Energy Dissipation Capability Research Articles

Cyclic pushout tests on high‐performance concrete‐filled steel tube columns for seismic applications

AbstractConcrete‐filled double steel tube columns (CFDST) made from high‐performance materials represent an advanced type of prefabricated composite components with excellent fire performance, enabling a slender design under high loading compared to traditional concrete‐filled steel tubes (CFST). CFST have been proven to be a viable solution under seismic loading, as they can achieve improved load‐carrying capacities (improved stiffness, strength, ductility, and energy dissipation capabilities) compared to conventional concrete columns. However, there is currently a lack of experimental and numerical investigations on CFDST.This paper presents experimental results on five load‐reversal pushout tests on high‐strength CFDST columns. The objective was to investigate the bond behavior between steel and concrete, as well as the accompanying adhesion, micro‐, and macro‐locking effects under cyclic loading in order to better assess the seismic performance of such structures. The results showed a continuous decrease for the interface carrying capacity as well as for the overall bond stress behavior for each new loading cycle. However, macro‐locking represents the dominant mechanism for composite strength and is strongly influenced by the geometric shape of the high‐strength steel tubes. Even in post‐interface carrying capacity range, significantly higher bond stress states were reached.

Experimental investigation on amplified multilayer viscoelastic damper and vibration mitigation evaluation subjected to wind loads

Methods to improve the damping efficiency of dampers have been extensively studied. This study proposes a multilayer viscoelastic damper with an amplified deformation device (MAVE), which combines a traditional viscoelastic damper (VE) with a lever amplification device. The proposed device utilizes multiple viscoelastic damping layers and a lever system to amplify the inter-story displacement, thereby increasing the damping force and enhancing energy dissipation capability. A mechanical model of MAVE was established, and model tests were performed to compare MAVE and VE. The test results demonstrate that MAVE can effectively amplify the deformation of the damper. The damping force of MAVE increased by 5.23 times, while the stiffness increased by 5.59 times, resulting in a 3.11 times increase in energy dissipation capacity. Furthermore, the deviations in the amplification factor and the comparisons between experimental and theoretical results were discussed. The experimental and theoretical deviations were within 10%. Finally, a numerical simulation was performed on a super-tall structure to demonstrate the vibration control capabilities of the MAVE system. By comparing the response of the structure and the energy consumption of the dampers, the vibration reduction efficiency of MAVE under wind loads was confirmed. The peak acceleration at the top floor was reduced by 51%, and the standard deviation (STD) acceleration was reduced by 37%. The peak displacement at the top floor was reduced by 80%, and the STD displacement of the same floor was reduced by 76%. MAVE effectively enhanced the comfort level of super-tall structures.

Seismic and resilient assessment on moment resisting frames with novel self-centering viscous dampers

A new type of self-centering viscous dampers (SCVDs) had been developed by the authors to create low-damage structures [1]. Then, the seismic and resilient performance of steel frames equipped with SCVDs were still mysteries waiting for being discovered. So, performance was analyzed among the five systems which were moment resisting, buckling restrained brace (BRB), self-centering (SC), viscous damper (VD), and SCVD frames. The 3- and 6- story frames with the aforementioned systems were subjected to 20 earthquake records of various ground types using nonlinear response history analysis. In comparison to the MRF system, the SCVD system exhibited a significant improvement. The maximum and residual story drift ratios were reduced by 90.27% and 97.78%, respectively. However, there was an increase in the maximum base shears and overturning moments of the SCVD system by 120.65% and 150.31%, respectively. Overall, MRFs equipped with SCVDs or VD parts possess better seismic and resilient performance with higher certainty than the other systems, in special, the total growth rate of the VD system can be reduced by 22.94% comprehensively. Furthermore, addition of energy dissipation capabilities is more effective in decreasing responses with higher certainty than stiffness or self-centering capabilities of the braces.

