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Buckling restrained braces (BRBs) enhance energy dissipation and ductility considerably by preventing the buckling of steel braces under cyclic loads during earthquakes and, thus, the strength degradation caused by buckling. This paper introduces and discusses the development of BRBs made with an elastomer known as phase change material (PCM), which has superior ductility and faster-filling properties than commonly used mortar while being approximately 50% lighter. BRBs filled with PCM have high ductility and good energy dissipation. To verify the seismic performance of the PCM BRB, axial brace tests and subframe tests were conducted. Using PCM as the filler in the axial tests ensured a stable tension and compression ratio (below 1.5), as recommended by the AISC provisions, and the core material fully withstood axial loads for six cycles beyond 1.5delta_bm. Global buckling occurred after 2.0delta_bm under compression, at which point the experiment was terminated. [ABSTRACT FROM AUTHOR]

In VSC-HVDC system for new energy island， surplus power consumption in the system during fault ride-through （FRT） is achieved by employing grouped AC energy-dissipating resistors of equal capacity. However， the presence of an excessively powered resistor group can inflict severe impacts on the system. Therefore， a novel optimal configuration method for energy-dissipating resistors with different capacities based on progression conversion and the switching strategy are proposed. Firstly， the operational characteristics of the grouped AC energy-dissipating resistors of equal capacity are analyzed. Subsequently， multiple groups of AC energy-dissipating resistors with varying capacities， collectively equivalent to the total capacity of the VSC-HVDC system， are configured， and different combinations of the resistors are employed to obtain varying dissipating powers. Finally， a model of the integrated grid is constructed and validated using the PSCAD/EMTDC simulation platform. Simulation results demonstrate that the proposed method and switching strategy enhance the precision of resistor switching， mitigate system impacts， shorten fault recovery time， and precisely consumes surplus power during fault ride-through.

In recent years various studies have explored the seismic behavior of controlled rocking masonry walls (CRMWs) that utilize both gravity loading for self-centering and additional energy dissipation (ED) devices to regulate the response (ED-CRMWs). However, these studies had limitations because ED devices were installed on or within the masonry wall, making repairs difficult or impossible after ED yielding or fracturing. This study presents the testing of two half-scale CRMWs that were constructed with supplemental flexural yielding Energy dissipation devices Accessible in a Steel base (EASt-CRMWs). The proposed EASt-CRMWs simplify the installation of the energy dissipation devices and overall wall construction, while also allowing for easy replacement following damage. The walls were subjected to quasi-static, cyclic loading up to drifts of 2.35%, after which the ED devices were replaced, and the same wall was tested again. Wall 2 was built with a steel plate at the rocking point between the steel base and the foundation interface. All five tests demonstrated a favorable self-centering response, with no significant damage to the walls. The ED devices were easily replaced between tests, and the damage was confined to them. Wall 2 had better performance because of the steel plates, which reduced damage to the mortar at the steel base-foundation interface, resulting in slightly decreased lateral load capacity at lower drift ratios upon retesting for Wall 1. Moreover, residual drifts were below 0.05% for all wall tests. Finally, a numerical model and a damage index proposed previously were validated based on the experimental work presented in this study as well as additional configurations of EASt-CRMWs presented in a previous recent study. The results demonstrate that the model can capture the overall response of the walls, and the damage index can accurately predict the location, type, and severity of the damage. [ABSTRACT FROM AUTHOR]

Copyright of Zhejiang Electric Power is the property of Zhejiang Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Corrugated steel plate shear walls (CSPSWs) can be applied to high‐rise building structures to serve as lateral load‐bearing and energy‐dissipating members. Arranging stiffeners on corrugated steel plates shows substantial potential to further improve the seismic performance of ordinary CSPSWs. This study experimentally and numerically investigated the hysteretic behavior of unstiffened and stiffened CSPSWs. Cyclic quasi‐static tests were conducted on four, 1/2‐scale, two‐story, single‐bay specimens with different corrugation orientations, including two specimens with unstiffened corrugated steel plates and two specimens installed with stiffened corrugated steel plates equipped with two pairs of stiffeners. According to the hysteretic curves of different specimens, the effects of corrugation orientations and arrangement of stiffeners were revealed in terms of the skeleton curves, energy‐dissipating capacity, and stiffness degradation. Then, finite element (FE) models, which were applied to gain a deeper understanding of the experimental results, were established, and validated against the test results. This study demonstrated that the arrangement of stiffeners was effective in improving the seismic performance of CSPSWs regarding the ultimate shear strength and energy‐dissipating capacity, while the influence of corrugation orientations on the performance of the specimens involved in this study could be ignored. [ABSTRACT FROM AUTHOR]

