Energy Dissipation Capability Research Articles

Exact Solution of Nonlinear TVMD Based on Maximizing Damping Enhancement Effect for Acceleration Response Control

The tuned viscous mass damper (TVMD) exhibits superior control effect and energy dissipation capability compared to the viscous damper (VD). Existing literature has primarily focused on the control of absolute acceleration response in structures by linear TVMD, with limited research on nonlinear damper for controlling structural performance and efficiency. This study proposes a methodology for determining the optimal parameters of linear TVMD. The closed-form solution of the nonlinear TVMD is derived through stochastic linearization based on the linear TVMD, aiming to minimize the damping ratio of TVMD by utilizing the damping enhancement effect of the system. For lightly damped structures, the closed-form solution remains a reliable method for accurately approximating TVMD design parameters. Compared to traditional fixed-point theory, the TVMD developed through the proposed methodology demonstrates superior control performance, especially in terms of absolute acceleration, with a smaller damping ratio and minimal deviation from the optimal state of the TVMD. Additionally, the study investigated the influence of the damping index on the optimal parameters and the efficacy of the TVMD in vibration control. It is observed that reducing the damping index can improve structural performance, particularly in long-period structures with small mass ratios, although it may reduce the efficiency of the TVMD. Notably, TVMDs with lower mass ratios maintain higher efficiency regardless of the structural natural period. The damping index does not affect the optimal frequency ratio or the mean square response. Ultimately, the effectiveness of the optimization method is displayed through the examination of response spectra following 22 real seismic events, showcasing its adaptability across various structural types. The comparison of the root-mean-square response between the VD and TVMD across different periods shows consistent results, with a maximum deviation of only 10%. The TVMD is highly effective at regulating the structural response, excelling particularly in controlling the absolute acceleration of long-period structures, where it reduces maximum absolute acceleration by 20% more than displacement. The proposed exact solution rapidly and precisely identifies the design parameters of nonlinear TVMD by the desired specifications, thereby offering theoretical guidance for practical engineering applications.

Investigation of scalable chiral metamaterial beams for combined stiffness and supplemental energy dissipation

Abstract Metamaterials have gained important interest in the research community attributable to advances in additive manufacturing enabling their fabrication at reasonable costs. The vast majority of their applications and demonstrations are at micro- and nano-scales, and challenges remained regarding the larger scale applications. In this paper, we are interested by the scalability of metamaterials, targeting structural engineering applications. To do so, we explore mechanisms capable of providing both bending stiffness and high-performance energy dissipation. Our study includes beams constructed with chiral topologies of different structural hierarchy orders, and we also explore three new topologies that we termed chiral friction, chiral-rectangular and chiral-hexagonal design to engineer the beams and the use of friction rods with tunable post-stress that inserted longitudinally through the beams to provide enhanced friction. The mechanical performance of the metamaterial beams is characterized through a series three-point bending tests. Of interest is to evaluate the bending stiffness, shape recoverability, and energy dissipation capabilities. We find that the chiral-hexagonal topology equipped with a non-stressed friction rod exhibit excellent energy dissipation capabilities, showing an improved loss factor by 11.9 times compared to the control beam using 68% of its materials density. Moreover, the use of the post-stress mechanism shows that it is possible to augment both its shape recovery and bending stiffness up to 99.3% and 47.1%, respectively. Overall, our investigation shows that it is possible to engineer scalable metamaterial beams targeting structural engineering applications, and that the use of topology optimization and strategically designed post-tensioning mechanism can allow tuning of mechanical performance.

