Structural Energy Dissipation Research Articles

Impact resistance of unequal diameter double U-shaped metal energy dissipation bearing

To effectively improve energy dissipation buffer performance in shed tunnel and building roof rockfall disasters, we designed and developed a metal energy dissipation buffer bearing for an overhead roof rockfall protection system and studied its impact resistance through an experiment using the finite element method. The results showed that the energy dissipation capacity of the unequal diameter double U-shaped bearing increased linearly with displacement, and it could be reused by mechanical stretching. Hence, it was an ideal energy dissipation bearing device. The optimal inner diameter ratio of the upper and lower U-shaped structure was 5/9, and the structural load-bearing and energy dissipation capacity could be adjusted by changing the thickness of the structure. The strain mode of the structure was large deformation in geometry and small deformation in material; hence, the structure gave full play to the deformation performance of the material. The structure could be used repeatedly, and the cushioning performance remained unchanged. These conclusions provide a scientific basis for the design of roof sheathing and tunnel sheds in practical engineering.

Performance optimization and loading rate-dependency of friction dampers with non-metallic friction materials

Non-Asbestos Organic (NAO) is widely used in automobile braking systems due to its low cost and stable performance. Meanwhile, NAO is also suitable for seismic energy dissipation of building structures, but further research was required. Configuration and loading rate are significant factors affecting the hysteretic performance of the friction damper. Thus, cyclic loading tests were conducted to evaluate the friction behavior of friction dampers with non-metallic friction pads (Non-Asbestos Organic (NAO) and Polytetrafluoroethylene (PTFE)), and the friction pairs were NAO-Steel and PTFE-Steel, respectively. A total of 13 specimens were designed to comparatively analyze the effects of the following factors on the mechanical performance of the friction damper: the configuration of the friction damper, loading rate, and reloading process after a reassembly. Firstly, some unnecessary friction needed to be avoided to keep the stable performance of the damper, such as the contact friction between the slot of the inner steel plate and friction pads or bolts. Secondly, the normal force of both NAO and PTFE friction dampers reduced gradually during the loading process. The former showed a higher cumulative loss rate, which increased with the initial nominal pressure. Again, the dynamic friction coefficients of NAO and PTFE friction dampers tended to be constant under high-speed loading, which was remarkably higher than that under low-speed loading. The dynamic friction coefficients of NAO and PTFE friction dampers were suggested to be 0.229 and 0.121 for structural analysis, respectively. Finally, compared with the first test of the friction damper, the reloading test results after a reassembly showed excellent reusability of both NAO and PTFE friction dampers.

Global sensitivity analysis on debris flow energy dissipation of the artificial step-pool system

For the prevention of debris flow hazards, step-pool and other energy dissipation structures have a bright future due to their economic and efficiency. In this paper, the sensitivity of the debris flow energy dissipation process and the correlation of factors were studied. First, the elementary effect method was adopted to analyze the sensitivity of factors and screen the insensitive factors. Then, the variance-based sensitivity analysis was applied to obtain the higher-order sensitivities of the remaining sensitive factors. Each numerical example was simulated by the material point method (MPM). The results show that the internal friction angle, cohesion and height of artificial step-pool units were the most important factors. These three factors show significant higher-order sensitivities. It is found that the energy dissipation of debris flow mainly depended on its internal friction angle and cohesion. The research method can be extended to most kinds of nonlinear geotechnical engineering problems.

A new concept for superior energy dissipation in hierarchical materials and structures

We propose a new conceptual approach to reach unattained dissipative properties based on the friction of slender concentric sliding columns. We begin by searching for the optimal topology in the simplest telescopic system of two concentric columns. Interestingly, we obtain that the optimal shape parameters are material independent and scale invariant. Based on a multiscale self-similar reconstruction, we end-up with a theoretical optimal fractal limit system whose cross section resembles the classical Sierpiński triangle. Our optimal construction is finally completed by considering the possibility of a complete plane tessellation. The direct comparison of the dissipation per unit volume δ with the material dissipation up to the elastic limit δel shows a great advantage: δ∼2000δel. Such result is already attained for a realistic case of three only scales of refinement leading almost (96%) the same dissipation of the fractal limit. We also show the possibility of easy recovering of the original configuration after dissipation and we believe that our schematic system can have interesting reliable applications in different technological fields.Interestingly, our multiscale dissipative mechanism is reminiscent of similar strategies observed in nature as a result of bioadaptation such as in the archetypical cases of bone, nacre and spider silk. Even though other phenomena such as inelastic behavior and full tridimensional optimization are surely important in such biological systems, we believe that the suggested dissipation mechanism and scale invariance properties can give insight also in the hierarchical structures observed in important biological examples.

