Self-centering Energy Dissipation Research Articles

Pseudo-dynamic tests of steel frame with disc spring self-centering energy dissipation braces under doublet earthquake and mainshock-aftershock sequence

To provide valuable insights into the seismic performance and self-centering behavior of self-centering braced systems, a 1/2-scale 3-story 1-bay steel frame equipped with disc spring self-centering energy dissipation braces (DS-SCBs) was designed, fabricated, and subjected to pseudo-dynamic testing. This testing encompassed various earthquake hazard levels, a doublet earthquake, and a mainshock-aftershock sequence. The experimental findings revealed the stable hysteretic response of the DS-SCB, with no observed degradation in stiffness or activation forces. Additionally, the test frame exhibited outstanding seismic performance, sustaining only confined damage under very rare earthquakes. Due to the presence of the DS-SCBs, the test frame performed commendable self-centering behavior, characterized by minimal residual deformations. Peak story drifts and floor accelerations under two earthquakes of the same hazard level were regarded as equivalent. Furthermore, the subsequent aftershocks exhibited no discernible impact on the seismic performance of the test frame. Floor acceleration spikes were observed at locations where the brace stiffness underwent changes or where adjacent stories moved in opposite directions. The steel frame equipped with DS-SCBs proved to be an attractive, low-damage alternative to conventional steel systems for the development of resilient urban areas.

Seismic performance assessment of RC bridge piers with variable hysteresis performance dampers

A novel variable hysteresis performance damper (VHD)—multi-stage slip friction damper is developed and applied to implement multi-level seismic resistance of structures. Different from the conventional slip friction dampers, which feature only a single type of slip friction surface, this innovative damper incorporates two types: a flat slip surface and a wedge slip surface. The quasi-static cyclic loading tests of the VHD were carried out to investigate its variable hysteresis performance. The test results revealed that the developed damper presented excellent adaptive performance, and its hysteresis behavior changed from a complete rectangle with efficient energy dissipation to a flag-shaped curve with exceptional self-centering capacity as deformation increases. Subsequently, the developed VHD with unique adaptive performance was applied in RC bridge piers (BP) to improve the seismic performance. Nonlinear time history and fragility analysis methods were employed to assess the seismic performance of the RC bridge piers with VHDs (BP-VHD) in deterministic and probabilistic manners, considering maximum and residual deformations as performance indicators. For comparison, seismic responses of RC bridge piers with traditional buckling restrained braces (BRBs) and self-centering energy dissipation braces (SCEBs) were also presented. The analysis and comparison results demonstrate that the developed VHD is as effective as BRB in reducing maximum deformation at small PGAs, meanwhile, it can effectively reduce the residual deformation of the structure to allowable values when the PGA is large. Furthermore, the failure probability of BP-VHDs is lower compared to piers with BRBs and SCEBs, particularly concerning maximum and residual drift ratios as performance indicators. The application of the VHD can effectively achieve the goal of multi-level seismic resistance for RC bridge piers.

Seismic performance of self-centering braced rocking frame with novel self-centering friction dampers characterized by low-secondary stiffness

Research has demonstrated that self-centering energy dissipation dampers (SCEDs) are effective devices for reducing the residual deformation of structures after a strong earthquake. However, the equivalent damping ratio of SCEDs is relatively lower than that of conventional dampers such as viscous dampers, BRBs, or friction dampers. According to displacement spectrums, the lower damping ratio could result in a lower natural period and higher equivalent stiffness of structures for a given displacement target, and thus the structures could attract more earthquake action to the structures. To alleviate the problem, a novel self-centering damper composed of elastic post-buckling plates and adjustable friction devices (PBSCFD) was proposed and used as the self-centering braces for a self-centering braced rocking frame (SBRF) structure for example. First, the theoretical force-displacement relationship of the PBSCFD was derived based on its configuration and work principle, and then a scaled PBSCFD was manufactured and tested to investigate its mechanical properties and verify the theoretical constitutive model. Subsequently, the SBRF structure with PBSCFDs was designed by the direct displacement-based seismic design method (DDBD), and its seismic performance was examined by elastic–plastic time-history analysis. Finally, the effects of the secondary stiffness ratio of the self-centering braces on seismic mitigation of the SBRF structure were investigated. The results show that PBSCFDs is characterized by classic self-centering behavior with low secondary stiffness, which can be designed to obtain significant control effects on the base/interstorey shear and interstorey drift ratio of the SBRF structure under rare and extremely rare earthquake compared to the conventional SCEDs with significant secondary stiffness.