Experimental study on seismically isolated systems using a novel roller-type bearing with energy dissipation capacity

The roller-type isolation bearing is highly effective in limiting the transmission of lateral seismic forces to the superstructure. This paper introduces a novel roller-type bearing with energy dissipation capacity (RB-EDC), which includes flat bearing seats, rollers, limit plates with energy dissipation capability, and limit rings. The RB-EDC is characterized by its excellent energy dissipation capacity, simple manufacturing process, low cost, vertical tensile bearing capacity and stable performance in extremely cold regions due to its specific configuration and materials. The design procedure for the RB-EDC is detailed herein. Subsequently, pseudo-dynamic comparison tests were conducted on both a seismic isolation system specimen and a RC column specimen under frequent and rare earthquake conditions to validate the damping performance of the RB-EDC. The seismic isolation system consists of the RB-EDC and an RC column identical to the RC column specimen. The results indicate that, compared to the RC column specimen, the column in the seismic isolation system specimen significantly reduces crack distribution ranges, rebar strain, concrete strain, and displacement at the column top under seismic actions. The RB-EDC exhibits significant energy dissipation capacity even during frequent earthquakes, demonstrating effective damping performance. However, the residual displacement of the RB-EDC increases with seismic intensity, which may impact the damping performance of the bearing in future potential earthquakes, indicating the need for further redesign to incorporate self-centering capacity.

Fluid-filled lattices for responsive orthotic insoles

Abstract Orthotic insoles are essential for alleviating discomfort and preventing injuries in the foot caused by high peak pressures in the plantar tissue. Traditional orthotic insoles, often prescribed to address these issues, are designed based on the static foot shape and pressure measurements, lacking responsiveness to dynamic movements. This study explores the behaviour of fluid-filled lattices for improving the functionality of orthotic insoles, focusing on energy dissipation and pressure redistribution capabilities. Using numerical homogenisation, the research integrates hyperelastic and permeability models to simulate the behaviour of Solid–Liquid Composites. Experimental tests validated these models, examining the influence of fluid viscosity and structural variations on energy dissipation and pressure distribution. Results show that fluid-filled lattices provide enhanced energy dissipation and reduce peak pressures by evening out the pressure distribution compared to non-fluid-filled samples. These findings highlight the potential of fluid-filled lattices to improve the performance and comfort of orthotic insoles.

Numerical Study on Seismic Performance of a New Prefabricated Reinforced Concrete Structural System Integrated with Recoverable Energy-Dissipating RC Walls

To enhance the performance of infill walls and reduce seismic damage, this paper proposes a novel prefabricated reinforced concrete (PRC) energy-dissipating wall, forming a new recoverable energy-dissipating PRC (ED-PRC) structural system. The system features pre-set gaps on both sides and the top of the PRC wall, with flexible materials filling the gaps on the sides. The top of the PRC wall is connected to the beam through several double-conical mild steel dampers to ensure the efficient transfer of horizontal shear forces between the main frame and the PRC wall. A numerical study was employed to investigate the seismic performance and the staged yield capacity. The results show that this design achieves a yielding sequence of dampers → wall → main frame. Furthermore, during the early to mid-phases of the cyclic loading simulations, the double-conical mild steel dampers with the low yield point utilized in the ED-PRC structural system exhibited exceptional energy dissipation capabilities. Notably, the LY100 dampers accounted for up to 61.84% of the total energy dissipation, with the LY160 and LY225 dampers contributing 55.35% and 50.25%, respectively. It indicates that the proposed ED-PRC structural system significantly enhances the ductility and the energy dissipation capacity under seismic loading while substantially reducing damage to the primary structure. The use of prefabricated components facilitates modular construction, allowing for quick dismantling and replacement after an earthquake, thereby rapidly restoring the structural seismic resilience.

Biomimetic Modular Honeycomb with Enhanced Crushing Strength and Flexible Customizability.

