Improved Energy Dissipation Research Articles

Experimental study on seismic performance of bridge pier with new HRB650E high-strength steel bar

To facilitate the application of high-strength steel in reinforced concrete bridge structures, this study explores the seismic performance of full-scale HRB650E high-strength reinforced concrete bridge piers. Initially, monotonic tensile tests were conducted on HRB400 and HRB650E steel rebars with the same slenderness ratio to analyze the differences in their mechanical properties. Subsequently, quasi-static cyclic tests were carried out on four square full-scale RC bridge piers to examine the influence of new high-strength rebars, stirrup ratios, and axial load ratios on the seismic performance. Based on the experimental results, a hysteresis model suitable for HRB650E reinforced concrete columns was developed. The findings indicate that the HRB650E steel bar exhibited lower uniform elongation and fracture elongation compared to HRB400 steel bar. The displacement at which HRB650E piers reached crack damage was 36 % higher than that of HRB400 piers, and they also showed lower residual displacements at all load levels. The maximum lateral load capacity and the ductility coefficient of HRB650E piers increased significantly compared to HRB400 piers. While the initial secant stiffness of both types was comparable, HRB650E piers exhibited a slower rate of stiffness degradation, resulting in higher secant stiffness at the ultimate state. They also demonstrated 35 % higher cumulative energy dissipation at the ultimate state. When the stirrup ratio of HRB650E piers was increased from 1.1 % to 1.7 %, there was a slight reduction in residual displacement, a small increase of the yield strength, and a minor improvement in the maximum lateral load capacity. Furthermore, a higher stirrup ratio was observed to improve energy dissipation levels at all loading stages. Increasing the axial load ratio of HRB650E piers from 0.1 to 0.2 allowed the piers to withstand greater deformations at the same repairable ultimate state, with significant increases in yield strength, maximum lateral load capacity, initial secant stiffness, and secant stiffness at the ultimate state, but a small increase in the cumulative energy dissipation. The hysteresis model for HRB650E RC columns, based on experimental data, exhibited good computational accuracy.

Mechanical properties and restoring force model of Squeezing Rub-type Particle Damper

The sliding effect of isolation bearings has been proven to effectively mitigate the seismic effects on large-span bridges. However, it also results in excessive relative displacement between the main girder and piers during earthquakes. In this study, a pioneering Squeezing Rub-type Particle Damper (SRPD) is developed to address this issue. In order to verify the damping characteristics of SRPDs and investigate the working principle of squeezing friction energy dissipation, five quasi-static tests were conducted on SRPDs using two particle damping materials with different compactness levels. In order to compare the energy dissipation performance, comparative tests were conducted on Non-Squeezing-type Particle Dampers (NSPDs) and SRPDs. Utilizing regression analysis, two skeletal curve models for SRPDs were proposed, alongside a detailed restoring force model that incorporates considerations for both the pinching effect and stiffness degradation phenomena observed during the loading and unloading phases. The experimental results demonstrate that the maximum damping force of SRPDs can reach 16 times that of NSPDs, and the energy dissipation of each loading cycle can reach 21.06 times that of NSPDs. SRPDs exhibits improved energy dissipation performance when using high-density blended quartz sand. After sand replenishment repairs,damping force and energy dissipation per cycle of SRPDs were significantly enhanced. The proposed restoring force models of SRPDs aligns well with the experimental curves, underscoring its efficacy in accurately characterizing the hysteresis performance of SRPDs.

FLEXURAL STRENGTHENING OF THERMALLY MODIFIED RUBBERWOOD GLULAM BEAMS WITH FRP UNDER STATIC AND CYCLIC LOADS

The purpose of this research is to investigate the flexural properties and cyclic response of strengthened with fiber reinforced polymer (FRP) of glulam beam made from thermally modified rubberwood. The efficiency of three different FRP was assessed based on the bonding properties. The experimental results demonstrated that the glass fiber-reinforced polymer (GFRP) showed the strongest adhesion. Static and cyclic flexural tests were also carried out to study the behavior of glulam beams. The static test results indicated that double sides strengthened glulam beam enhanced their flexural strength. The strengthened glulam beams under static load demonstrated a reduced deformation rate due to increased modulus of rupture compared to non-strengthening glulam beam. The cyclic load test showed the strengthening effect on improving energy dissipation and ductility, while the impairment of strength did not affect.