Evaluation of the Seismic Performance of Single-Plate Metallic Slit Dampers Using Experimental and Numerical Data

Passive energy dissipation systems and devices are helpful in mitigating the danger of earthquake damage to structures. Metallic slit dampers (MSDs) are one of the most efficient and cost-effective solutions for decreasing seismic energy intake. The potential importance of MSDs in managing vibrations and limiting structural fatigue continues to grow as research advances and new materials and designs are introduced. This study evaluated the seismic performance of single-plate MSDs (SPMSDs) through a combination of numerical simulation and assessment of experimental results. ABAQUS software was used to create an assembly consisting of endplates, bolts, and SPMSDs. A real-world earthquake scenario was simulated using cyclic loads based on ASCE/SEI standards, and displacement-measuring devices such as strain gauges and LVDT were employed to record the behavior of the SPMSDs. The results of the experiment are used to assess the compliance of the SPMSDs and discuss their behavior as they undergo minimum and maximum displacements due to minimum and maximum applied forces. The energy dissipation capabilities of the dampers are presented by analyzing and comparing the area of their hysteresis loops, equivalent viscous damping, and their damping ratios. Actual failure modes are identified and shown to describe the limitations and potential vulnerability of the dampers. The relative error between the lowest and greatest recorded forces from experimental data and numerical simulation ranges from 4.4% to 5.7% for SPMSD 1 and from 1.6% to 2.1% for SPMSD 2, respectively. These deviation values represent a satisfactory level of precision, demonstrating that the numerical simulation accurately predicts the actual performance and behavior of the dampers when subjected to cyclic stress. The topology optimization performed in this study yielded an improved geometry of the SPMSD suited for a corresponding maximum considered earthquake (MCER) displacement of ±33 mm. This research also suggests practical implementations of the investigated and improved SPMSDs.

Microstructure development and mechanical performance of MWCNTs/GNPs filled SEBS with different block content

AbstractPolystyrene‐poly (ethylene‐butylene)‐polystyrene (SEBS) nanocomposites have been regarded as promising thermoplastic elastomers for several industries owing to their distinct molecular platforms and properties. However, extending their applications requires a thorough understanding of the microstructural changes that nanoparticles induce in SEBS chains. In this work, we used two types of SEBS varying in polystyrene (PS) hard block contents to study the relationship between the structural changes and viscoelastic/mechanical properties of SEBS hybrid nanocomposites containing different multi‐walled carbon nanotubes: graphene nanoplatelets ratios. According to the results, the viscoelastic responses were strongly influenced by the PS block content and nanoparticles ratio, which had an appreciable contribution to the nanoparticles' dispersion state. This was explained in terms of intensified microphase separation induced by the favorable interactions between the carbon‐based nanoparticles and PS blocks. It was also found that the samples containing higher hard block content demonstrated more significant mechanical performance and toughness, which were enhanced by the addition of nanoparticles such that the highest ultimate strength of 24.58 MPa was obtained for the S30C0.5G0.5 sample. Furthermore, some mechanisms, including molecular disentanglements, dissociation of inter/intra‐molecular interactions, the orientation of the rubbery polyethylene butylene chains, and PS microdomain rearrangement, were supposed to interpret the energy dissipation capability of SEBS nanocomposites.

Nanoscale dynamic mechanical analysis on interfaces of biological composites

Biological composites incorporate structural arrays of rigid-elastic reinforcements made of minerals or crystalline biopolymers, which are connected by thin, compliant, and viscoelastic macromolecular matrix material. The near-interface regions of these biological composites grant them energy dissipation capabilities against dynamic mechanical loadings, which promote various biomechanical functions such as impact adsorption, fracture toughness, and mechanical signal filtering. Here, we employ theoretical modeling and finite-element simulations to analyze the mechanical response of the near-interface in biological composites to nanoscale dynamic mechanical analysis (DMA). We identified the dominating load-bearing mechanisms of the near-interface region and employed these insights to introduce simple semi-empirical formulations for approaching the mechanical properties (storage and loss moduli) of the biological composite from the nanoscale DMA results. Our analysis paves the way for the nanomechanical characterization of biological composites in diverse natural materials systems, which can also be employed for bioinspired and biomedical configurations.

