Energy Dissipation Components Research Articles

Seismic performance of prefabricated repairable RCS joints with replaceable multi-segment weakened plates

In order to enable the high-efficiency and easy-operation repairment of prefabricated reinforced concrete column-steel beam (RCS) structure after damage, a novel replaceable assembly RCS joint with multi-segment weakened plate (RCS-MWP) is proposed in this research. The design theory, construction, assembly process, replacement of MWP components and repairment after damaged were introduced. This configuration encompasses three sub-specimens: RCS-MWP, RCS-MWP1, and RCS-MWP2, with varying parameters such as pad thickness and number of weakened segments. For RCS-MWP1 and RCS-MWP2, only the energy dissipation components were replaced after the RCS-MWP were tested and damaged. A comparative study was conducted with a traditional RCS joint with a bolt connection (RCS-B). The test results indicated that the damage to the four specimens (RCS-B, RCS-MWP, RCS-MWP1, and RCS-MWP2) was mainly concentrated at the energy dissipation components, while the reinforced concrete (RC) columns and steel beams remained in the elastic stage with minimal damage. By comparing the RCS-MWP, RCS-MWP1, and RCS-MWP2 specimens, it was observed that RCS-MWP and RCS-MWP2 exhibited second-order buckling, which improved the bearing capacity and energy dissipation capacity. The cumulative energy dissipation of specimens with 8 mm pads in the multi-segmental weakened plate assemblies (RCS-MWP1 and RCS-MWP2) increased by 9% and 59.4% compared to RCS-MWP with 3 mm pads, providing enhanced nodal energy dissipation. The average positive and negative bearing capacities of RCS-B were 70.6% higher than those of the RCS-MWP group, which was caused by the low yield stress of multi-segment weakened plates. After eliminating the residual displacement of specimen RCS-MWP, the seismic performance of the RCS-MWP1 and RCS-MWP2 specimens was barely decreased after diagonally replacing the energy dissipation components. This demonstrates the rationality and feasibility of using replaceable MWP components to repair RCS-MWP joints after the earthquake. It should be noted that the residual displacements after unloading resulted in the restoration of the joints more challenging, hence, prestressing to achieve self-centering could be considered as a potential topic for future research. This proves the feasibility of replacing energy-consuming components.

Assembled self-centering brace with replaceable friction damper for seismic resilience: Development and mechanical behavior research

A novel seismic resilient brace, integrating a replaceable friction damper mechanism with an assembled self-centering device of combination disc springs, has been developed and investigated through experimental research. This brace can be named as the Assembled Pre-pressed Disc-springs Self-centering Replaceable Energy Dissipation (APD-SRED) brace. The working principles, structural configurations, fabrication process and mechanical behaviors of this bracing system were discussed and analyzed firstly in detail. Subsequently, five brace specimens were designed incorporating different axial pre-compression forces within a combination disc springs system and varying friction forces in the damper device. Test results exhibit a stable and repeatable flag-shaped hysteretic responses with satisfactory energy dissipation, which can be implemented under the low cyclic reversed loading. Additionally, it can be noted that the excellent seismic resilience performance can be obtained by maintaining a relative balance between self-centering and energy dissipation characteristics. The stiffness and strength of this brace can withstand cyclical loading without degradation, making superiorities against sequential design earthquakes without the replacement or repair, and facilitating replacement of the friction energy dissipation components to meet different demands. Moreover, the proposed calculation model can be validated accurately predicting the mechanical behavior of the APD-SRED brace by considering friction effects in disc-springs. This validation was achieved through comparisons with experimental results, and several crucial design factors influencing the brace's behavior were analyzed and discussed for practical application in a parametric design. Finally, drawing upon a combination of experimental and analytical studies, this study ultimately presented practical design recommendations.

