Energy Dissipation Devices Research Articles

Development of a novel buckling-restrained damper with additional friction energy dissipation: Component tests and structural verification

Aiming at solving the issue of the conventional buckling-restrained brace, i.e., the fixed yield strength and residual deformation, a novel buckling-restrained damper with additional friction energy dissipation (BFD) was proposed and tested in the present study. By fabricating an inner core with a small yield segment (SYS) and a large yield segment (LYS) connected in series and setting a friction device in parallel with the SYS, the dual stiffness and stable energy dissipation capacity of the BFD were achieved. Low-cycle fatigue tests were conducted on nine BFD specimens to investigate the influences of the length of the LYS, the length of the slotted holes, the bolt torque and the loading protocol on the hysteretic behavior of the BFD. The experimental results demonstrated that the strength of the BFD increased with the maximum strain of the LYS, whereas the low-cycle fatigue life of the BFD was negatively affected by the maximum strain of the LYS. The friction energy dissipation device could enhance the energy dissipation capability of the BFD throughout the working process. Moreover, the results from the numerical case study determined that the BFD could effectively control the displacement response of the SDOF system under different earthquake magnitudes.

Technological analysis of a prefabricated timber-based system for the integrated renovation of RC framed buildings

Most of the building stock in European seismic countries is highly energy-intensive and earthquake-prone since it was built before the enforcement of effective energy and seismic codes. Renovation actions that synergically integrate both energy-efficient and anti-seismic interventions are strongly needed in these countries. However, the implementation of such interventions is currently limited by barriers that are mostly related to the high cost and invasiveness of traditional seismic retrofit techniques. A new holistic design approach to the building renovation is required to overcome these barriers. This should result in innovative and integrated retrofit interventions able to specifically meet the needs of cost-effectiveness, quick installation, reduced users’ disruption, and low environmental impact. In this framework, the use of cross-laminated timber (CLT) has been recently investigated for retrofit purposes in light of its good mechanical and physical performance. In this research context, this paper illustrates a novel timber-based retrofit technology for RC framed buildings developed within the e-SAFE H2020 project. This technology consists of cladding the external building envelope with a new prefabricated timber-based shell that acts as seismic-resistant and energy-efficient skin, also contributing to renovating the architectural image of the building. The new skin combines structural CLT-based panels – equipped with novel devices for seismic energy dissipation – with non-structural wooden-framed panels. Specifically, this paper presents a construction analysis of the proposed retrofit technology, investigating its technical feasibility, versatility, and potentialities, as well as possible application limits.

Generalized response spectrum analysis based computational morphogenesis for metal gridshells with buckling-restrained braces subjected to seismic loading

Structural morphogenesis is widely used as a parametric tool to find an optimal structural shape of shell structures for a prescribed objective function and a given design load. However, the current optimization methods are limited to finding a geometry under only a specific static load like the dead load or an equivalent static seismic load for predefined geometrical shapes, and so can not be applied to free-form gridshells. This poses a challenge to achieving an efficient free-form shell structure in high seismic hazard areas. This paper aims to resolve this by presenting a computational morphogenesis method to obtain form-found shell structures by considering the dynamic seismic loads and the response reduction effects of seismic energy-dissipating devices using generalized response spectrum analysis. The method was applied to optimize the buckling-restrained brace layouts on target spherical metal gridshell structures with different diameter-to-height ratios. The resulting form-found structures had an efficient roof geometry, along with an efficient damper layout (to prevent member buckling and the dropout of finishing materials). Dampers were found to be more efficient if placed in the (relatively heavy) supporting structure instead of the roof, and a flattened but locally bulged roof shape proved to be the most efficient in mitigating the seismic response. The generalized response spectrum analysis significantly reduced the computation time while evaluating the displacement response with sufficient practical accuracy, although it slightly underestimates the acceleration response if compared to the conventional nonlinear response history analysis results.