Interfacial enhancement of CFRP/titanium alloy bonding joint by constructing a 3D interconnected CNTs network

Carbon fiber-reinforced polymer (CFRP)/titanium alloy joints offer exceptionally lightweight, superior fatigue behavior and impact resistance for aerospace applications. Nevertheless, Fiber-tear failure manifestly occurs in the CFRP/metal bonded joints due to the stress concentration of carbon fiber (CF) surfaces, and the adhesive cannot develop its full shear strength capacity, resulting in low shear strength. This drawback has limited the reliability of CFRP in full-scale structures where adhesive bonding is essential. In this study, a three-dimensional (3D) interconnected carbon nanotubes (CNTs) network was constructed on the CFs on the surface of CFRP to release the stress concentration. Carboxyl functionalized CNTs were grown on the surface of CFs, and then the CNTs were arranged in the adhesive to form a 3D network using ultrasonic-powered adhesive injection (UPAI) process. The interfacial bonding strength can reach up to 29.51 MPa, increasing by 30.7%. The growth of CNTs was verified by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The ultrasonic process can effectively promote the construction of 3D coiled/entangled and vertically aligned CNT structures, providing a more complex crack propagation path for the energy dissipation capability. FESEM and energy dispersive spectroscopy (EDS) tests of the cross sections of CFRP/titanium (Ti) alloy joints revealed that the ultrasonic process promoted mechanical anchoring owing to improved wettability and increased acoustic pressure within the adhesive. These results provide insights into future high-performance CFRP/metal hybrid joining technology of lightweight structures.

Buckling-controlled braces for seismic resistance inspired by origami patterns

Equipping energy dissipation devices in the structures is one of the effective methods to resist earthquake disasters. Here, a novel buckling-controlled brace inspired by origami (O-BCB) was proposed as anti-seismic technology for protecting engineering structures. A hierarchical design and analysis strategy was adopted for various types of origami patterns. An O-BCB based on Tachi origami pattern was manufactured, tested, and analyzed to verify the hysteretic performance under cyclic reversed loading. Considering the non-uniform distribution of deformation and stress in the Tachi patterned brace, two gradient design schemes in the lengthwise direction were proposed. To balance the bearing capacity and energy-dissipating capabilities of O-BCBs, the implementation of non-rigid origami patterns including pyramid, crash-box, and triangular patterns were analyzed. Results show that O-BCBs could provide valuable options for the development of earthquake-resistant technologies in the field of civil engineering.

Enhancing Mechanical Behavior and Energy Dissipation in Fiber-Reinforced Polymers through Shape Memory Alloy Integration: A Numerical Study on SMA-FRP Composites under Cyclic Tensile Loading.

Conventional fiber-reinforced polymers (FRPs) have a relatively linear stress-strain behavior up to the failure point. Therefore, they show brittle behavior until the failure point. Shape memory alloys, in addition to having high ductility and good energy dissipation capability, are highly resistant to corrosion and show good performance against fatigue. Therefore, using the SMA fibers in the production of FRPs can be a suitable solution to solve the problem of the brittle behavior of conventional FRPs. SMA fibers can be integrated with a polymeric matrix with or without conventional fibers and create a new material called SMA-FRP. This study investigates the effect of using different volume fractions of conventional fibers (carbon, glass, and aramid) and SMA fibers (NiTi) in the super-elastic phase and the effect of the initial strain of SMA fibers on the behavior of SMA-FRP composites under cyclic tensile loading. Specimens are designed to reach a target elastic modulus and are modeled using OpenSees (v. 3.5.0) finite element software. Analyzing the results shows that in the SMA-FRP composites that are designed to reach a target elastic modulus, with an increase in the volume fraction of SMA fibers, the maximum stress, residual strain, and strain hardening ratio are reduced, and the ability to energy dissipation capability and residual stress increases. It was also observed that increasing the percentage of the initial strain of SMA fibers increases the maximum stress and energy dissipation capability and reduces the residual strain and yield stress. In the investigation of the effect of the type of conventional fibers used in the construction of composites, it was found that the use of fibers that have a larger failure strain increases the maximum stress and energy dissipation capability of the composite and reduces the strain hardening ratio. In addition, increasing the elastic modulus of conventional fibers increases the residual strain and residual stress of the composites.

