Hysteretic Shear Research Articles

Tuneable vibration control of beams using granular multilayer composite

We explore a passive control solution of bending waves in beams, which takes advantage of the dissipative properties of granular media. It consists in a layer of particles confined between two beams and interacting with each other through their contacts. The inter-particles contacts are intrinsically dissipative due to friction, which efficiently works under shear. In practice, the mechanical response of such a multilayer inherit Hertz contact mechanics, thus conferring confining pressure dependent elasticity and dissipation. Previous work have shown that the hysteretic shear behaviour of a granular medium confined in a box can be reasonably captured by a single DOF model using Dahl model fed by an effective medium theory of granular media. Using this reduced model together with finite element method, we simulate the dynamic response of a three-layer composite beam whose core is made of confined frictional particles. This model makes it possible to characterize its elastic and damping properties, revealing in particular a high and tuneable loss factor with respect to shear strain amplitude and confining pressure, suitable for vibro-acoustics applications.

Reinforced ECC-UHPC-SCC composite modular framed shear wall systems under lateral cyclic loading

The shear strength and deformability of high performance reinforced composite framed shear wall systems made of Engineered Cementitious Composite (ECC), Ultra-High-Performance Concrete (UHPC) and Self-Consolidating Concrete (SCC) subjected to lateral cyclic shear loading to failure were investigated. A total of seven framed shear wall specimens were constructed using combinations of ECC or SCC wall, SCC frame and ECC or UHPC frame joints. The performance of such novel modular forms of walling systems were compared based on experimental results in terms of cracking, failure mode, hysteretic shear load-deformation response, shear load capacity, ductility, bearing capacity degradation, stiffness degradation, dissipated energy, viscous damping capacity, induced wall shear stresses and strain development characteristics. ECC walling system exhibited better structural performance compared to their SCC counterparts showing up to 40% higher load capacity forming significantly higher number of closely spaced diagonal cracks with up to 72% lower crack shear stress, 14% to 21% higher ductility, up to 2 times higher energy dissipation capacity and lower rate of stiffness/bearing capacity degradation through both hysteretic and damping actions. The incorporation of ECC and ECC or UHPC joint in frame significantly improved shear strength capacity of infill wall and overall framed shear wall system. ECC incorporated framed shear walls even with frames made of SCC and UHPC joints also exhibited superior performance. This study confirmed the superior performance of ECC material for the construction of reinforced framed shear wall with boundary frame made of ECC/SCC/UHPC combinations for better seismic resistance.

An unscented Kalman filter under unknown input without direct feedthrough for joint input and system identification of structural systems

Given the difficulty of accurately measuring external inputs acting on structures, the research on joint input-system identification has gained significant attention in recent years. Among them, several unscented Kalman filters under unknown input (UKF-UI) based methods have been proposed for joint input and system identification. However, the existing UKF-UI methods require unknown inputs to be presented in the observation equations, which is not always available in practical engineering. To solve this problem, an unscented Kalman filter under unknown input without direct feedthrough (UKF-UI-WDF) is proposed in this paper for real-time joint input and system identification of structural systems without direct feedthrough using limited response measurements. The proposed UKF-UI-WDF is derived for recursive identification of the structural states, parameters, and unknown inputs by integrating unknown input estimation into the conventional UKF framework. In each identification step, the unknown inputs are first identified by minimizing posterior residuals of measurements, and then the structural states and parameters are identified by a traditional unscented Kalman filtering using the identified unknown inputs. According to whether the uncertainty of the identified unknown inputs can be quantitatively described or not, two implementation algorithms are provided in this paper. In algorithm 1, only the mean values of unknown inputs can be identified. In algorithm 2, the unknown inputs are identified as a set of sigma points, so not only the mean values but also the variance of the unknown inputs can be estimated. The effectiveness of the proposed method is examined by the joint input and system identification of various case studies of linear and nonlinear hysteretic shear structures subjected to unknown external or base excitations, respectively. The results show that the proposed UKF-UI-WDF method can effectively perform real-time joint input-system identification of structural systems without direct feedthrough using limited response measurements.

