Shear Panel Damper Research Articles

Shape optimum design of shear panel damper made of low yield steel

Shape optimum design of shear panel damper made of low yield steel

Quasi-static test of assembled steel shear panel dampers with optimized shapes

A metallic shear panel damper with the shape optimized by stress contour lines is proposed in this study to mitigate stress concentration, reduce the effect of hot welds, and improve energy consumption efficiency. The stress contour line is defined according to the J2 plasticity theory, and the optimized shape is obtained by assuming that the points on the same contour line yield simultaneously. Different optimized shapes are developed considering various loading conditions. The design formulas for the stiffness and the strength are then derived, and further examined by nine dampers tested quasi-statically. Four are tested laterally under the vertical axial load to simulate real boundary conditions. All dampers can be easily installed or replaced because of the all-bolt connections. The test results demonstrate that the proposed metallic shear damper has a stable energy-dissipation capacity and a better low-cycle fatigue capability than traditional shear dampers without shape optimization. The stiffness and strength design values match the test values very well. The axial deformation in the specimen has been observed and identified due to the interaction among the cyclic axial-shear coupled plasticity, the geometric nonlinearity, and the higher lateral buckling modes. Compared with the non-optimized damper, the distribution of plastic deformation in the proposed dampers is more uniform, and the stress concentration is reduced significantly.

Feasibility of the evaluation of the deformation capacity of the shear panel damper by FEM

Taking advantage of large plastic deformation of low yield strength steel is beneficial for improving the seismic performance of the shear panel damper (SPD). To pre-evaluate the seismic performance of the SPD by simulations is very important for rapid design. However, the deformation capacity of the SPDs cannot be effectively judged by the finite element method (FEM). Here, SPDs which are designed based on different methods are analyzed and compared by simulations and experiment simultaneously. The stress/strain distribution and the stress/strain concentration factor of all specimens are first analyzed and compared based on simulation results. Furthermore, the deformation capacity of some SPDs is verified by experimental results. The relationship between the stress, or stress concentration factor, and deformation capacity of SPDs are obtained and discussed according to the simulation and test results. Not only is the relationship between the stress concentration factor and deformation capacity established quantitatively, but the optimization design method, which is most favorable for large deformation of the SPD, is also qualitatively analyzed in this research. The research results show that it is helpful for the rational pre-evaluation of the limit performance of the SPD based solely on FEM.

In-plane shape optimization of shear panel damper made of low yield steel

In-plane shape optimization of shear panel damper made of low yield steel

Assessment of post-earthquake serviceability for steel arch bridges with seismic dampers considering mainshock-aftershock sequences

This paper focuses on the post-earthquake serviceability of steel arch bridges installed with three types of seismic dampers suffered mainshock-aftershock sequences. Two post-earthquake serviceability verification methods for the steel arch bridges are compared. The energy-absorbing properties of three types of seismic dampers, including the buckling restrained brace, the shear panel damper and the shape memory alloy damper, are investigated under major earthquakes. Repeated earthquakes are applied to the steel arch bridges to examine the influence of the aftershocks to the structures with and without dampers. The relative displacement is proposed for the horizontal transverse components in such complicated structures. Results indicate that the strain-based verification method is more conservative than the displacement-base verification method in evaluating the post-earthquake serviceability of structures and the seismic performance of the retrofitted structure is significantly improved.

Hysteretic mechanical property of low-yield strength shear panel dampers in ultra-large plastic strain

The low-yield strength steel (LYS) has been a promising material to make shear panel damper in seismic engineering due to the large plastic deformation capacity. To take advantage of the energy absorption ability of the low-yield-strength steel shear panel damper (LYSPD), it is essential to obtain the accurate prediction for the stress-strain relationship of LYS especially for the high plastic deformation. However, most of the existing constitutive models for LYS are based on the plastic strain not more than 6%. Here, an improved constitutive model is developed to describe the plastic behavior in a large range of plastic strain up to 60%. First of all, the large plastic behavior with the necking effect under monotonic tension loading is considered and verified by test. Secondly, together with several constitutive models for describing the shear plastic behavior of LYS with and without consideration of cyclic hardening, the accuracy of these models are verified by the cyclic incremental test results of LYSPD. Moreover, an accurate model is calibrated by using the yield stress evolution of the two-surface theory. The developed model could be used to describe the mechanical properties for large plastic strain and to judge the stability of the structure in improved accuracy.

Ultra-low cycle fatigue performance evaluation of the miniaturized low yield strength steel shear panel damper

Merited as rapid assembly and replacement, the miniaturization design of the low yield strength steel shear panel damper has been attracted more attention of researchers. Functioned as damping structure, enough response displacement realized by large deformation capacity with enough low cycle fatigue life is very important for seismic design. Several types of tests are conducted to clarify the performance of the damper. The deformation capacity and low-cycle fatigue performance of the damper material are investigated through monotonic and constant amplitude cyclic shear tests. The deformation capacity of the actual damper affected by width to thickness ratio is verified by incremental amplitude cyclic shear tests. Combined with the constant amplitude cyclic shear tests of the damper, the failure degradation process from damper material to damper structure is systematically analyzed. According to the seismic design requirement, the deformation capacity of the damper when the fatigue cycle number is between 10 and 30 is discussed in detail. Both the accurate prediction and the simple and rapid prediction on the applicable deformation capacity of the damper are proposed according to the analysis of low-cycle fatigue life. This study provides an in-depth understanding of the damage evolution of a miniaturized damper which plays a significant role in the optimization design and practical application of the damper.

