Development of Energy-Dissipating Device for Rockfall and Debris-Flow Barriers

In this study on the development of energy-dissipating devices, a significant component of the ring-net system was investigated for the localization of a high-performance rockfall fence and debris flow barriers. The energy-dissipating device was developed as a structure that dissipated the resistance and frictional forces generated by the pipe passing through two steel bars, and the tensile force was transmitted by utilizing the pipe deformation. The performance of the developed energy-dissipating device was verified through simulation analysis and tensile tests. It was confirmed that the most effective dissipating device was made of a D60.5-3.2t pipe subjected to a rolling interval of 40 mm, and the device exhibited an energy-dissipating performance of 52.8-60.2 kJ/m.

Self-Centering Steel Frame Systems for Seismic-Resistant Structures

This paper introduces a review of self-centering steel frame systems for seismic-resistant structures. The components and basic mechanisms of the developing posttensioned connections and self-centering braces are briefly introduced. The structural details and seismic behaviors of the self-centering systems proposed in recent years, including connections, energy dissipating braces, and steel frames, are condensed in categories. The theoretical and experimental results indicated that self-centering action could minimize residual deformation and structural damage. The energy dissipating capability of the self-centering systems is greatly enhanced by the application of energy dissipating device. The shape memory alloys (SMAs) and prepressed springs which exhibited great potential in energy dissipation and recentering capability have been studied increasingly in recent years. Abundant numerical models were propounded to investigate the cyclic response of these self-centering systems. The current research challenges and the critical issues which need further study are discussed at the end of this paper.

Heating of Long-Stroke Magnetorheological Fluid Damper

Magnetorhelogical (MR) dampers are gradually used in military devices for shock isolation and civil structures for suppressing earthquake-induced shaking and wind-induced vibrations because of their mechanical simplicity, high dynamic range, low power requirements, large force capacity and robustness. Since MR fluid dampers are energy-dissipating device, the issues of heat generation and dissipation is important. In this study, phenomenon of viscous heating and consequent temperature increase in a long-stroke MR damper are presented. In addition, a theoretical model is developed which predicts the temperature increase in the long-stroke MR damper. This model is solved numerically and a new coupling method was proposed to analyze the electromagnetic-thermal coupling problem on the basis of the mechanism of coupled field. Aim at the high frequency of piston head moving back and forth, as well as the changing current, the simulation model is established. The results show that the temperature effect on the damping force is significant and provide a theoretical basis and calculation method for the design and analysis of long-stroke MR damper.

Effect of Width-to-Thickness Ratio on Large Deformation in Shear Panel Hysteresis Damper Using Low Yield Point Steel

Recently, building and other civil engineering structures are built with energy dissipating device in order to reduce the damages caused by earthquake. There are a number of seismic energy dissipating device and steel dampers are among many energy dissipation device which is widely used because they are easy for construction, maintenance and low cost. Shear panel damper (SPD) is a type steel damper that dissipates energy by metallic deformation or using hysteresis of material as a source of energy dissipation. Low yield point steel is a good material to be used as a hysteresis damper since it has excellent ductility performance. Nonlinear finite element analysis was carried out to predict the large deformation and hysteretic behavior of SPD using low yield point steel (SLY120) for different width-to-thickness ratio. In order to verify the analysis simulation, quasi-static loading was also conducted and from the comparison a satisfactory result was found.

The collapse of thick-walled metal tubes with wide external grooves as controllable energy-dissipating devices

This article focuses on the experimental and theoretical investigation of the axial crushing behaviour of thick-walled tubes with a number of wide grooves, cut from their outer surface, under both static and dynamic loading. While this structure is subjected to axial loading, plastic deformation occurs within the space of each wide groove, and thick portions (grooveless areas) control and stabilize the collapsing of grooved thick-walled tubes. Therefore, the kinetic energy is dissipated by the plastic collapsing of the structure between grooves. In the present study, quasi-static compression tests of specimens with various geometric parameters are performed. Dynamic tests of some specimens using a drop hammer apparatus are also carried out to study the dynamic effects on the collapsing and energy absorption behaviour of the shock absorber. Numerical simulations of axial crushing of the shock absorber under both quasi-static and impact loading, using LS-DYNA finite-element explicit code, are also carried out in this article, and their results are verified with experimental findings. Based on experimental studies, an analysis with consideration of strain hardening effects to predict mean crushing load and energy absorption of the structure under axial compression is developed. Through the performed experimental, numerical, and analytical studies, major parameters in the design of the shock absorber are characterized and possible collapse modes of deformation during axial crushing of the structure are identified. In the present study, experimental and theoretical studies show that the introduced structure can be considered as an efficient energy-dissipating device since it provides favourable crashworthiness characteristics.

Elasto-Plastic Model of a Seismic Energy–Dissipating Device

A model of a seismic energy–dissipating device is formulated. The dissipating element is a U-shaped strip that undergoes a large rolling-bending deformation while confined between parallel rigid walls. The strip is divided into a number of rigid elements pivoted to one another in a chainlike fashion. A step-by-step solution is developed by considering small increments in the applied load. Increments in the bending moments arising at the pivots are expressed in terms of the changes in the angles between adjoining elements on the basis of corresponding changes in stresses acting on discrete strips into which the cross-section is divided. The stresses are calculated by means of a bilinear elasto-plastic model. The solution keeps track of the points at which contact forces with the constraining walls are developed. Examples are worked out resulting in hysteretic cycles that are compared with published experimental results.