Dissipation Research Articles

Isostatic and frictional energy dissipating connecting systems for UHPC curtain walls: Design and experimental validation

Ultra-high performance concrete (UHPC) curtain wall is a new type of non-structural building envelope component. Given its large size and high cost, rational connecting systems should be employed to prevent potential seismic damage and economic losses. In this study, two novel connecting systems, including an isostatic connecting system and a frictional energy dissipating connecting system, were proposed for reinforced concrete (RC) frame with UHPC curtain walls. The design methods for these two connecting system were provided first. Then, to evaluate the feasibility of the proposed connecting systems and the corresponding design methods, three 1/2-scale RC frame structures (i.e., one bare frame without curtain walls, one with isostatic curtain wall connecting system, and one with frictional energy dissipating curtain wall connecting system) were designed and fabricated for pseudo-static tests. The damage evolution, failure mode, strength, stiffness, and energy dissipation capacity of the three test substructures were assessed. The test results demonstrated that through reasonable design, independent rocking deformation of the curtain walls was achieved in both the isostatic and frictional energy dissipating connecting systems, allowing the curtain walls to remain free from damage even under an inter-story drift of 1/36, thus validating the reliability of the proposed connecting systems and design methods. Further, compared to the bare frame, curtain walls employing the isostatic connecting system exhibited a negligible effect on the seismic performance of the frame. On the contrary, curtain walls employing frictional energy dissipating connecting system effectively enhanced the strength and energy dissipation capacity of the frame, allowing dual damage control for both walls and frame. Consequently, the frictional energy dissipating connecting system is considered to be a more rational method for enhancing the seismic performance of buildings.

Piezothermoelastic interaction in piezoelectric rods induced by a timed laser pulse without energy dissipation

The main aim of this article is to study the piezo-thermoelastic interaction in piezoelectric rods without energy dissipation due to a laser heat source with a timed pulse. Laplace transforms are used to represent the analytical solutions in the transformations domain. The governing equations of piezo-thermoelasticity in the Green and Naghdi model (GNII model without energy dissipation) in the presence of a laser heat source with a timed pulse are solved exactly in the Laplace domain, calculating the temperature, the stress, the displacement, and the electric potential. Numerical Laplace inversion is then used to find the general solution of the variables under study, which are then graphically shown.

Real-Time Structural Health Monitoring of Bridges Using Convolutional Neural Network-Based Loss Factor Analysis for Enhanced Energy Dissipation Detection

This study introduces a novel method for real-time structural health monitoring (SHM) of bridges using a convolutional neural network (CNN) model that leverages loss factor analysis. As bridge structures deteriorate over time, often accelerated by operational loads, maintaining structural integrity and safety becomes critical. The proposed approach utilizes the concept of a loss factor, which represents the process of energy dissipation across different vibration states, as a key indicator of structural health. This factor is computed from vibration energy spectra, which include amplitude and frequency components, processed through the CNN model for high sensitivity to structural changes. The results demonstrate that the energy dissipation of the bridge during operation can be categorized into signals from three distinct sources: structural responses, defects-related indicators, and noise interference. By monitoring variations in the loss factor over time, the model effectively identifies early signs of structural deterioration, which is critical for timely maintenance interventions. The study also highlights the adaptability to different load conditions and environmental factors, ensuring robust performance in various operational scenarios. The findings underscore the potential of the CNN model to transform SHM practices by enhancing early defect detection, supporting preventive maintenance, and ultimately extending the lifespan of bridge infrastructure.

Efficiently and consistently energy-stable [formula omitted]-phase-field method for the incompressible ternary fluid problems

Ternary incompressible fluid flows extensively exist in atmospheric science, chemical engineering, and energy and power engineering, etc. The phase-field method is popular in multi-phase fluid modeling thanks to its efficient ability of interface capturing. This work aims to develop an energy dissipation law-preserving and temporally second-order accurate algorithm for a ternary phase-field fluid system. To establish a simple energy estimation, an adapted auxiliary variable approach is used to transform the original model into its equivalent form. Later, a second-order backward difference strategy is used to design the fully decoupled and linear time-marching scheme. To improve the consistency between original and modified discrete energy functionals, a practical energy correction technique is presented. We analytically prove the discrete energy dissipation property and show that the energy estimation can be easily established without considering the complex treatments of nonlinear and coupling terms. To facilitate the interested readers, we briefly describe the numerical implementation in each time step. The numerical tests indicate that the proposed method not only has desired accuracy, but also satisfies the energy stability even if a larger time step is used. Moreover, the proposed method can well simulate various ternary fluid phenomena, such as the liquid lens, phase separation, droplet dynamics, Kelvin–Helmholtz instability, and billowing cloud.

