Energy Dissipation Devices Research Articles

PARAMETRIC STUDY ON SEISMIC PERFORMANCE OF COLUMN BASE WITH SHEAR TYPE ENERGY DISSIPATION DEVICES

To study the seismic performance of the steel column base with shear type energy dissipation device, the ABAQUS is used to analyze the parameters of nine column base joint models. The results of finite element calculation are compared with the test results to verify the model accuracy. The influences of the variation of cross-sectional area, width-thickness ratio and the axial compression ratio of the column, on the seismic performance of the column base, such as the resistance capacity, initial stiffness, energy dissipation capacity and self-reset capacity, are studied by using effective column base joint model. The results show that the resistance capacity of the column base is less affected by the width-thickness ratio; when the section area of the weakened section of the energy dissipation device increases to 1.1 times, the resistance capacity can be increased by 36%; when the axial compression ratio of the column base becomes 4 times larger, the resistance capacity can be increased by 58%. The results show that the energy dissipation capacity of column base joint is less affected by the axial compression ratio of steel column; when the section area of the weakened section of energy dissipation device becomes about 2.1 times of the original, the energy consumption of column base joint increases about 79%; when the width-thickness ratio of shear type energy dissipation device increases 3.1 times, the energy consumption of column base joint increases nearly 20%. In addition, the residual deformation of the column base has little influence on the width-thickness ratio of the energy dissipation device. When the weakened section area of the column base increases by one time, the residual displacement angle of the column base node increases by 209%; when the axial compression ratio of the steel column increases by two times, the residual displacement angle of the column base decreases by 54%. In conclusion, when the axial compression ratio is constant, the resistance capacity and energy dissipation capacity of the steel column base can be improved by increasing the cross-sectional area of the shear type energy dissipation device or increasing the width-thickness ratio of the shear type energy dissipation device.

Experimental investigation and seismic response behavior of a self-centering precast concrete frame with hysteretic dampers

A new type of self-centering precast concrete (SCPC) frame with hysteretic dampers is developed to obtain sufficient self-recovering and energy consumption characteristics. The working principle of a novel connection is presented, and seven cyclic loading tests with different parameters on three full-sized novel beam-column joints are investigated. Adequate seismic performances were experimentally observed in cyclic loading tests. Numerical simulation of the novel connection was performed using the OpenSees software. The elaborate simulation results and test results were well matched, such as the hysteretic behaviors, prestressed tendons forces, energy consumption and self-recovering characteristics. Furthermore, a prototype structure was modeled, and the elastoplastic dynamic responses at the design-basis earthquake (DBE) and the maximum considered earthquake (MCE) levels were studied. The results showed that the peak and residual interstory drifts (θmax and θr,max) achieved desirable demands. The post-tensioned strands avoided excessive yielding at the MCE level, and the novel frame had an adequate energy consumption behavior. In addition, incremental dynamic analysis and vulnerability analysis were performed. The 50-year exceedance probabilities of the Immediate occupancy (IO) and Repairable (RE) limit states taking θmax and θr,max as the evaluation indicators were also calculated, respectively. The results demonstrate that the novel frame has adequate seismic performance, greater reliability and less damage potential than the traditional self-centering precast concrete (SCPC) frame without energy dissipation devices.

An efficient cable-type energy dissipation device for prevention of unseating of bridge spans