Investigation of Improved Energy Dissipation in Stepped Spillways Applying Bubble Image Velocimetry

This study investigates skimming flow regimes, two-phase air–water flow conditions, and simple measures to improve energy dissipation in stepped spillways. Experiments were conducted using two different scale physical models, 1:50 and 1:17, within separate rectangular flumes to define scale effects. Flow patterns were analyzed using the Bubble Image Velocimetry (BIV) technique, which tracks air bubbles. The introduction of splitters resulted in a 7% increase in relative energy dissipation. Additionally, the length of inception was reduced to Li/ks = 10, thereby decreasing the potential for subsequent cavitation. Beyond the BIV experiments, two experiments were conducted on the large-scale model using Acoustic Doppler Velocimetry (ADV), with and without splitters, to examine the impact of splitters on the velocity profile above the crest. In the experiment with splitters, the vertical velocity vector (v) contributed to turbulence by changing direction, thereby reducing average velocities both in front of and behind the ogee crest. This led to a reduction in energy on the downstream side of the spillway. Although the small-scale model appears unsuitable for studying two-phase flow, the change in relative energy dissipation from the baseline to the splitter configuration was practically identical for both scale models, thereby supporting the findings of the large-scale model.

Mechanism of pre-tension on the impact response of plain weave fabric: Experimental and numerical investigation

The fabrics made of high strength and toughness fibers are increasingly used in the structural and individual protection. The research on energy dissipation mechanism and the improvement methods for improving energy dissipation of the fabric under impact, as well as the change of ballistic limit velocity under pre-stress, is relatively mature. However, the transmission mode and velocity of transverse wave in the fabric, as well as the method of accurate finite element simulation is still lacking. In this paper, the transverse impact response of ultra high molecular weight polyethylene (UHMWPE) fabric subjected to fragment impact is studied experimentally and numerically. A novel biaxial pre-tension fixture was developed, and fragment impact test of the fabric in pre-tension state was realized using a gas gun. The displacement-time history of each point on the fabric in three-dimensional space was characterized through 3-D DIC technology, and the process of transverse wave transmission on the fabric after fragment impact was obtained. The calculated results of the finite element model established by truss element agrees reasonably well with the experimental results. The experimental and numerical results indicate that the impact velocity of fragment affects the velocity of transverse wave in the fabric, but does not change its transmission mode. With the increase of pre-tension amount, the propagation mode changes from a cross shape to a rhombic shape and finally to a circular shape, and the wave velocity increases greatly. The wave transmission process in yarns at a mesoscopic level was analyzed through finite element simulation, and the transmission path was determined. It was found that pre-tension accelerated the wave velocity on the stepwise path, causing the transverse wave to reach a farther position in the diagonal direction of the fabric, resulting in different modes of wave transmission. The research content may provide more ways for the application of fabrics in protection.

Experimental study on seismic behavior of RCS joints with asymmetric friction connections and slabs

This paper introduces a new reinforced concrete column-steel beam (RCS) joint that employs asymmetric frictional connections (AFC) to improve energy dissipation and moment transfer, reducing stress concentrations within the joint’s core. Two RCS joint specimens with AFC and floor slabs were designed and tested under quasi-static loading to analyze the impact of bolt preload on seismic performance. The experimental results demonstrate that RCS joints with AFC and slabs exhibit favorable seismic behavior in terms of bearing capacity, energy dissipation, and stiffness degradation. Increasing bolt preload enhances the bearing capacity, stiffness, and energy dissipation capacity of the joints. The failure occurred at the steel beam splice connections, while only minor micro-cracks appeared in the reinforced concrete column when the joint's bearing capacity dropped below 80% of the peak load. Displacement at the column top was primarily influenced by steel beam and column deformation, with minimal contribution from joint core deformation. The use of AFC effectively reduced deformation in the joint core area, meeting seismic design code requirements for “strong columns-weak beams.”