Controlled rocking systems have been used in numerous structures around the world as a seismic force-resisting system. In a controlled rocking wall system, the wall is allowed to uplift from the foundation during seismic events, thus reducing the wall's lateral stiffness and minimizing its corresponding seismic force demands. This rocking mechanism is often controlled using posttensioning (PT) tendons, resulting in negligible residual deformations compared to conventional walls (i.e., with fixed bases). For these reasons, promising strides have been taken to apply the concept of controlled rocking systems to masonry walls; however, several issues have been encountered when using PT tendons due to the brittle nature of the masonry material in compression. To address this, the current study aims to reduce damage and improve the performance of controlled rocking masonry walls (CRMWs) by omitting PT, instead relying on gravity loads and energy dissipation to control the seismic response. Three strategies to achieve this improved performance are proposed and investigated. The first strategy involves using externally mounted, replaceable energy dissipation devices; the second strategy introduces a steel base for the rocking wall; and the third strategy considers confinement plates in the rocking toe region of the wall. To assess these strategies, the study develops and validates a numerical model to capture the performance of previously tested CRMWs. The model is then used to develop and experimentally validate an index for masonry walls to quantify their damage based on numerical results. Next, a suite of 20 CRMWs is designed, 5 of which incorporate PT tendons while the remaining 15 walls omit PT and incorporate one or more of the proposed strategies to reduce damage. Numerical models of all of the archetype walls are subjected to reversed cyclic loading protocols, and the amount of damage incurred is compared across each archetype wall. The results demonstrate that the proposed modeling technique and damage index are effective at capturing the response and quantifying damage in CRMWs and that the proposed strategies result in a lower damage alternative to posttensioned CRMWs (PT-CRMWs). [ABSTRACT FROM AUTHOR]

Computational fluid dynamics (CFD) provides a powerful tool for investigating complicated fluid flows. This paper aims to study the applicability of CFD in the preliminary design of linear and nonlinear fluid viscous dampers. Two fluid viscous dampers were designed based on CFD models. The first device was a linear viscous damper with straight orifices. The second was a nonlinear viscous damper containing a one-way pressure-responsive valve inside its orifices. Both dampers were detailed based on CFD simulations, and their internal fluid flows were investigated. Full-scale specimens of both dampers were manufactured and tested under dynamic loads. According to the tests results, both dampers demonstrate stable cyclic behaviors, and as expected, the nonlinear damper generally tends to dissipate more energy compared to its linear counterpart. Good compatibility was achieved between the experimentally measured damper force-velocity curves and those estimated from CFD analyses. Using a thermography camera, a rise in temperature of the dampers was measured during the tests. It was found that output force of the manufactured devices was virtually independent of temperature even during long duration loadings. Accordingly, temperature dependence can be ignored in CFD models, because a reliable temperature compensator mechanism was used (or intended to be used) by the damper manufacturer. [ABSTRACT FROM AUTHOR]

In recent years, various passive energy dissipation devices have been gradually applied to structural vibration control. Hysteretic dampers with hardening post-yielding stiffness (HDHPSs) could solve the problem of insufficient stiffness after the ordinary friction damper enters into its yield state, and realize multi-level seismic objectives and multi-stage energy dissipation. For hysteretic dampers with hardening post-yielding stiffness, computational formula of its resistance is given in this paper based on Wen-Gap connecting element, and the calculation formula of its equivalent yield strength is derived combining with the energy theory, which is verified by SAP2000 software. A 12-story steel frame with a weak story was strengthened by using HDHPSs and the dynamic performances of three frames are compared by using the connection element method proposed in this paper. The results show that the proposed formula of equivalent yield strength matches well with the numerical simulation results, which could provide a reference for seismic design of structures installed such dampers. The connection element method proposed in this paper is feasible to analyze the dynamic performances of structures with hardening post-yielding stiffness. The frame installed HDHPSs could effectively control the maximum displacement, which could meet the requirement of displacement performance target. This paper has certain reference significance for structural retrofit of existing structures. [ABSTRACT FROM AUTHOR]

This paper proposes a new element for modeling the energy-dissipation coupling beam to analyze the coupled shear wall structure under seismic loading. The new beam element includes 2 rigid beams and an energy dissipation device in the middle. The element stiffness matrix is derived based on principles of nonlinear mechanics. A procedure of the incremental-iterative solution is built using the Newmark method and adopted for solving the nonlinear equation of motion. A computer program using Matlab is developed to analyze the behavior of frame analogy which is modeled from the couped shear wall structure. Several numerical examples are presented to verify the developed program with the commercial finite element package SAP2000. The numerical results proved that the proposed program is efficient and reliable. The proposed element and program are then applied to analyze a 30-story coupled shear wall structure with energy dissipation devices. As a result, the locations of the device that provide effective seismic resistance for a 30-story coupled shear wall structure are in the region from the 5th to the 15th floor or assigned on all floors. [ABSTRACT FROM AUTHOR]