During earthquakes, large relative displacements can be generated between different structural parts of a bridge. This can lead to collisions between the girder ends and the abutments and can even result in the girder unseating. A widely used prevention method adopts unseating prevention systems. The commonly cable-type unseating prevention device (C-CUPD) has low energy dissipation capacity and its cable fractures easily during strong earthquakes. In order to address these shortcomings, an energy dissipation cable-type unseating prevention device (E-CUPD) with an energy absorption tube is proposed in this study. The paper describes the basic structure and working mechanism of the device, and then investigates its energy absorption characteristics and limit performance, drawing upon theoretical analysis, numerical simulations, and testing of a scaled model. The influence of structural parameters and loading velocity on the energy absorption characteristics of the device are discussed, and the seismic responses of the bridge equipped with the device under different seismic input intensities are studied. The results show that the longer the device, the thicker the tube, and the larger the diameter, the better the energy absorption performance, while the larger the outer diameter, the lower the energy absorption performance. The axial expansion load of the energy absorption tube increases with an increase in the impact velocity. Before and after the characteristic velocity of 1 m/s, the sensitivity of load to velocity is weakened and the variation range decreases gradually. The integrity of the bridge structure equipped with the E-CUPD is improved and the seismic force is evenly distributed among piers with an acceptable value of spring displacement. The device can effectively reduce the relative displacement of the piers and beam subjected to different earthquakes and can absorb a large amount of seismic energy. With the increase in the seismic input intensity, the limiting effect of the E-CUPD becomes more prominent. At the higher seismic input intensities, the relative displacement of the pier and the beam can be reduced by nearly 30% compared to bridge without device. Compared to the C-CUPD, the E-CUPD can improve the limiting performance by about 15%.

Displacement Spectra Damping Factors for Preliminary Design of Structures with Hysteretic Energy-Dissipation Devices

ABSTRACT A methodology based on probabilistic seismic risk analysis to estimate damping factors (Fmd) which modify the spectrum of elastic displacement with uniform annual exceedance rates (UAER), is proposed. Such factors take into account both a) energy dissipation of the hysteretic dissipaters and b) seismic hazard of the site. It is shown the importance of taking into account the type of soil for a proper selection of the dissipater characteristics. Mathematical expressions for Fmd factors are proposed. An example in which Fmd factors are applied using a displacement-based design approach is presented. The results are verified with time-history analyses.

A Simplified Design Strategy of Nonlinear Fluid Viscous Dampers for MDOF Structures

Energy dissipation devices are increasingly used as vibration mitigation systems owing to their efficiency. Therefore, many attempts were made to facilitate their design process. The design of fluid viscous dampers is summarized in the selection of suitable damping values and their location in the structure. This paper presents a strategy that estimates the damping coefficient value for nonlinear fluid viscous dampers in a straightforward manner. This minimizes the design time, and thus, more flexibility is offered for further design considerations. Combining a methodology that predicts a linear damping coefficient based on the concept of target-damping ratio, then, applying an equivalent energy-consumption approach to determine the nonlinear damping coefficient. This research gives a description of the method and its implementation by studying a structure equipped with a set of additional fluid viscous dampers. The results illustrate the efficiency and simplicity of the method.

Seismic performance assessment of multi-story steel frames with curved dampers and semi-rigid connections

Curved steel damper is an innovative energy dissipation device for seismic application. The performance of the curved steel damper has been well studied and experimentally tested. In addition, the behavior of one story curved damper semi-rigid frame (CDSRMF) has been studied extensively. In this study, the seismic performance of multi-story (3 story, 6 story and 9 story) CDSRMFs are extensively examined using nonlinear static (pushover analysis) and nonlinear dynamic analysis. The results show that the addition of the curved damper has significantly improved the stiffness, strengths and energy dissipation of the CDSRMFs. The formation and distribution of plastic hinges in CDSRMFs show that the significant part of nonlinear deformations is concentrated in curved damper elements instead of the primary elements. The curved damper can be used as a robust structural fuse which can be efficiently inspected and replaced as needed. The results demonstrate that multistory CDSRMF can be used as a reliable and resilient seismic force resisting systems.