An energy-based criterion for defining slope failure considering the coupling effect of groundwater table and impact loading

Slope instability poses significant risks in tunnel construction, particularly under the influence of impact loading and fluctuations in groundwater table. This study addresses the complexity of energy transformation and distribution in slopes affected by these factors. The research aims to analyze the local dynamic Factor of Safety (FOS) from the perspective of energy-based criterion, considering groundwater table, impact loading, and load position. Key findings indicate that the groundwater table is the most influential factor on slope stability, followed by load position and impact loading. The overall dynamic FOS was observed to peak at 0.35 s and trough appears at 1.0 s during impact loading, stabilizing after 2 s. The evolution of the overall dynamic FOS is explained from the energy dissipation and transformation mechanisms. These insights provide a critical basis for risk assessment and prevention in complex slope scenarios, contributing to sustainable infrastructure development in line with UN SDG 11 (Sustainable Cities and Communities).

Seismic performance of compressed earth block walls reinforced with common reeds

Compressed earth block (CEB) is a sustainable and cost-effective option for eco-friendly constructions. The blocks are produced without burning fossil fuels and have low embodied energy. The abundance of its constituents, including clay and sand, is another merit. However, the susceptibility of CEB constructions against seismic forces is still considered a prominent hindrance to their widespread acceptance. The study aims to improve the in-plane seismic performance of CEB walls by using common reeds as a natural reinforcing material. For this purpose, seven wall panels with dimensions of 1000×900×120 mm3 were constructed. Seismic loading was simulated using an incrementally increasing lateral cyclic displacement combined with a constant vertical stress of 0.3MPa. The results are discussed in terms of the hysteresis load-displacement responses, displacement ductility, energy dissipation, and stiffness degradation. Based on laboratory experiments, the strength and lateral displacement of the reinforced specimen with four vertical reeds were increased by 44% and 76%, respectively, compared to the non-reinforced ones. Ultimately, Seismic assessments and damage indexes of the tested walls indicated that the in-plane seismic performance of CEB walls could be significantly improved by using vertical sand-coated reeds.

Numerical study on dynamic response characteristics of proton exchange membrane water electrolyzer under transient loading

Under dynamic operating conditions, the proton exchange membrane water electrolyzers are prone to voltage overshoot, resulting in fluctuations under transient operation. In this paper, a three-dimensional, two-phase, non-isothermal model is developed to investigate the role of various factors on the dynamic response characteristics of electrolyzers. The results demonstrate that the overshoot phenomenon can be significantly mitigated by using a linear loading strategy and a multi-step loading strategy compared to a step loading strategy. Meanwhile, the effect of the flow field structure was examined, revealing that single-serpentine flow field exhibited excellent dynamic response performance. Additionally, calculated through multiple evaluation methods, it was found that the effect of loading magnitude was significantly greater than that of the other factors, including temperature, flow field structure and anode porous transport layer porosity. Finally, under combined variable load conditions, research revealed that whereas single-serpentine flow field shown benefits regarding dynamic response and energy dissipation.

Seismic performance and failure mechanisms evaluation of multi-story elliptic and mega-elliptic bracing frames: Experimental and numerical investigation