Experimental, mathematical model, and simulation of a dual-system self-centering energy dissipative brace equipped with SMA and variable friction device

The application of shape memory alloy (SMA) in seismic-resistant devices has received extensive attention due to its unique superelastic and shape memory effect. The poor energy dissipative capacity, insufficient reliability, and small bearing capacity are the main challenges that hinder the application of the developed SMA braces and dampers. The new system of self-centering energy dissipative (SCED) brace was proposed, fabricated, and tested, and the numerical model was defined and verified. The dates manifest that the load-displacement curve of the new dual-system SCED brace displays a typical flag shape. The new dual-system SCED brace exhibits the desirable energy dissipative ability and self-centering capacity and the theoretical and FE model established in this research can preferably express the hysteretic performance. The FE parametric analysis shows that the SMA screw preload has a small effect on the hysteretic curve of the new system brace, but it plays a decisive role in the shape of the hysteretic curve under small deformation. Furthermore, the bearing capacity and stiffness of the dual-system SCED brace can be adjusted by designing key parameters. The research shows that the new dual-system SCED device compensates for the shortcomings of the existing SMA braces and dampers, and it is a very promising and recommended self-centering energy dissipative device to use the wedge block system as the main energy dissipative system and SMA system as the main self-centering system.

Shake Table Tests on RC Double-Column Bridge Piers with Self-Centering Energy Dissipation Braces

Shake Table Tests on RC Double-Column Bridge Piers with Self-Centering Energy Dissipation Braces

Experimental and mathematical model of the variable friction adaptive self‐centering energy dissipative brace

AbstractThe self‐centering energy dissipative (SCED) brace can limit the maximum story drift and eliminate residual drift during an earthquake. The inadequate reliability or excessive complexity of the energy dissipative system, the contradiction between the energy dissipative system and self‐centering system, the limited elongation capacity, and the difficulty in replacement and reuse are the main challenges faced by the existing developed SCED brace. To solve these problems, a variable friction adaptive self‐centering energy dissipative (VFA‐SCED) brace has been proposed. First, the details of the VFA‐SCED brace are introduced, and the force analysis of each component and the working mechanism of the brace are expounded. Then, the equations that govern the brace performance have been derived, key parameters and mathematical models have been identified. Finally, the feasibility of the new system was demonstrated with a set of experiments, in which five specimens with different key parameters were fabricated, tested, and analyzed. The test results show that the hysteretic curve of the VFA‐SCED brace is typically flag‐shaped, and there is almost no residual deformation after multiple cyclic loadings, which means that the brace has good energy dissipative capacity and self‐centering ability, replaceable and recyclable for each component, and stable working performance. The elongation capacity, friction, energy dissipative capacity, and self‐centering ability can be changed by adjusting the relevant key parameters of the spring and wedge block, and the proposed mathematical model can well predict the force‐deformation hysteresis of the brace with different parameters. The results show that the VFA‐SCED brace successfully avoids the main obstacles of previous SCED braces.

Effect of corrosion on self-centering energy dissipative devices

This study reveals the effect of corrosion on the performance of typical self-centering energy dissipation devices for seismic resilience enhancement. Two types of SC devices, namely, high-strength steel ring spring-based SC damper (HSSR damper) and SMA ring spring-based SC damper (SMAR damper), are examined. These specimens were subjected to 720 h’ accelerated corrosion, corresponding to roughly 20 years’ exposure to city out-door environment. Numerical studies are carried out in ABAQUS to further interpret the test results. Among other important findings, the tests showed that the HSSR damper is likely to lose its self-centering capability after corrosion. The high-strength steel (HSS) rings were severely corroded, and the restoring force provided by the rings was insufficient to overcome the friction action. The SMAR damper showed much reduced sensitivity to corrosion. For both dampers, there was no damage to either the SMA/HSS rings or the other components under repeated loading, implying a low risk of corrosion-related low-cycle fatigue failure. The numerical study implies that the friction condition over the entire contact surface is not identical once the damper experiences corrosion. A “two-region modelling strategy” with a smaller friction coefficient and a larger friction coefficient leads to satisfactory agreements with the test results for the corroded HSSR damper. For the SMAR damper, a constant friction coefficient for the surfaces between inner and outer rings has been found to be appropriate for both non-corroded and corroded cases. Based on the limited experimental and numerical data, it is recommended that anti-corrosion measurement should be mandatory for HSSR dampers. Overstrength due to the long-term effect should also be considered in the design of HSSR dampers from a life-cycle design point of view. If no special anti-corrosion measurement is applied, an overstrength factor of 1.3 may be considered. Overstrength may be ignored for SMAR dampers. By representing the key components of SC devices as a group of springs, the analytical description of considered SC devices can be obtained.