Performance tests and analysis of shear panel dampers with aluminum alloy extrusions

Performance tests and analysis of shear panel dampers with aluminum alloy extrusions

Shape optimum design of shear panel damper made of low yield steel

Shape optimum design of shear panel damper made of low yield steel

Experimental investigation of low-yield-point steel shear panel dampers

Experimental investigation of low-yield-point steel shear panel dampers

Cyclic behaviour of low-yield-point steel shear panel dampers

In this paper, a new type of low-yield-point steel BLY160 is applied in the metallic shear panel damper device. To intensively investigate the seismic behaviour of the dampers, reversed cyclic loading tests are conducted to four groups of specimens, with the loading conditions and dimension parameters as test variables. The influences of the width-thickness ratio and corner perforation of the panel, the stiffening rib size and the cyclic load history are analysed. Through the experimental performance of test subassemblies, such as the hysteretic load-displacement loops, skeleton curves, deformation behaviour and failure modes, the earthquake mitigation effects of the damper devices are evaluated. In particular, conspicuous work-hardening is observed in the condition of cyclic deformation under both constant amplitude and increasing amplitudes loading. Contributed by the cyclic hardening of the low-yield-point steel, the energy dissipation capacities of the tested damper devices are approximately 1.5–2.5 times higher than that of a steel panel made of equivalent elasticity and perfectly plastic material. The complicated hysteretic performance with significant strain hardening can be accurately simulated by the kinematic-isotropic combined hardening model proposed in this paper, which incorporates the loading history effect by using the memory surface concept. The validity of the numerical model is verified by the comparison of the predicted cyclic behaviour and test responses.

Plastic Behavior of Metallic Damping Materials under Cyclical Shear Loading.

Metallic shear panel dampers (SPDs) have been widely adopted in seismic engineering. In this study, axial and torsional specimens of four types of metallic damping materials, including three conventional metallic steels as well as low yield strength steel 160 (LYS160), were tested in order to investigate the material response under repeated large plastic strain and low cycle fatigue between 10 and 30 cycles. The present study demonstrated that both the deformation capacity and fatigue performance of LYS160 were underestimated by the conversion from the traditional uniaxial tensile test. The main difference in the failure mechanism between LYS160 and the three conventional materials was determined from the scanning electron microscopy data. The dominant failure mode in LYS160 is stable interlaminate slip and not bucking. Our results provide physical insights into the origin of the large deformation capacity, which is an important foundation for the lightweight design of SPDs.

The Lightweight Design of a Seismic Low-Yield-Strength Steel Shear Panel Damper.

The lightweight design and miniaturization of metallic dampers have broad application prospects in seismic engineering. In this study, the superplastic property and the maximum energy dissipation capacity per unit mass of low-yield-strength steel (LYS) are investigated via comparison with those of several common metallic damping materials by tests. Additionally, the boundary constraints of an LYS shear panel damper are studied further. Our experimental results suggest that LYS is an excellent damping material for achieving the lightweight design goal. A novel design of a lightweight damper, having excellent deformation ability and robust mechanical properties, is presented. The findings of this study are expected to be useful in understanding the lightweight design of dampers.

Deformation Capacity of Steel Shear Panel Damper and its Reflection to AIJ Design Requirements

Shear panel dampers consisting of stiffeners and panels surrounded by four flanges are used as aseismic hysteretic dampers for buildings in Japan. Cracks can form easily in a shear panel damper when shear buckling occurs during the cyclic loading caused by a severe earthquake.For a relatively thin panel with a large width-to-thickness ratio, the damper’s plastic deformation capacity and the presence of shear buckling can be evaluated from the maximum deformation angle. However, when it is relatively small, very-low-cycle fatigue life for a relatively thick panel must be known to predict the usage limit of the damper, because the failure pattern changes when cracks form in the weld between the panels and flanges. Fatigue life relations for a thick shear panel damper with parameters of normalized width-to-thickness ratio and deformation angle are presented. A method for predicting the fatigue life under severe earthquake conditions is also presented. To validate the prediction expression, cyclic loading tests were performed on a shear panel damper and reviewed. The applicability of the method for predicting the fatigue life was confirmed through non-stationary cyclic loading tests. These results showed the validity and effectiveness of the expressions and the method.