The integration of biomimetic principles into the sophisticated design of honeycomb structures has gained significant traction. Inspired by the natural reinforcement mechanisms observed in tree stems, this research introduces localized thickening to the conventional honeycombs, leading to the development of variable-density honeycomb blocks. These blocks are strategically configured to form modular honeycombs. Initially, the methodology for calculating the relative density of the new design is meticulously detailed. Following this, a numerical model based on the plastic limit theorem, verified experimentally, is used to investigate the in-plane deformation models of modular honeycomb under the low- and high-velocity impact and to establish a theoretical framework for compressive strength. The results confirm that the theoretical predictions for crushing strength in the modular honeycomb align closely with numerical findings across both low- and high-velocity impacts. Further investigation into densification strain, energy absorption, and gradient strategy is conducted using both simulation and experimental approaches. The outcomes indicate that the innovative design outperforms conventional honeycombs by significantly enhancing the crushing strength under low-velocity impacts through the judicious arrangement of honeycomb blocks. Additionally, with a negligible difference in densification strains, the modular honeycomb demonstrates superior energy dissipation capabilities compared to its conventional counterparts. At a strain of 0.85, the modular honeycomb's energy absorption capacity improves by 36.68% at 1 m/s and 25.47% at 10 m/s compared to the conventional honeycomb. By meticulously engineering the arrangement of sub-honeycombs, it is possible to develop a modular honeycomb that exhibits a multi-plateau stress response under uniaxial and biaxial compression. These advancements are particularly beneficial to the development of auto crash absorption systems, high-end product transportation packaging, and personalized protective gear.

Building Ultrastrong, Tough and Biodegradable Thermoplastic Elastomers from Multiblock Copolyesters via a "Reserve-Release" Crystallization Strategy.

Simultaneously attaining high strength and toughness has been a significant challenge in designing thermoplastic elastomers, especially biodegradable ones. In this context, we present a class of biodegradable elastomers based on multiblock copolyesters that afford extraordinary strength, toughness, and low-strain resilience despite expedient chemical synthesis and sample processing. With the incorporation of the semi-crystalline soft block and the judicious selection of block periodicity, the thermoplastic materials feature low quiescent crystallinity ("reserve") albeit with vast potential for strain-induced crystallization ("release"), resulting in their significantly enhanced ultimate strength and energy-dissipating capabilities. Moreover, a breadth of mechanical responses of the materials - from reinforced elastomers to shape-memory materials to toughened thermoplastics - can be achieved by orthogonal variation of segment lengths and ratios. This work and the "reserve-release" crystallization strategy herein highlight the double crystalline multiblock chain architecture as a potential avenue towards reconciling the strength-toughness trade-off in thermoplastic elastomers and can possibly be extended to other biodegradable building blocks to deliver functional materials with diverse mechanical performances.

Eccentric compression behavior of CFRP-confined reactive powder concrete-filled steel tube slender columns

Ultra high and large-span structural components are needed in urban modernization construction to meet the engineering requirements. Reactive powder concrete-filled steel tubes (RPCFSTs) provide a cost-effective and efficient solution for optimizing space utilization in super high-rise buildings and enhancing the crossing capacity of bridge, which accords with such development. However, these components have inherent drawbacks in terms of local buckling and corrosion resistance. The use of carbon fiber reinforced polymer (CFRP) confinement to suppress this innate deficiency has been proven to show great advantages in limited trial results. This article establishes a comprehensive test scheme to investigate the eccentric compression performance of CFRP-confined RPCFST columns. A total of 11 specimens were prepared and subjected to biased compression test by varying the component length (400, 800, 1200, and 1600 mm), number of CFRP layers (0–3), and load eccentricity (0, 10, 20, 30, and 40 mm). The results showed that the CFRP confinement could effectively enhance the bearing capacity and energy dissipation capability of RPCFST columns while delaying the local buckling of slender specimens with low slenderness ratios. The improvement of ultimate load due to CFRP confinement exceeded 42.5 %. However, in specimens with higher slenderness ratios and with increasing load eccentricity, the confinement effect of the steel tube on the core RPC tended to weaken. An N–M interaction model for slender CFRP-confined RPCFST columns was established, and this model was validated to be in good agreement with the experimental results. The conclusions drawn from this study might given a solid foundation for the future application of CFRP-confined RPCFST structures.