Energy response analysis and seismic isolation strategy optimization of high-speed railway bridge-track system under earthquake action

The formulation and optimization of a seismic isolation strategy is crucial for improving the seismic performance of high-speed railway bridge-track systems (HSRBTS) under earthquake action. In line with this proposition, therefore, this paper studies the seismic isolation strategy optimization of HSRBTS based on an energy response analysis. More specifically, the energy dissipation distribution of common and isolation HSRBTS under different earthquake strength levels is analyzed. The results show that when the peak ground acceleration (PGA) is greater than 0.3g, the seismic input energy of isolation HSRBTS is smaller than common HSRBTS. With the increase of PGA, the total proportion of hysteretic energy dissipation increases while the proportion of damping energy dissipation decreases in common HSRBTS, with the opposite being observed in isolation HSRBTS. Bearings and piers are the main hysteretic energy dissipation components for HSRBTS. Thus, in view of the energy dissipation requirements and structural characteristics of HSRBTS, this paper proposes an energy-based optimization principle. Under the existing isolation HSRBTS, the seismic isolation strategy is optimized to achieve a uniform distribution in hysteretic energy dissipation, while the effectiveness of the optimized seismic isolation strategy is submitted to further verification.

Seismic performance of carbonated recycled aggregate concrete shear walls

The carbonated modification method is recognized as an effective method to enhance recycled aggregates (RA), but there is currently a lack of research on carbonated recycled aggregate concrete (CRAC) used for structural engineering. This paper investigated the impact of CRAC on the seismic performance of shear walls, quasi-static tests of one natural aggregate concrete (NAC) shear wall and four concrete shear walls with different replacement ratios (30 %, 50 %, 70 %, and 100 %) of carbonated recycled aggregate (CRA) were conducted. The ductility, energy dissipation, stiffness, strength degradation, and lateral displacement components of CRAC shear walls were evaluated. The results indicate that the seismic behavior of the shear walls degraded as the replacement rate of CRA increased. Based on the comprehensive evaluation of failure patterns and seismic performance, the replacement rate of CRA is suggested to be taken as 70 % in the concrete shear walls. Finally, the strut-and-tie model was validated as an effective method for predicting the shear capacity of CRAC shear walls, and the accurate softening coefficient constant C of the strut-and-tie model for CRAC and RAC shear walls was proposed.

Development of a novel full-scaled self-centering brace with notched steel tubes

A novel self-centering brace with notched steel tubes (SCB-NST) was developed and experimentally studied. The proposed SCB-NST consists of a novel notched steel tube (NST) for energy dissipation and disc springs for self-centering, respectively. Three full-scaled specimens were tested to investigate the hysteresis behavior under cyclic loading. These specimens include a brace with NST only, a brace with disc spring only, and an SCB-NST. The first two tests were specifically conducted to obtain the contributions of the NST and disc springs alone, respectively. The test results illustrate that the first proposed NST displays excellent energy dissipation and deformation capabilities. The proposed SCB-NST exhibits a stable flag-shaped hysteresis behavior, distinguished self-centering, and significant energy dissipation capacity without residual displacement. Furthermore, experimental findings reveal that the disc spring functions as a secondary defense line of the SCB-NST system upon sudden failure of the NST. The cyclic test of the brace with disc spring only shows that the friction between the disc springs should not be neglected, especially when quantities of large-diameter disc springs are stacked. The modular design of the proposed SCB-NST facilitates the replacement of energy-dissipating components, allowing for efficient maintenance and ultimately achieving the design objective of promoting reusability and resource conservation. The SCB-NST, equipped with two NSTs featuring different ultimate displacements, has been confirmed through finite element analysis to have three defense lines, which improves the reliability and redundancy of the SCB-NST system. The parametric finite element analysis results reveal that the thickness of the energy-dissipation ring has the most significant influence on the load-bearing capacity and energy-dissipation capability of the SCB-NST. Concurrently, the pre-pressed force of the disc spring is crucial for eliminating the residual displacement of the SCB-NST.