This study presents dynamic test results on a recently developed damper placement known as the tackle-damper configuration. This innovative setup integrates a viscous damper alongside two inclined tackles, each comprising multiple turns of wire ropes threaded between upper and lower sheaves. This configuration has the ability to amplify damper deformations and forces based on the mechanical advantage of the tackle. Four specimens of tackle-damper configurations are tested under different dynamic harmonic and seismic loadings. Obtained results indicated that tackle-damper configuration changes pure viscous behaviour of the fluid viscous damper to an amplified viscoelastic behaviour. It is verified that energy dissipation in the tackle-damper configuration arises from two sources, i.e. fluid viscous damper and capstan friction between the wire ropes and the sheaves. Ideally, deformation and force amplification factors in the tackle-damper configuration should depend solely on the number of wire ropes and the inclination angle of the tackle. However, it has been found that true force amplification factor is much larger than the ideal value due to the capstan friction. Moreover, true deformation amplification factor can also be much smaller than the ideal value. This is attributed to the elastic stretching of individual wire ropes within the tackles. Therefore, both friction and wire rope elongation substantially affect the true amplification capabilities of the tackle-damper configuration. • Tackle-damper configuration substantially amplify force and energy dissipation of the damper. • Capstan friction and wire rope elongation have significant effect on the true behavior of tackle-damper configuration. • Tackle-damper configuration changes pure viscous behavior of the viscous damper into an amplified viscoelastic behavior. • Mechanical advantage of tackle can be used to amplify contribution of energy dissipating devices. [ABSTRACT FROM AUTHOR]

This paper proposes a new element for modeling the energy-dissipation coupling beam to analyze the coupled shear wall structure under seismic loading. The new beam element includes 2 rigid beams and an energy dissipation device in the middle. The element stiffness matrix is derived based on principles of nonlinear mechanics. A procedure of the incremental-iterative solution is built using the Newmark method and adopted for solving the nonlinear equation of motion. A computer program using Matlab is developed to analyze the behavior of frame analogy which is modeled from the couped shear wall structure. Several numerical examples are presented to verify the developed program with the commercial finite element package SAP2000. The numerical results proved that the proposed program is efficient and reliable. The proposed element and program are then applied to analyze a 30-story coupled shear wall structure with energy dissipation devices. As a result, the locations of the device that provide effective seismic resistance for a 30-story coupled shear wall structure are in the region from the 5th to the 15th floor or assigned on all floors.

Summary: An optimization approach for the seismic design of yielding moment‐resisting frames (MRFs) with nonlinear fluid viscous dampers (FVDs) is presented. As the optimal design of new buildings is addressed, no parameters are set a priori, and the properties of both the structural elements and the dampers are simultaneously optimized. The goal of the optimization is to minimize the cost of the system (structure + dampers), while code requirements and performance constraints are considered. The performance of the structure is evaluated using a nonlinear time history analysis (NTHA), accounting for the nonlinear behavior of both the MRF elements and the added FVDs. The optimization problem is first formulated as a mixed‐integer problem suitable for a solution by zero‐order optimization. Then, the problem is reformulated in a continuous differentiable form and solved using an efficient gradient‐based optimization approach. This is done by utilizing discrete material optimization (DMO) functions to achieve a good initial design for the cross‐sections and the FVDs. This initial design accounts for the important aspects of design, some directly and some indirectly. The responses of interest are computed using a probabilistic approach while considering ensembles of ground motions. Numerical examples show the robustness of the presented methodology and its efficiency demonstrated on a five‐story MRF and a real‐scale irregular nine‐story MRF. [ABSTRACT FROM AUTHOR]

