Mild Steel Damper Research Articles

Numerical Study on Seismic Performance of a New Prefabricated Reinforced Concrete Structural System Integrated with Recoverable Energy-Dissipating RC Walls

To enhance the performance of infill walls and reduce seismic damage, this paper proposes a novel prefabricated reinforced concrete (PRC) energy-dissipating wall, forming a new recoverable energy-dissipating PRC (ED-PRC) structural system. The system features pre-set gaps on both sides and the top of the PRC wall, with flexible materials filling the gaps on the sides. The top of the PRC wall is connected to the beam through several double-conical mild steel dampers to ensure the efficient transfer of horizontal shear forces between the main frame and the PRC wall. A numerical study was employed to investigate the seismic performance and the staged yield capacity. The results show that this design achieves a yielding sequence of dampers → wall → main frame. Furthermore, during the early to mid-phases of the cyclic loading simulations, the double-conical mild steel dampers with the low yield point utilized in the ED-PRC structural system exhibited exceptional energy dissipation capabilities. Notably, the LY100 dampers accounted for up to 61.84% of the total energy dissipation, with the LY160 and LY225 dampers contributing 55.35% and 50.25%, respectively. It indicates that the proposed ED-PRC structural system significantly enhances the ductility and the energy dissipation capacity under seismic loading while substantially reducing damage to the primary structure. The use of prefabricated components facilitates modular construction, allowing for quick dismantling and replacement after an earthquake, thereby rapidly restoring the structural seismic resilience.

Study on plug-pin energy-dissipating joint with integrated mild steel dampers

Plug-pin joints are designed for easy assembly and fast construction. Full-scale experiments were carried out on three exterior beams-to-column joints subjected to reversal cyclic loading. It has been proved from experimental results that the proposed connection not only guarantees structural integrity but also moves the plastic hinge away from the column edge. Based on the experimental results, a novel plug-pin connection with integrated mild steel dampers is proposed. The energy dissipation joint fully adopts a dry connection method, and the joint's ductility is significantly improved by the integrated energy-dissipating steel plates. Finite element models are established to study the effects of different diameters of steel bars and thicknesses of energy-dissipating steel plates on structural response and mechanical properties under low cyclic reciprocating loads. Parameter studies were carried out, and the obtained results indicate that the proposed joints can bear a greater displacement load than that of cast-in-place joints and achieve greater energy dissipation. The maximum bearing capacity of the joint can be improved by increasing the thickness of the energy-dissipating steel plates, but the bearing capacity decline period of the joint will appear in advance under the same order of loading. If designed properly, structures installed with the plug-pin joint will be expected to adjust the order of plastic hinge development, thus achieving better seismic performance.

Probabilistic seismic performance assessment of low-damage self-recovering prefabricated concrete frame subjected to near-field pulse-like earthquakes

The low-damage self-recovering prefabricated concrete (SRPC) frame using modular mild steel dampers is illustrated. Six low-cyclic repeated loading tests adopted 5 types of modular mild steel dampers were performed on the same fabricate joint specimen in turn. Based on the field test results and the displacement-based seismic design (DBSD) approach, a new SRPC deficient frame with four sizes of mild steel dampers are established, and elastoplastic time history analysis are conducted on four scenarios under near-field earthquakes respectively. To evaluate the collapse resistance of the new structure moduli designed in accordance with current design codes without considering the near-field earthquakes in the earthquake-prone regions, the probabilistic seismic performance assessments (i.e., hazard, fragility, risk) are conducted at the DBE and MCE earthquake levels under near-field ground motions. Annual and 50-year probability of exceedance (POE) results reflect that the new framework relieves the failed progression with a lower POE and meets the performance safety criteria under the near-field earthquakes. Furthermore, setting appropriate dimensions of mild steel dampers at the beam-column joints can effectively enhance the collapse resistance and whole safety of the new SRPC frame. This research will further promote the establishment of a reliable earthquake design method for new low-damage SRPC structures under near-field earthquakes.

