Maximum Relative Displacement Research Articles

Imaging in-operando LiCoO2 nanocrystallites with Bragg coherent X-ray diffraction

Although the LiCoO2 (LCO) cathode material has been widely used in commercial lithium ion batteries (LIB) and shows high stability, LIB’s improvements have several challenges that still need to be overcome. In this paper, we have studied the in-operando structural properties of LCO within battery cells using Bragg Coherent X-ray Diffraction Imaging to identify ways to optimise the LCO batteries’ cycling. We have successfully reconstructed the X-ray scattering phase variation (a fingerprint of atomic displacement) within a ≈ (1.6 × 1.4 × 1.3) μm3 LCO nanocrystal across a charge/discharge cycle. Reconstructions indicate strained domains forming, expanding, and fragmenting near the surface of the nanocrystal during charging, with a determined maximum relative lattice displacements of 0.467 Å. While discharging, all domains replicate in reverse the effects observed from the charging states, but with a lower maximum relative lattice displacements of 0.226 Å. These findings show the inefficiency-increasing domain dynamics within LCO lattices during cycling.

Comparison of a 10-Story Tunnel Formwork Structure with Different Soil Classes According to the 2018 Earthquake Regulations

In this study, elastic design spectra were defined and compared for a 10-story tunnel formwork structure based on different soil types according to the new earthquake regulations implemented in March 2018. The tunnel formwork project used in the comparison was obtained from a static project author in Istanbul Esenyurt. Earthquake data affecting the design were selected for soil classes ZA, ZB, ZC, ZD, and ZE using coordinates 41.0114327 latitude and 28.676468 longitude from AFAD. Earthquake loads were applied in both X and Y directions to the building under consideration. The maximum relative floor displacements, overturning moments, and base shear forces in the structure were obtained using earthquake data for the ZC soil class.

Stability of osteotomy in minimally invasive hallux valgus surgery with "8" shaped bandage during gait: a finite element analysis.

Hallux valgus, a common foot deformity, often necessitates surgical intervention. This study evaluates the biomechanical alterations in patients post-surgery, focusing on the efficacy of an "8" bandage fixation system to promote optimal recovery. A three-dimensional (3D) model was constructed using CT data from a patient with hallux valgus. A quasi-static finite element analysis (FEA) was conducted in conjunction with gait analysis to evaluate the biomechanical changes at the osteotomy site under "8" shaped bandage fixation following hallux valgus surgery. The effects of the "8" shaped bandage on the stability of the osteotomy site and bone healing were investigated at three load points during the gait cycle. During the Loading Response (LR), Midstance (MSt), and Terminal stance TSt phases, the osteotomy end experienced maximum Von Mises stresses of 0.118, 1.349, and 1.485MPa, respectively. Correspondingly, the maximum principal stresses, all of which were compressive along the Z-axis, were 0.11662N, 1.39266N, and 1.46762N, respectively. Additionally, these phases showed a maximum relative total displacement of 0.848mm and a maximum relative shear displacement of 0.872mm. During the stance phase, the osteotomy end of the first metatarsal is predominantly subjected to compressive stress, with the relative displacement within the safe range to promote healing. The application of an "8" bandage for external fixation after surgery can maintain the dynamic stability of osteotomy sites post-minimally invasive hallux valgus correction during the gait cycle, thereby promoting the healing of the osteotomy ends.