Cyclic shear test and stiffness study of a cross-section-type shear connector connection

In a prefabricated concrete frame-eccentrically steel brace structure, a solid connection is needed between the shear link damper and the concrete member to ensure successful plasticity developments in the damper. A new cross-section-type (CST) shear connector connection has been proposed as the critical component of the assembly connection to improve shear resistance. Four cyclic shear tests were performed to investigate cyclic shearing performance and failure modes with different connector configurations. Failure modes, hysteretic shear strength developments, skeleton curves, and strain distributions at the CST shear connectors were analyzed. Parametric numerical simulations were conducted to investigate the extended influences of various design parameters on shear bearing performance. Nonlinear behaviors primarily begin with concrete cracking, and the failure of CST shear connectors mainly occurs due to concrete damage around CST shear connectors. Increasing concrete strength, connector number, and connector section dimensions can enhance shear stiffness and strength. However, the thickness of the connector endplate and the length of the connector have limited influence. A theoretical calculation method with clear physical meanings and comprehensive considerations for influencing factors was proposed for calculating the initial shear stiffness. The theoretical equation demonstrates high efficiency, with a maximum error of 7.69%. Finally, the design method of the proposed CST shear connector connection was proposed.

Mechanical Properties of Improved Multiple-Layers Viscoelastic Damper

Viscoelastic dampers (VEDs) have been implemented successfully to reduce structural vibrations due to earthquakes and wind events. Conventional VEDs consist of two viscoelastic (VE) layers chemically bounded at their entire contact surface to three steel plates. This configuration has proven to be efficient in controlling the structure vibration. It has also been reported that VEDs can dissipate energy at any level of vibration, producing damping forces. However, when very large damping forces are required, the shear area of the VE layers and the steel plates should be increased to reach the target damping force since the energy is dissipated by hysteretic shear deformation developed in the VE material. Two main issues are associated with this large area. First, the steel plates are more susceptible to experiencing buckling due to out-of-plane deformations. Second, the overall size of the damper becomes larger which is not desirable from the architectural perspective and sometimes from the space usage perspective. As a solution, this study proposes an innovative VED so-called multiple-layers viscoelastic damper (MLVED) able to produce larger damping forces. The proposed MLVED consists of four VE layers bounded between five steel plates. The dynamic mechanical properties of MLVED are initially investigated through a full-scale test. With the test results, the finite element model is developed and calibrated using the commercial software ABAQUS. At a later stage, the calibrated model was used to investigate numerically the mechanical performance of MLVED if different VE layers areas and thicknesses are considered. Results indicated that the proposed MLVED possesses good energy dissipation capacity and its mechanical properties are strongly influenced by strain amplitude rather than loading frequency. Numerical results also showed that the damper is effective in dissipating energy even if different VE layers areas and thicknesses are considered. However, an optimal combination between the area and thickness of the VE layers needs to be found to maximize the damper performance.

Comparative Study on Axial Magnetorheological Effect and Shear Magnetorheological Effect of Magnetorheological Elastomer

The magnetorheological effect of magnetorheological elastomer (MRE) suggests that the viscoelasticity of MRE can be reversibly regulated by magnetic fields in real time. Presently,MRE intelligent variable stiffness isolation device mainly employs the magnetorheological effect of materials in the shear direction, in which case the research on MRE magnetorheological effect is largely focused on the shear direction. However,in the vertical isolation,such study mainly deals with the axial magnetorheological effect of MRE. Our paper,which studies the magnetorheological effect of MRE under axial load through experiments, tries to draw a comparative analysis between the magnetorheological effect with that under shear load. Based on the electronic universal testing machine and excitation device,the axial magnetorheological effect test system was designed,and the shear magnetorheological effect was studied by rotating rheometer. Under the two operating modes,the magnetic field intensity was adjusted between 0~184kA/m, whereas the strain amplitude range varied from 5% to 15%. The tension-compressive hysteretic curves and shear hysteretic curves of MRE under different magnetic fields were obtained,and the viscoelastic mechanical parameters under different working conditions were calculated. The test results show that MRE has good characteristics of magnetostrictive variable modulus and variable damping under axial load. Compared with shear mode,the storage modulus and loss modulus under tension-compressive mode are improved, while the damping loss factor is relatively smaller.