Parameters Design of Transverse Seismic Dampers for Complex Bridge Types—an Example of a Double-width Double-tower Cable-stayed Bridge

Large and complex bridges usually have significant nonlinear effects. In the design of seismic and other dynamic characteristics, it is usually impossible to obtain results from simple force calculations. In this paper, taking the mechanical parameters of the complex structure of double wide double tower cable-stayed bridge as an example, a shear damper in seismic field is designed. The experimental results show that: (1) The shear type mild steel damper can improve the lateral seismic performance of cable-stayed bridges. (2) Because the double span cable-stayed bridge is connected by dampers between towers, the mechanical parameters of dampers will affect the natural structure of the bridge, and there is no obvious linear relationship between the yield force of the damper and the bending moment at the bottom of the tower.

Optimal Vibration Control Design of Antenna Mast on Super High-Rising Structures Against Multi-Hazards of Earthquake and Wind

Antenna mast structures are usually set on top of modern super high-rising structures to meet the requirements of communication and aesthetics, and such buildings are highly sensitive to horizontal loads that can greatly increase the acceleration and displacement responses during their life-cycles owing to the inherent high flexibility and low damping. As a result, the antenna masts with small mass and stiffness may suffer serious whiplash effect under the earthquake or wind excitations. In this paper, a multi-hazard protective system with hybrid isolated and energy-dissipated devices of isolation bearing, viscous damper and mild steel damper is presented for the typical inserted antenna mast structures on super high-rising structures. To determine the optimum parameters of the hybrid system that maximize the structural control efficiency under a single hazard of earthquake or wind load, as well as the coupled conditions of these two hazards, an optimization method based on the genetic algorithm is developed for the presented hybrid control system to resist various hazard scenarios. Objective functions are further proposed to penalize the accelerations and relative displacements at the top of the antenna mast structure. Taking a super-tall TV tower as an example, the OpenSeesPy platform is employed to establish the finite element (FE) model. The numerical results show that the optimization scheme for the hybrid energy-dissipated antenna mast system under a single hazard is not suitable for the other hazard condition, while the optimized results for the multi-hazard condition can give consideration to the effects of both earthquake and wind. Moreover, the sensitive analysis is performed to investigate the effects of each parameter of the hybrid system on the objective functions. It can be concluded that the proposed hybrid system performs well under earthquake, wind and coupled multi-hazards, which is of practical significance for the vibration control of antenna masts on super high-rising structures.

Experimental study on effects of U-shape dampers on earthquake responses of a base-isolated LNG inner tank

Base-isolated liquefied natural gas (LNG) storage tanks are prone to violent liquid sloshing and large isolator displacements when subjected to near-fault earthquakes, which are characterized by long-period velocity pulses and large-amplitude displacements. Employing supplemental damping into isolation systems is an effective method to control the displacement of isolators. This paper aims to investigate effects of U-shape dampers on earthquake responses of an inner steel tank isolated by multiple friction pendulum bearings (MFPB). Two materials were selected to manufacture the U-shape dampers, i.e., Mg-Al alloy and mild steel. Hysteretic behaviors of MFPBs with and without U-shape dampers were first evaluated by quasi-static cyclic tests. Afterward, shaking table tests were conducted on a 1:25 scaled steel tank with different isolation systems. Results showed that the U-shape dampers could be used to effectively control the displacement of the isolators. Under the excitation of near-fault ground motions, the peak displacement of isolation bearings with Mg-Al alloy dampers decreased by 16 % ∼ 26 % and that with mild steel dampers decreased by 20 % ∼ 22 %. Meanwhile, adoption of U-shape dampers exhibited excellent reduction effects in both acceleration and hydrodynamic pressure of the tank. In comparison with MFPB, isolation bearings with U-shape dampers exhibited a more plumper hysteresis curve and higher energy dissipation capacity provided by sufficient slides of the bearings.