A review of structural diversity design and optimization for lattice metamaterials

Metamaterials are a type of groundbreaking engineered materials with unique properties not found in natural substances. Lattice metamaterials, which have a periodic lattice cell structure, possess exceptional attributes such as a negative Poisson’s ratio, high stiffness-to-weight ratios, and outstanding energy dissipation capabilities. This review provides a comprehensive examination of lattice metamaterials. It covers their various structures and fabrication methods. The review emphasizes the crucial role of homogenization methods and multi-scale modeling in assessing metamaterial properties. It also highlights the advancement of topology optimization through advanced computational techniques, such as finite element analysis simulations and machine learning algorithms.

Action of liquid tune mass dampers and base isolation in high rise buildings

In areas where earthquakes are common, high-rise structure seismic resistance is a major concern. The purpose of this research is to determine whether base isolation and liquid tuned mass dampers (LTMDs) can improve tall building seismic performance. A symmetrical G+8 story RCC structure in Zone V with medium grade soil is analyzed using ETABS software, Response Spectrum Analysis, and Equivalent Static Analysis to see how the structure behaves under different load combinations. For various structural configure rations, including basic models, models with water tanks, and models with base isolation, key factors such joint displacement, storey drift, base shear, and time period are evaluated. The results show that as compared to baseline models, models with damping and isolation systems exhibit much lower joint displacements, base shear forces, and story drift. In particular, base isolation models perform better in terms of reducing structural deformations and resisting lateral forces. Furthermore, shorter time periods and higher frequencies are routinely observed in base isolated models, suggesting enhanced dynamic response and energy dissipation capabilities. The paper also covers the flexibility and benefits of using LTMDs and base isolation to reduce seismic threats. Buildings can be successfully separated from ground motion by base isolation systems, and dynamic response can be countered by LTMDs using regulated liquid sloshing. The attraction of LTMDs in improving overall stability is increased by their adaptability in minimizing torsional and lateral vibrations. The study concludes by emphasizing how crucial it is to use cutting-edge structural retrofitting methods, including base isolation and LTMDs, to improve the seismic resistance of high-rise structures. In earthquake-prone areas, engineers and legislators may proactively protect tall buildings and guarantee a safer, more robust built environment by incorporating these technologies into construction standards and design procedures.

Optimizing steel plate shear wall performance: influence of infill plate thickness and connection length to vertical boundary elements

The Steel Plate Shear Wall (SPSW) is widely used as a lateral force resisting system in areas prone to high seismic activity. This is because of its exceptional ductility and ability to dissipate energy. Previous studies have indicated that disconnecting the infill plate from the Vertical Boundary Element (VBE) can decrease the demands on the column. The observed outcomes lead to a decline in both the energy dissipation capability and the lateral load-bearing capacity. The primary goal of this investigation is to mitigate stress on the column while concurrently reducing both the energy dissipation and lateral force capacities. To accomplish this, a partial connection will be established between the infill plate and the Vertical Boundary Element. Thus, the overarching objective of this research is to identify the optimal connection length that minimizes the demands on the column while simultaneously curtailing the reduction in energy dissipation and lateral force capacities. Using Abaqus software, twenty models with different infill plate thicknesses and lengths of connection between the infill plate and Vertical Boundary Element were analysed. To determine the optimal length of connection between the infill plate and Vertical Boundary Element, the energy dissipation capacity, lateral load capacity, and column stresses were evaluated and compared. The maximum dissipation of energy occurs at a connection length of 75% between the infill plate and Vertical Boundary Element and an infill plate thickness of 12 mm. In contrast, the greatest lateral load capacity is achieved at connection lengths of 50% between a 25 mm infill plate thickness and a Vertical Boundary Element weight of 25%. The column stress reaches its minimum value when the infill plate measures 20 and 25 mm, and it reaches its maximum value when the infill plate measures 6 mm and 12 mm. By increasing the thickness of the infill plate and minimizing its connection to the Vertical Boundary Elements, the column stress in Vertical Boundary Elements can be decreased, while simultaneously enhancing lateral load capacity and maintaining an adequate level of energy dissipation.