Surrogate models for seismic response analysis of flexible rocking structures

AbstractSeismic design tools are based on surrogate models of the designed structure and the responses of those surrogates to earthquake ground motions. To design symmetric flexible rocking structures, a surrogate model that includes rocking and flexure is needed. In this paper, we derive the equation of motion of a flexible multi‐degree‐of‐freedom (MDOF) structure rocking on its base in modal coordinates. Then, we introduce a set of two‐degree‐of‐freedom (2DOF) surrogate models that accounts only for the first elastic vibration mode of the multimass structure and its rotation about the base pivot points. We investigate the surrogates' ability to represent the dynamics of an elastic MDOF structure that uplifts and rocks and the interaction between rocking and flexure. Therein, we detail the simplifications for the equations of motion of the 2DOF surrogate models and the adopted rocking impact model, and develop and check the sliding initiation condition. We show that the simplified 2DOF surrogate model responses compare well to experimental results. Then we assess the 2DOF surrogate model accuracy in representing the earthquake response of the MDOF model using Cloud Analysis and the coefficient of determination approach. We find that simplified 2DOF surrogate of the MDOF model is quite accurate () in estimating its maximum relative top displacement and acceptably accurate () in estimating its maximum base rotation based on a thousand randomly generated flexible rocking structure earthquake response analyses. Lastly, we discuss using the simplified 2DOF surrogate model of symmetric flexible rocking structures in preliminary seismic design, and give examples featuring a continuous elastic hollow semi‐conical chimney and an inelastic flexible MDOF structure, both with a base that may uplift.

U-shaped and V-shaped tuned liquid column dampers in vibration reduction of earthquake-induced buildings: A comparative study

The comparative study of a V-shaped tuned liquid column damper (VTLCD) and a U-shaped tuned liquid column damper (UTLCD) to minimize the dynamic response of a building under seismic loadings is investigated in this paper. A VTLCD is an improved form of a traditional UTLCD, in which the V-shaped liquid column of a VTLCD replaces the horizontal liquid column of a UTLCD. The equations of motion of an earthquake-excited MDOF building equipped with a VTLCD or UTLCD are established in this study. The operating conditions and geometric constraints of VTLCD and UTLCD are analyzed to build optimization problems. Herein, two main targets of optimization problems are considered, including the maximum relative displacement used to assess structural safety and the maximum absolute acceleration used for the purpose of human safety. Next, configurations of VTLCD and UTLCD are optimized based on data from the El Centro earthquake, with the peak ground acceleration (PGA) being 0.5 g, corresponding to each target mentioned above. Then, these configurations are tested under ten random earthquakes with different peak ground accelerations (PGAs). The present work results show that VTLCD has a more compact size compared with UTLCD. Furthermore, the vibration reduction capacity of VTLCD is higher than that of UTLCD (having the same mass as VTLCD) when the system is subjected to earthquake loads with different PGAs, especially for earthquakes with a high PGA.

Coseismic deformation and interseismic strain accumulation of the 2024 MS 7.1 Wushi earthquake in Xinjiang, China

On January 23, 2024, a magnitude 7.1 earthquake occurred in Wushi County, Aksu Prefecture, Xinjiang, China. The epicenter was located at the Maidan Fault, which is known for its left-lateral strike-slip and thrust characteristics within the Tianshan seismic zone. In this study, we used Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) observations to investigate the characteristics and mechanisms of both the coseismic and interseismic deformation. The main findings are as follows: 1) The InSAR coseismic deformation displays clear thrust characteristics, with a maximum relative displacement of ∼ 0.8 m along the line of sight, thereby indicating a thrust-type earthquake. 2) The majority of the slip during the earthquake occurred within a 60 km × 40 km area, with depths ranging from 4 to 26 km. The maximum slip of the fault was about 2.3 m, corresponding to a moment magnitude of 7.0. 3) The seismogenic faults primarily exhibit thrust-type movement characteristics during the interseismic period and possess a clearly defined locking state. The earthquake rupture depth aligns with the depth of locking during interseismic periods. 4) The seismogenic structure experienced compressive deformation in a north–south direction prior to the earthquake, with the epicenter located on the surroundings of the high-strain area, as indicated by the GNSS strain rate.