Seismic retrofitting of SMRFs using varied yielding cross-section damper: A companion paper

This paper is a companion paper to our recent research titled “Seismic Performance of a New S-shaped Mild Steel Damper with Varied Yielding Cross-sections”. In this study, the newly developed varied yielding cross-section damper is employed for seismic retrofitting of steel moment-resisting frames (SMRFs) and a retrofitting design method without performing nonlinear time-history analysis is proposed. The damper has the feature of preventing energy dissipation plate from plasticity concentration-induced failure and of being conveniently replaced post-earthquake. Its hysteretic behavior has been verified through a series of cyclic loading tests. Three prototypes respectively with 3, 9 and 20 stories are adopted as typical low-, mid- and high-rise SMRFs to be damper-retrofitted. And the dampers are designed using the proposed retrofitting procedure in which performance objective of different seismic hazard level and story drift concentration are incorporated. Subsequently, experimentally validated numerical modelling approach for the damper is provided, and detailed numerical models for the bare frames (BFs) and damper-retrofitted frames (DFs) are established. In order to analyze the effectiveness of the developed dampers and the retrofitting design method, seismic performance of the BFs and DFs is assessed by conducting pushover and nonlinear dynamic analyses. The results indicate that the retrofitting strategy can significantly enhance the bearing capacity against strong earthquakes and mitigate the structural damages by reducing inter-story drift ratio and residual inter-story drift ratio; the proposed retrofitting design procedure has ability to achieve the expected seismic performance level and mitigate the story drift concentration.

Seismic performance of a new S-shaped mild steel damper with varied yielding cross-sections

In this paper, a novel replaceable metallic energy dissipation device named S-shaped mild steel damper with varied yielding cross-sections (VYSSD) is proposed. The VYSSD mainly consists of consumption plate, outer limit plates and fixed bottom plate, in which the consumption plate is the energy dissipation element and can be easily replaced after earthquakes. Under action of external loads, section curvature of each segment of the consumption plate changes and the sections gradually enter yielding state to dissipate energy through flexural plasticity. A total of 18 VYSSD specimens were cyclically tested under quasi-static and fatigue loads to investigate the hysteretic behavior and seismic performance. The results show that the VYSSD has pump hysteretic loops, good low cycle fatigue performance and desirable displacement capacity. It is capable of avoiding plastic deformation concentration of traditional metallic dampers, and the failure mode is dominated by fatigue crack propagation. Moreover, a solid finite element model which can effectively simulate the hysteretic behavior and plasticity development of VYSSD was built, and the practical design formulas were suggested through parametric studies considering different geometric dimensions. Finally, a representative 20-story benchmark model was employed for seismic resilient application of the VYSSD. The structures with and without damper retrofitting were numerically modelled for conducting nonlinear dynamic analysis and seismic fragility analysis. The analyses illustrate that the VYSSD can significantly enhance the structural seismic performance, and exceedance probabilities of damage, demolition and collapse for the damper-fused structure are much lower than that of the original structure.

Design and numerical simulation of a new type of staged yield mild steel damper

In order to make up for the lack of single form of energy dissipation of the existing mild steel dampers, a new type of staged yield mild steel damper is proposed by combining two different forms of energy dissipation steel plates. Its construction and energy dissipation mechanism are introduction, based on the relevant theory, the expression of mechanical properties parameters are derived, and the finite element software ABAQUS is used to simulate the staged yield mild steel damper with different parameters. The results show that the staged yield mild steel damper not only possesses full hysteretic loops and excellent energy dissipation capacity, but also achieves staged yield function effectively. The height of the staged yield mild steel damper is an important factor affecting its yield displacement and hysteretic performance.