Study on Numerical Model and Dynamic Response of Ring Net in Flexible Rockfall Barriers

Developing reliable, sustainable and resilient infrastructure of high quality and improving the ability of countries to resist and adapt to climate-related disasters and natural disasters have been endorsed by the Inter-Agency Expert Group on Sustainable Development Goals (IAEG-SDGs) as key indicators for monitoring SDGs. Landslides pose a serious threat to vehicle traffic and infrastructure in mountain areas all over the world, so it is urgent and necessary to prevent and control them. However, the traditional rigid protective structure is not conducive to the long-term prevention and control of landslide disasters because of its poor impact resistance, high material consumption and difficult maintenance in the later period. Therefore, this study is aimed at the flexible rockfall barriers with good corrosion resistance, material saving and strong cushioning performance, and proposes a fine numerical model of a ring net. This model is used to simulate the existing experiments, and the simulation results are in good agreement with the experimental data. In addition, the numerical model is also used to study the influence of boundary conditions, rockfall gravity and rockfall impact angle on the energy consumption of the ring net. It is indicated that the fixed constraint of four corners increases the deformability, flexibility and energy dissipation ability of the ring net. Apart from that, the influence of gravity on the energy dissipation of the overall protective structure should not be neglected during the numerical simulation analysis when the diameter of rockfall is large enough. As the impact angle rises, the impact energy of the rockfall on the ring net will experience a gradual decline, and the ring at the lower support ropes will be broken. When the numerical model proposed in this study is used to simulate the dynamic response of flexible rockfall barriers, it can increase the accuracy of data and make the research results more credible. Meanwhile, flexible rockfall barriers are the most popular infrastructure for landslide prevention and control at present, which improves the ability of countries to resist natural disasters to some extent. Therefore, the research results provide technical support for the better development and application of flexible rockfall barriers in landslide disasters prevention and control, and also provide an important and optional reference for evaluating sustainable development goals (SDGs) globally and regionally according to specific application goals.

Seismic fragility assessment of traditional air-cooled support structure and air-cooled support energy dissipation structure based on IDA method

In this paper, the effectiveness of the modeling method is verified by the finite element analysis of the preliminary test. Three finite element models of traditional air-cooled support structure, ‘large diameter RC tubular columns + LBRB’ energy dissipation structure and ‘small diameter RC tubular columns + LBRB’ energy dissipation structure are established. Based on IDA method, the fragility of air-cooled support structure and energy dissipation structures is studied. The study shows that the addition of LBRB can effectively improve the horizontal-torsional coupling phenomenon of the structure, improve the ductility and seismic performance, and reduce the failure probability of the structure. Adding LBRBs and reducing the diameter of RC tubular columns can play the role of LBRB energy dissipation to a greater extent, so that the structure can obtain stronger anti-collapse capacity and better economy, which is more conducive to the realization of seismic performance-based fortification goal. It is suggested that three-dimensional ground motion input should be used for fragility analysis. If the dimension of ground motion input is reduced, the assessment results will be biased to danger.

Design optimization of fuzzy controllers in building structures using the crystal structure algorithm (CryStAl)

The current study uses a recently-developed metaheuristic method called Crystal Structure Algorithm (CryStAl) to achieve optimized vibration control in structural engineering. More specifically, this algorithm, which is inspired by the well-established crystallographic principles underlying the formation of crystalline solids in nature, is applied to the optimization of fuzzy logic controllers in building structures. To demonstrate the capability of this method in solving real engineering problems, two real-size building structures, one with three and the other with twenty stories, are considered. The fuzzy controllers are implemented through an active control system to control the seismically-induced vibrations of the structures intelligently. The evaluation criteria utilized to assess the overall performance of the optimization method applied to the fuzzy control system are presented and discussed. Through nonlinear structural analyses, the ductility, energy dissipation, and other nonlinear characteristics of the structures are also considered as the structural responses to be controlled. The computational results obtained from this novel metaheuristic algorithm are compared with those of the other expert systems from the optimization literature. The findings of this paper demonstrate that the Crystal Structure Algorithm is capable of outranking the other methods in the majority of considered cases.