Numerical Simulation of Polymeric Strap Material Reinforced Walls Under Seismic Excitation

This paper presents a comparison between the two-dimensional finite element and experimental results of shaking table tests on six one-third-scale polymeric strap or polymeric geostrip reinforced walls performed under seismic excitation at given peak ground accelerations [Formula: see text]. The effects of initial tangent stiffness or the stiffness of polymeric strap material [Formula: see text] and the slope angle of the cohesionless backfill material [Formula: see text] on the maximum relative displacement, [Formula: see text], of the reinforced earth wall, the values of the horizontal incremental dynamic earth pressure [Formula: see text] with distributions, acceleration responses, horizontal dynamic active earth pressure coefficient [Formula: see text] and maximum dynamic tensile forces [Formula: see text] were assessed in this study. Moreover, the vertical dynamic active earth pressure coefficients [Formula: see text] and the angles of the resulting dynamic active force with horizontal [Formula: see text] were predicted from the numerical analysis. Closely matched responses between the experimental and numerical studies were attained. Data obtained from experimental and numerical studies illustrated that increasing the slope angle of the cohesionless backfill material resulted in an increase in the values of horizontal displacement in the walls, and in dynamic earth pressure and root mean square acceleration [Formula: see text]. Increasing the stiffness of the reinforcement material caused a decrease in horizontal reinforced earth wall displacement and increases in dynamic earth pressure. In addition, the conventional pseudostatic limit equilibrium methods overestimated [Formula: see text] values, whereas they underestimated [Formula: see text] values, and the recommended [Formula: see text] values by current design codes were not found to be compatible with the numerical and experimental results.

Coseismic Deformation Obtained by Various Technical Methods and Its Constraint Ability to Slip Models of Maduo Earthquake

The coseismic deformation field on both sides of the fault, especially the distribution and change characteristics of near-field deformation, not only provides important constraints for the fine inversion of the slip distribution model but also serves as an important basis for the anti-disruption defense of the cross-fault linear engineering facilities. In this paper, we used Sentinel-1 satellite data to obtain the coseismic deformation field of the Maduo earthquake by using InSAR and offset techniques. We quantitatively compared the coseismic displacement of the three types of data: InSAR, offset, and optical images. The results show that optical images and offset provided more robust near-fault (<2 km) deformation insights than InSAR, which exhibited irregular deformation patterns due to incoherence near the fault. The maximum relative displacements for InSAR and offset observations are ~2.8 m and 4 m, respectively. Then we tested various fault slip models with different data constraints, revealing that a combined inversion of GPS, InSAR, and offset data offers superior constraints on slip distribution. This integrative approach effectively captured both shallow and deep fault slip, particularly near the fault zone. The eastern branch fault model, jointly constrained by GPS, InSAR, and offset data, is the optimal coseismic slip distribution model for the Maduo earthquake, and the maximum slip is 5.55 m.

Determination of Sexual Dimorphism and Morphological Variation of Pool Barb, Puntius sophore (Cypriniformes, Cyprinidae), Using Landmark Based Geometric Morphometric Analysis

Geometric morphometrics is an efficient way to quantify biological shape variation and its covariation with other biotic or abiotic factors. The geometric information of an object is measured in a non-linear shape space after removing size, orientation, and position-related effects. This study was aimed to determine sexual dimorphism and morphological variation in body shape using landmark-based morphometrics by means of relative warp analysis. The indigenous freshwater fish Puntius sophore (Cyprinidae) was selected as the model organism for the study. Adult male and female individuals were collected during July-August 2019 (breeding season) and March–April 2019 (non-breeding season) from the ponds of Bolpur, West Bengal, India. Prior to analysis, the images were digitised using the appropriate fourteen landmarks and relative wrap analysis was performed using appropriate software. The results were then analysed, and the maximum relative displacements of adjacent landmarks were interpreted using canonical variate analysis (CVA) and principal component analysis (PCA). Significant body shape differences were found to be present in the non-breeding season and breeding season (male and female) populations of the species. Thus, geometric morphometrics can be used to understand the sexual dimorphism in natural populations of small fish species.