Seismic performance of square concrete-filled steel tubular column-composite beam single-side bolted joints: An experimental and numerical study

The seismic behavior of square concrete-filled steel tubular (SCFST) column-composite beam single-side bolted joints has not been fully investigated. To address this gap, both experimental and numerical studies were conducted, focusing on the impact of various parameters. This research entailed constructing and testing nine prototypes of SCFST column-composite beam single-side bolted joints, scaled to a 1/2 zoom ratio, under conditions simulating seismic loads. Variables considered in these tests included the presence of stiffener ribs, bidirectional stirrups, the section height of the steel beam, and the axial compression ratio. A finite element model was developed and its accuracy was affirmed through comparison with the experimental outcomes. The analysis encompassed several aspects: the hysteretic response, skeleton curves, strain, ductility, stiffness degradation, and energy dissipation. The findings revealed that the design of bidirectional stirrups is crucial, especially under high axial compression ratios (n = 0.8), in preventing compression-flexure failures at the column ends. The hysteresis curves of the specimens manifested in two distinct shapes: spindle-shaped with bidirectional stirrups and bow-shaped without them. Enhancements such as the addition of stiffener ribs or an increase in the steel beam’s height resulted in a more comprehensive hysteresis curve, and improvements in the initial rotational stiffness, flexural bearing capacity, and energy dissipation capability of the specimens were observed. Notably, even when the beam-column bending capacity ratio in the SCFST column-composite beam single-side bolted joint reached 1.5, the joint’s energy absorption was predominantly governed by the beam’s energy dissipation.

Energy dissipation and power flow analysis based on acoustic black hole laminated beams

To enhance the understanding of the dynamic performance of composite beams, assessing their energy accumulation and dissipation capabilities is crucial. The purpose of this paper is to establish a dynamic analysis model of acoustic black hole (ABH) laminated beams based on the Timoshenko beam theory and isogeometric method and to analyze structural intensity and power flow. The vibration governing equation for the ABH laminated beam is derived by calculating its potential and kinetic energy. The convergence of the results is confirmed through multiple mesh refinements, while the model's accuracy and applicability are substantiated through comparisons with the literature, traditional finite element simulations, and experimental data. This investigation into the power flow and structural intensity under varying parameter conditions elucidates the energy transfer mechanisms within ABH laminated beams, offering valuable insights for the deployment of ABH technologies in practical engineering applications.

Experimental investigation on lateral performance of southern pine nailed connections under monotonic and cyclic loading

Connections are responsible for maintaining the integrity and safety of wood structures when subjected to lateral force induced by wind or seismic event. The aim of this study is to provide a better understanding of monotonic and cyclic response of timber-to-timber nailed connections. A total of 48 groups of double-shear nailed connections were tested to investigate the effect of different variables on the lateral resistance performance of connections. Representative parameters derived from practical nailed timber connections were considered, including nail diameter, nail type, and load-to-grain angle. It is found that the failure modes of the specimens loaded monotonically are attributed to bending yield of nails. Conversely, under cyclic loading, the majority of nail failures occur as a result of fatigue fracture, which is caused by the repetitive bending stress. A reduction in ductility ranging from 76.9 % to 92.7 % is observed in specimens subjected to cyclic loading, as compared to those under monotonic loading. Utilizing larger-diameter nails as connectors can markedly improve the load-bearing capacity, ductility, and energy-dissipation capabilities of connections subjected to cyclic loading. Helically threaded nails (HTN) have a 29.4 % higher lateral capacity than smooth shank nails (SSN), but a 29.9 % lower stiffness and 22.9 % lower ductility. Experimental load capacities were compared with existing calculation models, and Eurocode 5 was identified as the most suitable design code for predicting the lateral performance of nailed timber joints. Two analytical models were proposed to better simulate the load-slip behavior of nailed connections under monotonic and cyclic loading conditions, respectively.