Simultaneous layout and size optimization of nonlinear viscous dampers for frame buildings under stochastic seismic excitation

Viscous dampers, as effective energy-dissipation devices, have been widely used for seismic mitigation of building structures. Due to the intrinsic uncertainties of structural parameters and earthquake ground motions, to obtain an optimal performance of structural control, the stochastic design optimization of viscous dampers for buildings is essential. This paper establishes a new dynamic reliability-based optimization framework to address the simultaneous layout and size design of nonlinear viscous dampers in frame buildings, considering the dual randomness of both nonstationary seismic excitations and uncertain structural model parameters. Firstly, a mixed integer optimization problem for nonlinear viscous dampers, including discrete and continuous design variables, is formulated, and the design target is to minimize the cost of the dampers subjected to performance constraints on dynamic reliability of building structures. Then, sequential approximate mixed integer programming with trust region is proposed to solve the optimization problem. Moreover, direct probability integral method is suggested to assess the dynamic reliability and its sensitivity with respect to design variables. Finally, accounting for both stochastic nonstationary seismic excitations and random structural parameters, the optimized results of two numerical examples indicate that the proposed method is a competitive choice for realizing the layout and size optimization of limiting types of nonlinear viscous dampers in frame buildings. To ensure the same target performance of buildings in terms of the probability of exceeding the target value of inter-story drift, the larger peak ground acceleration of stochastic ground motions is, the more cost of dampers is required for seismic protection of buildings.

Seismic performance of the combined viscous-steel damping system suffering from oil leakage

The combined viscous-steel damping system is a passive energy dissipation device consisting of a fluid viscous damper and a steel yielding damper in series. However, many viscous dampers installed in structures have been suffering from severe oil leakage. This study aims to assess the influence of the leaked viscous damper on the seismic performance of the combined system. Cyclic tests were conducted on the viscous damper with different leakage levels to obtain its degraded hysteretic performance. The modeling method of the leaked viscous damper was proposed according to the experimental result. The locking behavior and seismic mitigation effectiveness of the combined system suffering from oil leakage were investigated based on a single-degree-of-freedom system. The result reveals that (i) The leaked viscous damper cannot generate damping force at the beginning of the reverse movement of its piston, which is reflected in the hysteretic curves as a “gap” phenomenon. (ii) The proposed modeling method can accurately simulate the damping characteristics of the leaked viscous damper. (iii) In spite of the leakage severity, the combined system possesses reliable locking behavior and decent vibration mitigation effectiveness under earthquakes. (iv) The combined system is superior to the viscous damper in mitigating seismic-induced displacement when suffering from oil leakage.

Stochastic seismic analysis of structures with nonlinear eddy current dampers

Eddy current damper (ECD), a contactless energy-dissipating device, is applying to control the vibration induced by earthquake and strong wind in civil structures. Combining with motion magnification mechanisms improves the damping effect of the ECD while significantly strengthens its nonlinearity. The response of single degree of freedom and multi-degree of freedom system with ECDs under a stationary stochastic earthquake characterized by the power spectral density function is evaluated using the stochastic linearization technique and expressions of the equivalent linear damping coefficient based on force criterion and energy criterion have been found, respectively. Comparisons with results obtained by Monte Carlo simulations confirm that for the nonlinearity of eddy current dampers the force-based criterion stochastic linearization technique gives accurate estimation.