A novel self-centering friction damper with elastic post-buckling plates to retrofit bridge bents

The self-centering energy dissipation dampers (SCEDs) have been demonstrated in mitigating the residual deformation of structures under strong ground motions. However, existing researches show that the damping force demand of SCEDs is higher than conventional dampers such as viscous dampers, BRBs or friction dampers for same design displacement of self-centering retrofitted structures, which could lead to higher base shear and acceleration responses of structures. In order to alleviate the problem, a novel self-centering damper composed of elastic post-buckling plates and adjustable friction devices (PBSCFD) was proposed. Compared with conventional SCEDs, the proposed PBSCFD has low secondary stiffness and adjustable energy dissipation capacity, which is beneficial to control the additional internal force of members adjacent to the damper in self-centering retrofitted structures. Based on the configuration and working principle of the PBSCFD, the theoretical force-displacement relationship of the damper was derived. Subsequently, a scaled PBSCFD was manufactured and tested under quasi-static loading to investigate its mechanical properties and to verify the theoretical constitutive model. In order to demonstrate the seismic performance of PBSCFDs, the double-column bridge bent retrofitted with PBSCFDs was designed by direct displacement-based seismic design method (DDBD), and its seismic performance was examined by elastic-plastic time-history analysis. Finally, effects of secondary stiffness ratio of self-centering dampers on seismic mitigation of self-centering retrofitted bridge bent were investigated. The results show that PBSCFDs have certain advantages in controlling the base shear and acceleration of the retrofitted bridge bent compared to conventional SCEDs with significant secondary stiffness.

Mechanism development and experimental validation of self-centering nonlinear friction damper

Current seismic engineering philosophy focuses on preserving life by guaranteeing that structural components can dissipate earthquake energy through inelastic cycles. Recent seismic events have shown that such a practice might lead to significant financial losses, downtime, and further social impacts. Alternatively, recent efforts have changed this paradigm towards next-generation seismic design solutions. This new philosophy adopts innovative energy dissipation devices to protect structural components, hence ensuring life safety with few impacts on the building’s functionality. This way the structure can be inspected and/or repaired immediately after the earthquake with only minor disruptions. This paper presents a novel self-centering energy dissipation device, named the Self-Centering Nonlinear Friction Damper (SCNFD). The SCNFD utilizes pre-compressed double-acting spring cases attached to a pivot hinge with slotted holes to provide self-centering capacity, while friction pads dissipate energy. The proposed SCNFD is fully customizable as the springs and friction pads can be adjusted and/or replaced after inspection. The first part of the paper presents the SCNFD mechanism in detail and the set of equations that govern its response characteristics. The second part discusses the prototype validation with cyclic experimental tests, where its results indicate the proposed equations are well suited to model the SCNFD response. The third part presents a detailed parametric study to quantify the effects of different parameters on the SCNFD response. Finally, the last part includes a design methodology so that engineers can easily define the sizes of SCNFD components to achieve the desired target performance for using in different applications.

Seismic performance of an assembled self-centering buckling-restrained brace with controllable initial stiffness

An innovative assembled self-centering buckling-restrained brace (ASC-BRB) with controllable initial stiffness is introduced. The brace consists of a self-centering system and an energy dissipation system. Unlike existing post-tensioned self-centering energy dissipation braces, whose initial stiffness has high uncertainty and is sensitive to machining errors, the proposed ASC-BRB can obtain highly controllable initial stiffness because of its unique working mechanism. Therefore, structural seismic response uncertainties can be reduced significantly. The configuration, working mechanism, and theoretical restoring force model of the ASC-BRB are first presented. Quasi-static tests are then conducted to examine the feasibility of the brace, and typical flag-shaped hysteretic behavior and stable energy dissipation capability are observed. The main components of the ASC-BRB keep intact after repeated loadings, except for the core plates, which are damaged; however, the core plates can be easily replaced. This observation highlights the superiority of the ASC-BRB in terms of damage concentration and high recoverability. The proposed theoretical restoring force model can accurately predict the hysteretic response of the brace, especially for the initial stiffness, with the predicted value being within 5 % of the experimental value. A simplified numerical model is developed and used in a parametric study conducted to examine the effects of two key design parameters on the brace behavior. Furthermore, the effect of machining errors on the initial stiffness of the ASC-BRB is studied. An analysis of steel frames with ASC-BRBs indicates that the ASC-BRB can effectively reduce the residual inter-story drift and help achieve a peak floor acceleration response comparable to that of the frame with BRBs. However, the peak inter-story drift is amplified owing to the lower initial stiffness of the proposed brace. On the basis of a system-level parametric analysis, recommended optimized design parameters of the ASC-BRB are presented to facilitate efficient control of structural seismic responses.