Impact response of additively manufactured density-graded open-cell foams

Additive manufacturing has made it possible to fabricate materials that were unachievable with traditional methods. This study focuses on understanding the deformation behavior and energy absorption mechanics of additively manufactured cellular materials with gradually varying densities. Foams have unique deformation behavior due to their intricate topology and composition, resulting in excellent energy dissipation capability. Varying the density can significantly influence their deformation response and improve energy absorption and impact resistance. Voronoi tessellation is employed to model the foams, as it effectively captures the cell morphology in foam structures and produces stochastic cellular topologies accurately. Resin-based additive manufacturing techniques are employed to fabricate cellular materials with varying density configurations for low-velocity and high-velocity impact experiments. The study demonstrates that density-graded foams effectively dissipate a broad spectrum of impact energies, surpassing uniform counterparts by transmitting reduced stress, especially at lower energy levels. This characteristic enhances their suitability for advanced energy absorption applications. The results also show that at high impact velocities, the direction of density gradation influences energy dissipation and peak stress transmission.

A comparative study of low cyclic loading effects on plastic strain, nonlinear damping, and strength softening in fiber-reinforced recycled aggregate concrete

The incorporation of fibers significantly enhances the properties and structural performance of recycled aggregate concrete. This study introduces Fiber-Reinforced Recycled Aggregate Concrete (FRAC) by integrating steel fibers (SF) and polypropylene fibers (PPF) into the recycled aggregate concrete (RAC) matrix. A comprehensive series of cyclic loading tests, including reload and unload sequences, were conducted to meticulously analyze the deterioration of strength and energy dissipation capabilities of SF/PPF-reinforced RAC. The research examines the effects of fiber characteristics, volume ratios, lengths, and diameters on strength degradation after the peak stress along the stress-strain curve. Degradation models based on plastic strain were proposed for both SF-reinforced RAC and PPF-reinforced RAC. The study further investigates the fluctuation of strain energy in FRAC under low cyclic loading, revealing the correlation between plastic strain energy and equivalent viscous damping ratio. A nonlinear viscous damping model that accounts for the influence of the reinforcing index (RI) is proposed. This model effectively predicts the degradation of strength, the evolution of plastic strain, and the dynamics of nonlinear viscous damping in composite materials with varying fiber content. Ultimately, this research provides essential technical insights for the practical engineering application of RAC.

Effect of entropy evolution on electromagnetic response mechanism of carbon-coated medium- and high-entropy oxides

Metal oxides have attracted much attention due to their potential in electromagnetic wave absorption. However, the inherent energy dissipation capabilities of low-entropy metal oxides pose challenges in designing materials with optimal entropy levels. The regulation of entropy structure is anticipated to facilitate the development of novel electromagnetic functional materials featuring abundant active sites, adjustable specific surface area, stable crystal structure, unique geometric compatibility, and distinctive electronic structure. This study compared the electromagnetic loss performance of low, medium, and high entropy metal oxides in carbon matrices. As entropy increases, the number of phases expands, leading to enhanced interface polarization losses and improved impedance matching. However, further increases in entropy result in performance decline due to lattice distortions and mismatches in dielectric constant and magnetic permeability. Experimental data and theoretical analysis reveal that performance enhancement in medium-to high-entropy metal oxides is attributed to their unique morphology and the synergistic effects of multiple metal components, which enhance interfacial and defect polarization mechanisms. Heterogeneous interfaces and lattice defects provide additional polarization sites, aiding in the conversion of electromagnetic energy into heat. The presence of intermediate phases effectively absorbs and dissipates electromagnetic waves, thereby enhancing the overall absorption capability.