Optimum sizing design of steel frame structures through maximum energy dissipation of friction dampers under seismic excitations

This paper focuses on optimum sizing design of steel frame structures equipped with friction dampers (FDs) in order to prevent the vulnerable effect of an earthquake. The fundamental concept is to maximize the energy dissipation of implemented FDs under different seismic excitations. The FDs utilized as passive energy dissipation devices in a steel structure increase the energy dissipation capacity of the structure by decreasing the seismic demand during an earthquake. In this context, the Pall friction dampers (PFDs) are implemented as diagonal damped brace members in investigated structures. Three different earthquake records (Kobe, Kocaeli-Duzce, Erzincan) are utilized to acquire nonlinear dynamic responses of the steel frame structures through time-history analyses. The open application programming interface (OAPI) functions are used to integrate a finite element modelling based structural analysis program, SAP2000, with a design optimization algorithm encoded in MATLAB for achieving the exact structural behaviours by synchronously data transferring. As an optimizer, one of the recent nature-inspired metaheuristic techniques, so-called Grey Wolf (GW) algorithm is used. Initially, under effect of seismic excitations, the steel frame structures are optimally sized for attaining minimum design weights without implementing the PFD elements by subjecting only strength, displacement, drift, and geometric structural design constraints taken from AISC-LRFD practice code provisions. Afterward, in order for optimally modelling the PFD elements, the frames are equipped with PFDs to calculate optimum yield strengths that is defined as slip load of a PFD. To do so, the GW algorithm ensures the maximizing of the dissipated energy and controls the yield strengths between the stories since the shear force due to the earthquake increases towards the base of the structure. Eventually, the provisions-based sizing design optimizations of the steel frame structures equipped with optimally modelled PFD elements are conducted under seismic excitations for conclusive evaluations.

Component Test, Fracture Simulation and Experimental Study on Steel and Shear Panel for Seismic Resistance

AbstractThis paper summarizes the experimental campaign carried out for the development of a new steel energy dissipative devices named Slit Dampers (SDs) designed for earthquake protection of structures. SDs consist in shear steel plates with appropriately shaped cut‐out portions of material for allowing maximum spread of plastic deformation along the device and then maximizing the hysteretic dissipative behavior. A total of eighty‐two steel shear plates with different openings and thicknesses are tested to investigate their behavior under cyclic pseudo‐static loading. Six types steel shear plates are studied, including the SD with narrow slits that divide the plate into rectangular links, and the butterfly fuse with a diamond‐shaped opening that create butterfly shape links in the plate. Other varying test parameters are: loading rate, material strength, and the number of in‐parallel damper elements. It is expected that the proposed model can be successfully used to predict the behavior of dampers in real‐world applications.

Comparative Study on Seismic Behavior of High–Rise Steel Building with and Without Friction Damper and Fluid Viscous Damper: A Review

Abstract: Seismic forces are induced on the structure present in earthquake prone areas. These are induced due to the movement of tectonic plates. Multi-storey buildings are those that have more than two stories, hence undergo large amount of deflection due to their slender structure. Due to the deflection caused by the ground accelerations during earthquakes, the structure is unstable and the structure undergoes damage which is not safe. Passive energy dissipation devices are gaining significance in design of earthquake resistant structures because of their effective performance in controlling seismic effects on structures during earthquake. Friction dampers and fluid viscous damper are passive energy dissipating devices which are used widely as seismic control devices. The present study was conducted analytically on a 15-storey steel frame with regular and irregular configuration and performance of structure against non-linear time history ground movement with and without friction damper and fluid viscous damper. Time history ground acceleration data of Bhuj earthquake (2001) were applied on the structure and the response of friction damper and fluid viscous damper was analyzed and compared. The analysis of the structure for the non-linear dynamic ground acceleration was conducted using ETABS software. The results show that when a friction damper is used instead of a fluid viscus damper, storey displacement is greatly reduced by 25.52%. whereas results shows that storey shear, storey drift, and storey acceleration are greatly reduced by 27.75%, 30.39% and 15.27%, when fluid viscous damper is used instead of a friction damper.