Axial compression performance of rubberized concrete-filled steel tubular stub columns after fire exposure: Experimental investigation and calculation models

Rubberized concrete (RuC) has emerged as a promising eco-friendly solution for structural elements, offering improved energy dissipation, damping characteristics, and ductility. Incorporating rubber particles into concrete-filled steel tubular (CFST) columns presents an environmentally conscious alternative for various structural applications. However, understanding its performance post-fire is crucial for safe design application, an area currently lacking comprehensive research. This study investigates the structural behavior of sixteen axially loaded circular RuCFST columns after exposure to fire. The columns, with diameters of 219 mm and 377 mm, are filled with normal concrete and RuC, containing 5 %, 15 %, and 30 % replacement of natural fine and coarse aggregate with rubber particles. Following ISO-834 fire standards, the specimens undergo elevated temperatures and subsequent application of compressive axial loads to determine their post-fire behavior. Analysis includes examination of failure modes, temperature-time relationships, axial load-deformation curves, and strain and stress development in the columns. Microstructural analysis using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) is conducted to study internal morphology before and after exposure to high temperatures. Results indicate non-uniform and nonlinear distributions of maximum temperatures across cross-sections, with historical temperature affecting residual capacity more significantly with increased rubber content and decreased column size. Load-bearing capacities decrease by up to 30 % and 22 % for small and large RuCFST columns, respectively, after exposure to fire. Residual axial stiffness also declines, with reductions of nearly 55 % and 42 % for small and large columns, respectively. In contrast, ductility improves in fire-exposed specimens, with columns having a 30 % rubber replacement ratio showing the highest enhancement. A novel method for calculating post-fire residual load capacity based on the average historical maximum temperature is introduced, demonstrating high accuracy and offering a valuable tool for assessing and reinforcing RuCFST columns after fire exposure.

Finite Element Analysis of Prefabricated Semi-Rigid Concrete Beam–Column Joint with Steel Connections

This paper introduces a novel type of prefabricated semi-rigid concrete beam–column joint, aiming to examine its load-carrying capacity and seismic performance in comparison with a traditional cast-in-place joint. This study utilized the ABAQUS 2020 software to establish finite element models for both types of joints and conducted finite element analysis under low circumferential reciprocating displacement loads. When comparing the energy dissipation capacity, ductility, ultimate load-carrying capacity, stress mechanism, and damage mode, a comprehensive evaluation of the two types of joints was performed. Furthermore, this study investigated the impacts of various factors such as the axial compression ratio, concrete strength, reinforcement strength, and connector strength on the ultimate load-carrying capacity, ductility, and energy dissipation performance of the joints. Based on the findings, the newly combined joint exhibited a substantial 31.7% increase in its ultimate load-carrying capacity, along with a notable 7.23% enhancement in ductility and an improved energy dissipation capacity when compared with the cast-in-place joint. As a result, it can be concluded that the seismic performance of the new joint surpasses that of cast-in-place joints. Additionally, this study examined the impact of modifying relevant parameters on the seismic performance of the new prefabricated semi-rigid concrete beam–column joint.