Experimental study and design methodology of sacrificial-energy dissipation beam-column joint

To enable secondary energy-dissipation components to actively attract and dissipate seismic energy, a new type of sacrificial-energy dissipation beam-column joint (SEDJ) was proposed. This study validates the performance of the proposed SEDJ through full-scale quasi-static loading tests. The rotation angle of the proposed SEDJ at the beam end, corresponding to the peak strength Fu, can be controlled within 1/250 - 1/50. In addition, the beam and column components remain elastic, thereby achieving the seismic performance objectives of "no damage, sacrificial-energy dissipation, and no collapse under service-level (SLE), design-basis (DBE), and maximum-considered (MCE) earthquakes", respectively. This study enhances the design of the SEDJ by adopting a built-in sleeve connection scheme to significantly reduce the free-stroke displacement, and a double-coupling block scheme to solve the issue of stress concentration in friction plates that leads to cracking. Furthermore, the efficiency of the installation and disassembly of friction plates is improved, thus enabling the rapid replacement of bolts and friction plates after strong earthquakes. Finally, a practical engineering design methodology is proposed that decouples the bending moments of the sacrificial MR and energy-dissipation MS stages, this methodology activates the sacrificial mechanism under DBEs or MCEs to protect primary beam and column components, and will provide potential insights for the development and application of innovative structural components based on the sacrificial mechanism design philosophy.

A novel resilient system of self-centering precast reinforced concrete walls with external dampers

The seismic vulnerability of concrete structures has prompted the development of innovative approaches to enhance earthquake resistance. Recent earthquakes have demonstrated the challenges of repairing concrete buildings damaged beyond feasible restoration. In response, research in structural engineering has increasingly focused on damage-resisting reinforced concrete walls, offering improved self-centering behavior and damage mitigation compared to traditional counterparts. Self-centering walls, employing a rocking mechanism, exhibit effective damage minimization and residual deformation reduction. This study introduces a robust approach to precast reinforced concrete walls, comprising a precast reinforced concrete shear wall integrated with an external energy dissipation component. The energy dissipation element, a reinforced concrete column attached externally on both sides of the wall, acts as a new damage-limiting component with enhanced energy dissipation capacity. Utilizing the general-purpose Finite Element (FE) software ABAQUS, a three-dimensional simulation of experimentally investigated self-centering precast reinforced concrete walls was developed. The finite element model was validated and subsequently employed to assess the performance of the proposed system under cyclic loading. Various design parameters of the reinforced concrete energy dissipation element, including cross-sectional area, wall height proportion, concrete strength, primary reinforcement yield strength, and reinforcement ratio, were investigated. Additionally, the suggested system underwent cyclic loading in multiple scenarios simulating subsequent earthquakes. The finite element analysis results indicate that the proposed method, with a well-designed energy dissipation element, ensures minimal damage, a controlled increase in lateral resistance, sufficient energy dissipation capacity, and the required resilience following successive seismic events.

Evaluation of Hysteretic Performance of Horizontally Placed Corrugated Steel Plate Shear Walls with Vertical Stiffeners

Corrugated steel plate shear walls (CSPSWs) have been widely utilized as lateral-resistant and energy-dissipating components in multistory and high-rise buildings. To improve their buckling stability, shear resistance, and energy-dissipating capacity, stiffeners were added to the CSPSW, forming stiffened CSPSWs (SCSPSWs). Evaluating the hysteretic performances of SCSPSWs is crucial for guiding seismic design in engineering practice. In this paper, the dissipated energy values of the SCSPSWs with different parameters were calculated. Based on the obtained dissipated energy values, the elastoplastic design theory of stiffeners was established, and the evaluation of the hysteretic performance of the SCSPSWs was provided. Firstly, a finite element (FE) model for analyzing the hysteretic performance of the SCSPSWs was developed and validated against hysteretic tests of the CSPSW conducted by the authors previously. Subsequently, using the validated FE model, approximately 81 examples of SCSPSWs subjected to cyclic loads were analyzed. Hysteretic curves, skeleton curves, secant stiffness, stress distribution, and out-of-plane displacement were obtained and examined. Results indicate that increasing the bending rigidity of the vertical stiffeners and the thickness of the corrugated steel plates, as well as reducing the aspect ratio of the corrugated steel plates, is beneficial for enhancing the load-carrying capacity, stiffness, and energy dissipation capacity of the SCSPSWs. Finally, the transition rigidity ratio μ0,h was proposed to describe the hysteretic performances. When the rigidity ratio is μ = 50, dissipated energy values of the SCSPSW could achieve 95% of the corresponding maximum dissipated energy. In engineering practice, hence, it is recommended to use stiffeners with a rigidity ratio of μ ≥ μ0,h = 50 to ensure desirable energy-dissipating capacity in the SCSPSW.