Abstract A buckling-restrained steel plate shear wall with inclined slots (simply referred as "slotted SPSW") consisting of an inner steel plate sandwiched between two precast concrete panels, has been developed as an energy dissipation device of structures. The steel strips between inclined slots behave like a series of buckling-restrained braces to dissipate the energy through inelastic axial deformation when subjected to cyclic loading. This paper experimentally investigated the seismic behavior of slotted SPSWs. Three half-scale specimens were fabricated and tested under quasi-static cyclic loading. Details for proper fabrication of slotted SPSWs were firstly configured. The results illustrated that the slotted SPSW could sustain the target lateral drift ratio (2%) without a reduction of shear force and energy dissipation capacity. Moreover, the tested specimens exhibited stable fatigue hysteresis loops when the cyclic loadings were repeated 30 times at 1.5% peak lateral drift ratio. The maximum drift ratio of tested specimens reached 3.5%, and the cumulative plastic ductility factor was larger than 200. The experimental results indicate that the slotted SPSW is capable of providing high lateral force-resisting and energy dissipation, which can be widely used in engineering structures. Highlights • Three half-scale specimens were fabricated and tested under quasi-static cyclic loading. • Details for proper fabrication of the slotted SPSW were configured. • The slotted SPSW is capable of providing high lateral force-resisting and energy dissipation. [ABSTRACT FROM AUTHOR]

Conservation of heritage buildings has become a very important issue in many countries, as it is in Italy, where a great number of existing buildings of historical–artistic importance are seismically vulnerable. To improve existing building behavior, researchers focus on the design of retrofit interventions. This paper presents the application of energy dissipation devices in the retrofit of two existing Reinforced Concrete (RC) buildings, both irregular in plan and along their heights, designed for gravitational loads only. These buildings are representative of Italian public housing built in the 1960s and early 1970s. Technical information and mechanical properties of materials are presented, and non-linear analyses are carried out to evaluate the buildings’ behavior under earthquake loads. Many of their structural members do not satisfy the verifications required by the Italian Building Code. Retrofit interventions with buckling-restrained axial dampers in one building and viscous fluid dampers in the other are proposed. The verifications of the retrofitted buildings and the amount of the energy absorbed by the devices with respect to that absorbed by the unretrofitted buildings show the effectiveness of the proposed interventions. Moreover, it is demonstrated that adequate dispositions of the dissipative devices in plan and along the height increase the torsional stiffness of the buildings, improving their structural response under seismic action.

Abstract To determine the load transfer mechanism and dynamic response characteristics of an adaptive anchor cable (AAC) equipped with a mechanical energy dissipation device, a shaking table model test was conducted on rock slope test models anchored with a system consisting of several AACs that were fabricated based on a landslide mass in Xiangjiapo. During the test, the strain of the AAC structure and the dynamic response of the slope model were monitored to determine the anchoring mechanism of the AAC system and the dynamic characteristics of the AAC system-anchored slope model. The sliding-sleeve energy dissipation device of the AAC automatically adjusted its tension or deformation to allow its deformation to be consistent with that of the rock and earth mass, thereby buffering the impact at the instant of the start of seismic loading. The constant sliding resistance of the AAC determined its working conditions under a certain seismic loading condition. When the constant sliding resistance was set excessively high, the energy dissipation device was ineffective under the seismic loading. When the constant sliding resistance was set too small, the AAC slid at the instant of the start of seismic loading. However, when the constant sliding resistance and the sliding distance were set to proper values, the AAC slid gradually in a stepwise motion, and its peak strain was significantly lower. The test results can be used as a reference for designing cut slopes in regions of high seismicity and in selecting anti-seismic engineering measures for these slopes. [ABSTRACT FROM AUTHOR]

This paper proposed a method using wind-resistant energy dissipation damper to reduce the wind-induced damages to low-rise buildings with gable roof. In order to study the influence of the wind-resistant energy dissipation devices on the wind pressures applied to the roof, wind tunnel experiments were carried out for the buildings with three types of roofs, namely, roof without energy dissipation devices, vertical-parapets with energy dissipation devices, and vertical-parapets without energy dissipation devices. The experimental results show that the wind-resistant energy dissipation devices can greatly reduce the worst negative pressure over the whole roof. The absolute value of mean negative wind pressure coefficients for the most vulnerable area of the windward roofs, such as that near the ridge and close to the conjunction between the roof and gable, can be decreased by 50 percent. The wind-resistant energy dissipation devices can also affect the wind pressures of the leeward roof area, in which the absolute value of mean negative wind pressure coefficients can be decreased by 15 percent. Finally, the wind pressures of low-rise buildings with gable roof in the wind field were numerically simulated using finite element software. The results show that the distribution of wind pressure on the roof is consistent with the results of wind tunnel experiments. [ABSTRACT FROM AUTHOR]