The Seismic Performance of Infill and Retrofitted Structural Walls under Earthquakes

To account for the effects of infill walls, the Iranian Code reduces the period of the structure. As a result, filler walls in the plane of structural frames result in significant changes in the properties they possess; therefore, the resistance, stiffness, ductility, distribution of internal forces, and other characteristics of such a frame with an empty frame differ greatly. In this research using 7 far-field earthquakes, a nonlinear time history analysis was performed on reinforced concrete frames with and without masonry infill walls. The maximum relative displacements between the stories were determined. Also, to evaluate the seismic performance of structural masonry walls, the fragility curve of unreinforced masonry walls retrofitted with FRP sheet based on different scenario under the effect of earthquake loads has been investigated by the finite element method. According to the results, the presence of infill walls reduces the number of plastic hinges as well as the maximum relative displacement between the stories. Furthermore, by increasing the number of FRP sheet layers and the reinforced area of the FRP sheet to the entire wall of an unreinforced structural wall, the seismic behaviour of the wall is more effective than other reinforcement patterns and damages the wall less.

A novel tuned liquid damper for vibration control in high-frequency structures

This paper presents a novel device as an alternative to the classical tuned liquid damper (TLD). Unlike conventional TLDs, the proposed device is capable of controlling the dynamic response of high-frequency structures and is therefore called a high-frequency tuned liquid damper (HF-TLD). In this device, the use of a series of springs capable of exerting a force on the liquid surface through a floating roof is proposed. The restoring force of these springs is added to the gravitational restoring force, increasing the natural frequency of the device. This is first demonstrated by an experimental characterization of the frequency response, showing that the HF-TLD is able to react in a frequency band starting at 2.5Hz. On the other hand, experimental results under seismic loading demonstrate that the HF-TLD is effective in reducing the maximum relative displacements of a structure having a fundamental frequency of 3 Hz. This reduction averages 20% when 5% of the structural mass is assigned to the device.

Study of the corrective effect of different fixators on pectus excavatum during Nuss procedure

Background. A funnel chest is one of the most common chest deformities, which leads not only to cosmetic problems in adolescents, but also to cardiopulmonary complications. The main method of surgical correction is the Nuss procedure. The issues of the interaction between the fixator and the sternocostal joint depending on the choice of the plate length and the location of the tunnel for the fixator inside the chest to exit it on the opposite side remain undefined. Goal: to study the maximum relative deformities and displacements that occur in the chest model depending on the correction for pectus excavatum. Materials and methods. Four schemes for the correction of a funnel chest were modeled: 1) medial delivery of the fixator, the entry point is parasternal, using one retrosternal plate with transverse stabilizing bars (a short plate); 2) lateral passage of the fixator, the point of entry and exit from the chest is at the level of the anterior axillary line, using one retrosternal plate with transverse stabilizing bars; accordingly, the sternal plate is longer, ends at the level of the midaxillary line (a long plate); 3) a double plate with transverse bars connecting the plates with the help of screws (a short bridge-type fixator) with medial delivery; 4) a double plate with transverse bars connecting the plates with the help of screws (a long bridge-type fixator) with lateral delivery. The models were loaded with a distributed force of 100 N applied to the sternum. Results. When correcting pectus excavatum with a short plate, the cartilages of the fourth ribs turn out to be the most deformed — 3.3 %. In the cartilages of the ribs located above, deformities are in the range from 2.7 to 3.1 %. The use of a long plate decreases the relative deformities of the cartilage on almost all ribs. The scheme of correction using a short bridge-type fixator allows significantly reducing the deformities of all costal cartilages. The maximum is observed in the cartilage of the second and first ribs — 2.0 and 1.8 %, respectively. Replacing a short bridge-type fixator with a long one leads to the fact that the cartilages of the upper ribs remain deformed — 1.8 %, and a deformity gradually decreases to 1.0 % in the cartilages of the fourth ribs. The maximum movements in all schemes for pectus excavatum correction fall on the xiphoid process. The maximum displacement of 6.0 mm in the xiphoid process occurs when using a short plate. Replacing the plate with a long one decreases the displacement of the xiphoid process to 5.0 mm. When using a bridge-type fixator, the displacement of the xiphoid process is determined at the marks of 4 and 3 mm for a short and long fixator, respectively. Conclusions. All the investigated indicators testify to the advantages of a double bridge-type fixator. The medial passage of the fixator (short plates) has greater corrective forces on the anterior chest wall during elevation, which should be considered when choosing a correction technique. However, the lateral application of the fixator distributes the corrective effect by area, which can be important in preventing erosion of the tissues of the inner chest wall, the need for extended elevation of the depression in flat-concave forms of pectus excavatum, and the reduction of pain syndrome in the postoperative period.