RESEARCH ON THE INFLUENCE OF MILD STEEL DAMPERS ON SEISMIC PERFORMANCE OF SELF-RESETTING PIER


 
 
 In order to improve the energy consumption capacity of the assembled self-resetting pier, the mild steel damper is added to the prefabricated self-resetting pier to form a prefabricated self- resetting pier with an external mild steel damper. Two sets of pier models were established by numerical simulation. On the basis of verifying the correctness of the traditional prefabricated self- resetting pier model, the two sets of pier models were subjected to low-cycle reciprocating loading to study the influence of the mild steel damper yield strength parameters and the pier axial compression ratio parameters on the seismic performance of the pier structure. The results show that compared with traditional prefabricated self-resetting piers, the hysteresis curve of self-resetting piers with mild steel dampers is fuller, and energy consumption and bearing capacity are greatly improved. With the increase of the yield strength of the mild steel damper, the energy consumption capacity will decrease when the loading displacement is less than 25mm, but the overall energy consumption capacity will increase. As the axial compression ratio of the pier column increases, the bearing capacity and energy consumption capacity of the structure increase significantly, but the impact is not obvious when the axial compression ratio exceeds 0.052.
 
 

Influence of mild steel damper design parameters on energy dissipation performance of low-damage self-centering precast concrete frame connections

Based on the characteristics of replaceable energy dissipating devices of low-damage self-centering precast concrete frame connections (LDSCPC), an LDSCPC joint specimen and five mild steel dampers with different design parameters are designed. The effects of design parameters of mild steel dampers on mechanical properties and energy dissipating performance of LDSCPC joints are studied by cyclic load tests and finite element (FE) analysis. The results shows that the residual deformation of mild steel damper is mainly concentrated in the horizontal energy dissipation strip and its internal angle connected with the vertical energy dissipation strip; increasing the size of the energy dissipation strip can further improve the bearing capacity of mild steel damper, but the performance improvement is more evident after 1.5% drift; the mild steel damper with thickness of 12 mm can save material and play a better role than the thickness of 10 mm and 14 mm; The detailed FE model has enough accuracy in predicting the behavior of LDSCPC connections. The pinching behavior of the damper can be avoided by a preload of 155 kN, which can improve the energy dissipation performance by at least 40%. The corner of horizontal and vertical energy dissipation strips is the area with relatively severe damage. The element damage on the horizontal energy dissipation strip may cause the damper to fracture, which should be paid attention to in the further analysis and optimization design.

A novel self-centering energy-dissipating wall panel with framed beams as boundaries

In order to expand the application of self-centering members or structures, a novel self-centering energy-dissipating wall panel is reported in the paper. It consists of prefabricated concrete wall panels, post-tensioned (PT) tendons and replaceable mild steel dampers at wall toes. The wall panels are expected to be used in steel frames, providing lateral resistance for structures, localizing the damage and reducing the residual deformation. For this purpose, the tested subassembly involving the wall panels with frame beams as boundaries was presented. A total of six full-scale specimens were tested under cyclic loads. Configurations of dampers and initial pre-tension of PT tendons were varied to study their impacts on seismic behavior of the walls. Failure modes, lateral responses, energy-dissipating capacity, self-centering ability and force of PT tendons were also investigated. Test results show that the dampers are used to dissipate energy, and the PT tendons can provide the restoring force. The combination of them gives the walls a dual capacity of energy dissipation and resilience. Based on the compatibility of force and deformation among the steel beams, the wall panels, the dampers and the PT tendons, the theoretical methods for estimating the stiffness parameters and strength parameters of the walls are derived. The experimental skeletons, which are expected to be used in subsequent structural designs, can be accurately predicted by using these parameters.

Slotted Beam‐Column Energy Dissipating Connections: Applicability and Seismic Behavior

