of measurement noise, the proposed method can adaptively select and retain a series of latest valid data and ignore outdated information, of which the advantage is highly improving the accuracy and promptness of instantaneous stiffness estimation. The numerical study shows that the DTSE method has better accuracy and promptness of tangent stiffness estimation when compared with other existing methods. In a PSD test involving a sliding isolator, the DTSE method is utilized to analyze the cumulative energy error, the result of which shows the cumulative energy error is negative and decreases gradually. The analysis of experimental results demonstrates that the undershooting error of actuator added extra energy into the PSD testing system. Thus, the proposed method provides a desirable solution to instantaneous stiffness estimation.

Calculation and Experimental Technique for Determining the Damping Properties of Composite Materials

Polymer coatings are widely used for effective vibration damping of sheet or hull structures of different engineering systems. The article presents a calculation and experimental technique that enables improved accuracy and validity of damping properties determination of polymer coatings. Mathematical models to determine the parameters of the experimental specimen having a homogenous strain state of the polymer coating are obtained. Experimentally confirmed that the use of coatings based on adhesive compositions such as "Sprut" increases by 18...28 times the damping capability in metal structures. An addition of fillers in adhesive compositions "Sprut" type in a proportion of 30...50% of its weight reduces by 2.4 times the damping properties of metal structures.

Numerical Modelling of Cylindrical Specimen under Mixed-Mode Loading Conditions

Mixed mode loaded fatigue specimens are not used very frequently. The main reason is that there are still very few qualitative results, which would help with better understanding of how the mode II and mode III are affecting the overall crack propagation. On the other hand, there is considerable number of parts loaded in mixed mode. Studying fatigue failure of roller bearing elements made of polymer material was a motivation to design a new experimental specimen for study of fatigue behaviour of the material loaded in mixed mode. The contribution presents developed FEM model of such specimen with focus on determination of fracture mechanics parameters of propagating cracks.