Steel Shear Panel Damper Research Articles

Seismic behavior of self-centering precast segmental bridge piers with external auxetic steel shear panel dampers

Precast self-centering segmental bridge piers have gained significant attention in bridge construction. Among them, development of the energy dissipation devices that are applicable for the self-centering bridge piers has been a major focus over the past three decades. This study develops a novel post-tensioned precast segmental bridge piers (SC-PSBPs), incorporating replaceable external auxetic steel shear panel dampers (ASSPDs) at the bottom and connecting steel plates at the intermediate segments. The seismic behavior of the SC-PSBPs is investigated through experiments and numerical simulations. Auxetic metamaterials are utilized to develop two kinds of perforated steel plates, including elliptical and peanut-shaped perforations, for the ASSPDs. Eight SC-PSBP specimens are tested to study failure patterns, hysteresis response, residual displacement, segment gap opening behavior, and local response of steel components. Test results show that the proposed SC-PSBP, equipped with unbonded post-tensioning (PT) tendons and ASSPDs, exhibits stable hysteresis response and self-centering capacity with minimal concrete damage. Plastic deformation is concentrated in the ASSPDs, while the intermediate connecting steel plates behave elastically throughout the loading history. A numerical model is developed to investigate the influence of design parameters on the hysteresis behavior of SC-PSBPs. Parametric analyses using the validated FE models explore the seismic behavior of SC-PSBPs with different geometries of ASSPDs, connecting steel plates, and initial PT forces. Numerical results show that both the ASSPDs and the connecting steel plates are imperative to achieve the desired rocking and damage concentration mechanisms of SC-PSBPs. The numerical findings also indicate that decreasing the porosity of ASSPDs effectively enhances the bearing and energy dissipation capacity of SC-PSBPs, as well as increases their residual displacement.

Study on energy dissipation performance of low-yield-point steel shear panel dampers

To investigate the energy dissipation performance of low-yield-point steel shear panel dampers (LSSPD), the eleven full-scale LSSPD specimens were designed and tested. By conducting quasi-static cyclic tests and numerical simulations, the influence of shear plate aspect ratios, flange plate thickness, numbers and layout of stiffeners on the failure modes for energy dissipation performance of LSSPD have been investigated. The results indicate that: The energy-dissipating capacity of the damper is positively correlated with the shear plate's cross-sectional area. Increasing the flange plate thickness can improve the bearing capacity and energy dissipation of LSSPD, but with a limit. The stiffeners can enhance the ultimate bearing capacity of the damper. A single stiffener in both horizontal and vertical directions effectively controls the out-of-plane buckling deformation of the shear plate. It achieves a damper with a full hysteretic curve and a high energy dissipation capacity. However, the arrangement of stiffeners on different sides will decrease the ultimate bearing capacity of the damper. Through finite element supplementary analysis, it is recommended to select the shear plate aspect ratio between 20 and 41, and the flange restraint coefficient βf should not be <10 for damper design. Meanwhile, limiting the stiffener restraint coefficient βs within 45 is recommended to achieve better energy dissipation performance for low-yield-point dampers.

Finite element modeling and design recommendations for low-yield-point steel shear panel dampers

Finite element modeling and design recommendations for low-yield-point steel shear panel dampers

Explainable machine learning models for probabilistic buckling stress prediction of steel shear panel dampers

Steel shear panel dampers are widely used as passive energy-dissipation devices in earthquake-resistant structures. The out-of-plane buckling stress of the core plate included in the steel shear panel damper is critical for obtaining the desired lateral force-resistant and hysteretic energy-absorbing capacities. However, the existing calculation method of buckling stress of the steel shear panel damper cannot well address the effects of the steel material’s and geometries’ inherent uncertainties. This paper intends to develop the probabilistic buckling stress prediction models of steel shear panel dampers using machine learning methods considering the steel material’s and geometries’ uncertainties. To this end, the nominal buckling stress prediction models are first developed using different machine learning algorithms based on finite element analysis results where the efficiency of the finite element models has been validated through test results. The analysis results confirm the highest accuracy of the artificial neural network (ANN) model. The SHapley Additive exPlanations (SHAP) and feature importance analysis methods are adopted for interpreting the developed prediction models. The analysis results indicate that the yielding stress of steel (fy), the height-to-width ratio (α), the width-to-thickness ratio (β), and the initial imperfection (δ) show significant influences on the nominal buckling stress of the steel panel damper while the thickness of the core plate (t) shows negligible effects. The probabilistic buckling stress prediction models are further developed based on the trained ANN model considering the combined uncertainties of steel materials and geometries by the Latin hypercube sampling method. The efficiency of the developed probabilistic buckling stress prediction models is confirmed by capturing the probability density of the numerical simulation results. The global sensitivity analysis (GSA) method is introduced for investigating the influence of the design parameters on the discreteness of the probabilistic buckling stress. It has been found from the analysis results that the uncertainties of the yielding stress of steel (fy) and the initial imperfection (δ) have significant influence, that of the height-to-width ratio (α) have limited influence, and that of the width-to-thickness ratio (β) and the thickness of the core plate (t) have negligible influence on the buckling stress of the steel panel damper. For practical application, the interactive software named “PBSSD” is developed and provided for predicting the probabilistic buckling stress by inputting the nominal design parameters of steel material and geometries.