A semi-active friction damper (SAFD) can be employed for the seismic protection of structural systems. The effectiveness of an SAFD in absorbing seismic energy is usually superior to that of its passive counterpart, since its slip force can be altered in real time according to structural response and excitation. Most existing SAFDs are controlled by adjusting the clamping force applied on the friction interface. Thus, the implementation of SAFDs in practice requires precision control of the clamping force, which is usually substantially larger than the slip force. This may increase the implementation complexity and cost of SAFDs. To avoid this problem, this study proposes a novel position-controlled SAFD, named the leverage-type controllable friction damper (LCFD). The LCFD system combines a traditional passive friction damper and a leverage mechanism with a movable central pivot. By simply controlling the pivot position, the damping force generated by the LCFD system can be adjusted in real time. In order to verify the feasibility of the proposed SAFD, a prototype LCFD was tested by using a shaking table. The test results demonstrate that the equivalent friction force and hysteresis loop of the LCFD can be regulated by controlling the pivot position. By considering 16 ground motions with two different intensities, the adaptive feature of the LCFD for seismic structural control is further demonstrated numerically. [ABSTRACT FROM AUTHOR]

A systematic design method for actualizing a passive control structure that can effectively exert its capabilities to minimize damage from an earthquake has yet to be presented. In particular, a clear method for placing EDDs that can improve seismic capability under earthquake delivery has yet to be presented, causing the dependence on the design of placing the damper after repetitive response analysis and trial and error work directly. However, in order to obtain seismic capability that the designer intends, the designer needs to be able to predict optimum placement of the damper prior to response analysis and determine the design result to be reliable. This study aims to suggest a design process of passive control structure, which includes design and placement of the damper for obtaining the seismic capability of the passive control structure as intended by the designer. Also, dynamic response analysis was conducted on structures designed using the design process suggested in this study to confirm whether the seismic capability intended by the design has been achieved, verifying the validity of the design process. [ABSTRACT FROM AUTHOR]

This paper presented seismic behavior of a novel Self-Buckling-Restrained (SBR) Steel Plate Shear Wall (SPSW) that was made by two Incline-Slotted Infill Plates (ISIPs) which were tied together by one rubber plate. The directions of the incline slots on the two ISIPs were opposite. Stable cycling responses of the SBR-SPSW could be achieved since at least incline strips on one plate were in tension under the cycle load. At the same time, the strips in tension could provide lateral support to those in compression on the other plate. Behaviors of the SPSW with two ISIPs and with one Solid Infill Plate (SIP) were compared to show advantages of the proposed SBR-SPSW. The stress state changed from the tension-compression bi-direction stress state in a SIP to uniaxial tension or compression in an ISIP. The cracks that usually encountered in a solid steel infill plate under repeated shear buckling could be avoided. And the incline steel strips yielded sequentially that could provide energy dissipation capacity at small drift ratio. At the same time, the ISIP could always ensure the plate yield prior to the frame yield. Parameters of ISIP, including the infill plate thickness, the strips width and the slot width, were investigated through finite element analyses. Shear strengths of the SPSW with two ISIPs decreased with the increase in slot width and increased with the increase in strip width. Design recommendation for the SBR-SPSW was provided as results of theoretical and numerical analysis. The shear strength of the SBR-SPSW made by two ISIPs could be calculated by simplified theoretical equations on the safe side. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a novel buckling-restrained steel plate shear wall with inclined slots (simply referred as “slotted SPSW”) that can be used as an energy dissipation device of structures. The slotted SPSW consists of boundary members and an inner steel plate with inclined slots sandwiched between two external concrete panels which provide lateral restraints. The steel strips between the inclined slots behave like a series of struts to dissipate the energy through inelastic axial deformation during reversal loading. Theoretical analyses and finite element monotonic pushover analyses are conducted to investigate the general behavior of slotted SPSWs. Calculations for shear resistance is determined to consider the reduction coefficient of inclined slots. Some key parameters, such as the width of steel strips, and steel panel slenderness, are investigated through numerical analyses. A half-scale slotted SPSW quasi-static cyclic test was carried out to provide the data about the general behavior of the slotted SPSWs. When a slotted SPSW is properly detailed and fabricated, bucking failure of the steel strips can be avoided and the slotted SPSW can sustain a roughly 2.8% lateral drift ratio without a reduction of the shear force and energy dissipation ratio. [ABSTRACT FROM AUTHOR]

The increasingly demanding performance requirements trigger the development of new devices to eliminate the limitations concerning the post-earthquake performance of available seismic protection systems. The prerequisite for economical earthquake-resistant bridges is the structures’ capacity to absorb and dissipate a large amount of seismic energy. A widely considered strategy for enhancing this capacity is through the use of passive energy dissipation systems for seismic protection of structures. It has been known that majority of the available energy dissipation systems are non-usable after a major earthquake, which increases the risk of collapse during an aftershock. The focus of the current study is given to introduce a new type of passive energy dissipation device with a pending patent that is testified to have an improved energy dissipation capacity without suffering any damage while absorbing energy. Thus, the proposed damper does not require an immediate expensive replacement and keeps its operational capabilities and effectiveness during aftershocks. The paper presents the dynamic performance tests of the first full-scale prototype of the damper that eventually prove it to be a promising design with an improved energy dissipation capacity and stable behavior during and after the dynamic event.