Energy dissipating joint can effectively strengthen the connection of prefabricated buildings. In the present study, a new slotted mild steel damper was installed at the beam end of the prefabricated structure to form as the energy‐dissipating joint of the beam‐column. By using ABAQUS software, a finite element (FE) analysis was conducted for the single‐story‐and‐span of the single‐frame structure with a slotted damper as energy‐dissipating joint. The result shows that the damper was the first to yield in the structure and performed well in energy dissipation, indicating its reasonable design of structure and connection. The energy dissipation mainly occurred at the flange of the variable cross sections, between which beam‐ribbed webs ensured the required bearing capacity and stiffness and provided a reliable connection. The hysteretic curves were obtained by analyzing the mechanical properties of the slotted damper under pure bending and pure shearing. In the OpenSees platform, the Steel02 Material model and the twoNodeLink element were used to fit the hysteretic curves; this method was employed for the parametric simulation of the slotted energy dissipation. The dynamic characteristics and seismic response of the controlled structure with slotted energy dissipating joint were also analyzed and compared with those of the uncontrolled structure in the OpenSees platform. The results show that the period of the controlled structure was prolonged and the top story acceleration decreased, indicating its effect in reducing seismic response. The shear‐dependent seismic reduction ratio was about 35%, while the drift‐dependent seismic reduction ratio was about 10%. The seismic performance of bottom story was better than that of the top story, and the damper has good energy dissipation performance in the bending direction. Some detailed design criteria are put forward and consequences for design on the basis of the performed simulations are shown.

Performance Research and Optimization of Corrugated Mild Steel Damper with considering Weld Failure

ABSTRACT Four new kinds of corrugated metal dampers were designed to investigate the behavior of energy consumption. The experimental results show that the mild steel damper has a preferable seismic capability. In addition, the method of simulating weld failure is proposed through using the cohesive crack model, and the mild steel damper is analyzed from the views of weld failure. The recommended value of the minimum weld strength is 1.2 times more than the material strength of steel. Finally, this paper further proposes an optimization scheme to improve the plastic utilization efficiency of the energy dissipation plate.

Seismic performance assessments of precast energy dissipation shear wall structures under earthquake sequence excitations

This paper presents a novel precast energy dissipation shear wall (PEDSW) structure system that using mild steel dampers as dry connectors at the vertical joints to connect adjacent wall panels. Analytical studies are systematically conducted to investigate the seismic performance of the proposed PEDSW under sequence-type ground motions. During earthquake events, earthquake sequences have the potential to cause severe damage to structures and threaten life safety. To date, the damage probability of engineering structures under earthquake sequence has not been included in structural design codes. In this study, numerical simulations on single-story PEDSW are carried out to validate the feasibility and reliability of using mild steel dampers to connect the precast shear walls. The seismic responses of the PEDSW and cast-in-place shear wall (CIPSW) are comparatively studied based on nonlinear time-history analyses, and the effectiveness of the proposed high-rise PEDSW is demonstrated. Next, the foreshock-mainshock-aftershock type earthquake sequences are constructed, and the seismic response and fragility curves of the PEDSW under single mainshock and earthquake sequences are analyzed and compared. Finally, the fragility analysis of PEDSW structure under earthquake sequences is performed. The influences of scaling factor of the aftershocks (foreshocks) to the mainshocks on the fragility of the PEDSW structure under different damage states are investigated. The numerical results reveal that neglecting the effect of earthquake sequence can lead to underestimated seismic responses and fragilities, which may result in unsafe design schemes of PEDSW structures.

Investigation on Seismic Performance of Bidirectional Self-Centering Reinforced Concrete Frame Structures by Shaking Table Tests

This paper presents an experimental study on the seismic performance of a bidirectional self-centering reinforced concrete (RC) frame structure. In the structure, the column-base joints, which were installed with external mild steel (MS) dampers, could uplift freely and the beam-column joints could open effectively under earthquake excitations. Angle steels and MS dampers were installed at the beam-column joints in the structural X and Y directions, respectively. During the gap opening of the joints, unbonded posttensioned (PT) steel wires, which passed through the plastic ducts inserted in the RC beams and columns, provided the structure with the ability to return to pre-earthquake positions, and the yielding MS dampers and angle steels dissipated the seismic energy. A 1/2-scale two-story model structure was designed and constructed. Shaking table tests were performed on the structure under four different types of earthquake excitations with increasing seismic hazard levels. The test results indicated that the self-centering RC frames installed in both the directions showed satisfactory seismic performance, with only slight damage to the main structure after extreme earthquakes. The natural frequencies of the self-centering frames installed in both the directions degraded progressively, mainly because of the prestress loss of the PT steel wires and the yielding of the MS dampers. The structure showed desirable self-centering ability with very small residual deformation under ground motions of all hazard levels. The structural deformation was mainly concentrated at the column-base and beam-column joints, and hence, damage to the concrete beams and columns was considerably alleviated. In addition, the residual gap opening of the joints was minimal.