Experimental and theoretical analysis of novel shear - Flexural combined metallic damper

Energy devices are generally installed to improve the structural energy dissipation capacity and damping with the aim of absorbing the input energy and decreasing the damage of the parent structure. One of the most widely employed energy devices is metallic damper. This paper proposed a novel shear - flexural combined (SFC) metallic damper, in which the shear plate was clamped by the flexural plates on both sides to engender the interactive work between them. One pure shear and four SFC dampers were prefabricated with the identical nominal yield strength. Different shear - flexural thickness ratios (ts/tf) and spaces of flexural plates (s) were applied for the tested specimens. Cyclic tests were then performed to reveal their hysteretic performance and mechanical behavior. Strain distributions of shear and flexural plates indicated that the flexural plate provided satisfactory constraints for the shear plate to form local buckling between the adjacent two flexural plates in the post buckling stage. A high ts/tf might lead torsional failure of flexural plates due to the contact force induced by the buckled part of shear plate. More importantly, a modified force - displacement model was proposed to predict the mechanical behavior of SFC dampers. The buckling strength of shear plate was discussed to make the modified model coincide well with the experimental data. The experimental and analytical results confirmed that the proposed SFC damper had superior seismic performance and was suitable to be employed in building structures in earthquake regions.

Metal members stiffened by bistable components for the protection of naval architectures under periodic loading

ABSTRACT Naval architectures are required to simultaneously have high stiffness and high damping to bear periodic loading and suppress resonance that is possibly caused by ship self-excitation vibration. A protection approach, namely, metal members stiffened by bistable components, is proposed. This approach not only achieves high stiffness but also exhibits excellent energy dissipation compared to that of traditional approaches under periodic loading. A two-degree-of-freedom (2-DOF) model of a Euler beam stiffened by a bistable component is derived and characterised by two potential wells. The influence of the structural parameters and energy dissipation mechanisms of the coupled bistable-linear (CBL) beam on the laws of the potential energy wells are studied via theoretical model. In the end, a panel stiffened by optimally designed CBL beams, according to the parametric studies, effectively dissipate the dynamic energy and protect the structure by staying within the elastic range found in the finite element model (FEM).

Effectiveness of masonry infill walls on steel frames with different beam-column connections under progressive collapse

In this study, the effectiveness of masonry infill walls on steel frames with different beam-column connections under progressive collapse was investigated through a parametric study. A vertical force was applied to the center steelcolumn to represent the progressive collapse of steel frames. This study focused on the three most common types of steel beam-column connections found in steel structures: shear, bolted, and welded connections. Single-story (1/3 scale) steel-framed configurations with single shear and bolted beam-column connections and another infilled wall steel frame with welded connection from the literature were tested experimentally under a middle column loss event to validate the accuracy of 3D finite element models created with ABAQUS software. The verified finite element simulations were then used to study the performance of progressive collapse resistance for 12 various types of steel frames with masonry infill walls with three different types of beam-column connections. The effects of the full infilled frame, bare frame, and infilled frame with openings were explored. The size, location, and shape of the openings in the infilled frame, and the performance of these parameters with respect to the change in the type of beam-column connection were evaluated. In accordance with their mechanisms of failure and load–displacement behavior, masonry infill walls were compared in flexural and catenary action phases. The findings show that infill walls considerably improve the steel building’s structural strength and energy dissipation against progressive collapse.

Study on Identification Method of Motion States at Interface for Soil-Structure Interaction Damping System

The damping system characterizes the spatial distribution of structural energy dissipation. Identifying a damping system is the premise for determining the dynamic analysis method. Concepts of nonlinear processes and non-classical damping systems are often confused without theoretical primary and experimental verification. This paper proposes an identification method of damping systems based on motion states at the interface by analyzing the correlation between the damping system and dynamic characteristics. The relationship between the change of damping system type and relative motion states at the interface is studied by investigating multiple material properties through shaking table model tests of a large-scale soil-structure interaction (SSI) system. The results show that a nonlinear system can demonstrate the characteristics of the classical damping system as soon as there is no mutation of motion states at the interface of the system. The identification method of damping system based on motion states at the interface can reflect the change of dynamical characteristics of the system under linear and nonlinear processes.

Fragility analysis and collapse margin capacity assessment of mega-sub controlled structure system under the excitation of mainshock-aftershock sequence

The mega-sub controlled structure system (MSCSS) is a revolutionary type of energy dissipation structure. Its damping performance can be improved further with the addition of dampers, lead rubber bearings (LRB), and other components, but its seismic performance in the mainshock-aftershock sequence has yet to be investigated. The incremental dynamic analysis approach is employed in this study to determine the vulnerability of MSCSS during the mainshock-aftershock sequence, as well as its fragility curve. Following that, the effect of aftershock intensity on the structural fragility curve is explored, as well as the possibility of exceeding each limit state for the four structures under the excitation of the mainshock-aftershock sequence from the aspect of failure probability. In addition, the collapse margin ratio (CMR) of four structures is solved, the structural residual collapse margin capacity is investigated, and the structure's seismic reserve capacity is assessed. The findings also demonstrate that putting LRB on the additional column improves the seismic resistance of MSCSS.