Seismic response of electrical cabinets considering primary-secondary structure interaction with contact nonlinearity of anchors

ABSTRACT Seismic assessment of safety-related equipment in a Nuclear Power Plant (NPP) is more demanding compared to general structures owing to their role in the safe operation and shutdown of the plant. In-cabinet response spectra (ICRS) is thereby generated to qualify the performance of the sensitive devices installed in a cabinet. This study presents the effect of post-installed anchor interaction on the seismic response of an electrical cabinet to drive the ICRS considering primary-secondary interaction (PSSI). Nonlinear hysteretic shear behavior of the anchor connection and its interaction with the floor was considered. An equivalent numerical model was developed to imitate the nonlinear behavior of the anchor bolt. The numerical behavior of anchor was validated using the recent available experimental results. A parametric study for the coupled and uncoupled condition was also considered. The seismic response manifests the nonlinear interaction of anchor bolt that is significant to be considered. The response amplification in a coupled system with anchors nonlinearity is more significant than the floor response spectra (FRS) method and the fixed boundary condition. Moreover, for tuned and nearly tuned primary-secondary systems under the linear and nonlinear connection is also addressed.

FRP-Reinforced Concrete–Steel Double-Skin Tubular Coupling Beam Subjected to Reversed Cyclic Loading

Abstract A fiber-reinforced polymer (FRP)-reinforced concrete–steel (FRCS) double-skin tube was developed for use as a new type of coupling beam, and its hysteretic shear performance was investigat...

A Monotonic Smeared Truss Model to Predict the Envelope Shear Stress—Shear Strain Curve for Reinforced Concrete Panel Elements under Cyclic Shear

In previous studies, a smeared truss model based on a refinement of the rotating-angle softened truss model (RA-STM) was proposed to predict the full response of structural concrete panel elements under in-plane monotonic loading. This model, called the “efficient RA-STM procedure”, was validated against the experimental results of reinforced and prestressed concrete panels, steel fiber concrete panels, and reinforced concrete panels externally strengthened with fiber-reinforced polymers. The model incorporates equilibrium and compatibility equations, as well as appropriate smeared constitutive laws of the materials. Besides, it incorporates an efficient algorithm for the calculation procedure to compute the solution points without using the classical trial-and-error technique, providing high numerical efficiency and stability. In this study, the efficient RA-STM procedure is adapted and checked against some experimental data related to reinforced concrete (RC) panels tested under in-plane cyclic shear until failure and found in the literature. Being a monotonic model, the predictions from the model are compared with the experimental envelopes of the hysteretic shear stress–shear strain loops. It is shown that the predictions for the shape (at least until the peak load is reached) and for key shear stresses (namely, cracking, yielding, and maximum shear stresses) of the envelope shear stress–shear strain curves are in reasonably good agreement with the experimental ones. From the obtained results, the efficient RA-STM procedure can be considered as a reliable model to predict some important features of the response of RC panels under cyclic shear, at least for a precheck analysis or predesign.