Investigation on unstable flow characteristics and energy dissipation in Pelton turbine

The internal flow scale of a Pelton turbine is variable, and the interaction between the jet and the bucket has strong transient characteristics, resulting in an incomplete understanding of its internal vortex structure evolution and energy dissipation mechanisms. In order to reveal the influence of vortices on the flow regime and energy dissipation mechanisms in the turbine, this paper establishes the correlation between the unsteady flow characteristics and energy dissipation inside the Pelton turbine based on the energy balance equation and quantifies the energy losses inside the turbine. The results indicate that vortex structures present a non-uniform distribution inside the jet, which disrupts the uniformity of the jet velocity distribution, resulting in an uneven distribution of high-vorticity zones on the bucket surfaces and intensifying flow interference among the buckets. The strong shear flow caused by the downstream flow detachment of the needle guide, the turbulent boundary layer on the jet surface, and the wake effect downstream of the needle tip are the main reasons for the dissipation of fluid kinetic energy. The distribution range of energy loss on the rotating bucket closely corresponds to the position of the high-vorticity zone. Energy dissipation inside the turbine is primarily in the form of turbulent kinetic energy, and the injectors and runner are the primary energy dissipation components. Moreover, inside the injectors, each form of energy loss remains relatively constant, whereas inside the runner, its rotation induces fluctuating energy losses attributed to Reynolds stress work. The results contribute to an enhanced understanding of the energy dissipation characteristics and complex flow mechanisms within the turbine, providing reference for the optimisation and efficient operation of the multi-nozzle Pelton turbine.

Cyclic behavior of a web hourglass-shaped pin damper made of low-yield-strength steel: Experimental and numerical analyses

Web hourglass-shaped pins fabricated from low-yield-strength steel (LYSWHPs) can be utilized as energy dissipation (ED) components in the connections of steel structures to effectively enhance ED and reduce damage to the primary structural components under intense earthquakes. First, quasi-static tests were carried out on three LYSWHP specimens made of LY225 steel; when bolted to its supporting plate, each exhibited a stable, suitable hysteretic response, excellent ED capacity, high ductility factor of 5.01–9.55, and excellent plastic deformation. Axial force effects and large plastic strains significantly increased the strengths of the LYSWHPs, with the maximum overstrength factor reaching 2.36. A finite-element analysis model was established in ABAQUS and confirmed against the behaviors of the test specimens to perform parametric analyses on individual and group LYSWHP models. The results demonstrated that the shape of the LYSWHP significantly affects its load-carrying capacity, ED capacity, and failure mode; the shape factor and slenderness ratio of the ED segment should be within 0.375–0.75 and 2.75–4.25, respectively, to ensure the desired behavior. The number of LYSWHPs, supporting plate thickness, and LYSWHP shape significantly affect the hysteretic behavior of an LYSWHP group. When the supporting plate provides strong restraint, the ED capacity and ductility of each LYSWHP is fully developed, all cumulative damage is concentrated within the LYSWHPs while the supporting and loading plates remain elastic, and the group will exhibit ductile failure. The findings of this study provide reference for the practical application of LYSWHPs in building structures.