Seismic mitigation of continuous girder bridges equipped with U-shaped stainless steel dampers under near-fault earthquake excitations

Bridges that are close to seismic faults may suffer from severe damages under earthquake excitations. To enhance the seismic performance of continuous girder bridges, this paper presents a combined energy dissipation system (CEDS), incorporating isolation bearings and U-shaped stainless steel dampers. The U-shaped stainless steel dampers are equipped between every two bearings, and the top and bottom ends of dampers are fully fixed with the girders and the bent caps, respectively. Considering the strained conditions under seismic loadings, the mechanical property of U-shaped stainless steel dampers is numerically investigated with the loading directions of 0, 45, and 90 degrees. The hysteretic behavior of U-shaped stainless steel elements affected by the geometric parameters, i.e., the width, the thickness, the radius of arc segment, and the length of straight section, are further investigated. After that, a continuous girder bridge is adopted to verify the feasibility of the combined energy dissipation system, and two groups of U-shaped stainless steel dampers are designed for continuous piers and transition piers, respectively. The results turn out that the U-shaped stainless steel element shows excellent energy dissipation capacity. The maximum relative displacement between the girders and bent caps of piers can be effectively reduced by adopting the CEDS, which prevents the girders falling from supporting seats, and it is more effective in the longitudinal direction of bridges with the seismic reduction rate of 20–70%. Though the installation of U-shaped stainless steel dampers enhances the constrict of the top of piers, the maximum drift ratio increases in an acceptable range.

Research and practice on a new flexible quasi-static test platform for railway vehicle anti-collision posts

ABSTRACT Aming at the shortcomings of the existing crushing test platform for rail vehicles, a design strategy was proposed and a new flexible quasi-static test platform was developed. The elastic-plastic performance of the anti-collision posts of a typical subway vehicle was experimentally investigated based on the developed test platform. The obtained results show that the proposed design strategy is correct and feasible for guiding the design of the flexible quasi-static test platform. The developed new test platform equips with the functions of elastic-plastic tests for anti-collision posts and has good stability with maximum relative displacement of 1.52 mm and 2.22 mm in central collision/corner post elastic-plastic test. The central collision/corner post of the typical subway vehicle has good elastic-plastic performance and could meet the requirements of ASME RT-2-2014. This study provides practical references for the development of a quasi-static crushing test platform for rail vehicle-end structures.

A simplified analysis method for estimating the peak responses of recentering structures with viscous damping systems

AbstractRecentering structure with a viscous damping system is an emerging structural system with remarkable seismic resilience. This system can exhibit sufficient energy‐dissipating capacity during a major earthquake and eliminate the residual deformation through recentering mechanism afterward. However, the seismic response of the considered system is still confusing due to its complex dynamic behavior. Thus, it is hard to estimate the peak responses of the system during a major earthquake. This study proposes a simplified analysis method for estimating the peak responses of recentering structures with viscous damping systems based on an equivalent two‐stage substitute model. Considering the considerable strain energy of recentering structures during vibrations, this method proposes to employ effective stiffness based on the equal‐energy principle in an equivalent two‐stage substitute model. Based on this concept, corresponding equations are derived for capturing the peak transient responses of the considered system. Results of response history analysis validate that the proposed method can reasonably estimate maximum relative displacement, relative velocity, and absolute acceleration. Given its satisfactory accuracy, this method is promising while conducting seismic design of recentering structures with viscous damping systems.