A new physical parameter identification method for shear frame structures under limited inputs and outputs

A new physical parameter identification method with a name of EKPF-LS is proposed for shear frame structures under limited inputs and outputs by a combination of extended Kalman particle filter (EKPF) and least square (LS) algorithm. The basic principle of EKPF-LS is to establish the proposed distribution function of the particle filter through EKF-LS. In this method, EKPF is introduced to get rid of the restriction of Gaussian white noise model and reduce the linearization error caused by EKF. Meanwhile, LS is utilized to address the problem of unmeasured excitation estimations. The effectiveness and accuracy of the proposed EKPF-LS method is verified by a numerical example of a four-story hysteretic shear frame under an earthquake excitation and an experimental test of a four-story shear type frame using Gaussian white noise and sine sweep signal as excitations, respectively. Gaussian colored noises are then added to the solved and measured response signals in the numerical example and experimental test, respectively. The results demonstrate that the proposed method can identify the stiffness of shear frame structures effectively and is superior to the existed EKF-LS approach when the structural system is nonlinear structural system or Colored noise model.

Critical Response of Multi-Story Damped Bilinear Hysteretic Shear Building Under Multi Impulse as Representative of Long-Period, Long-Duration Earthquake Ground Motions

The critical response is investigated for a multi-story damped bilinear hysteretic shear building model under a multi impulse as a representative of long-period long-duration earthquake ground motions. The critical response for an elastic-plastic single-degree-of-freedom (SDOF) model under a multi impulse was derived in the previous papers. However, it is difficult to derive the critical response for a multi-degree-of-freedom (MDOF) model under a multi impulse because the phase lag among masses induces a complicated situation. In place of deriving an explicit critical response, a criterion on the criticality of the multi impulse for the elastic-plastic MDOF model is derived and the properties of the critical responses are clarified. In the analysis, a new concept of ‘Multi Impulse Pushover (MIP)’ is introduced and the progressive performance evaluation for the increasing input level is conducted. The analysis of energy response (input energy, dissipated energy, etc.) and the comparison with the response to the corresponding sinusoidal wave are made to enhance the reliability and practicality of the proposed method using the multi impulse as a substitute of sinusoidal waves which are representatives of long-period long-duration earthquake ground motions.

Experimental study on mechanical properties of casting high-capacity polyurethane elastomeric bearings

The laminated elastomeric bearings are widely used structure isolation devices. However, the production and economic efficiency of current rubber bearings are limited by the long-time high-temperature vulcanization process. This study proposes the use of casting polyurethane elastomer (CPUE) substituting rubber in manufacturing laminated elastomeric bearings whilst considering the formula of conventional and improved shear performance formula. Mechanical properties, such as uniaxial tension, hysteretic shear and anti-peel strength, between the conventional and improved materials were compared, and the findings indicate that the use of block technology by introducing hydroxyl-terminated small molecular alcohol can improve the ultimate deformation and anti-peel ability. Moreover, 2 scale-reduced and 24 full-scale new bearings were employed to investigate their vertical compression and horizontal–lateral deformation ability considering different formulas and shape factors. Test results show that the CPUE bearings equipped large vertical bearing, favourable horizontal deformation and excellent energy dissipation capacity. The comparison between the two types of formulas suggest that the new formula can successfully increase the ultimate deformation and centralised failure mode at the expense of acceptable compression modulus decrease.

Development and seismic performance of staggered and out-of-plane joints between concrete-filled steel tubular column and reinforced concrete beam

This article presents a staggered and out-of-plane connection between concrete-filled steel tubular column and reinforced concrete beam (SOC-TCB). SOC-TCB is taken from the basement roof joint of Suning center, which is a height of 341.85 m in China. In this joint system, the H-shaped steel brackets are welded with steel tube to transfer shear and moment. Moreover, the reinforcing bars are interrupted by steel tube and lapped with steel bracket. To investigate the seismic behavior of SOC-TCB, four types of SOC-TCBs were tested under reversal cyclic loading. The differences between specimens were staggered height and out-of-plane angle. Seismic performance was evaluated based on hysteretic behavior, failure mode, shear deformation, rotational deformation, and energy dissipation. The results showed that the shear deformation of joints was extremely small and the plastic hinges were formed at reinforced concrete beams. Due to insufficient anchorage length of longitudinal bars, anchoring failure was found in the reinforced concrete beams. However, SOC-TCB showed better seismic behavior as long as sufficient anchorage of longitudinal bars was ensured.