Seismic performance of new detailing RCS connection with different axial compression ratio and FBP thickness

Reinforced Concrete column and Steel beam (RCS) structural system has been extensively studied due to the effective use of concrete and steel material and cost efficiency. Bearing failure and constructability were two main issues of RCS joint in practical engineering. To improve these two deficiencies, the authors proposed a whole-section diaphragm type RCS joint. This study aimed to examine the impact of axial compression ratio and face bearing plate (FBP) thickness on the seismic behavior of the proposed joint. In this research, six RCS joint specimens were designed to achieve joint failure and tested under cyclic loading. Shear failure was identified as the typical failure mode. The results revealed that higher axial, compression ratio could lead to higher cracking loads, with improved load-carrying capacity, stiffness, and energy dissipation capabilities. Additionally, the joint bearing distortion reduced as the axial compression ratio increased. All specimens displayed spindle-shaped hysteresis loops while the specimen without axial compression exhibited pinching effect. The presence of parallel FBPs significantly improved the shear capacity. However, as the thickness of the parallel FBPs increased from 6 mm to 10 mm, the load-carrying capacity showed limited enhancement. Moreover, a comparative analysis of current calculation methods was conducted. The results demonstrated that the AIJ and CECS347:2013 formulas showed acceptable accuracy in predicting the joint shear strength. These findings validated the applicability of the existing methods for proposed composite joints, while the effect of the axial compression ratio required further evaluation.

Experimental study on seismic performance of damaged masonry walls reinforced with high-polymer cementitious composite material

Masonry structures are one of the most traditional and economical structural forms that are extensively used worldwide. However, severe damage to the masonry structures during past earthquakes addresses their vulnerability to seismic loadings. Therefore, it is critical to develop effective and efficient seismic reinforcement measures for masonry structures. This study proposes a structural retrofitting method for masonry walls that employs a corrosion protection liner (CPL) and high-polymer cementitious composite material (HPCCM). Cyclic in-plane pseudo-static tests were performed on six masonry wall specimens comprising three unreinforced and three seismically damaged masonry walls retrofitted with CPL-HPCCM. This experimental study explored the hysteretic behavior, deformation capacity, and failure mechanism of masonry wails after rehabilitation with the proposed retrofitting method under cyclic loading. The test results indicate that the CPL-HPCCM structural retrofitting method is an effective structural retrofitting technique that significantly enhances the lateral load-bearing capacity and energy dissipation capability of masonry walls. Even for the severely damaged masonry wall specimens, the lateral load-bearing capacity, lateral stiffness, and overall ductility of the wall specimens after retrofitting with CPL-HPCCM were restored to or improved beyond those of the intact wall specimens. Compared with the non-retrofitted specimens, the lateral load-bearing capacity of the CPL-HPCCM retrofitted specimens exhibited a substantial improvement, with a minimal increase of 14.6 %. In addition, the CPL-HPCCM method also enhanced the energy dissipation capacity of the wall specimens over 1.95 times compared to the non-retrofitted specimens. Finally, a lateral load-bearing capacity prediction equation was proposed for CPL-HPCCM-reinforced masonry walls based on experimental results.

Anti-progressive collapse performance and design method of novel T-stub connections

To address the insufficient anti-collapse capacity of T-stub connections due to premature failure, this study proposes a novel T-stub connection (NTC) by adding four V-shaped laminated plates. Monotonic loading tests are conducted on the T-stub web and V-shaped laminated plate to analyze the influence of geometric parameters on their deformation and load-bearing capacity. The working mechanism of NTC is investigated through the validated numerical models by analyzing the failure mode, impact force history, deformation pattern, internal force development, and energy dissipation. The research results indicate that, compared to the T-stub connection, the NTC exhibits two-phase failure characteristics, which begin with the fracture of the bolt-hole in the T-stub web, followed by the gradual straightening and eventual fracture of the V-shaped laminated plates. NTC undergoes three stages under impact loads: peak, oscillation, and platform stages. The addition of V-shaped laminated plates enhances the ductility of NTC by 93 %−130 % and its energy dissipation capacity by 189 %−235 %. This significant enhancement in deformation and energy dissipation capabilities can be attributed to the addition of the V-shaped laminated plates. The deformation and bearing capacity calculation formulas for both the T-stub web and V-shaped laminated plate are provided. Additionally, a design method for NTC is proposed based on theoretical analysis, and its rationality is verified through numerical examples involving three different sets of beam and column sections.