Design and implementation of a measuring system used to evaluate the mechanical performance of the bone fixators

PurposeThis measuring system is designed to effectively simulate the mechanical reliability of the operated bone fixators. It can be used to pre-evaluate the mechanical performance of the operated fixator on the patients, including the static mechanical properties and fatigue properties when the patient walks after the operation.Design/methodology/approachIt is mainly composed of a one-dimensional platform, a force sensor, a high measuring precision displacement sensor and a servo motor. Loading (which is used to simulate the loading status of the fixators after the operation) of the system is realized by the rotation of the servo motor. It can be read by a high precision force sensor. The relative displacement of the broken bone is obtained by a high precision laser displacement sensor. Corresponding theoretical analysis is also carried out.FindingsCalibrated results of the system indicate that the output voltage and the measured force of the force sensors possess an excellent linear relationship, and the calculated nonlinear error is just 0.0002%. The maximum relative displacement between the operated broken bone under 700 N axial force is about 1 mm. Fatigue test under 550 N loading for 85,000 cycles also indicates the feasibility of the design.Originality/valueThis device is successfully designed and fabricated to pre-evaluate the mechanical performance of the bone fixators. High precision force sensor and displacement sensor are used to successfully increase the measuring ability of the system. This will offer some help to pertinent researchers.

Stress-strain state of composite multi-layer stay rope considering breakages in reinforcing elements and nonlinear distribution of mechanical properties

Purpose. Formulation of an algorithm for considering the influence of continuity breakages in fiber reinforcing elements on stay rope strength. Methods. Construction and analytical solution of a mathematical model of interaction for parallel fiber reinforcingelements connected through elastic material, in a case of continuity breakage of individual elements in reinforcement. Findings. A static strength calculation algorithm for a multi-layer stay rope with breakages in one cross-section of reinforcing elements is developed. It is established that a continuity breakage of an arbitrary element of a stay rope reinforcement leads to a significant change in internal loads of only the adjacent reinforcing elements and is practically independent of a nonlinear deformation character of cable components. Greater loads on reinforcing elements occur in a case of breakage of a corner reinforcing element, and the smallest loads – in a case of breakage of a central one.It is established that a number of rows of reinforcing elements in a stay rope and location of a damaged reinforcing element do not significantly affect displacement of cable end and do not affect distribution of loads among reinforcing elements in a damaged cross-section. Displacements depend on a ratio of shear modulus of elastic material and Young's modulus of reinforcing elements; the ratio is varied along cable length. It is established that a reinforcing element location with discontinuity does not significantly affect the character of relative growth of stay rope deformations in a case of nonlinear character of elastic shell deformation. Deformation nonlinearity of cable components does not affect redistribution of forces in stay rope with damaged reinforcing elements. Maximum relative displacements of reinforcing elements and the resulting maximum shear angles of material located between reinforcing elements are smaller than a value of the assumed nonlinearity coefficient. Characters of displacements of reinforcing elements are qualitatively similar. Scientific novelty. An analytical algorithm is developed for calculating a stress-strain state of a multilayer stay rope considering its design, nonlinearly of mechanical properties of its components distributed along the cable with damage to an arbitrary group of reinforcing elements in one cross-section. Practical significance. The developed algorithm allows considering a nonlinear deformation character of stay rope components on its stress state in a case of breakages in an arbitrary number of reinforcing elements arbitrarily located in a stay rope with a continuity breakage in one cross-section. The algorithm can be applied to determine a stress-stress state of a stay rope with breakage in a cross-section infinitely distant from rope ends. The algorithm allows considering the influence of breakages in reinforcing elements on rope strength, which increases rope reliability in a structure.

Experimental Analysis of Watertightness Performance of Interfaces between Masonry and Steel Structures Subjected to Accelerated Aging