Railway round-ended hollow tall piers are widely used in the high-intensity mountainous areas of Southwest China. However, this gravity/tall pier based on the ductility design approach has a large mass and significant inertia force. To control the plastic damage of the pier under strong ground motion and reduce the seismic force transmitted to the foundation, this paper proposes the method of damage control through the design of a rocking pier with energy dissipation devices and applies it to the typical hollow tall piers of a railway. Static and nonlinear time-history analyses were performed using 3D finite element models to compare the near-fault seismic responses of a conventional fixed base pier (FB–P), a free rocking pier (F-RP), and a rocking pier with additional energy dissipation devices (D-RP). The results show that under the action of near-fault ground motions, the D-RP system based on the pier damage control design accurately controls the pier column to avoid exceeding the expected damage level; the F-RP and D-RP systems basically achieve "zero" residual displacement after ground motion. The additional energy dissipation devices at the bottom of the rocking pier effectively suppress the collisional action at the rocking interface and significantly reduce the responses of both the internal force at the pier bottom and the displacement at the pier top. The velocity pulse effect of the near-fault ground motion has a significant amplification effect. The addition of energy dissipation devices at the pier bottom can effectively reduce the amplification effect and the discreteness of the seismic response and improve the post-earthquake predictability of this type of bridge pier. • A method of damage control through the design of a rocking pier with energy dissipation devices is proposed in this paper. • The addition of energy dissipation devices to the rocking pier enables control of the damage to the tall pier. • The rocking pier is conducive to the rapid recovery of the train operation function of railway bridges in high seismic intensity areas. [ABSTRACT FROM AUTHOR]

Equipped with many advantages, such as low yield strength, low yield ratio, high elongation, severe plastic deformation and good energy dissipation ability, low-yield-point steel is very suitable for use in metal energy dissipation devices. Based on different materials (Q235 steel and low-yield-point steel) and different parabola openings, two types of energy dissipation steel plates underwent different yield displacements and then were assembled into a new open-hole energy dissipation device, which could achieve the goal of two-stage energy dissipation under small and large earthquakes. To obtain the failure modes and energy dissipation mechanism under the low reversed cyclic horizontal loads and observe relevant hysteretic curves and skeleton curves, the new energy dissipation device was studied and analyzed by means of theoretical analysis, experimental research, and numerical simulation analysis. Based on parametric analyses, the effects of the height, thickness and opening coefficient of the steel plate on the energy dissipation ability of the new energy dissipation device were emphasized. Thus, the key parameters affecting the energy dissipation behavior were obtained. Finally, a force-restoring model of the new energy dissipation device was put forward, and the calculation formulas were given for many parameters, including stiffness, yield displacement, yield load, ultimate displacement and ultimate load. The results show that the new open-hole energy dissipation device has the advantages of superior energy dissipation performance, obvious energy dissipation in two stages, and wide application prospects in structural seismic design. [ABSTRACT FROM AUTHOR]

Steel dampers, as an energy dissipation device, have been widely used to provide good seismic performance for building structures in strong seismic zones. Steel dampers for building structures are required to have adequate plastic deformation capacities so that they would not reach failure during strong ground motions and the aftershocks. However, the hysteretic behaviors of steel dampers considering the aftershock effects still remain unclear. In this study, wall damping system with a steel damper is proposed and tested. Steel damper in the wall damping system is installed horizontally at the bottom slit of the reinforced concrete wall aiming to dissipate energy during earthquake and prevent damage of the building structures, which could not only provide good seismic performance but could also be easily repaired after an earthquake. Test was conducted cyclically to simulate the effects of aftershocks, which can cause additional damage to already weakened structures from a main shock. Based on the test results, the seismic behavior of damping system was discussed with emphasis on the dissipated energy. [ABSTRACT FROM AUTHOR]