Hysteretic characteristics of shear panel damper made of low yield point steel

This study aims to identify the failure mode and hysteretic characteristics of shear panel damper made of low yield point steel (SLY120). The failure mode of shear panel damper is different depending on the width-to-thickness ratio (d/t) parameter. Quasi-static cyclic loading test was carried out on four different d/t ratio shear panel damper specimens. The non-linear finite element analysis was conducted using ANSYS LS-Dyna. The finite element analysis results were in good agreement with the experimental hysteresis curve.

Development of a buckling restrained shear panel damper

Steel shear panel dampers (SPDs) have been widely used in structural seismic design. The low cycle fatigue damage for SPD often occurs close to the welded stiffener, significantly weakening the fatigue performance of the damper. A novel steel shear panel damper called a buckling restrained shear panel damper (BRSPD) is proposed in this paper. A BRSPD has two main parts, an energy dissipation plate and two restraining plates. No stiffener is welded to the energy dissipation plate. The two restraining plates clamp the energy dissipation plate with bolts on both sides to prevent out-of-plane buckling. Quasi-static tests of five specimens were carried out to investigate the performance of the BRSPDs. The test focused on the stiffness and strength of the restraining plates and the gaps between them and the energy dissipation plate. The tests showed that the restraining plates with adequate stiffness and strength can effectively restrain the out-of-plane buckling of the energy dissipation plate. Numerical analysis of the BRSPD was conducted using the general finite element program, ABAQUS, to supplement the test results. A design method for the restraining plates and the bolts is suggested based on the test and analysis results.

Research on Dissipation and Fatigue Capacity of Nonstiffener Shear Panel Dampers

Passive energy dissipation control system can effectively control structure response under seismic action. As a form of passive energy dissipation control, yielding steel shear panel dampers can dissipate energy of the ground motion very well with the plastic deformation. By monotonic cyclic loading, hysteretic performance of the 15 mm thick core-board nonstiffener shear panel damper is tested, and the test shows that the damper has a superior hysteretic performance. Using finite element analysis software ABAQUS, and taking height to thickness ratio of the core-board as variable, the qualitative analysis on the damper is carried out, and results show that the critical height to thickness ratio of shear panel damper is between 30 and 35. Three groups of 15 mm thick core-board nonstiffener shear panel dampers are tested by constant amplitude cyclic loading under different amplitudes; the results show that the fatigue performance is fine and the damper is a good energy dissipation device.

Seismic Performance Upgrading for Underground Structures by Introducing Shear Panel Dampers

A new method of upgrading seismic performance for underground structures is proposed in this paper. Both single-story and double-story underground subway stations are studied. Using the famous single-story Daikai Station model, by which the reliability of the numerical model is verified, seismic efficiency of Shear Panel Damper (SPD) in underground structures is proven. Then, in order to design appropriate and efficient SPDs for underground structures, strength ratio, one of the design parameters, is employed to investigate the seismic performance of structures. The recommended optimum range of strength ratio is given. Afterwards, typical double-story three-span stations with different SPDs layout forms are analyzed to figure out the optimal placement of SPDs. And some interesting conclusions are obtained, which may provide a convenient way to design SPDs in multi-story underground structures.

Shape optimization design of steel shear panel dampers

Steel shear panel dampers (SSPDs) have a reasonably good and stable energy dissipation capacity, and are widely used in engineering to enhance the structural safety of buildings in large earthquakes. Efforts to improve the low cycle fatigue performance of SSPDs have focused mostly on the arrangement of the stiffeners or on the effects of the material properties. The shape of the SSPD plate has not been well investigated. This paper presents a shape optimization method for improving the low cycle fatigue performance of SSPDs. The shear plate shape of the SSPD is taken as the variable in the optimization process. The low cycle fatigue performance of the SSPD is assumed to have a negative relationship to the maximum equivalent plastic strain in the cyclic loading process. The equivalent plastic strains are obtained using the finite element software ABAQUS. The simulated annealing method is adopted for the optimization, which is capable of solving optimization problems involving strong nonlinear systems. In the optimization, four types of SSPDs with different aspect were modeled and the optimal shape of the SSPD for each case was derived. It can be found that the low cycle fatigue performance of the SSPD was significantly improved and the global optimal solution showed better performance compared to the local optimal solution.

The performance of low-yield-strength steel shear-panel damper with without buckling

Low-yield-strength steel (LYS100, yield stress 100 N/mm2) is utilized here to design a shear panel damper for its high ductility. Deformation capacity of the low-yield-strength steel shear panel damper (LYSPD) is known to be affected by out-of-plane buckling which denies precise prediction by the buckling ratio obtained using empirical equations. Therefore, a preliminary investigation into the relationships between the buckling ratio and the deformation capacity of LYSPD is made via static increment tests. A modified equation is proposed to address plastic deformation for the design. As the loading speed of LYSPD goes rather high with large deformation capacity, dynamic tests are conducted to ascertain whether the out-of-plane buckling is affected by the loading speed. Test results reveal that the influence of loading speed on the LYSPD’s out-of-plane buckling is negligible and high deformation capacity is advisable for the application of LYSPD to the design of the damper.