Study on seismic behavior and collapse risk of super high-rise braced mega frame-core tube structural system

The braced mega frame-core tube (BMFCT) structure could provide an efficient lateral-force resisting (LFR) system for high-rise or super high-rise buildings, especially for those higher than 500 m. The BMFCT structure is a dual LFR system, including the outer braced mega frame and the inner core tube. The seismic behavior and design method of this structural system is not clear. In this study, a parametric study based on collapse risk-targeted analysis is conducted to clarify seismic mechanism and performance and to make clear means of matching reasonable stiffness and setting energy-dissipation components. Five comparable BMFCT structures with different mega brace stiffness proportions and frame-tube stiffness ratios are designed. An efficient elasto-plastic modeling method is introduced to establish the accurate FE models. The corresponding collapse risks are calculated through Incremental Dynamic Analysis and fragility theory. The results show that the structural collapse risk increases with the increased frame-tube stiffness ratio. Therefore，the stiffness and bearing capacity of peripheral frames should be strengthened to ensure the structural collapse margin. On the other hand, the collapse resistance capacity gradually decreases with the increasing of the mega brace stiffness. Thus, the stiffness proportion of mega braces should be recommended to meet the basic lateral stiffness requirements, which shall not exceed 35 % of the overall structural stiffness. Moreover, the distribution feature and ideal arrangement of the energy dissipation components are proposed. The seismic design recommendation based on the uniform collapse risk is also proposed for the BMFCT system, which serves a reference for the structural design of super high-rise buildings.

Seismic behavior of precast prestressed concrete frame joints with different energy dissipation designs

The unbonded post-tensioned precast concrete joint based on PRESSS (Precast Seismic Structural System) technology has a simple form, convenient construction, and strong deformation-recovery properties. In this paper, both experimental and theoretical analysis methods were used to study the influence of different energy dissipation components on the seismic performance of the unbonded post-tensioned precast concrete joint. First, based on the existing ‘plug-and-play’ energy dissipation device, this paper improved its construction and designed two types of joints with new external energy dissipaters and internal energy-dissipating bars, respectively. Subsequently, low-reversed cyclic loading experiments were conducted. The two joints’ seismic performance indexes, failure mode, hysteresis curve, skeleton curve, ductility coefficient, and residual deformation were compared and analyzed. The experimental results showed that internal energy-dissipating bars exhibited greater energy dissipation. In contrast, the joint with the new external energy dissipater had higher initial stiffness than the joint with internal energy-dissipating bars. In addition, the force transmission mechanism and the calculation formula of the initial rotational stiffness of the joints were deduced through theoretical analysis, and the theoretical derivation was further verified by combining the experimental values. Overall, both joints conformed to the definition of semi-rigid connections in EC3, and the joint design conformed to the “strong column and weak beam, strong joint and weak member” principle. Finally, a new anchoring system for the energy dissipaters is proposed to ensure the effective connection between the energy dissipater and the bearing.

Influence of manufacturing factors on compressive behavior of soft architected composite with a 3D-printed cellular core

Soft material is widely used for energy dissipation in a diverse range of applications from shoe soles to bridge bearings. Recent advances in additive manufacturing enable more new classes of materials such as soft architected composites (SAC) with 3D-printed cores that are embedded into a soft matrix. SAC has demonstrated excellent load-carrying capacity, ductility, and energy absorption under compression compared to soft material alone, but the influence of key manufacturing factors remains unknown. In this work, we conducted experimental investigations on SAC specimens considering various manufacturing parameters, including the printing materials, volume fraction, filling pattern, and printing parameters. Notably, the SAC with the gyroid filling pattern demonstrates superior specific stiffness and specific energy absorption. The effect of the printing parameters on the SAC was non-linear, and the optimal values were influenced by the core geometries. The SAC unit filled with gyroid pattern and manufactured using optimized printing parameters exhibited significant improvement in specific stiffness and specific energy absorption over those with the same mass of reinforcing phase. These results can guide the further design of similar architected composite by considering the appropriate selection of manufacturing parameters and geometric designs. With the improved mechanical properties, the concept of SAC can be further used in developing lightweight and high-performing energy absorption and dissipation components and devices.