Optimization of the Curved Metal Damper to Improve Structural Energy Dissipation Capacity

Structural curved metal dampers are implemented in various applications to mitigate the damages at a specific area efficiently. A stable and saturated hysteretic behavior for the in-plane direction is dependent on the shape of a curved-shaped damper. However, it has been experimentally shown that the hysteretic behavior in the conventional curved-shaped damper is unstable, mainly as a result of bi-directional deformations. Therefore, it is necessary to conduct shape optimization for curved dampers to enhance their hysteretic behavior and energy dissipation capability. In this study, the finite element (FE) model built in ABAQUS, is utilized to obtain optimal shape for the curved-shaped damper. The effectiveness of the model is checked by comparisons of the FE model and experimental results. The parameters for the optimization include the curved length and shape of the damper, and the improved approach is conducted by investigating the curved sections. In addition, the design parameters are represented by B-spline curves (to ensure enhanced system performance), regression analysis is implemented to derive optimization formulations considering energy dissipation, constitutive material model, and cumulative plastic strain. Results determine that the energy dissipation capacity of the curved steel damper could be improved by 32% using shape optimization techniques compared to the conventional dampers. Ultimately, the study proposes simple optimal shapes for further implementations in practical designs.

Investigation of different infill wall effects on performance of steel frames with shear beam-column connections under progressive collapse

This article examined steel frames with shear beam-column connections to determine the effectiveness of different masonry infill walls under progressive collapse. This research concentrated on the shear connection, which is the most common type of steel beam-column connection in steel buildings. Furthermore, this work experimentally evaluated one-third-scale steel-framed configurations with a single shear beam-column connection and another infilled steel frame wall configuration from the literature to verify the validity of 3D finite element models developed using the program ABAQUS. Finite element models were then used to investigate 16 different kinds of steel frames with infill masonry as well as the influence of multiple frames and the number of stories. In addition, the effects of a fully infilled frame and those of a bare frame and an infilled frame with openings were compared in flexural and catenary action phases. Results revealed that the steel building’s structural strength and energy dissipation against progressive collapse are significantly improved by infill walls.

Single and multiple TMD optimization to control seismic response of nonlinear structures

Tuned mass dampers (TMDs) are control devices used for supplemental energy dissipation in civil structures. In the case of structures that exhibit a nonlinear dynamic response under seismic action, their performance is affected by both the duration of the dynamic excitation and the detuning effect. In order to improve the TMD effectiveness in this scenario, the parameters of three different TMD configurations are optimized in the present work using the particle swarm algorithm. In the optimization process, two different objective functions are considered. The performance of the three optimal TMD configurations is evaluated on three single-degree-of-freedom structures with different fundamental periods subjected to a set of far-field records and a set of near-fault ground motions with strong velocity pulses. From the results of this analysis, it is found that in general, the configuration with two TMDs in series tuned to a frequency of 50% of the fundamental frequency of the healthy structure obtained the highest effectiveness when the ductility demand is greater than 5. In the case of medium-period structures with the highest ductility demand imposed by far-field ground motions, a reduction in the median ductility demand of 26% is achieved with a mass ratio of 25%. A lower effectiveness is observed against near-fault records, especially in short-period structures. Finally, the effect of the optimized TMD on multi-degree-of-freedom structures is analyzed.

Two-phase SPH–FD depth-integrated model for debris flows: application to basal grid brakes

In some cases, debris flow consists of low-permeability soils in which run-out distances, velocities and lateral spreading are highly influenced by pore-water pressures. Basal screens are energy dissipation structures designed to reduce these velocities and run-out distances. These structures consist of grids built on horizontal decks where basal pore pressures of debris flows are made equal to the atmospheric pressure, which increases basal friction. Once the debris flows exit the structure, basal pore pressure increases as the basal surface is impermeable again, but the values have been reduced. In order to model these phenomena, it is necessary to use debris flow simulation models considering two phases and pore-water pressures. Here, a depth-integrated two-phase smooth particle hydrodynamics (SPH) model, previously developed by the authors, is improved by including the vertical structure of pore-water pressure. This is done by incorporating finite-differences meshes associated to each SPH node that represents a solid particle. In this way, a higher precision is obtained in describing excess pore pressure along depth, including the influence of vertical consolidation, height variation and changes in basal permeability. The proposed model is applied to describe debris flows with two different ranges of soil permeability propagating over grid structures. The authors have used laboratory tests run at the Norwegian University of Science and Technology and studied the efficiency of the basal grids by comparing cases equipped by them and cases without any obstacle. The results obtained from the proposed numerical experiments suggest that the proposed two-phase coupled model is able to properly reproduce the behaviour of debris flows, describing more accurately the time–space evolution of pore-water pressures during the whole propagation stage, considering both propagation impermeable beds and pore pressure dissipation structures such as grids.