Spring-like behavior of cementitious composite enabled by auxetic hyperelastic frame

A novel highly compressible auxetic cementitious composite (ACC) is developed in this work. Contrary to conventional cementitious materials, such as plain concrete and fiber reinforced concrete, the ACC shows strain-hardening behavior under uniaxial compression: the stress continuously increases with strain up to approximately 40 % strain. On one hand, in the early compression stage, the ACC exhibit highly recoverable deformability of 10 % strain under cyclic loading (20 times higher than the constituent cementitious material). In addition, the ACC shows fatigue damage until the stiffness/strength and energy dissipation plateau values are reached after 500 cycles. At 2.5 % strain amplitude, the plateau stiffness/strength is approximately 120 MPa/3 MPa, while these values are only 25 MPa/1.2 MPa at 5 % strain amplitude. In contrast, the energy dissipation plateau of the ACC is independent from the amplitude and remains at 0.05 J/cm3. On the other hand, due to the strain-hardening behavior, the ACC exhibits significantly improved energy dissipation capacity compared to both the conventional cementitious materials and the auxetic frame. This behavior is achieved by a tailored composite action: integrating cementitious mortar with 3D printed thermoplastic polyurethane (TPU) auxetic frame. A rotating-square auxetic mechanism was designed for the TPU frame for the ACC to achieve the tailored cracking behavior. The horizontal ACC cells enable large deformability by enlarging the crack width under the confinement of the auxetic frame, while the vertical cells work as stiffening phase to ensure load resistance. Owing to the outstanding mechanical properties, the ACC shows great potential to be applied in engineering practice where high compressive deformability is required, for instance yielding elements for squeezing tunnel linings.

A Review on Slit Steel Shear Walls: Development, Implementation, and Performance

Over centuries, natural phenomena have claimed a large number of lives and caused large amounts of damage. However, they were the reason for the development of knowledge and science. In engineering, there is no doubt that earthquakes were the driving force behind many design philosophies and advanced technologies. In this regard, steel plate shear walls (SPSWs) represent one of the technologies employed in both new constructions and existing structures to bolster lateral load resistance. In addition to its high elastic stiffness and strength, SPSWs often experience significant pinching during their hysteretic response unless heavily stiffened. Thus, numerous investigations have been performed recently to enhance the seismic behavior of SPSWs during severe ground shaking. The shear walls of steel plates have been studied in various ways, including stiffened and unstiffened steel plates, low yield strength steel plates, SPSWs perforated with circular holes or vertical slits, steel walls with stiffened and unstiffened openings. A stiffened SPSW panel dissipates significantly more energy than an unstiffened panel, as well as exhibiting a ductile and stable behavior. In view of its high elongation, the SPSW with low yield point has the best damping capacity. It has been demonstrated that steel walls perforated with circular holes have improved energy dissipation, in addition to allowing utilities to pass through their openings. Vertical slits on steel plate shear walls produce an exceptionally full hysteresis loop with improved performances. Slit steel walls (SSWs) can sustain a drift of over 3% while experiencing minimal hysteresis degradation. Additionally, a frame with a SSW can endure up to 6% drift without significant damage, surpassing expected ductility levels of a special moment frame, particularly with efficient slit geometry.

Energy dissipation enhancement of wire rope isolators

Wire Rope Isolators (WRIs) are critical in mitigating vibrations in various engineering applications, particularly in seismic isolation. Despite their inherent advantages, the effective damping of WRIs significantly diminishes with increased deformation amplitudes, creating the need to develop improved configurations to enhance their damping capabilities. This paper presents the results of two new experimental approaches to improve energy dissipation in WRIs: applying coatings to wire strands to modify the viscous medium between them and utilizing external confining wires to increase inter-strand frictional forces. Experimental tests were conducted on treated WRIs using sinusoidal displacements across different configurations, including tension-compression, inclined at a 45° angle, shear, and roll. The study evaluated the impact of three coating materials and introduced external confining wires made of steel, copper, aluminum, and solder on the damping properties of WRIs. Among these, steel wires demonstrated a notable increase in damping effectiveness due to their high modulus of elasticity. The results indicate that techniques like confining wires can significantly enhance damping effectiveness at various deformation levels. The findings suggest valuable directions for refining the energy absorption features of WRIs.