Seismic Reinforcement System of RC Structure Using Eccentric Brace Frame

This paper introduces an eccentric brace system (EBS) based on an energy dissipation device for seismic retrofitting. Particularly, an EBS-based seismic reinforcement method (SRM) is proposed, and a damper system is constructed based on this method by considering performance enhancement and cost reduction. In a column reinforcement test, the yield strength and maximum strength of a direct web connection test piece (reinforced only via the direct bonding of the web) were marginally lower than those of a plate and web direct connection (PWC) test piece (reinforced by the direct bonding of the column and steel plate). However, the yield strength and maximum strength of the direct web connection test piece were 2.17–3.09 times those of the unreinforced specimen. In addition, it was verified that the strength decreased by approximately 13–18% compared with that of the PWC test piece. Moreover, a significant strength improvement effect could be achieved even when the web of the H-beam was attached directly to the reinforced column. The plate strength improved moderately because of the installation of the additional plate. In addition, in a reinforced frame test, the yield strengths of the SRM-I (simple reinforcement frame) and SRM-II (shear reinforcement frame with K-type inserts) test pieces were 1.27 and 2.47 times greater than that of the reinforced concrete frame specimen. Further, the maximum strengths of the SRM-I and SRM-II test pieces were 2.22 and 2.95 times greater than that of the reinforced concrete frame specimen. The rate of reduction in stiffness for the reinforced concrete frame specimen was the highest and that for the SRM-II test piece was the lowest. A review of the crack pattern, load–displacement relationship, accumulated energy dissipation, and stiffness reduction rate revealed that the SRM-II specimen displayed the highest seismic performance.

Development of Retrofitting Technique for Seismically Vulnerable Open Ground Storey Reinforced Concrete Buildings

Retrofitting is a technique wherein the damaged structure is strengthened to original design requirements. During 2001 Bhuj earthquake in Gujarat, India many open ground storey building damaged. So there is an urgent need for retrofitting of damaged buildings. This calls for techniques that are technically sound and economically feasible to upgrade deficient and damaged buildings. Also, Portland cement (PC) production is under critical review due to high carbon dioxide gas released to the atmosphere and Portland cement is also one among the most energy-intensive construction materials. So retrofitting of existing deficient building using eco-friendly material which could promise higher structural performance than the original building is required. The main contributions is development of retrofitting technique of seismically damaged building using Geopolymer concrete and Chevron steel bracing with passive energy dissipation devices. Experimental studies are carried out using the 4 m × 4 m tri-axial shake table test facility to evaluate the seismic performance of bare frame, Open ground storey building, X-plate retrofitted building, Shear wall retrofitted building. Two three storied half scale model buildings, one open ground storey (OGS) building and a bare frame building are tested for different earthquake inputs in the shake table. The acceleration spectrum of IS1893:2002, soft soil is used as seismic input for the above tests. The failure modes and crack pattern of buildings after the seismic test are analysed. The damaged OGS building after the shake table test is retrofitted. The local retrofitting of columns and beam-column joints in the ground storey is carried out using Geopolymer concrete. The global retrofitting of building is formulated with Chevron type steel bracing incorporating X-plate damper in the ground storey. Sweep sine tests on OGS building before and after retrofitting with X-shaped metallic damper is carried out. The natural frequencies and mode shapes of the models are evaluated. The retrofitted OGS building is again subjected to shake table test to the study the seismic performance under varying amplitude as per IS 1893:2002 ground motion. The same model buildings are analysed in SAP 2000 to predict the seismic performance of the retrofitted RC frames.An innovative technique of retrofitting the seismic damaged building using Geopolymer concrete and construction of shear wall is explored. Two Reinforced Concrete shear walls are constructed inside the open ground storey building as global retrofitting technique. Sweep sine test is carried out after retrofitting with shear wall. The fundamental frequency of open ground storey building increased from 3.75 Hz to 7.25 Hz due to the addition of shear wall. The pushover test on building is carried out. The pushover analysis is carried out to study the seismic response of reinforced concrete building with local and global retrofitting using SAP 2000 software. Comparison of experimental and analytical push over curves is plotted. A significant improvement in the strength and stiffness of the open ground storey building after retrofitting with shear wall is observed.

Pressurized Sand Damper for Earthquake and Wind Engineering: Design, Testing, and Characterization

AbstractThis paper presents the development, testing, and characterization of an innovative low-cost fail-safe sustainable energy-dissipation device in which the material surrounding the moving pis...