Post-earthquake functionality assessment of MRFs enhanced by resiliently lateral-resistant and bottom systems

The accumulated stiffness and strength degeneration of rigid bottom joints and uneven lateral deformation mode of the moment-resisting frame (MRF) during earthquakes can result in disastrous structural failures. Damage accumulation, excessive residual inter-story drift, and the lack of self-centering behavior and energy-dissipation capacity in structures are major challenges in controlling losses after earthquakes. This paper aims to propose a self-centering energy-dissipation (SCED) system that enhances the seismic performance of MRFs. This system, called the resilience-enhanced MRF (ReMRF), utilizes a rocking truss as a lateral-resistant structure and incorporates two bottom joints with SCED capabilities into the MRF design. These bottom joints, referred to as the Buckling Restraint Steel Plate (BRSP) bottom joint and the Light Self-Centering (LSC) bottom joint, are composed of key components such as BRSPs and post-tensioned (PT) strands, respectively. Structural design methods and parameters for the rocking truss and bottom joints are discussed to determine optimal values for balancing stiffness demand, SCED capacity, and construction convenience. Special attention is paid to the working stability of the bottom joints during earthquakes and the effectiveness of the SCED system. Results indicate that the performance of the bottom joints and the SCED system is in line with expectations. The findings from both pushover and time history analyses have substantiated that ReMRF outperforms MRF in terms of achieving higher seismic performance objectives. It is intuitively demonstrated by several quantitative metrics derived from static and dynamic analyses, including the overstrength factor, ductility factor, drift concentration factor, peak inter-story drift, and residual inter-story drift.

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.

Development and application of a deformation-amplified self-centering energy dissipation device

Suitable seismic response reduction devices can substantially improve the seismic performance of engineering structures. However, devices with wide applicability and multi-function are lacking. A novel deformation-amplified self-centering energy dissipation (DA-SCED) device suitable for reducing the seismic response of different engineering structures is proposed in this paper. Self-centering of the device is achieved by a pre-pressed combined steel disc spring. The elastic–plastic hysteretic deformation of the lead rod is used to dissipate the earthquake energy. The shear deformation of the lead rods is amplified because the arc lengths of the lead rod embedded points and the connecting rod hinged point are proportional to the distances of both to the disc center when the steel disc rotates; the former distance is designed to be larger than the latter. Pseudo-static tests were conducted under reciprocating tension and compression of a full-scale model to determine the mechanical properties and seismic energy dissipation capacity of the device. A numerical simulation was performed to analyze the factors influencing mechanical performance. In addition, a restoring force model of the device was established and verified, and the seismic energy dissipation capacity was studied using a prefabricated segment pier. The results indicate that the DA-SCED device has good self-centering and energy dissipation abilities. Its hysteresis curves show flag-shaped characteristics, and the maximum residual displacement after unloading is only 0.97 mm. The self-centering capacity can be improved by increasing the disc spring pre-pressure, and the energy dissipation capacity can be enhanced by increasing the deformation amplification ratio and the diameter and number of the lead rods. The proposed restoring force model can describe the mechanical properties of the device accurately. Furthermore, the DA-SCED devices used in the prefabricated segment pier have satisfactory energy dissipation and self-centering performance under seismic action. After installing the device at the bottom of the pier, the transverse and longitudinal opening deformations between the cushion cap and bottom segment are decreased by 41.52 % and 46.75 %, the displacements of the pier top are reduced by 16.34 % and 31.63 %, and the shear forces of the pier bottom are reduced by 12.26 % and 11.96 %, respectively. The device can reduce the seismic responses and the level of damage to the pier, and improve the self-centering ability and seismic performance of the structure.