Analysis on the optimal damper quantity of energy dissipation structure

In practical application, the design of energy dissipation usually adopts the concept design, that is, to estimate damper quantity by repeating calculation. However, few studies have quantitatively analyzed the energy dissipation structure. This paper proposed two analysis methods to analysis the damper quantity of energy dissipation structure, the multiple-yield-strength method, and the damping-performance-curve method. Both of them can calculate the optimal damping quantity of the structure by adding metal dampers. The multiple-yield-strength method refers to that the yield strength of the metal damper is set by the multiple of the yield strength of the original structure. The optimal damper quantity of metal dampers can be analyzed by time history analysis. The damping-performance-curve method refers to that the target story displacement of the original structure is set. According to the relationship between the target displacement and the shear force in the damping-performance-curve, the stiffness of the original structure to achieve the target story displacement angle is derived, the stiffness is taken as the optimal damping of the metal damper. The optimal damping quantity is added to the original structure for comparative study which is calculated by the two methods. Both of them have reference value, and it could be beneficial for the promotion of energy dissipation.

Wave Energy Dissipation in a Shallow Coral Reef Lagoon Using Marine X‐Band Radar Data

AbstractA novel approach for estimating wave energy dissipation on a coral reef barrier is studied using X‐Band radar technology. The prominent features of coral reefs, including the delineation of reef morphological structure, wave energy dissipation and wave transformation processes are obtained in a reef lagoon in San Andres Island, Colombia. Results show that reef attenuates incident waves by approximately 75% due to both frictional processes and wave breaking, with an equivalent bottom roughness of 0.20 m and a wave friction factor of 0.18. These parameters are comparable with estimates reported in other shallow coral reef lagoons as well as at seagrass meadows obtained using in‐situ measurements. Also, the mean height of the reef elements Hbed and its standard deviation σb are also estimated in the entire radar coverage area. Hbed and σb (0.5 and 7.66 cm respectively) are in the same order of magnitude of measured data reported by previous studies and in good agreement with the geometric parameters proposed by in‐canopy flow models for branched species, such as Stylophora and Pocillopora, which are also common in the coral carpets of San Andres Island. This work proposes a completely novel use for X‐Band radars by describing prominent features in barrier‐reef systems including the delineation of the reef structure and wave energy dissipation.

Enhance the energy dissipation ability of sleeve-type negative stiffness structures via a phase-difference mechanism

Sleeve-type negative stiffness structures (ST-NSSs) can dissipate harmful mechanical energy in a reusable and controllable approach, and they are lightweight and with high mechanical performance, thus have a wide range of application prospects in many engineering fields. However, the load-displacement curve of existing ST-NSSs exhibits a waved shape, which has limited their energy dissipation ability (The ideal energy dissipation structure is required to have a stable and controllable load response). In this work, a new strategy is proposed by combing multiple ST-NSS cells in parallel with a phase-differences mechanism to improve the energy dissipation ability. A theoretical model is created to predict the load-displacement relationship of the parallel structure; a program is developed to obtain the numerical solution of the problem, and these two approaches are verified by quasi-static loading-unloading experiments. The results show that the proposed strategy can significantly improve the energy dissipation ability of parallel structures using a small number of negative stiffness cells. Additionally, it is found that by limiting the displacement range, the energy dissipation ability of the parallel structure can be further improved. This study brings a new way to design reusable, programable, high-performance, and highly adaptable negative stiffness structures for dissipating harmful mechanical energy in impacting and vibration.

Proposing a butterfly-liked metallic damper for passive energy dissipation in structures

A novel energy dissipating device, a butterfly-liked metallic damper (BLMD), is proposed in this paper. The main features of the proposed damper with low fabrication cost are easily assembled and replaced in various damper brace configuration systems, such as toggle brace damper system (TBDS) and diagonal brace damper system (DBDS). A series of experiments for identifying the hysteretic behaviour of BLMDs was conducted. Experimental results showed that a BLMD with a superior hysteretic curve had acceptable ductility and energy dissipation behaviours under quasi-static cyclic loading. In addition, BLMDs were installed in different brace systems in sixteen-story concrete frame structures, and the dynamic responses of the buildings to seismic excitations were compared and analysed. The results indicate that this BLMD provides superior vibration control and can significantly improve seismic performance of structures during strong earthquakes.