A variable stiffness energy dissipation device for drift control of steel frames

A novel variable stiffness energy dissipation device is conceptualized and numerically studied in this paper. The proposed device is a passive device that consists of an array of helical springs arranged in the form of a series of von Mises trusses anchored between two tubes. Under an external excitation, the tubes move relative to each other and energy is dissipated when the von Mises trusses undergo snap-through and snap-back actions. After presenting the theoretical underpinning of this device, its behavior is programmed using C++ and incorporated into the framework of an open-source software OpenSees. Non-linear time history analyses are then performed on several shear, moment resisting and braced frames to demonstrate the effectiveness of the device in dissipating energy and reducing structural deformations. The results show that the proposed device is capable of reducing both the peak and residual displacements of shear and moment frames, and preventing brace buckling of braced frames under three different levels of earthquake severity.

Deformation‐based design of seismically isolated bridges

AbstractA performance‐based design procedure is proposed for seismically isolated bridges with/without supplemental energy dissipation devices. Considering multiple performance levels (PLs), the proposed method initially identifies the critical hazard level and “near‐optimal” alternatives of the isolation system. Both performance and economy are evaluated based on the inelastic response of reduced‐degree‐of‐freedom (RDOF) isolation and energy dissipation systems. Nonlinear response history analysis (NLRHA) of the multi‐degree‐of‐freedom (MDOF) system is employed in successive design steps, corresponding to different PLs, to refine the design solution through the control of a broad range of material strains and deformations. The above characteristics aim to deliver a rigorous and broadly applicable design method that reduces the high computational effort characterising complex design frameworks, while addressing identified deficiencies of alternative displacement‐based methods. The efficiency of the proposed design methodology is demonstrated by applying it to an actual bridge that was previously designed for ductile behaviour. Alternative isolation and energy dissipation schemes are investigated. Assessment of the design through NLRHA reveals in all cases enhanced seismic performance and cost reduction in the substructure design, thus rendering base‐isolation an appealing design alternative.

Seismic performance of precast CFDST segmental column with hybrid energy dissipation devices

Precast segmental column has various advantages as compared to traditional cast in-situ monolithic column. The major issues of such column are the concrete compressive damages at the toes of the segments and limited energy dissipation due to the rocking mechanism. This study explores a new design of precast segmental column with damage resistant features and hybrid energy absorption system. Super elastic shape memory alloy (SMA), external energy dissipation devices and concrete-filled double-skin steel tubes (CFDST) segments are used to form a seismic resilient precast segmental column. Specifically, the SMA rebars provide the column with good self-centring ability; the external replaceable energy dissipation devices provide extra energy dissipation capacity; the use of CFDST segments mitigates the concrete damage. It is found that the proposed column performs well with small residual displacement, satisfying energy dissipation and minor damage.

A novel seismic energy dissipation device: Laboratory tests, mathematical modeling, and numerical analysis

Seismic energy dissipation devices are used in buildings to dissipate seismic energy in the event of an earthquake. These devices use steel and its yielding properties to dissipate the input seismic energy and protect the building’s structure from damage and failure. There are many types of seismic energy dissipation devices, but all share the same goal of dissipating seismic energy. As part of an ongoing research program, a novel steel seismic energy dissipation device has been proposed. The device is made of a curved diaphragm plate made of mild steel. The diaphragm plate is welded to flanges and transverse stiffeners and can be connected to beam–column joints with a number of bolts. The damper and its geometric variants have been designed and tested in the lab under quasi-static cyclic loading conditions. In the present study, we briefly discuss the experimental program and its main outcomes; however, the main objectives will be mathematical modeling and numerical simulations. The proposed dampers are found to exhibit a stable nonlinear hysteretic behavior with small and large load–deflection loops. This behavior is an indicator of the damper’s capabilities in dissipating significant amounts of input energies with varying intensities. Mathematical modeling of the proposed damper was performed using the Bouc–Wen–Baber–Noori (BWBN) model of hysteresis to simulate the degradation of the device after repetitive loading cycles. The identification of the BWBN model parameters is discussed in detail. Nonlinear finite element buckling analysis was found to be in good agreement with test results of the best performing variant. Interesting results about the shear stress distribution at different buckling stages are presented and discussed in detail.