Seismic performance of controlled-rocking concentrically braced frames designed by the equivalent energy procedure

Recent earthquakes in New Zealand and Japan showed that structures designed according to modern building codes might suffer significant damages with hefty financial and social losses. The primary reason lies in the seismic design approach, where most seismic force resisting systems (SFRS) were designed to prevent structures from collapse during strong earthquake shaking, without considering the damage and the usability of the structure after an earthquake. In this paper, a controlled rocking-concentrically braced frame (CR-CBF) is proposed. CR-CBF is a fused structural system that uses a combination of post-tensioned tendons (PTs) and energy dissipation devices (EDs) to create a controlled-rocking mechanism to minimize structural repair costs and down time after a strong earthquake. PTs are placed in the structure to provide the restoring forces and to minimize any residual deformation in the structure, while EDs are placed at the base of a structure to dissipate the earthquake energy. To ensure the CR-CBF can achieve high performance, two (CR-CBF) prototypes with different heights are designed using the novel equivalent energy design procedure (EEDP). The EEDP procedure allows designers to select different performance objectives at different shaking intensities. The results of nonlinear dynamic analyses of the CR-CBFs show that CR-CBFs have superior seismic performances as intended and can be efficiently designed using EEDP. Finally, the seismic performance of CR-CBF against collapse is assessed using incremental dynamic analysis (IDA) outlined in the FEMA-P695 methodology. The results show that the CR-CBFs designed by EEDP have sufficient safety against collapse, hence it can be used as an efficient seismic force resisting system.

Parametric Study on Self-centering Precast Concrete Frames with Hysteretic Dampers

The self-centering precast concrete frame structure combines the advantages of industrialization and low earthquake damage, and its energy dissipation capacity and seismic performance have always been the focus of research. This paper proposed a kind of self-centering precast concrete frame with hysteretic dampers (SCPCHD). Its modular design makes the energy dissipation device and components easy to repair and replace. In order to obtain the optimal design, the finite element models of SCPCHD frames with different layout types of post-tensioned (PT) tendons and different shapes of hysteretic dampers are established, and the elastoplastic dynamic time-history analyses are carried out. The results show that the layout types and vertical margin of PT tendons have little effect on the displacement response of the frame structure. Compared to linear PT tendons, polygonal PT tendons can better bear the bending moment of the beam and reduce the stress of longitudinal reinforcements in the beam. The reduce effect of shortening the vertical margin on the tensile damage of beam concrete is obvious in the frame with polygonal PT tendons, but not obvious in the frame with linear PT tendons. Rational design of the prestressing force also plays a crucial role in the energy dissipation capacity of SCPCHD frames.

Experimental study on seismic vibration control of an offshore wind turbine with TMD considering soil liquefaction effect

Wind energy is clean and sustainable. Taiwan is establishing offshore wind farms using wind turbines in the Taiwan Strait. However, these are located in an earthquake-prone area with sandy seabed conditions. To ensure their safety and reliability, the turbines’ support structure must be protected against wind, waves, and seismic loads. Tuned mass dampers (TMDs) are commonly employed to reduce structural vibrations. A TMD is more simply incorporated into turbine structures than are other energy dissipation devices. In this study, a 1:25-scale test model with a TMD was constructed and subjected to shaking table tests to experimentally simulate the dynamic behavior of a typical 5-MW wind turbine with a jacket-type support structure and pile foundation. The scaled-down wind turbine model has a nacelle without rotating blades; therefore, the aerodynamic and rotational effects due to the rotating blades were ignored in this study. A large laminar shear box filled with saturated sandy ground was used to simulate the typical seabed conditions of Taiwanese offshore wind farms. The TMD system was designed to be tuned the first-mode frequency of the test model. Two ground accelerations, selected by considering wind farm site condition and near-fault characteristics, were used for excitation in the test. The responses of the test model with and without the TMD system were compared, and the influence of soil liquefaction on the effectiveness of TMD vibration control was addressed.