Steel buildings often experience failure at the interfaces between their vertical exterior enclosure systems (VEESs) and structural elements. This phenomenon generates various pathological manifestations in steel buildings, resulting in the precocious decay of the structure and the diminishment of its service life. The treatment of these interfaces is essential for ensuring their proper performance and watertightness, and to protect the durability of the steel structure. This paper proposes a method for treating common interface joints between masonry and steel structures with the application of an EPDM (ethylene propylene diene monomer) elastomer membrane. The main goal of this building technique is to ensure the durability and watertightness of the interface’s joints when they are subjected to aging triggered by heat exposure and thermal shock. The experimental models tested consisted of a steel frame and a conventional masonry vertical enclosure system with ceramic blocks plastered with cement mortar. The models were subjected to ten cycles of heat exposure and thermal shock for the purpose of simulating accelerated aging, followed by a watertightness experiment that simulated the action of both rain and wind pressure. The interfaces between masonry and the steel structure proposed in this study allowed adequate differential movements between the parts, without damage to joints and masonry. Only small cracks were observed in the outer test region of all of the interfaces tested. In the regions of the joints treated with the EPDM membrane, no alterations were visible to the naked eye. During the cycles of the heat exposure and thermal shock test, the maximum relative horizontal displacements observed in the joints were 0.743 mm for vertical joints and 0.230 mm for horizontal joints, indicating the accurate reproduction of the behavior expected from an untied interface. The results obtained in the previously mentioned watertightness test showed that no humidity stains were found on the inner face of any of the specimens, even after the continuous application of a pneumatic pressure of 400 Pa for eight hours. Therefore, the results indicated satisfactory performance in terms of durability and watertightness in all evaluated cases, indicating that the application of an EPDM membrane can be effective in preventing water leaks in the interfaces between masonry and steel elements, thus contributing to ensuring the steel structure’s durability.

Nonlinear modelling for structural damage assessments of reinforced and coated longitudinally coupled slab tracks

Interface debonding and slab end arching of the anchor-reinforced and coated longitudinally continuous slab tracks have been unprecedentedly investigated in this study. A novel finite element model of the longitudinally continuous slab track has been established by incorporating a tailored cohesive zone model to mimic nonlinear constitutive relationships. The new model has been validated by over 100 field measurement data. This paper is the first to assess the influences of the dual applications of anchors and coatings on the damages of the longitudinally continuous slab tracks, and to identify the effectiveness of different track maintenance methods in mitigating track damages. This study exhibits new findings: (1) In comparison with traditional tracks, the tracks constructed with anchors, coatings, and the combined use of both can reduce the maximum vertical relative displacement between the concrete slab and the mortar layer by 75%, 40%, and 85% respectively. (2) In comparison with 4 anchors, 6 or more anchors in each slab can help to prevent inner interface defects. However, an increase in anchor quantity above 6 anchors does not have a significant impact on the interface damage mitigation. (3) For the anchor-reinforced tracks, the organic coating outweighs the inorganic coating to improve interface damage mitigation.

Performance of tuned particle impact damper and tuned mass damper seismic control systems considering mainshock-aftershock

Generally, seismic structural design codes have been defined in accordance with a single shock or mainshock. Also, seismic control systems are usually designed and studied based on single events. considering that ground motions in seismic zones are not a single event and usually several remarkable aftershocks accompany a mainshock, the seismic behavior of controlled structures and performance of the seismic control systems are not clear under real seismic sequences. The current study investigates the seismic behavior of a 3D seismic controlled steel structure and the performance of the seismic control systems under seven real mainshock-aftershocks using non-linear implicit analysis. A tuned particle impact damper (TPID) was used that combines a passive TMD and a particle impact damper (PID) to increase efficiency and performance by working out-of-phase with the main structure and increasing energy absorption. The efficiency of the TPID and TMD seismic control systems was studied by comparing the seismic behavior of the TPID-controlled, TMD-controlled and uncontrolled structures under seismic sequences. The parameters of the frequency response, top-story maximum relative displacement, structural damage (residual displacement) and inter-story drift ratio were studied. Additionally, by considering the structural system as a closed adiabatic isolated system with ground motion energy as the only system input energy, the absorbed kinetic and potential (inelastic dissipated energy) energies in seismic control systems were calculated and compared. Results showed that both TPID and TMD seismic control systems are efficient under seismic sequences. But the TPID system is a more efficient seismic control system compared to the TMD system. Also, this case showed that because of the high performance of the TPID and TMD seismic controlled systems, unlike the moment-resisting uncontrolled structures, there is no need to consider seismic sequences in the design of TPID- and TMD-controlled structures.