Seismic Performance Assessment of a RC Bridge Retrofitted with SCEBs Under Near-Fault Pulse-Like Ground Motions

ABSTRACT A novel self-centering energy dissipation brace (SCEB) was developed to enhance the seismic resilience of bridges. In this paper, the replaceable SCEBs are installed between the double-column bent transversely and at the abutment longitudinally. Taking both the seismic safety and resilience into consideration, the seismic performance of bridges retrofitted by braces under near-fault (NF) pulse-like ground motions was evaluated by the probabilistic approach. Results show that the original and retrofitted bridges exhibit higher damage probabilities under NF pulse-like ground motions. The bridges retrofitted with SCEBs exhibit better seismic resilience than the bridges with buckling restrained braces when intensity measure increases.

Seismic resilient rocking shear wall with dual self-centering energy dissipation system: Introduction and A preliminary study

In this paper, a new rocking shear wall with dual self-centering energy dissipation system is proposed for seismic resilient application. It mainly consists of pinned RC wall, pre-pressed disc spring friction damper (PDSFD) and pre-pressed disc spring brace with U-shaped steel damper (PDSBUSD), while the pinned wall with PDSFD located at the bottom (PDSFD-wall) and the PDSBUSD form the dual system to resist lateral load and dissipate energy. This study aims to introduce its details and preliminarily investigate the seismic performance. Firstly, mechanical models of PDSFD and PDSBUSD are revealed and reliable numerical models for them are built to analyze the hysteretic performance. Subsequently, theoretical skeleton model and design principle of PDSFD-wall component are derived, following which the cyclic behavior under different design parameters is numerically analyzed. Combined the above analyses, theoretical hysteresis model and design procedure of the presented rocking shear wall are given, and the influence of critical parameter on its cyclic behavior is discussed by performing numerical simulations. The results show that the theoretical hysteresis models are in accordance with the numerical results; by improving with PDSFD and PDSBUSD the bearing, energy dissipation and self-centering capacities are significantly enhanced, while the damage of RC wall is significantly reduced; the designed rocking shear walls exhibit desirable seismic resilience with about 80% of the energy dissipated by the replaceable friction and steel dampers, and the expected dual yielding energy dissipation mechanism is realized. During the design, it is suggested that the preload of PDSBUSD should be no less than the yielding strength of the steel damper; the ratio of preload to friction force for PDSFD adopts 1.5; the ratio of lateral resistance contribution of PDSBUSD to PDSFD-wall adopts 0.2–0.5.

Seismic performance upgrade of substandard RC buildings with different structural systems using advanced retrofit techniques

There has been ongoing deliberation to arrive at promising retrofit strategies for pre-seismic code reinforced concrete (RC) structures. Against this backdrop, the research reported in this study puts forth solutions by focusing on advanced retrofit approaches for improving the seismic performance of substandard RC buildings with structural systems common to medium seismicity regions. High-performance reinforced concrete (HPRC) jacket application and self-centering energy dissipative (SCED) braces are the contemporary retrofit alternatives prioritized in this study to upgrade RC structural systems deficient in stiffness, strength and/or ductility. While these retrofit techniques were previously investigated at the member level, this study focuses on implementing thin-HPRC jacket applications, innovative outrigger-belt truss SCED bracing systems, and hybrid approaches on three-dimensional (3D) fiber-based numerical models representing substandard RC structures with different heights. Inelastic pushover analyses and multi-record dynamic response simulations are conducted to assess the retrofit alternatives by monitoring several local damage indices (LDIs) and the related global damage measure (GDM). The study confirms the effectiveness of retrofit measures for a moment-resisting frame building (MRF) deficient in lateral capacity and a high-rise shear wall (SW) building with insufficient global ductility. The presented systematic methodology accounts for the redistribution of seismic demands after retrofitting critical elements and enables selecting effective seismic retrofit solutions, namely SCED bracing system for MRF structure and hybrid retrofit for the high-rise SW building, using probabilistic seismic performance assessment along with cost and practical considerations.