Seismic behavior of steel reinforced precast concrete shear wall with replaceable energy dissipators

To improve the seismic performance of the precast shear walls, a steel-reinforced precast concrete shear wall with replaceable low-yield-point (LYP) steel energy dissipators (SPCE-Wall) was developed. The design approach and analytical model of SPCE-Wall which applied equivalent fiber elements to simulate the steel-reinforced precast concrete panel and fiber element to simulate the LYP steel were adopted in the study. After validating the analytical finite model, the seismic behavior of the SPCE-Wall and parametric study were performed in OpenSees. The results indicated that SPCE-Wall exhibits an enhanced bearing capacity, energy dissipation capability and initial lateral stiffness under monotonic and cyclic loading compared with the steel-reinforced concrete wall without energy dissipators. The relative energy dissipation ratio of the SPCE-Wall exceeds 0.125, which satisfies the ACI ITG T5.1 recommendation to avoid the long-term oscillation of the structure resulting from inadequate damping. Parametric study analysis shows that the bearing capacity of the SPCE-Wall is affected by the axial compression ratio, length of the wall panel and the steel area including channel steel, steel bars and LYP plates. And the displacement ductility of the wall is considerably influenced by several structural properties including axial compression ratio, length of the wall and diagonal angle steel.

Experimental and theoretical investigations of post-tensioned precast reinforced concrete bridge pier with external replaceable energy dissipaters

This study presents a post-tensioned (PT) precast reinforced-concrete bridge pier with external replaceable energy dissipaters (PRCB-EREDs). The EREDs provide both bending resistance and energy dissipation (ED) capacity, and the unbonded PT strands enable prefabricated construction and self-centering capabilities. This study introduces the construction, assembly process, and post-earthquake repair technology of the PRCB-EREDs. Subsequently, parametric quasi-static tests were performed by altering parameters, such as the initial PT force and the size of core energy dissipation steel plate in the ERED (ERED-CEDP). The test results indicated that the precast pier column remained essentially elastic, with damage localized within the ERED-CEDP, exhibiting good deformation and ED capabilities. The hysteresis curve of the specimen was full and stable, and the curves before and after repair were essentially identical, confirming the feasibility of the repair. With an increase in the initial PT force, both the stiffness and bearing capacity were improved, and better self-restoration effects were achieved. For test conditions with the same ERED-CEDP thicknesses but different initial PT forces, the ED capacities were almost the same. Finally, the load-resisting mechanism of the PRCB-ERED piers was analyzed and theoretical model of hysteretic behavior was proposed and verified.

Study on the pier bottom self-centering seismic isolation structure of the high-pier continuous rigid frame bridges

Four seismic isolation specimens were designed, fabricated, and subjected to physical loading tests to enhance the seismic performance of a high-pier continuous rigid-frame bridge. A finite element model of the seismic isolation structure of the high-pier was established using numerical simulation software. The entire bridge model was established based on the multi-scale modeling method to investigate the seismic response of the high-pier continuous rigid frame bridge under different seismic waves. The results indicate that the seismic isolation pier has self-centering and energy dissipation capabilities. The seismic isolation pier has satisfactory energy dissipation capacity and ductility when the ratio of the long-axis and short-axis radii is 1.5. The results of the finite-element simulation corresponded well with the experimental results. Significant damage occurred to the concrete at the bottom and corner of the pier, and the reinforcement did not reach its yield strength throughout the loading process. Therefore, measures must be implemented to ensure the seismic performance of the structure. The pier bottom self-centering seismic isolation structure effectively absorbs shocks, as evidenced by reduced absolute acceleration and relative displacement at the pier top, decreased shear force and bending moment at the pier bottom, and minimized girder displacement. It was recommended that the ratio of the long-axis and short-axis radii be adopted as 1.5–2.0 and that the pier height be selected as 60 m–100 m. These results provide a reference for the research and applications of this type of structure.

The Effect of ECC Materials on Seismic Performance of Beam—Column Subassemblies with Slabs

The main objective of this investigation was to study the influence of an Engineered Cementitious Composite (ECC) on the seismic performances of beam–column–slab subassemblies. Tests and simulations were conducted on several models. The bearing capacity of the ECC model was 15% higher than that of the RC member, the deformability increased by 19%, and the energy dissipation capability increased by 34%. The use of an ECC in the slab could reduce the contribution of the reinforced bars in the slab to the flexural strength of the beam. At a drift of 2%, the range of the yielding bars in the slab of the RC models was 5h to 6h. However, the yield range of reinforcement in the slab of the ECC models was nearly 3h. As a result, the ECC subassemblies were prone to reach a “strong column and weak beam” yield mechanism.