Hysteresis Performance Analysis of Damping Energy Dissipating Corrugated Steel Plate Shear Wall System

As a buckling-resistant component, the corrugated steel shear wall was adopted to restrain the local buckling of the steel plate. The mild steel damper was also added to improve the energy dissipation capacity of the structure, forming a new damping energy-dissipation corrugated steel plate shear wall system (DCSW). In order to study the hysteresis behaviour of DCSW, 5 nonlinear FEMs were established by ABAQUS, with the consideration of corrugated steel plate placement, mild steel dampers arrangement and openings form. Their ultimate bearing capacity, ductility, stiffness and energy dissipation performance were compared and evaluated. The results indicated that the DCSW system had better bearing capacity and energy dissipation capacity. The ultimate bearing capacity of structure with corrugated steel plate shear walls and mild steel dampers increased by 37%~43% and 11.4%~13% respectively, combining using those two elements, their ultimate bearing capacity increased by 52%~56%, and their ductility was also improved significantly.

Performance simulation analysis and comparison of different shearing mild steel dampers

Mild steel dampers are widely used in the field of engineering structures energy dissipation and seismic reduction because of its advantages such as easy manufacturing, low cost and easy installation and replacement. In order to analyse and compare the performance of the different mild steel dampers, eight different shape shearing mild steel dampers are designed in this paper, and the simulation analysis is conducted using Finite Element Method (FEM) of ABAQUS/Standard. And the bearing capacity, initial stiffness and energy dissipation capacity of the different shearing mild stell dampers are compared according to the simulation results. The analysis and comparison results show that the performance of shearing mild steel damper is greatly affected by its shape. Therefore, the different shearing mild steel dampers should be selected reasonably according to the engineering requirements.

Design Method of The New Damping Energy Dissipation Corrugated Steel Plate Shear Wall System

In order to improve the lateral stiffness of the steel frame, natural anti-buckling corrugated steel shear wall was combined with mild steel dampers, forming a new damping energy-dissipation corrugated steel plate shear wall system (DCSW). The design method of the DCSW system was proposed based on plastic analysis. To study the seismic performance of this system, the nonlinear FEM of the DCSW system was established by ABAQUS, and the analysis on bearing capacity and energy dissipation capacity was carried out. The results showed that the DCSW designed by this method had high lateral bearing capacity and energy dissipation capacity. The lateral ultimate bearing capacity increased by 50% and lateral displacement reduced by 43% with corrugated steel plate shear wall and mild steel dampers.

EXPERIMENTAL STUDY ON THE SEISMIC PERFORMANCE OF DAMPED OUTRIGGERS

The outriggers are the key components of super tall buildings. Increasing the energy dissipation capacities of outriggers has significant value on improving the structural seismic performance. Based on the pseudo-static test of a conventional outrigger, the seismic performance of outriggers with different dampers was investigated through experiments in this study. The results indicated that the auxiliary devices should be installed to ensure the pure shear deformation state of the dampers. Installing either mild steel dampers or friction dampers at the end of the outrigger could improve its energy dissipation capacity and prevent its components from being damaged. As the stiffness and strength of a friction damper can be decoupled, the design process of such damper in the outriggers was much operable, making it more adoptable and promotable in engineering practice. Moreover, the feasibility of using mild steel dampers in the outriggers was also analyzed in this study. It was found that due to the coupling of stiffness and strength of mild steel dampers, the design requirements for the stiffness and strength of outriggers were hard to meet simultaneously. Therefore, further in-depth studies on the application of outrigger with mild steel dampers are needed.