New precast self-centering rocking shear wall with multiple hinged joints: Description and design approach for seismic protection of buildings

This paper proposes a novel precast self-centering shear wall with multiple hinged joints (PSCSWMHJ) as an alternative seismic resilient system, which is composed of pinned precast walls, pre-compressed disc spring devices (PDSD) and self-centering energy dissipation braces (SCEDB). It is featured by a dual self-centering system with the PDSD-wall component and the SCEDB resisting lateral loads. Seismic energies are expected to be mainly dissipated by S-shaped steel plate dampers installed in the SCEDB, while the precast walls are protected from damages. The damper is characterized by flexure-tension strengthening behavior that is beneficial to control structural displacement under strong earthquakes, and its seismic performance has been experimentally and numerically studied. The main objective of this study is to investigate rocking mechanism and seismic resilient design method for the PSCSWMHJ. In present study, mechanic models for the PDSD and the SCEDB are presented, and the SCEDB's hysteretic behavior is analyzed through numerical parametric studies. Rocking mechanism for the PDSDS-wall component and the PSCSWMHJ are theoretically revealed and numerically validated. Meanwhile, the influence of design parameters on their hysteretic behavior is discussed. The results show that the PSCSWMHJ has flag-shaped hysteretic curve and most of the energy is dissipated by dampers in the SCEDB. Subsequently, the step-by-step design procedure is proposed on the basis of energy balance concept for realizing seismic resilience of the PSCSWMHJ. Nonlinear dynamic analyses indicate that the design procedure is capable of achieving the expected performance objectives and the pre-selected yielding mechanism; the proposed PSCSWMHJ exhibits excellent self-centering capacity and good functional recoverability.

Modeling methods of self-centering energy dissipation braces using OpenSees

Self-centering energy dissipation (SCED) braces as a high-performance structural member has been extensively investigated in the last decade. The unique hysteretic behavior of the SCED brace generally dominates the seismic performance of building structures. This paper presents three available simulation methods for predicting the hysteretic behavior of a typical SCED brace in the widely-used open-source computational platform OpenSees. The simulation methods are implemented using the built-in material and element libraries in OpenSees, and aim to investigate the advantages/disadvantages between different modeling methods. Furthermore, two general-purpose self-centering (SC) uniaxial hysteretic models are developed and implemented for modeling different types of SCED braces. Representative validation studies are then presented through using the developed material models to predict the experimental results of the SCED braces under cyclic loading. The SC hysteretic models can capture primary characteristics of hysteretic responses with reasonable accuracy. Additionally, an improved truss element is also proposed for straightforward application of the developed SC models. The users are able to define the experimentally-observed hysteretic features of the SCED braces in line with the envelopes established in the developed material models. A shaking table test of the SCED braced frame in the literature is further simulated to verify the feasibility of the developed material models and modified truss element under seismic loadings. The research outcomes validate a more convenient and accurate method for predicting the behavior of SCED braces and provide some useful insights on the modeling methods in OpenSees.

A Novel Self-centering Braced Double-column Rocking Bent for Seismic Resilience

ABSTRACT A novel self-centering braced double-column rocking bent (SBRB) consisting of a double-column rocking bent and traditional or self-centering energy dissipation braces is developed analytically and numerically to enhance the seismic resilience. The analytical model of the SBRB is established, and numerical models of the SBRB are built to evaluate its seismic performance. Numerical results indicate that the SBRB is featured by prominent seismic performance including high lateral stiffness and strength, stable energy dissipation ability and good self-centering capability. The parameters of braces, axial force ratio, tendon prestress, and confinement play significant roles in the seismic responses of SBRB.

Seismic design and performance of a steel frame-shear plate shear wall with self-centering energy dissipation braces structure

The steel plate shear wall with self-centering energy dissipation braces (SPSW-SCEDB) is a new seismic lateral resistant component. This paper outlines the performance requirements of the steel frame-shear plate shear wall with self-centering energy dissipation braces (SF-SCSPSW) structure and presents a direct displacement-based seismic design method for the structure. A combined strip model of the SPSW-SCEDB that considers the effect of the bolted connection on the wall plate is established. The comparison of the simulated and experimental results shows that the model can accurately predict the strength and hysteretic behavior under cyclic loading. The 8- and 15-story prototype buildings were designed using the presented method. The results of nonlinear dynamic analysis showed that larger inter-story deformations occurred on the lower floors, and the inter-story ratios gradually decreased with an increase in the number of floors. The maximum inter-story drift ratio (1.73%) of the 8-story structure under mega earthquakes and the maximum residual drift ratio (0.018%) of the 15-story structure under large earthquakes were less than the limit values (2% and 0.5%). Local yielding occurred between the brace connection and the column under mega earthquakes, but the columns remained in an elastic state. The seismic responses of the SPSW-SCEDBs in the two structures met the performance requirements of being elastic and suffering light and moderate and serious damage under frequent, medium, large, and mega earthquakes, respectively. The effectiveness of the proposed design method was verified.