Vibration-Reduction Strategy for High-Rise Braced Frame Using Viscoelastic-Yielding Compounded BRB

A buckling-restrained brace (BRB) serves as a typical load-bearing and energy-dissipative device for the passive control of structures under seismic loading. A BRB is generally designed to not yield under frequently occurring earthquake (FOE) and wind loads, resulting in it having less effectiveness in vibration reduction compared with post-yielding performance. To address this dilemma, this study proposed the concept and technique details of the viscoelastic-yielding compounded BRB (VBRB). Different from a conventional BRB, a VBRB is fabricated by attaching the viscoelastic damper (VED) to the surface of a BRB’s steel casing, ensuring a compatible deformation pattern between the VED and the BRB’s steel core. A dynamic loading test of VBRB specimens was carried out in which 0.2 Hz~0.6 Hz in loading rate and a maximum of 550 kN in load-bearing capacity had been applied, verifying the feasibility and performance of the VBRB. Subsequently, a parametric design procedure was developed to determine the required VBRB parameters so that the maximum elastic drift response of the structure could be reduced to the code-prescriptive value. The wind-resistance and seismic performances of the VBRB were critically evaluated through dynamic time-history analyses on a 48-story mega VBRB-equipped frame designed according to the Chinese seismic design code (GB50011-2010), and the effectiveness of the approach was also verified. Results indicate that the VBRB has advantages over a conventional BRB by providing a multi-stage passive energy dissipation capacity, resulting in a better vibration-control effect than conventional BRBs for structures subjected to wind load and seismic excitations.

The key to suppress vortex-induced vibration: Stability of the structural mode

The vortex-induced vibration (VIV) problem is common in nature and engineering fields. Current passive or active control methods try to suppress VIV by changing the flow field or improving the flow stability based on the recognition that VIV is caused by resonance. But is VIV really caused by resonance? Tuned mass damper (TMD) has been used in VIV or other vibration control for many years. However, is TMD simply an anti-resonance or energy dissipation device in VIV suppression? With the ARX(Autoregressive with exogenous input)-based reduced-order model (ROM) and the fluid–structure interaction numerical simulation, the physical mechanism of the VIV suppression with TMD in the lock-in region is investigated at a low Reynolds number (Re=60). According to the root loci, the introduction of TMD does not change the unstable wake mode, but effectively improves the stability of the structural mode. The results obtained by numerical simulation reveal that the violent vibration turns to a micro-amplitude response and the final response frequency is consistent with the vortex shedding frequency. Therefore, VIV is a stability problem rather than a dynamic response problem. Meanwhile, TMD suppresses VIV via structural mode stability enhancement rather than anti-resonance and energy dissipation. In addition, the study also found that when the TMD natural circular frequency is between 0.65 and 1.0, the vibration suppression effect is independent of the initial amplitude. This frequency range happens to be the region where the structural mode is tightly coupled with the wake mode.

Study the Comparative Effect of Different Link Dampers on G+25 High Rise Buildings in Seismic Zone IV

Abstract: The usefulness of a high-rise building equipped with different types of link dampers (such as bilinear dampers, fluid viscous dampers, and frictional dampers) for the purpose of controlling seismic vibration is discussed in this study. Due to their safe, efficient, and cost-effective design, dampers have gained a lot of popularity in recent years for the purpose of controlling vibration in structures. They are frequently employed in structural vibration control to reduce seismic risks and, with the use of passive energy dissipation devices, can enhance the dynamic responsiveness of both new skyscrapers and existing high-rise structures. The structure's structural safety and serviceability are improved, and the controlling devices stop the building from collapsing during an earthquake, thereby greatly reducing damage. This paper would discuss the high rise RCC structures (G+25), with different Link dampers for seismic vibration control and study the effect of dampers on it using ETABS software.