Deformation and energy dissipation of steel box girders of cable-stayed bridges subjected to blast loadings

Steel box girders are widely used in cable-stayed bridges, while they are prone to severe damage under explosions. This paper investigates the deformation and energy dissipation of steel box girder of cable-stayed bridges under blast impact, caused by the accidental explosions of tanker trucks and vehicles. In this study, Hypermesh and LS-DYNA are employed to simulate the dynamic responses of a real steel box girder cable-stayed bridge under explosions. The deformation response and energy absorption of the box girder under explosions are investigated. Several failure modes and failure processes are analyzed and summarized. The findings indicate that the failure mode of an orthotropic steel bridge panel under blast impact is primarily local damage, with the damage process being divided into three stages: local plate deformation, fragment formation, and petal formation. For bridge deck explosions, the main energy dissipation components of steel girders are the bridge panel, web, diaphragm and rib stiffeners. The research results can provide the basis for the follow-up study on the anti-explosion safety of bridge structures.

Numerical simulation and seismic performance analysis of sacrificial-energy dissipation beam-column joint

To enable secondary energy-dissipating components to actively attract and dissipate seismic energy, a new type of sacrificial-energy dissipation beam-column joint (SEDJ) was proposed for frame structures. During strong earthquakes, the post-yield strength of the SEDJ was actively weakened by the shear failure of the bolts, and the friction between the friction plates and metal plate ensured that the SEDJ could fully dissipate the seismic energy. Meanwhile, the adjacent column and beam components remained elastic after the earthquake, so as to achieve the purpose of protecting the main beam and column components. Based on finite element analysis of the SEDJ using a solid element model, the expected seismic performance of the SEDJ was verified through displacement-controlled monotonic and cyclic loading tests. The peak strength Fu and post-yield strength Fr of the SEDJ could be controlled by adjusting the shear strength of the bolts and the preload of the friction plate and metal plate connecting bolts. Furthermore, the effectiveness of the SEDJ was evaluated by applying it to a three-story steel frame structure, and a parametric analysis was conducted. The results indicate that appropriately and actively reducing the post-yield strength of the SEDJ, with Fr/Fu equal to 0.3, provides the most favorable effect on improving the plastic dissipation energy distribution of the beam and column components and reducing the damage to the bottom column under strong earthquakes. Meanwhile, the structure meets the requirements of inter-story drift under design basis earthquakes and the collapse resistance under maximal considered earthquakes. The SEDJ only requires the replacement of the bolts and friction plates after the earthquake. Therefore, this study can provide new ideas for designing seismic-resilient structures.

MODELLING SHORELINE EVOLUTION AT COLLAROY-NARRABEEN, DUE TO COMBINED CROSS-SHORE AND LONGSHORE SEDIMENT TRANSPORT PROCESSES

Changing wave climates and sea levels are leading to enhanced pressures on coastal communities and infrastructure. Coastal managers require better predictive tools in order to predict current and future coastal evolution and mitigate the potential impacts of coastal erosion and flooding. This contribution utilises a longshore extension and simplification of the Forecasting Coastal Evolution (ForCE; Davidson, 2021) profile model to examine the shoreline evolution of the Collaroy-Narrabeen embayment. The resulting one-line model combines cross-shore and longshore sediment transport processes, and unlike previous one-line models of this kind, both (longshore/cross-shore) terms are derived from the same theoretical arguments. Both model components are founded on equilibrium principles, whereby sediment transport is directly related to the disequilibrium in longshore and cross-shore components of wave energy dissipation.

Evaluating the effect of infill walls on seismic responses of post-tensioned self-centering concrete frames based on a new analytical model

This paper proposes a numerical model with the lump plasticity rotational springs for the simulation of post-tensioned self-centering (PTSC) concrete frames. The analytical connection model that is able to properly capture the joint responses and connection damage is incorporated in the rotational springs. The static and dynamic numerical results are validated against those obtained using the fiber-based structural model. Furthermore, the proposed numerical model is adopted in the seismic response prediction of PTSC frames with infill walls (IWs) and various energy dissipation components. Incremental dynamic analysis is performed through the scaling schemes based on Sa(T1) and PGA, and the effects of IWs and energy dissipators on the structural responses under different ground motion inputs are compared. The numerical results indicate a remarkable reduction in the inter-story drifts of the PTSC frames with IWs as compared to the bare frames under the same Sa(T1). Nevertheless, when subjected to ground motions with large PGAs, the damage of IWs would induce rapidly increased inter-story drifts in the lower floors, which may exceed the drifts of bare frames under the same earthquake intensity. This study highlights the accuracy of the proposed numerical model and the importance of considering IWs in the seismic response predictions of PTSC concrete frames.