In recent decades, researchers have evaluated the seismic performance of the innovative Elliptic-Braced Resisting Frames (ELBRFs) only in single-story single-span configurations. Although numerical studies have investigated the behavior of multi-story ELBRF configurations, the lack of laboratory data has cast doubt on the reliability of these numerical results. To address this gap in knowledge, this article evaluates the seismic performance and failure mechanisms of multi-story ELBRFs through a laboratory program and compares them with a developed type of this bracing system known as Mega Elliptic-Braced Resisting Frames (MELBRF). The key contribution of this research is the provision of laboratory test data for multi-story ELBRF and MELBRF systems, which can be utilized to validate numerical models and investigate their seismic characteristics. In this study, laboratory tests are used to examine the cyclic behavior and to calculate parameters such as strength, ductility, stiffness, energy dissipation, seismic performance, and failure modes in multi-story specimens. To this end, an experimental test of a 1/6 scale single-span four-story ELBRF specimen and a two-span four-story MELBRF specimen under cyclic quasi-static loading was conducted. Next, the seismic behavior of the proposed specimens is compared with other types of bracing systems such as X-, V-, Inverted-V, Two-Story X-, and Two-tiered diagonal braced frames in a story-base model under cyclic quasi-static loading through nonlinear FEM analyses. The results indicated that the yielding of elliptic braces would delay the failure mode of adjacent elliptic columns and thus help tolerate significant nonlinear deformation to the point of ultimate failure. The response modification factor in ELBRF and MELBRF is 7.3 and 6.5, respectively. Symmetrical behavior, high energy absorption, appropriate stiffness, and high ductility in comparison with conventional systems are some of the advantages of the proposed systems.

Recrystallization and spheroidization mechanisms in Ti6246 alloy under thermomechanical treatment

This paper provides a detailed analysis of the dynamic microstructure evolution of Ti-6Al-2Sn-4Zr-6Mo alloy (Ti6246) through a 4-pass hot rolling process. Additionally, it examines the effect of heat treatment on microstructure evolution during the post-annealing of the hot-rolled alloy. During the rolling process, dynamic recrystallization (DRX) predominantly takes place in the α-phase, leading to grain refinement and spheroidization as a consequence of DRX and lamellae spheroidization. Spheroidization of the lamellar structure is more pronounced in the 2-pass rolling process, while the level of DRX is greater in the 4-pass rolling process. The dislocations present within the α lamellae accumulate and entangle at the sub-grain boundary, leading to the formation of a high-angle grain boundary (HAGB). Meanwhile, the β phase infiltrates the grain boundaries of the α phase, leading to the formation of spheroidized equiaxed α grains. Schmid factors associated with the pyramidal slip systems are relatively high, facilitating the activation of slip systems during hot rolling processes. The evolution of the α-phase morphology during heat treatment processes in various rolling passes is primarily driven by static recrystallization (SRX) and grain boundary terminal migration mechanisms. The deformed microstructure volume fraction diminishes and transforms into substructures and recrystallized grains through post-annealing. Post-annealing facilitates the dissipation of stored deformation energy with increasing temperature, leading to a decrease in dislocation density and an enhancement in the extent of recrystallization. Accumulated deformation during rolling and the temperature of the heat treatment both play a role in affecting the static spheroidization process. Greater accumulated deformation and elevated post-annealing temperatures are advantageous for achieving grain spheroidization. The grain boundary splitting process is more pronounced, and the deformation energy is elevated during the 3,4-pass rolling.

Fe-SMA for enhancing both structural robustness and seismic resilience: A pioneering study

Low-cycle fatigue (LCF) failure has been recognized as one of the most common failure modes of structures experiencing a major earthquake; on the other hand, progressive collapse, possibly triggered by impact, blast, or fire, is another dangerous consequence to structures when in the absence of adequate robustness design. Due to varied performance demands, addressing both issues with consistent design solution can be challenging. This paper proposes a new multi-hazard protection concept utilizing iron-based shape memory alloy (Fe-SMA) components to improve both the robustness (against progressive collapse) and seismic resilience (against earthquake-induced LCF failure) of steel frames. Fe-SMA has emerged as a promising material in the field of civil engineering due to its unique thermal-induced shape recovery, superior low cycle fatigue (LCF) resistance, and outstanding ductility. In this paper, the angle form of Fe-SMA components is selected, serving as energy dissipation elements in steel beam-to-column connections which are crucial for ensuring structural safety/integrity against various hazards. Experimental investigations were conducted to understand the basic mechanical properties of Fe-SMA angles under monotonic tensile and LCF loading, followed by comprehensive numerical studies demonstrating the use of Fe-SMA angles for steel beam-to-column connections against cyclic loading as well as ‘column loss’. The results confirmed that Fe-SMA is capable of resisting cyclic loading with much improved LCF life, and meanwhile, offers significantly enhanced chord rotation capacity as well as maximum dynamic load resistance of beam-to-column connections against progressive collapse.