Hybrid braced frame with buckling-restrained and strong braces to mitigate soft story

The steel concentric braced frames (CBFs) are the common structural system for buildings. Unlike high strength and stiffness, brace buckling in CBFs results in high nonlinear behavior, which causes damage concentration in one or a few stories during a severe earthquake. This paper proposes a hybrid CBF bracing system to reduce soft-story mechanisms and improve the structural behavior of the CBF system. The proposed system is composed of a buckling restrained brace (BRB) or an energy dissipation device and a strong brace (SB) in one span. The strong braces are designed to have an elastic performance during an earthquake. The direction of BRB and SB are changed, inversely, story by story in a zigzag form. This configuration leads to paradoxical results: stiffness and ductility. This improves both the soft story mechanisms and the buckling capacity of CBFs. In this study, a set of 6-story structural models with different bracing patterns including inverted-V, multi-X, zipper, hexa (hexagonal bracing configuration), and strongback braced frames were evaluated through nonlinear static (pushover) and dynamic analyses (IDA). The collapse performance of structural models was assessed by comparing the seismic behavior of conventional CBFs with similar bracing configuration based on FEMA P695 criteria. From the evaluation of collapse fragility curves, the hybrid bracing system had more safety margin against collapse during severe earthquakes than conventional CBFs.

Pulse-like near-fault ground motion effects on controlled rocking steel cores

Controlled rocking steel cores (CRSCs) with reliable self-centering capability have been known as a low-damage seismic force-resisting system. The flag-shaped hysteresis response of CRSCs can be provided using unbonded post-tensioning tendons and replaceable energy dissipation devices. This paper examines the seismic performance of CRSCs subjected to a suite of pulse-like near-field and far-field ground motions. Non-linear dynamic response analysis is performed for 3-, 6-, 9-, and 12-story archetypes with single and coupled configurations. Results are quantified for different seismic responses, and the influences of earthquake type and structural configuration are compared from various aspects. The findings indicate remarkable changes in the performance of CRSCs due to modeling and ground motion properties. The outcomes reveal that rocking-core archetypes are efficient for mitigating residual damage and restricting peak displacements under both far- and near-field motions.

Performance-based optimal distribution of viscous dampers in ‎structure using hysteretic energy compatible endurance time excitations

Performance-based optimization of energy dissipation devices in structures necessitates massive and repetitive dynamic analyses. In the endurance time method known as a rather fast dynamic analysis procedure, structures are subjected to intensifying dynamic excitations and their response at multiple intensity levels is estimated by a minimal number of analyses. So, this method significantly reduces computational endeavors. In this paper, the endurance time method is employed to determine the optimal placement of viscous dampers in a weak structure to achieve the desired performance at various hazard levels, simultaneously. The viscous damper is one of the energy dissipation systems which can dissipate a large amount of seismic input energy to the structure. To this end, hysteretic energy compatible endurance time excitation functions are used and the validity of the results is investigated by comparing them with the results obtained from a suite of ground motions. To optimize the placement of the dampers, the genetic algorithm is used. The damping coefficients of the dampers are considered as design variables in the optimization procedure and determined in such a way that the sum of them has a minimum value. The behavior of the weak structure before and after rehabilitation is also investigated using endurance time and nonlinear time history analysis procedures in different hazard levels.

Finite element parametric study on the cyclic response of steel frames equipped with comb-teeth dampers

Comb-Teeth dampers (CTDs) are a new type of metallic yielding dampers developed for passive control of structures. These dampers are installed between the floor beam and chevron braces in steel frames. They are made up of identical teeth combined in parallel with each other during loading and dissipate the input energy by in-plane plastic deformations. Experiments and numerical simulations have verified the effectiveness of CTDs as an energy dissipation device in structures. However, a comprehensive parametric study has not yet been performed on the behavior of these dampers. The parametric study provides exciting findings that could guide the future design of frames equipped with CTDs. This paper presents a comprehensive numerical parametric study on the cyclic response of single-story single-bay steel frames equipped with CTDs. Numerical modeling is validated using the results of an experimental study. The studied parameters are end fillet radius, thickness, geometric shape coefficient, and height of damper teeth. The results show that all the studied parameters can considerably affect all the behavioral characteristics of the frame.