Welding Performance of Low-Yield-Strength Steel Shear Panel Dampers Under Large Plastic Deformation

Welding Performance of Low-Yield-Strength Steel Shear Panel Dampers Under Large Plastic Deformation

Experimental evaluation and numerical simulation of low-yield-point steel shear panel dampers

Shear panel dampers are considered as a type of reliable passive energy dissipation device for seismic resistant structures with a damage-controlling concept. It has been revealed that the shear bulking of core plates and the premature failure of boundary plates are the main concerns for a shear panel damper that result in insufficient energy dissipation and undesirable ultra-low cycle fatigue performance. This study utilizes square steel tubes serving as out-of-plane stiffeners for the core plates made of a low-yield-point steel with a nominal yield stress of 225 MPa (named LYP225 steel). Meanwhile, a reduced flange plate section is adopted to mitigate the end fracture. An experimental study is carried out on three full-scale damper specimens with different flange plates and loading protocols. The test results show that the square tubes well prevent the bulking of the core plates and all the specimens exhibit plump hysteretic response and satisfactory energy dissipation capacity. The reduced plate sections reduce the likelihood of crack propagation occurring at the flange end, and thereby improve the ultra-low cycle fatigue performance. In order to develop the numerical model of shear panel dampers, a combined-hardening constitutive model with a memory surface is applied to represent the plasticity of LYP225 steel. Based on a plasticity analysis, a simplified calibration procedure is proposed associated with the three-dimensional constitutive model, where the plasticity parameters of LYP225 steel are determined using only the monotonic tensile test data. Eventually, the numerical results of uniaxial specimens and damper specimens are in good agreement with the test results, which validates the effectiveness of the constitutive model and the proposed calibration method.

An efficient approach for optimum shape design of steel shear panel dampers under cyclic loading

The low-cycle fatigue performance of shear panel damper (SPD) highly depends on the geometry of its shape and the criterion considered for its design. The main contribution of the current study is to find the optimum shape of the SPD subjected to cyclic loading by considering two different objective functions. The maximum equivalent plastic strain and the ratio of energy dissipation through plastic deformation to the maximum equivalent plastic strain are selected as the first and second objective functions, respectively. Since the optimization procedure requires high computational efforts, a hybrid computational approach is used to perform two paramount phases of estimating the inelastic responses of the SPD and solving the optimization problem. In the first phase, as an alternative for the time-consuming finite element analysis of the SPD, a weighted-support vector machine model is developed to predict the inelastic responses of the SPDs during the optimization process. In the second phase, the optimum shape of the SPD is found by using the whale optimization algorithm (WOA). The results indicate that both design criteria lead to the optimum-shaped SPDs with a significant improvement in their low cycle fatigue performance in comparing with the initial rectangular shape while a slight reduction in their energy dissipation capacity. Moreover, the second design criterion is slightly better in the performance improvement of the optimum-shaped SPDs compared with the first one. In addition, the weighted-based SVM approach can accurately predict the inelastic responses of the SPDs under cyclic loading, and its combination with WOA results in finding the optimum solutions quickly.

Accurate prediction of shear buckling capacity of low-yield-strength steel considering plastic deformations

Owing to a high plastic deformation capacity, low-yield-strength steel (LYS) shear panel dampers have been widely used in structural seismic engineering. Meanwhile, there is still no effective method to evaluate the shear buckling capacity of LYS shear panel dampers under plastic deformation. Thin-walled cylinders approximated as shear panels are adopted to experimentally analyse the plastic buckling. The effects of the shape aspect ratio and the width-to-thickness ratio on the deformation capacity are discussed. The buckling behaviour is directly judged and analysed by measuring the out-of-plane deformation of the specimens. By analysing different plastic modulus during buckling, it is found that the critical plastic buckling stress can only be predicted accurately when the variable deformation theory incorporated with the stable plastic deformation is adopted. The critical buckling strain of the LYS can be evaluated by the width-to-thickness ratio solely. This study will be of significant value in the analysis of the buckling capacity of LYS in the plastic-deformation range.

Non-parametric shape design optimization of elastic-plastic shear panel dampers under cyclic loading

In this work, we develop a non-parametric shape optimization method for designing low yield steel shear panel dampers (SPDs) under cyclic loading to enhance their energy dissipation capacity and verify it by experiments. Considering material nonlinearity (elastic-plastic) and geometric nonlinearity (large deformation), we formulate a shape optimization problem based on the variational method for 3D solid continua under cyclic loading, in which the plastic work in terms of von Mises equivalent stress is used as the objective function under a volume constraint. Considering the optimality conditions for the plastic work maximization problem, we theoretically derive the shape gradient function based on the Lagrange multiplier method, the material derivative formula, and the adjoint variable method. The derived shape gradient function is used to the H1 gradient method for designing the optimal shapes of 3D solid continua. We apply the developed shape optimization method to design SPDs made of low yield steel, which is an elastic-plastic material owning high-energy dissipation capacity. Cyclic enforced displacements acting on SPDs are used for simulating cyclic loading and evaluating the capacity of energy absorption of SPDs. To evaluate the nonlinear finite element analysis, we also perform cyclic loading test on SPDs. Two design examples of SPDs without and with holes are optimized to verify the validity of the developed shape optimization method. The results show that the developed optimization method works effectively to enhance the plastic work of SPDs. As a feature, this method can design SPDs more efficiently when considering the variation in the thickness direction.

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.

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.

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.

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.

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.

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.