NSM-CFRP rods with varied embedment depths for strengthening RC T-beams in the negative moment region: Investigation on high cyclic response

Throughout its service life, structural reinforced concrete (RC) encounters cyclic loads and the load amplitude might always vary, leading to a mixed high and low-cycle failure. This research investigates the high cyclic response of RC T-beams strengthened in the negative moment region using near-surface mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) rods. The distinctive aspect lies in exploring varied embedment depths, including the introduction of half-embedded configurations as an alternative NSM technique. The study comprehensively analyzes load-carrying capacity, failure modes, energy dissipation, ductility, stiffness degradation, and strain behavior, providing insights into the effects of loading rates on structural response. Through an experimental program comparing fully-embedded (BF-D) and half-embedded (BH-D) CFRP rods with a control beam (BN-D) under high-rate cyclic loading, significant increases in ultimate load capacity (21.23% for BH-D and 30.86% for BF-D) are demonstrated despite debonding occurrences. The findings highlight a trade-off between benefits (enhanced ultimate load capacities, improved energy dissipation, and increased stiffness) and drawbacks (reduced ductility and tendencies toward brittle behavior) under high loading rates. Furthermore, a rate-dependent material formula is developed and validated, predicting the flexural strength of the negative moment region in good agreement with experimental results. Finally, this research contributes practical solutions to RC element strengthening challenges and advances understanding of NSM-CFRP-strengthened beam, emphasizing the impact of loading rates on structural response.

Design analysis and simulation of serpentine-shaped piezoelectric cantilever beam for pipeline vibration-based energy harvester

<abstract> <p>This study investigated the design and simulation of a novel serpentine-shaped piezoelectric cantilever beam to harness pipeline vibration energy. As the demand for sustainable energy sources increases, harvesting piezoelectric energy from environmental vibrations offers an attractive way to use low-power devices. The purpose of the proposed serpentine configuration is to improve energy dissipation efficiency by maximizing the piezoelectric material exposure to dynamic mechanical stress caused by pipeline vibration. The design process included finite element analysis simulations performed using COMSOL Multiphysics software to optimize the geometry of the cantilever beam. The serpentine structure was strategically designed to take advantage of the flexural vibration caused by the pipeline and its operating dynamics. Extensive simulations evaluated the piezoelectric cantilever beam, taking into account various parameters such as beam size, shape and material properties. From the analysis conducted in COMSOL Multiphysics software, the model was able to produce up to 14.38 V at the resonant frequency of 263 Hz. The simulation results show the effectiveness of the serpentine-shaped piezoelectric cantilever in generating electrical energy from the pipeline vibrations within the safe vibration region of the pipeline from 10 to 300 Hz.</p> </abstract>

Ballistic performance of bio-inspired hybrid interleaved composite structures suitable for aerospace applications

We investigate the ballistic performance of an aircraft engine containment casing demonstrator, made of composite materials with a novel bio-inspired hybrid interleaved design, under high-velocity impact (HVI) at a specific angle. Firstly, we apply a bio-inspired (BI) helicoidal design to develop a large-scale monolithic laminate concept made of carbon fibre-reinforced polymer (CFRP). Then, we hybridise the developed BI laminate concept with interleaved blocks of Zylon fibre (PBO)-reinforced polymer to develop a large-scale BI hybrid interleaved laminate concept. We then further hybridise the developed BI hybrid concept with titanium (Ti) foils (located at the impact face) so that in total we have three large-scale laminate concepts. We manufacture 6 large-scale laminates from each concept with dimensions of 225 × 225 mm and a target areal weight of 0.95 g/cm2. We then test them (perpendicularly) under HVI ranging from 150 to 300 m/s to obtain the ballistic limit and energy dissipation. Secondly, after selecting the best-performing developed laminate concept, we scale it up to develop industrial demonstrator panels with a target areal weight of 1.5 g/cm2 and dimensions of 550 × 360 mm. We test the panels under HVI at an angle of 55° with a larger and heavier projectile, to more closely represent a fan blade-off event onto the engine casing. The results of the large-scale laminate concept tests show that the BI hybrid interleaved CFRP/PBO concept outperformed the rest of the concepts with 54% and 34% improvement in energy dissipation compared to that of quasi-isotropic (QI) and the BI monolithic CFRP, respectively. Our results show that small-scale designs for HVI-resistant CFRP-based laminates cannot be simply assumed to exhibit an equivalent performance for industrial applications with thicker laminates, heavier projectiles and impacts at an angle.