Thermodynamic, transport, and radiation properties of HFO-1336mzz(E) mixtures as eco-friendly SF6 alternatives

HFO-1336mzz(E) is proposed as a novel alternative to SF6 due to its low greenhouse effect and high insulation strength. Typically, it is mixed with CO2 or Air to lower its boiling point to meet the minimum operating temperature. To better understand the thermophysical properties of the gases’ arcing plasma, the composition, thermodynamic properties, transport properties, and net emission coefficient of 30% molar fraction of HFO-1336mzz(E) mixed with CO2 or Air at temperatures from 300 K to 30 000 K at 0.12 MPa are calculated. It is found that HFO-1336mzz(E) mixtures have similar turbulent energy dissipation and thermal interruption capability to the pure SF6. Analysis of radiation characteristics demonstrates that the HFO-1336mzz(E) mixtures at 0.12 MPa exhibit stronger radiation emission compared to SF6 at 0.1 MPa, which indicates good arc radiation dissipation capabilities within such mixtures. This study reports the properties of thermal plasma of HFO-1336mzz(E) mixtures for the first time. These findings not only provide fundamental data for further magneto-hydro-dynamic calculations for arcing process but also put forward the potential application of these mixtures as arc interruption medium in medium voltage switchgears.

Composite sepiolite/chitosan layer-by-layer coated flexible polyurethane foams with superior mechanical properties and energy absorption

Flexible polyurethane foam composites with enhanced stiffness and energy dissipation have been prepared via a facile layer-by-layer assembly approach. The composite foams consisted of naturally abundant nanoclay/chitosan multilayers (up to six) deposited onto the foam struts via dip-coating. The nanoclay/chitosan polyurethane foams were characterised using infrared spectroscopy, scanning electron microscopy, elemental mapping and μ-CT scanning. Quasi-static mechanical compression of the foams with 6 bilayers showed a 202% increase in the stiffness and a 33% enhancement in the damping loss factor compared to the uncoated pristine foam. Vibration transmissibility tests showed that the dynamic modulus of the 6-bilayer coated foams was 3 times that of the pristine foam. Remarkably, impact tests registered a 50% decrease in the transmitted impact force of these sepiolite/chitosan layer-by-layer coated open cell polyurethane foams, demonstrating their improved energy dissipation capability compared to other nanocoated foams in open literature.

Experimental Research on the Bond Performance between SMAF-ECC Composites and Steel Bar.

Combining Engineered Cementitious Composites (ECC) with shape memory alloy (SMA) fibers can form SMA fiber reinforced ECC (SMAF-ECC) that has excellent deformation recovery and energy dissipation capabilities. Substituting some of the tensioned concrete with this new composite material, along with steel bars, is expected to significantly improve the seismic energy dissipation and self-recovery capabilities of traditional reinforced concrete components. However, a reliable bond between steel bars and SMAF-ECC is critical to ensure their synergistic performance. In this paper, the failure mode and bond strength of steel bars and SMAF-ECC were studied through direct tensile tests, and the influence factors such as steel bar diameter, bond length, and SMAF volume fraction were analyzed. A bond-slip constitutive model for steel bars and SMAF-ECC was proposed. The results show that the failure mode of the tensile test specimens is mainly steel bar pull-out failure; the incorporation of SMAF significantly enhances the bond strength between the steel bar and matrix; increasing the steel bar diameter and bond length both lead to a decrease in bond strength while increasing the SMAF volume fraction can significantly increase the bond strength. Among them, the specimen with a steel bar diameter of 12 mm, bond length of 70 mm, and SMAF volume fraction of 0.5% has the largest increase in bond strength, reaching 52.96%. The proposed improved bond-slip constitutive model is in good agreement with the bond-slip curve obtained in the experiments, with a determination coefficient of 0.99. The research results of this paper provide an important theoretical basis for promoting the engineering application of SMAF-ECC materials.