Numerical Investigation of Energy Dissipation Device to Improve Seismic Response of Existing Steel Buildings with Soft-First-Story

Retrofitting buildings in densely populated areas with a soft story configuration on the first floor can pose a daunting challenge to the community. Against this backdrop, this study set out to evaluate the seismic retrofit strategy's adequacy in enhancing the seismic performance of buildings with a soft story. The proposed strategy utilizes an earthquake energy dissipation device consisting of a combination of a diagonal brace and a metallic-yielding damper at the ground story level. Two prototype buildings, one with five and the other with ten floors, were chosen to assess the proposed retrofit strategy's seismic response through nonlinear static and dynamic analyses. The seismic capacity, lateral displacement response, maximum inter-story drift ratio, energy dissipation, and collapse fragility are the major response parameters used to compare original and retrofitted buildings. The nonlinear static analysis results revealed that the seismic capacity for buildings equipped with a yielding damper was higher than that of the original buildings. It was also found that retrofitted frame buildings had a desirable structural behavior with a higher value of dissipated energy and a lower value of residual displacements and inter-story drift ratio, in turn reducing the likelihood of soft-story failure.

Optimal Location of Energy Dissipation Box in Long Distance and High Drop Gravitational Water Supply System

In the long-distance and high-drop gravitational water supply systems, the water level difference between the upstream and downstream is large. Thus, it is necessary to ensure energy dissipation and pressure head reduction to reduce the pipeline pressure head. The energy dissipation box is a new type of energy dissipation and pressure head reduction device, which is widely used in the gravitational flow transition systems. At present, there is still a dearth of systematic knowledge about the performance of energy dissipation boxes. In this paper, a relationship between the location of the energy dissipation box and the pressure head amplitude is established, a theoretical optimal location equation of the energy dissipation box is derived, and numerical simulations using an engineering example are carried out for verification. The protective effects of an energy dissipation box placed at the theoretical optimal location and an upstream location are compared. The results indicate that for the same valve action time, the optimal position allows effectively reducing the total volume of energy dissipation box. The oscillation amplitudes of the water level in the box and the pressure head behind the box are markedly reduced. Under the condition that the water level oscillation of the energy dissipation box is almost the same, the optimal location offers better pressure head reduction protection performance than the upstream location.

Seismic response of multi-storey building using different vibration technique-A review

This review presents the high performance of failure-resistant structural device system for the sustainable and flexible buildings. Firstly, the motivation and basic principles as well as methodology of the developing device system are explicitly illustrated. Then, the structural detail and seismic response of base isolation systems, namely, lead Rubber Bearing (LRB), HDLRB isolators, viscous damper (Base Isolation with in-Parallel Dissipation system: BIPD) and sliding bearing isolator (Base Isolation with in-Series Sliding system: BISS) are summarized. The theoretical and experimental study results was shown that all four types of isolator system can be able to minimize damage after seismic an earthquake to the structural system. The viscous damper devices and energy dissipate as well as viscoelastic and fluid viscous dampening can be able to enhance the energy dissipation capacity of structural system under an earthquake loading. A placement of L shape, shear walls at the structural configuration plan is given more efficient behavior under seismic load than all other placements of shear walls at the building’s configuration. Many numerical specimens of tunnel form buildings were constructed and modelled to analyze and interpreted the dynamic and static cyclic response of structures against seismic force. The deformation of the dynamic response of tunnel form building was smaller by using Carbon Fiber Reinforced Polymer (CFRP) repairing and retrofitting method. Contradictory, the usage of base isolations, energy dissipation devices, shear walls and tunnel form buildings can enhance the efficiency of structures under seismic force by reducing the economic cost saving in their construction.

Influence of Rotation-restrained Energy-dissipation Device on the Seismic Performance of a Curved Isolated Bridge

ABSTRACT This article proposes a rotation-restrained energy-dissipation device (RED) for the seismic control of a three-span curved isolated bridge. The configuration and working mechanism of RED are introduced in detail, and the finite element and simplified model are therefore derived. The seismic responses, parametric analysis and ground motion sensitivity analysis of the isolated bridge with and without RED are conducted to study the effectiveness of RED. Results show that RED can significantly reduce the displacement of the deck and the deformation of the isolated bearings, and make the column shear force at middle and side piers more balanced.