Titanium Nitride-Gold Nanoislands: Harnessing Electrical and Optical Properties for Enhanced Localized Surface Plasmon Resonance Sensing

Titanium nitride-gold nanoislands (TANIs) are experimentally investigated to explore their electrical and optical properties induced by the incorporation of Au into TiN. A film is first fabricated on a glass substrate using the radio frequency (RF) magnetron sputtering technique at 300 K, with a thickness of approximately 20 nm (± 2.5 nm) and an Au:TiN ratio of 0 to 0.47. Subsequent thermal annealing provides a nanoisland structure of TiN-Au. Characterization techniques such as X-ray diffraction and X-ray photoelectron spectroscopy confirmed the presence of TiN and Au in the fabricated TiN-Au nanoislands. Spectroscopic ellipsometry measurements show that the TANIs posses excellent optical properties. Furthermore, numerical evaluations of energy dissipation are conducted to assess carrier transport deterioration due to the inelastic scattering effects in the TANIs and the inclusion of Au in the nanostructure significantly have reduced the dielectric loss tangent at energies greater than 4.5 eV, compensating for high losses and enhancing optical performance. The biosensing capability of TANIs is also demonstrated with the sensing of biotin, such that a strong biotin-phase response relationship is formed with a limit of detection of 0.842 ng/ml. This study contributes valuable insights into the electrical, optical and biosensing properties of TANIs, providing direction for sensing applications, where the optimization of the TANIs structure could bring about advancements in optical performance and pave the way for the potential design of novel plasmonic sensors.

Experimental study on the hydrodynamic behavior for a novel compound anti-vibration submerged floating tunnel system

Anchor cable-type submerged floating tunnel (SFT) is susceptible to large amplitude vibration responses under wave-current excitations. This becomes a critical issue to the safety, stationarity, and driving comfort of SFT. In this study, a novel compound anti-vibration SFT system is proposed, featuring a three-tube SFT reinforced with a rigid truss and an external floating energy dissipation device with polyvinyl chloride (PVC) porous media. The hydrodynamic behavior of the proposed compound SFT system is experimentally explored and compared with that of conventional SFTs utilizing a large wave-current flume. Sensitivity analysis for the key parameters of SFT is conducted using hydrodynamic parameters (such as wave height and wave period), structural type, and structural parameters (draft depths). The results show that the proposed SFT system has excellent anti-vibration performance when compared to conventional SFTs, reducing over 10 and 60 times in translational and rotational motion, respectively. The proposed SFT system with the floating tank at half draft depth shows the best anti-vibration performance under different wave-current excitations. The proposed SFT system achieves excellent anti-vibration performance without increasing the burden on cable tension, solving a common issue in conventional anti-vibration methods. The findings offer valuable insights into the anti-vibration design and application of SFT.

Mathematical model and experimental verification of self-centering energy dissipative brace equipped with disc spring and wedge block

The novel self-centering energy dissipation brace composed of disc spring group and wedge block group (DW-SCB) is introduced. The working mechanism of the DW-SCB and the force mechanism of each component are described. The stress analysis of the disc spring group (DSG) and the wedge block group (WBG) were carried out, and the DW-SCB theoretical prediction model was established. Three specimens with different disc spring preload lengths were fabricated, tested, and discussed. Furthermore, the established theoretical model was verified, and the theoretical model correction method considering the processing and assembly errors of the DSG was proposed. The tested data show that the hysteresis curve of DW-SCB is a typical flag shape, and there is almost no residual displacement after multiple loading. An increase in the preload length of the disc spring increases the yield load and bearing capacity of the DW-SCB but has no change on the stiffness of DW-SCB. All the components of the three specimens were not damaged after multiple loadings, which show that the DW-SCB has stable multiple seismic performance and recoverability. Significant, although the machining error of the disc spring leads to a large error between the experimental and theoretical curve of the DSG, the error correction method of the DSG proposed in this study can improve the prediction accuracy of the theoretical model, making the DW-SCB theoretical prediction model more accurate and reliable. The theoretical model considering the error of DSG can better predict the stiffness and load of DW-SCB, which can provide a reference for engineering design and application.