Dynamic response of square sandwich panels with stagger-layered honeycomb cores under intensive near-field air blast loading

Metallic honeycomb sandwich panels have been widely used in energy dissipation due to large plastic deformation under impact/blast loading. In this paper, the dynamic response of a honeycomb sandwich panel with stagger-layered core under intensive near-field air blast loading is investigated. Comparative experiments are conducted for stagger-layered and typical honeycomb sandwich panels with the same geometrical size and mass. Numerical simulation has been undertaken based on the experiments. Numerical results coincide well with experimental results on the deformation/failure modes and center-point deflection of back face sheet. The influence of layer number as well as the geometrical parameters on the energy absorption ability of sandwich panels is clarified. Results show that stagger-layer arrangement of honeycomb core greatly improves energy dissipation capability of sandwich panels compared to typical one with the same mass. The increase of layer number and cell size benefits this effect. These findings indicates that core stagger-layer arrangement is a well choice to improve energy dissipation ability of sandwich panels under air blast loading, especially for highly intensive near-field blast loading.

Latching control: A wave energy converter inspired vibration control strategy

Latching control is a phase optimization control mechanism for improving the energy conversion efficiency of a wave energy converter (WEC). This paper, for the first time, extends the latching mechanism to vibration control to improve energy dissipation efficiency. An innovative semi-active latched mass damper (LMD) is proposed in this paper by integrating conventional tuned mass dampers (TMD) and the latching mechanism. First, the theoretical models of WEC and TMD are compared. Second, the mathematical model of an LMD installed on a single-degree-of-freedom structure is established, and three latching control strategies with different latching time instants, latching durations, unlatching time instants, and required information feedback are tested. Subsequently, the performance of the LMD is evaluated through the comparison with the detuned and optimally tuned TMDs. The characteristics of the latching control force are analyzed in terms of phase, component, energy dissipation, and damping enhancement effect. Lastly, the feasibility and effectiveness of the proposed LMD with three different latching strategies are proven. The latching control can reduce the stiffness component and increase the damping component of the control force, thereby optimizing the phase lag between the control force and the structural response. The proposed latching mechanism and strategies for vibration control can provide an innovative solution to improve the effectiveness of high-frequency detuned dampers, facilitate the design of long-period dampers, and develop adaptive semi-active dampers in the future.

Dynamics of nonlinear energy sink with a polynomial damped frequency converter

In recent years, significant strides have been made in enhancing stiffness design to improve energy dissipation efficiency. Nevertheless, there appears to be limited discourse on the concept of decomposing vibrational energy into multiple frequencies to enable concurrent dissipation. This paper introduces an innovative isolator denoted as NES-C, characterized by polynomial variable stiffness, consisting of a nonlinear energy sink and a polynomial damped frequency converter (PDFC). Tristate NES-C and quad-state NES-C configurations are realized by exploiting the nonreciprocal nature of energy propagation within the PDFC framework. Numerical simulations reveal that NES-C exhibits adaptive stiffness modulation contingent upon vibration intensity, facilitates frequency decomposition, and exhibits superior damping characteristics compared to the conventional Type I NES. Investigation into the influence of various parameters on the vibration mitigation performance of NES-C reveals that quad-state NES-C exhibits heightened robustness relative to tristate NES-C, particularly in cases involving smaller initial impulses. Additionally, the amalgamated attributes of PDFC impart enhanced programmability to NES-C design.