This paper presents a novel buckling-restrained steel plate shear wall with inclined slots called slotted SPSW to be used as an energy dissipation device for earthquake resistance. In the slotted SPSW, a steel plate with inclined slotted holes is sandwiched in between two external concrete panels which provide lateral restraint to achieve stable energy dissipation under cyclic reversal loading. Theoretical analysis and finite element monotonic pushover analyses are conducted to investigate the stability of slotted SPSWs. Global buckling and local buckling resistances of slotted SPSWs are determined. Some key parameters, such as the gap between steel plate and concrete panels, bolt spacing, width of steel strips, and steel panel slenderness, are investigated through numerical analyses. The shear force and lateral drift behavior of the slotted SPSW is found to be affected by the physical gap between the concrete panels and inner steel plate. The minimum concrete panel thickness for providing the effective lateral restraint to prevent buckling failure of the inner steel plate is determined based on the bolt spacing. [ABSTRACT FROM AUTHOR]

The benchmark structure used in this study is the lumped mass finite-element model of 91/5 highway overcrossing located at Southern California. The effectiveness of the non-linear fluid viscous (FV) spring damper on the benchmark highway bridge subjected to six bi-directional ground motion is investigated. A parametric study is carried out to find the optimum vibration period, the damping coefficient and the velocity exponent of the FV spring damper. The methodology of the technique is to achieve adequate energy dissipation by combining the stiffness and viscous damping effect in one system. Combination of a horizontal elliptical hysteresis loops of the non-linear viscous damper plus elastic stiffness of the spring produce a dynamic inclined hysteresis loop, which has no permanent displacement at the end of the excitation. Due to inclined hysteresis loop, non-linear FV spring damper has significantly reduced the responses, such as, base shear, mid-span displacement and especially abutment displacement of the benchmark highway bridge, in comparison with the other control device. [ABSTRACT FROM AUTHOR]

This paper describes the cyclic performance of non-uniform steel strip dampers. The shapes proposed are (a) a dumbbell-shaped strip, (b) a tapered strip, and (c) an hourglass-shaped strip. Each of these strip shapes was designed to reduce stress concentration when subjected to cyclic loadings. In order to evaluate the performance of the dampers, six specimens were tested cyclically. Cumulative damage caused by hysteretic motion was effectively distributed throughout the entire height of the strips, and SEM microstructures of the fracture surfaces represented a typical ductile failure mode. The experimental results showed that the proposed strip dampers indicate excellent seismic performance compared to conventional prismatic slit dampers. Furthermore, it was verified that structural performance can be accurately estimated using the design equations presented in the paper. [ABSTRACT FROM AUTHOR]

Abstract: The seismic response of a structural system equipped with friction-type energy dissipation devices is generally nonlinear. The main reason for this nonlinearity is the friction mechanism that possesses two possible motion states, referred to as stick and slip states. The essential force and kinematic conditions of a friction damper, in these two states, are different. In this paper, by employing a state-space formulation and a linear integration scheme, the discrete-time solution of dynamic response of a structural system equipped with multiple friction devices, which can be in either a stick or slip state, was derived in a single and unified form. The nonlinear friction forces, in each time step of analysis, were solved by satisfying both the force and kinematic conditions of certain motion states. Based on a derived discrete-time solution, a numerical analysis procedure was proposed, which allows the time interval of analysis to remain constant, even at the transition of stick and slip states; thus, it is a systematic and efficient method for numerical implementation. The solution of the method was compared with the analytical free-vibration response of a single DOF system, and also with the harmonic and seismic responses simulated by other conventional numerical methods. These examples demonstrate the accuracy and stability of the proposed method. [Copyright &y& Elsevier]

The goal of this paper is to investigate the feasibility of a proposed combined polymer composite damping system. A new composite damping system, which consists of a polymer honeycomb and a viscoelastic solid material is introduced. This new system is primarily intended for energy dissipation and vibration control, whereby the combined viscoelastic system serves as an interface layer within lightweight composite panels subjected to in-plane shear. The basic concept and mechanical properties for combining the polymer honeycomb with 3M solid viscoelastic materials are investigated under different strain inputs and frequencies. Subsequently, numerical models are established in which the effect of the temperature and frequency are taken into account. The analysis results given by the simplified numerical modeling agree with the results of the experiment. This study also leads to useful information with respect to the optimum design of the combined damping system. [Copyright &y& Elsevier]