Seismic performance of novel RC shear wall with replaceable self-centering energy-dissipation components

A novel reinforced concrete (RC) shear wall with replaceable self-centering energy-dissipation components (RSECs) symmetrically installed at the bottom corner of the wall panel is proposed in this study. The RSEC consists of self-centering part and energy-dissipation part, which not only dissipates most of the seismic energy but also provides the restoring force for the wall to return initial position after yielding of the component. The RC wall with RSECs is designed to reduce the damage to the main part of structural wall and the residual deformation of the structure. The structural details and design considerations of the RC shear wall with RSECs are introduced. To verify the seismic performance of RC shear walls with the new replaceable corner components, the numerical mode is developed for the new type of shear wall and validated by experimental results. Parametric studies of RC wall with RSECs are then conducted to investigate the effects of the stiffness and pre-pressure force of disc spring group, the bearing capacity ratio of RSEC, and the thickness of embedded steel plate. The results indicate that the RC wall with RSECs has moderate bearing capacity and lateral stiffness, good energy-dissipation capacity, excellent self-centering capability and the characteristics of low damage. The function of the RC wall with RSECs can be quickly restored by replacing RSECs after the strong earthquake.

A comparative study of self-centering precast concrete walls with replaceable buckling-restrained yielding plates or friction dissipation components

Two new unbonded post-tensioned (PT) self-centering precast concrete wall systems with excellent reparability and seismic resilience are investigated in this paper through cyclic loading testing of four large-scale precast walls. As major innovative features, reparability and seismic resilience of the structures are achieved by using externally connected replaceable buckling-restrained yielding plates (Type I) or friction components (Type II), and steel jackets to confine concrete at wall toes. Both types of wall specimens showed excellent self-centering, energy dissipation, and ductile behavior over 3.5–4% lateral drift without significant strength reduction, demonstrating remarkable advantages over monolithic cast-in-place (CIP) walls and self-centering precast concrete walls with yielding reinforcing bars. The damage in the proposed walls concentrated in the external energy dissipation components, with minor concrete cracking and no concrete crushing at the completion of testing, making repairs feasible by replacing the damaged components. The energy dissipating capacity for the Type II wall was significantly greater than those for the Type I walls at relatively small drift levels due to the large initial stiffness of friction-based damping. As there was no significant damage in the friction damping components throughout testing, the energy dissipation for the Type II wall was much more stable than those for the Type I walls. Comprehensive finite element models were also developed for both types of walls, which satisfactorily captured the global and local behaviors, including prediction of minor concrete damage, steel and concrete strains, and nonlinear behavior of the energy dissipation components. A parameter study was subsequently conducted to investigate the effects of losses in the friction bolt force and PT force on the wall behavior. Overall, both types of walls can be used in the life-line structures that have great demand for fast reparation and restoration of their original lateral resistance and energy dissipation after a major earthquake.

Study on energy transition of dense particulate flow in a horizontal agitator

Hammer mill cuttings cleaner is an efficient low-temperature drying cuttings equipment. In order to investigate the main components of energy dissipation and the flow characteristics of granular flow in grinding systems. The energy dissipation model of dense particle flow is established by numerical simulation and validated by macroscopic experiment. The results show that the particle flow mainly moves in a circle along the wall of cylindrical vessel. The main parts of energy dissipation are sliding friction consumption of particle, the inelastic collision between particles and sliding friction between particles and container; the input energy is a linear function of particle filling rate. The flat blade can provide higher efficiency at the same operational conditions. The study lays a theoretical foundation for the industrial application of Thermal-mechanical cuttings cleaner of drill cuttings and provides a reference for the optimization of blade configuration.