Seismic demands on nonstructural components anchored to concrete accounting for structure‐fastener‐nonstructural interaction (SFNI)

SummaryThis paper investigates the influence of the hysteretic shear behavior of postinstalled anchors in concrete on the seismic response of nonstructural components (NSCs) using numerical methods. The purpose of the investigation is to evaluate current design requirements for NSC and their anchorage. Current design guidelines and simplified methods, such as floor response spectra (FRS), typically approach the dynamics of the structure‐fastener‐NSC (SFN) system using simplified empirical formulae. These formulations decouple the structure from the NSC and neglect the behavior of the anchor connection, with the assumption of full rigidity. There is a lack of knowledge on the complex interaction between a host structure, the fastening system, and the NSC, herein referred to as structure‐fastener‐nonstructural interaction (SFNI). More specifically, it is important to investigate whether and how the actual hysteresis shear behavior that takes place in the anchorage could alter the seismic response of the SFN system and its components. Herein, the results of extensive nonlinear dynamic analyses (NLDA) with different models for the anchorage force‐displacement relationship are presented and compared with those obtained with FRS procedures and current code provisions. The anchor models include (a) linear‐elastic, (b) bilinear, and (c) a recently developed hysteresis rule. The results of the NLDA showed that the first two approaches are not able to reflect the behavior of an anchor loaded in dynamic shear. Moreover, when using the more refined hysteresis model, it appears that current code provisions might underestimate the component and anchor shear amplification factors for rigid NSC fixed to the host structure through anchors.

A Hysteretic Constitutive Model for Reinforced Concrete Panel Elements

A simple yet effective constitutive model-referred to as the “Fixed Strut Angle Model” (FSAM)-is presented in this paper for simulating the nonlinear axial/shear behavior of reinforced concrete membrane (panel) elements subjected to generalized and reversed cyclic loading conditions. In the formulation of the FSAM, normal stresses in cracked concrete are calculated along fixed crack (strut) directions. Shear stresses developing along crack surfaces, which are calculated using a simple friction-based constitutive relationship, are superimposed with the concrete stresses along the struts, for obtaining the total stress field in concrete. Model predictions were compared with panel tests results available in the literature, at various global and local response levels. The model was demonstrated to reasonably capture the overall response characteristics of reinforced concrete panels, including hysteretic shear stress vs. strain behavior, shear stress capacity, hysteretic shear stiffness attributes, ductility, pinching behavior, governing failure mode, principal strain and stress directions, and local deformations.

Influence of shear‐axial force interaction on the seismic performance of a piloti building subjected to the 2017 earthquake in Pohang Korea

AbstractThis study aims to investigate the influence of shear‐axial force interaction on the seismic performance of a piloti‐type building subjected to the Pohang earthquake. For this purpose, a four‐story piloti‐type building in Pohang, Korea whose columns were brutally damaged by the 2017 Pohang earthquake, one of this country's strongest earthquakes in modern history, was chosen as the object of the study. Columns of this piloti‐type building were designed with insufficient transverse reinforcement, resulting in an increased potential for shear‐axial failure. The piloti‐type building was simulated using Zeus‐NL, an efficient analysis and simulation platform developed for earthquake engineering applications to perform nonlinear time history analysis. A hysteretic shear model in Zeus‐NL capable of accounting for the variation in column axial force was adopted to capture the effect of the shear‐axial force interaction, caused by a combination of horizontal and vertical ground motions. The shear model was validated by comparing the simulated and experimental results. The seismic performance of the piloti‐type building under the effect of the shear‐axial force interaction was compared with that under the shear effect only. Results have indicated that shear effect and shear‐axial force interaction effect significantly reduce column maximum shear force and increase column drift demand. The influence is more intense considering shear‐axial interaction. The seismic response in terms of hysteretic behavior, energy dissipation, and stiffness degradation is presented and discussed.