Experimental study on the seismic behavior of all-steel buckling-restrained brace with constrained coupler

This study proposes a novel all-steel buckling-restrained brace (BRB), in which cross-shaped (or H-shaped) steel members and double steel tubes are employed for the core members and buckling-restraining members, respectively. The core members are equipped with a constrained coupler in the central region. The square outer tube, welded to one end of the bracing system, uses spacers to prevent buckling of the inner tube. The hexagonal inner tube is connected to a constrained coupler by welding, thereby preventing the buckling of the core members. The constraint system provides a quadruple restraint mechanism comprising the inner tube, outer tube, constrained coupler, and spacers. Global and local stability are analyzed based on Eulerian theory, the principle of virtual work, and yield line theory, respectively. Cyclic loading tests were performed on four test specimens of the proposed BRB and four traditional BRBs without constrained couplers. Comparative analysis, through cyclic loading tests, reveals that the proposed BRB exhibits a stable energy dissipation performance post-yielding under compression, outperforming the specimens without constrained couplers in terms of the equivalent viscous damping ratio, cumulative plastic deformation, and the compression-strength adjustment factor. Furthermore, the numerical model was constructed and validated using the test results. The effects of the core width-to-thickness ratio and the gap size between the core member and inner tube on hysteretic behaviors were investigated. The contributions of this study can provide a reference for the application of BRBs in the engineering of more complex high-rise buildings and mega-spatial structures.

Seismic performance study of corrugated pipe through-hole shear walls

To greatly reduce the construction difficulty of the connections between precast shear walls and save the cost, a new reinforcement connection technology with through-hole corrugated pipes is proposed in this paper. Focus on the seismic performance of precast shear walls based on this connection technology, a cast-in-place shear wall (CW) and three pieces of corrugated pipe through-hole shear walls (PCW) are tested through a low-cycle loading test. A numerical simulation model is established by using the ABAQUS software to verify the validity of the test results. The results show that the failure mode and the distributions of the cracks in PCW are basically the same as those in CW, except for that there are short cross oblique cracks occurred on the surface of the walls corresponding to the position of corrugated pipes; the bearing capacity of PCW is close to that of CW, but the ductility and energy dissipation capacity of PCW are higher than those of CW. Furthermore, the effects of the number and inner diameter of corrugated pipes and the diameter of reinforcements in pipes on the seismic performance of precast shear walls are mainly studied. The results of this study can provide important references for engineering application in the precast shear wall structures.

Environment-tolerant, inherently conductive and self-adhesive gelatin-based supramolecular eutectogel for flexible sensor

Although hydrogels have attracted increasing attention in the stretchable devices, the low adhesion properties and poor environmental adaptation still seriously restrict their development and application. Herein, we focused on the interaction between polymer networks with disperse media and their resultant influence on gel performance, and constructed self-adhesive and environment-tolerant gelatin/polyacrylamide supramolecular-polymer double-network (Gelatin/PAM SP-DN) eutectogels using multiple supramolecular interactions between natural macromolecule and well-designed deep eutectic solvent (DES). The dual networks of Gelatin/PAM SP-DN eutectogels produced significant supramolecular forces with DES, including hydrogen bonding and electrostatic interaction, contributing to enhance the energy dissipation capacity. Additionally, the Gelatin-PAM SP-DN eutectogels were more prone to generate strong bonding force to various substrates, showcasing both in-situ and ex-situ adhesion performance, and even being used for wet and underwater adhesion. The eutectogels revealed excellent environmental tolerance to maintain excellent mechanical flexibility, conductivity and adhesion at high and low temperatures, ensuring the constructed sensor to sensitively and reliably perceive strain, pressure and human motions over a wide temperature range. Also, the eutectogel demonstrated great potential as a temperature sensor. This work opens up a new horizon in the design of multifunctional and environment-tolerant natural macromolecule-based gel materials for flexible electronics, human-machine interaction and health diagnosis.