Conservation of heritage buildings has become a very important issue in many countries, as it is in Italy, where a great number of existing buildings of historical–artistic importance are seismically vulnerable. To improve existing building behavior, researchers focus on the design of retrofit interventions. This paper presents the application of energy dissipation devices in the retrofit of two existing Reinforced Concrete (RC) buildings, both irregular in plan and along their heights, designed for gravitational loads only. These buildings are representative of Italian public housing built in the 1960s and early 1970s. Technical information and mechanical properties of materials are presented, and non-linear analyses are carried out to evaluate the buildings' behavior under earthquake loads. Many of their structural members do not satisfy the verifications required by the Italian Building Code. Retrofit interventions with buckling-restrained axial dampers in one building and viscous fluid dampers in the other are proposed. The verifications of the retrofitted buildings and the amount of the energy absorbed by the devices with respect to that absorbed by the unretrofitted buildings show the effectiveness of the proposed interventions. Moreover, it is demonstrated that adequate dispositions of the dissipative devices in plan and along the height increase the torsional stiffness of the buildings, improving their structural response under seismic action. [ABSTRACT FROM AUTHOR]

Conventional slit dampers are widely used for the purpose of seismic retrofitting, however, the structure of these dampers is susceptible to fractures, due to stress concentration at the ends of the strips in the event of large earthquakes. To address this issue, a novel radius-cut coke-shaped strip damper featuring improved ductility is proposed herein. This damper was developed based on the moment distribution over the strip when both its ends were constrained. The height-to-width ratio of the strip was increased to induce bending rather than shear deformation, and the reduced beam section method was employed. A radius-cut section was used to intentionally focus the stress to induce the plastic hinge. This reduced the fracture fragility of the specimen, resulting in an increased inelastic deformation capacity. Cyclic loading tests were conducted to verify damping performance against earthquakes. Experiments and finite element analyses proved that the coke-shaped damper exhibits improved ductility. The final fracture occurred in the radius-cut section after sufficient energy dissipation during cyclic loading. The results also indicated further improvements in strength due to the membrane effect under cyclic loading, caused by the tensile resistance of the strip due to its constrained ends. [ABSTRACT FROM AUTHOR]

It has been shown that having a low post-elastic (secondary) stiffness for conventional structures can be beneficial in terms of putting a limit on base shear of the structure although it could result in having a residual and permanent drift. A well-recognized example can be Buckling-Restrained Braced Frames (BRBFs) offering stable, repeatable and reliable damping while suffering from residual displacements owing to low secondary stiffness. This paper introduces a new type of self-centring brace with a flag-shape behaviour possessing a zero post-elastic (secondary) stiffness, Self-Centring Zero-Stiffness Brace (SC-ZSB), bringing the benefit of systems with minimal secondary stiffness without their deficiency. Basically, the elastic damage-free buckling of the brace is combined with the friction damping to form the intended flag-shape behaviour with zero post-elastic stiffness. The introduced bracing system will recover and re-centre at the end of buckling without any inelastic deformation, strength and stiffness degradation meanwhile providing passive damping. The proposed SC-ZSB is experimentally validated using a scaled self-centring brace. Besides, a comparative study is performed using OpenSeeS software to illustrate the seismic performance of the SC-ZSB in comparison with a BRB Frame. The results demonstrate that SC-ZSB system efficiently limits the base shear of the structure with an almost similar inter-story drift of the BRB frame, while it can eliminate any residual drifts as well. • A new self-centring brace has been introduced using elastic buckling. • The Post-elastic stiffness of the SC-ZSB is zero and it can be beneficial where there is a limit on base shear. • SC-ZSB provides self-centring characteristics than can be used for retrofitting of the structures [ABSTRACT FROM AUTHOR]

This paper presents a buckling-restrained steel plate shear wall with inclined slots (simply referred as "slotted SPSW") with own boundary columns, which can be used as a novel lateral force resistant system. The slotted SPSW is only connected with the structural beam, which reduces the effect on the structural column, avoiding premature failure of the structural column. Therefore, numerical analyses are used to investigate the interaction between the boundary column and the slotted SPSW. The formula of the minimum flexural boundary column stiffness is provided. Some key parameters, such as the steel plate aspect ratio, slenderness, and the width of inclined slots, are studied through parametric analysis. Numerical analyses results show that the axial force, shear force and bending moment increase with the steel plate aspect ratio, and decrease with the increasing of steel plate slenderness and the inclined slot width. Then theoretical calculation method of internal force in the boundary column is provided. Finally, in order to understand the seismic behavior of the slotted SPSW with boundary column under quasi-static cyclic loading, one full-scale test specimen is designed and tested. When boundary column is properly designed, the slotted SPSW with boundary column has a ductile behavior and stable energy dissipation capacity. • A buckling-restrained steel plate shear wall with inclined slots owning boundary columns is proposed. • The interaction between columns and the slotted SPSW is numerically investigated. • Design methods for the boundary column of the slotted SPSW are provided. • One full-scale specimen was fabricated and tested under quasi-static cyclic loading. [ABSTRACT FROM AUTHOR]