Nonlinear estimation of the Bouc-Wen model with parameter boundaries: Application to seismic isolators

The Bouc-Wen model is one of the most widely used parametric models of hysteresis. The exactness of the Bouc-Wen model depends on the correctness of the model parameters that are subjected to bound constraints in accordance with their physical meaning. Constraints and nonlinearities of the model introduce a complexity for the parameter estimation. In this paper, a constrained unscented Kalman filter (CUKF) is proposed in order to identify the hysteresis model parameters in a robust and reliable way. The adopted parameter estimator has been compared with the well-known extended Kalman filter (EKF) that is often used for nonlinear system identification. The effectiveness of the proposed approach has been verified by numerical simulations and experimental tests. In particular, for the experimental verification of the CUKF, the Bouc-Wen model has been adopted to describe the hysteretic shear behaviour of a seismic isolator. The results show that the CUKF provides better parameter identification than the EKF also taking into account parameter boundaries.

Modelling of R/C members accounting for shear failure localisation: Hysteretic shear model

SummaryReinforced concrete (R/C) frame buildings designed according to older seismic codes represent a large part of the existing building stock worldwide. Their structural elements are often vulnerable to shear or flexure‐shear failure, which can eventually lead to loss of axial load resistance of vertical elements and initiate vertical progressive collapse of a building. In this study, a hysteretic model capturing the local shear response of shear‐deficient R/C elements is described in detail, with emphasis on post‐peak behaviour; it differs from existing models in that it considers the localisation of shear strains after the onset of shear failure in a critical length defined by the diagonal failure planes. Additionally, an effort is made to improve the state of the art in post‐peak shear response modelling, by compiling the largest database of experimental results for shear and flexure‐shear critical R/C columns cycled well beyond the onset of shear failure and/or up to the onset of axial failure, and developing empirical relationships for the key parameters defining the local backbone post‐peak shear response of such elements. The implementation of the derived local hysteretic shear model in a computationally efficient beam‐column finite element model with distributed shear flexibility, which accounts for all deformation types, will be presented in a companion paper.

Comparison of different models for high damping rubber bearings in seismically isolated bridges

Steel-reinforced high damping natural rubber (HDNR) bearings are widely employed in seismic isolation applications to protect structures from earthquake excitations. In multi-span simply supported bridges, the HDNR bearings are typically placed in two lines of support, eccentric with respect to the pier axis. This configuration induces a coupled horizontal-vertical response of the bearings, mainly due to the rotation of the pier caps. Although simplified and computationally efficient models are available, which neglect the coupling between the horizontal and vertical response, their accuracy has not been investigated to date.In this paper, the dynamic behaviour and seismic response of a benchmark three-span bridge are analysed by using an advanced HDNR bearing model recently developed and capable of accounting for the coupled horizontal and vertical responses, as well as for significant features of the hysteretic shear response of these isolation devices. The results of the analyses shed light on the importance of the bearing vertical stiffness and how it modifies the seismic performance of isolated bridges. Successively, the seismic response estimates obtained by using simplified bearing models, whose use is well established and also suggested by design codes, are compared against the corresponding estimates obtained by using the advanced bearing model, to evaluate their accuracy for the current design practice.

Smart Lead Rubber Bearings Equipped with Ferrous Shape Memory Alloy Wires for Seismically Isolating Highway Bridges

ABSTRACTShape memory alloys (SMA) can substantially improve the damping capacity and re-centering capability of elastomeric isolators. The objective of this study is to assess the seismic performance of smart lead rubber bearings (LRBs) equipped with double cross ferrous SMA wires. Hysteretic shear response of SMA wire-based LRB is determined using finite element method. The seismic response of a multispan continuous steel girder bridge isolated by SMA-LRB is evaluated. Hybrid SMA-LRB bearing exhibits a significantly lower shear strain demand (up to 46% reduction) and a higher energy dissipation capacity (up to 31% increase) compared to the LRB.