Mechanical Failure Characteristics and Energy Dissipation Laws of the Coal–Concrete Combination under Impact Rates

Mechanical Failure Characteristics and Energy Dissipation Laws of the Coal–Concrete Combination under Impact Rates

Development of self-centering and energy-dissipating dual-stage reinforced concrete rocking column-base system

Reinforced concrete (RC) frame is one of the most commonly adopted forms of building structure worldwide. However, server damages can develop in columns during earthquakes which often lead to the catastrophic collapse of the entire structure. In this paper, the novel dual-stage RC rocking column-base system with low-damage characteristics is proposed and tested. The system composes of the unbonded-buckling-restrained-brace (UBRBs) as the sacrificial energy-dissipation component and steel coat at column base to prevent concrete crushing. To prevent column overturning and base slippage while rocking, limiters and contact bars are used to establish the mechanism which limit the column uplift in an extreme earthquake and allow the column reinforcements to yield. Two column performance stages separated by the activation of limiter mechanism are established. In the first stage, the reinforcements of rocking column-base remain elastic while UBRBs yield to dissipate energy. In the second stage, the reinforcements of rocking column-base enter plasticity through the activation of limiter mechanism to dissipate additional energy and prevent column overturning. The hysteresis tests on UBRBs are performed which finds that the UBRBs with equilibrant triangle cross-section and no filling demonstrate stable hysteresis behavior and decent energy dissipation capacity. Experiments on the rocking column-base system demonstrated that the proposed system remains fully elastic at the drift of 0.18 %. Further, the system remains structurally intact at the drift of 2 % and its original performance can be rapidly restored through UBRB replacements. Immediately after 2 % drift, the limiter mechanism is activated and the entire system enters plastic state and dissipates significant energy. With the activation of the limiter mechanism, the bearing capacity of the rocking column-base increases sharply by almost 30 % as a result of column reinforcement yielding, demonstrating the characteristics of dual-stage performance. The system maintains higher levels of bearing capacity until 5 % drift then its peak capacity before the activation of limiter mechanism, indicating the significant ductility potential of the system. Additionally, the system shows reasonable capacity to self-center through axial load and gravity.

Excellent flame retardant and tough epoxy thermosets with imidazolium tributyl phosphate ionic liquid

The brittleness and flammability of epoxy thermosets (EP) have largely limited their applications. In this work a phosphorus-containing ionic liquid 1-methylimidazolium tributyl phosphate ([Mim]TBP) is designed and synthesized to develop high-performance and flame-retardant epoxy thermosets. [Mim]TBP significantly accelerates the curing and improves the toughness of epoxy thermosets. The tensile toughness, tensile strength, impact strength and flexural strength of samples with 10phr [Mim]TBP increase by 419.7 %, 100.2 %, 71.7 % and 58.3 %, compared with pure EP, respectively. The increased toughness is due to the significant energy dissipation caused by the ionic bonds breaking between Mim and TBP. When the [Mim]TBP content exceeds 10 phr, the limiting oxygen index (LOI) can reach over 30 % and UL-94 test pass the V-0 rating. The peak heat release rate (pHRR), total heat release (THR), total smoke release (TSR) and peak CO production (PCOP) values effectively decrease by 31.5 %, 30.6 %, 48.3 % and 6.3 %, respectively, thanks to the gas and condensed phase mechanisms of the [Mim]TBP. A new strategy was provided for the development of toughness and fire safety performance epoxy thermosets for high-performance industrial applications.

Effect of Vertical Location of Post-Opening on Seismic Behaviour of RC Shear Wall: Experimental and Numerical Analysis

The seismic performance of reinforced concrete (RC) shear walls with post-openings is critical in civil engineering. This study investigates the influence of post-opening positions on the seismic behaviour of RC shear walls through both experimental and numerical approaches. Four shear wall specimens with varying positions of post-openings were subjected to pseudo-static tests. Additionally, Finite Element Method (FEM) simulations were employed to further analyse the structural responses of shear walls with post-openings. The results show that the vertical position of post-openings significantly affects the failure mode, peak bearing capacity, and overall seismic performance. Peak bearing capacity reductions were observed, with central and bottom openings diminishing capacity by up to 17.5% and 15.1%, respectively, while top openings had a minimal impact. Openings also influenced pre-crack initiation, yielding behaviour, and stiffness degradation, with central openings causing the most significant effects. The ductility and energy dissipation capacities of the shear walls were also affected by opening positions. Bottom post-openings led to a maximum ductility reduction of 18.4%, while top openings increased ductility by up to 24.6%. Energy dissipation capacity decreased with lower post-opening locations, with central and bottom openings reducing capacity by 78.9% and 63.0%, respectively. These findings emphasize the importance of considering opening location in the seismic design of RC shear walls to optimize structural performance.