Experimental and analytical investigations of steel shear buckling-inhibited energy dissipation devices

This study presents the development and cyclic performance assessment of steel buckling-inhibited shear yielding devices (St-BISYDs). These devices consisted of thin steel plates as the main energy dissipating elements and modular built-up restrainers as the buckling inhibition mechanism. St-BISYDs are designed to achieve a shear strain of at least 20% without buckling to maximize the energy dissipation potential by minimizing the heat-affected zone (HAZ) and using the bolted connections. Ten specimens with two geometric configurations, namely, hourglass and rectangular, steel plates were experimentally tested under quasi-static displacement-controlled cyclic loading. The proposed restrainers greatly enhanced the cyclic performance of St-BISYDs and helped the St-BISYDs to reach the target shear strain level without significant strength and stiffness degradation under cyclic loading. An analytical study is conducted to predict the force-deformation characteristics of St-BISYDs. Experimental results of the tested specimens are also compared with other similar energy dissipation devices. Further, nonlinear modeling parameters are proposed for the force-deformation response of St-BISYDs which can be directly used in the design practices.

Metallic Yielding Dampers and Fluid Viscous Dampers for Vibration Control in Civil Engineering: A Review

Structural vibration is a widespread issue occurred in the field of civil engineering. The passive energy dissipation devices are being increasingly popular for protecting structures from external excitations due to their high performance and no need for external energy. They can be divided into displacement-dependent dampers and velocity-dependent dampers, among which the metallic yielding dampers (MYDs) and fluid viscous dampers (FVDs) are the most representative. This paper presents an overview of the MYD and FVD, aiming to reveal their defects and provide suggestions for future development. The basic concept, the mechanical models, the design approaches, and the applications in civil engineering of the two dampers are reviewed. In particular, the obstacles in application and preference in research of these two dampers are summarized, and their merits and drawbacks are further discussed. Emphatically, the strategies for improvement and future development trends are explored.

Optimal Mixed Placement and Capacity Distribution of Buckling-Restrained Braces and Conventional Braces on a Large Metal Spatial Structure Without Rigid Diaphragm Assumption

This paper presents a design application of the proposed generalized response spectrum analysis (GRSA)-based seismic optimization method to a large metal spatial structure (constructed in Japan) where a rigid diaphragm assumption is not available and displacement responses are disproportionally distributed in a story. It also discusses the optimal mixed placement and capacity distribution of buckling-restrained braces (BRBs) and conventional braces (CBs) to minimize both the story drift response and the number of BRBs (i.e., the introduction cost of expensive energy-dissipation devices used as dampers). GRSA is a quick and efficient analysis method for estimating the reduced seismic responses of structural models with a large degree of freedom, and GRSA-based computational optimization enables a more efficient seismic design process than trial-and-error approaches with time-consuming nonlinear response history analysis. In this study, the efficiency is verified through a comparison with the Japanese standard BRB design method. According to the results, the optimal design solution by the proposed method has approximately 20% less steel tonnage of BRBs than that obtained from the standard method, whereas the seismic performance is equal to or better than the others. Moreover, although engineers should still consider the possibility of damage concentration, the brace configuration of the substructure where BRBs and CBs are arranged in adjacent stories is the most effective for reducing both the number of BRBs and the story drift response.

Seismic isolation technology for prestressed segmental precast piers

Prestressed segmental precast (PC) piers, with insufficient energy dissipation capacity, are seldomly adopted on bridges in seismic areas. To improve the seismic performance of PC piers, this study proposes a functional separation seismic isolation device (FSID), serving as a supplementary replaceable energy dissipation device. Full-scale field load tests on a real-world PC pier were carried out to qualify the seismic performance of this type of piers. Based on the results of tests and supplementary numerical analysis, an optimal design of the FSID was achieved. The numerical results show that the FSID has multi-stage statuses and reaction models. By optimizing the design parameters, FSID can enable the PC piers to satisfy the required seismic performance under various levels of earthquakes. Therefore, the performance-based seismic design of PC piers can be achieved using the FSID.