Seismic performance of RC columns strengthened with HSSSWR meshes reinforced ECC under high axial compression ratio

The cyclic loading tests under high axial compression ratio were performed to investigate the seismic performance of full-scale reinforced concrete (RC) columns strengthened with high-strength stainless steel wire rope (HSSSWR) meshes reinforced engineering cementitious composite (ECC), considering different axial compression ratios and strengthening schemes. The test results show that the seismic performance of RC columns was greatly improved after being strengthened. Specifically, the failure modes of the columns were changed from flexure-shear failure to compression-flexure failure, and the ductility and energy dissipation capability were significantly improved by 69.6% and 474.6%, respectively. Besides, the HSSSWR meshes reinforced ECC jacket was confirmed to be a more efficient strengthening scheme, compared with strengthening with only ECC or lateral HSSSWRs reinforced ECC. The RC columns still showed good ductility and energy dissipation capacity after being strengthened with HSSSWR meshes reinforced ECC under high axial compression ratios of 0.5 and 0.7. Finally, taking into account the confinement effects of ECC, lateral HSSSWRs, and stirrups, an analytical model used for predicting the envelope curve of strengthened columns with HSSSWR meshes reinforced ECC jackets under cyclic loading was proposed, which was in good agreement with the test results.

Machine learning-based design of a seismic retrofit frame with spring-rotational friction dampers

In this study a machine learning-based design procedure for a new seismic retrofit system is presented and its seismic retrofit capability is validated by intensive seismic analyses. The retrofit system consists of a steel frame with rotational friction dampers (RFD) at beam-column joints and linear springs at the corners providing both energy dissipation and self-centering capabilities to existing structures. The performance-based seismic design procedure of the spring-rotational friction damper (SRFD) retrofit system is developed using a genetic algorithm (GA) and an artificial neural network (ANN). The performance of the presented retrofit system and its optimum design procedure is evaluated using case study models for multi-limit states by investigating seismic fragilities, life-cycle cost (LCC), and seismic Resilience Index (RI) before and after the retrofit. According to the analysis results, the SRFD retrofit system proved to be effective in decreasing story drifts, seismic fragility, and LCC of the retrofitted structures significantly. The retrofitted models turn out to be more resilient and recover better than the un-retrofitted models after earthquakes. The developed performance based design procedure is proved to be effective in seismic retrofit of case study structures to satisfy multi-level design objectives.

Investigation of The Effect of Geometry Inner Thickness on New Designed Auxetic Structure

Poisson’s ratio is important mechanical property of materials and structure. Material and Structure showing negative Poisson’s ratios are called Auxetic. Properties of the Auxetic structures are very important to design the new structure, especially mechanical properties of the Auxetic materials that have structurally and functionally mission. Many researchers made experimental and theoretical works apropos this matter. In this study, the newly designed Auxetic lattice structure Poisson’s ratio was checked over via exploiting finite element analysis. 14 different lattice structures with respect to inner lattice thickness configurations are investigated. All examined structures have a negative Poisson’s ratio. Inner lattice thickness is increased; negative Poisson’s ratio values are decreased (closes to -1.) in these examined lattice structures. 4x2 lattice orientation has lowest Poisson’s ratio than 4x4 Lattice structure Poisson’s ratio, 4x2 is more Auxetic. 4.9 mm inner lattice thickness and 4x2 lattice matrix examined example has lowest Poisson’s ratio that is -0,55. Beneficial to indicate the purview of the structure on the applied force, the stiffness values and the stiffness/mass values were examined. Their energy dissipation capabilities were analyzed.

Seismic Performance Analysis of the Two-Dimensional Isolation Device for Double-Layer Grid Structure

The isolation technologies are adopted to protect the long-span space structures from serious damage under the action of earthquakes. When the isolation system is applied to the space structures, both horizontal and vertical vibration control effects on the structures should be concerned. In this paper, a two-dimensional earthquake isolation and mitigation device (TEIMD) composed of a high-damping viscoelastic (VE) core pad and VE dampers is proposed. Based on the dynamic shear experiment results of the VE damper, the energy dissipation capability of VE material is preferable. Then, the nonlinear equivalent stiffness and equivalent damping ratio of the TEIMD in horizontal and vertical directions are evaluated by using the numerical simulation method. The TEIMDs are arranged on the column top of a double-layer grid structure to assess the isolation effectiveness of the novel device. The dynamic analysis results of the double-layer grid structure with and without TEIMD reveal that this novel device can significantly reduce the acceleration response of the upper grid by relying on the strong energy dissipation performances in the horizontal and vertical directions. This research also verifies the feasibility of applying the TEIMD to the double-layer grid structure, which can effectively dissipate the vertical vibration energy of the structure.