Cyclic performance of middle partially encased composite braces

The utilization of reinforced concrete to fill the middle section of the H-shaped steel in middle partially encased composite brace (MPECB) effectively restrains the buckling deformation of the steel plates, mitigates compression instability, and enhances the compressive stiffness and bearing capacity of the brace component. To investigate the hysteresis performance and energy dissipation capacity of MPECBs, axial hysteresis tests were conducted on four MPECBs and one comparative H-shaped steel brace. The experimental results revealed that the failure mode of MPECBs involved warping deformation of flange plate and separation from the concrete. Compared to steel brace, MPECBs exhibited significantly improved energy dissipation capacity in the early loading stage, as well as enhanced compressive capacity, while showing minor change in tensile capacity. Additionally, finite element models (FEMs) were developed, and parameter analysis was performed. The FE analysis confirmed that the variations in reinforcing bars and stirrup spacing had a minor influence on the bearing capacity of MPECBs in comparison to modifications in the cross-sectional dimensions of H-shaped steel. However, reducing the stirrup spacing can enhance the utilization of the concrete in MPECB, allowing for its performance to be more effectively harnessed. Furthermore, the formula for calculating the tensile capacity of MPECB was proposed, and the design process for MPECB was summarized based on the calculation method.

Numerical modeling of hydraulic jumps at negative steps to improve energy dissipation in stilling basins

The performance of stilling basins including a negative step was analyzed addressing its effect on the energy dissipation efficiency, dimensions and structural properties of the hydraulic jump, streambed pressures and pressure fluctuations. Six different cases were simulated, considering two possible relative heights for the step and three possible Froude numbers. The results show that the step yields to lower subcritical depths, allowing smaller basin dimensions. Nevertheless, it tends to slightly increase the roller length of the jump. Concerning the relative energy dissipation, results confirm the improvement derived from the step presence. The internal flow occurring in the jump was also analyzed, and more specifically the subzones generated upstream and downstream the impingement point. The results prove the contribution of the negative step in the stabilization of hydraulic jumps in the stilling basin. In particular, a general decrease of the streambed pressure is observed. In addition, pressure fluctuations are significantly reduced due to the negative step size influence on the hydraulic jump. Furthermore, the effectiveness of the computational fluid dynamics (CFD) techniques to simulate stilling basin flows and to adequately characterize the hydraulic jump performance was confirmed.

Experimental and numerical study of a hollow laminated viscoelastomer-filled steel tube damper for seismic application

This study proposed a hollow laminated viscoelastomer-filled steel tube damper (HLVSTD), which consists of a hollow laminated viscoelastomer, a steel tube, and two connection end plates. Three HLVSTD specimens and two solid laminated viscoelastomer-filled steel tube dampers (SLVSTD) were designed based on the fabrication processes and the laminated viscoelastomer. Cyclic loading tests were carried out to investigate their energy dissipation performance, mechanical behavior, failure mode, and cyclic loading behavior. The fabrication processes more conducive to damper energy dissipation performance was given. Then, numerical models were established in ABAQUS and verified by the experimental test. Further numerical analysis was conducted to gain insight into the working mechanism and stress distribution of the HLVSTD. Finally, the bilinear model and Bouc-Wen model were compared to better capture the hysteretic response of the damper. The results indicate that HLVSTD has stable hysteresis behavior, the maximum equivalent viscous damping ratio is 44.31%. Hollow laminated viscoelastomer and solid laminated viscoelastomer can effectively prevent steel tube buckling. Compared to the SLVSTD, the HLVSTD has a higher energy dissipation capacity and saves 16% raw materials. The steel tube of cambered surface achieved full cross-section yielding, which is beneficial to improve energy dissipation capacity and ensure reliable end connection. The calculation results of the initial stiffness and the yield force agreed well with the test results. The Bouc-Wen model is suggested for capturing the mechanical behavior of the proposed HLVSTD in the real seismic application.