Reduction Of Displacement Research Articles

Controlling base movement of MSE walls using recycled plastic pins

Sliding failure of Mechanically Stabilized Earth (MSE) retaining walls is a common problem when the shearing resistance developed between the wall base and foundation soil is insufficient. Highway MSE wall base failures can cause significant maintenance, repair, and cost implications for the state department of transportation. Controlling base movement using Recycled Plastic Pins (RPP) can be a potentially cost-effective and sustainable solution. RPPs are primarily manufactured from recycled plastics and have been successfully used for stabilizing shallow slope failures. The objective of the current study is to demonstrate the effectiveness of using RPPs for increasing the sliding resistance of an MSE wall. Four field test sections were constructed, out of which three were reinforced with different combinations of RPP sizes and spacings, while one was left unreinforced as a control section. Regular performance monitoring of the test sections was conducted using vertical inclinometers along with earth pressure plates. More than a year of results indicated a 75–88% reduction in lateral displacement of the reinforced wall base when compared with the control section. Additionally, the lateral earth pressure on the wall facing was decreased by 55–72% in the reinforced sections compared to the control section.

Seismic pounding mitigation of asymmetric-plan buildings by using viscoelastic links

Connection of adjacent buildings with viscoelastic links (VE) has been proved to be an efficient method for preventing or at least attenuating the structural collisions during earthquakes. The efficiency of this pounding mitigation method was extensively studied in the past, mostly based on assuming a two-dimensional problem without addressing the effects of plan irregularities. In this paper, the effect of VE links between adjacent asymmetric-plan buildings is studied in detail. First, two adjacent one-story models with various structural as well as link-wise dynamic parameters are analyzed under white-noise input. The inelastic behavior of the adjacent buildings is also taken into account. The response of two adjacent 5 story buildings is then evaluated under the actual earthquake record to validate the findings obtained under white-noise analysis. Results demonstrate that not only plan asymmetries do not necessarily lead to higher responses compared to the symmetric adjacent buildings, but the linked-to-unlinked response ratio would be efficiently reduced by providing supplemental damping in the link elements. As the link stiffness decreases, the reduction in the relative displacement of the buildings due to supplemental damping could be up to 80% and even more. Results also reveal that it is possible to obtain a dominant modal damping ratio up to twice than that in symmetric plans for certain plan eccentricities.

Computational modelling of dynamic soil-structure interaction in shear wall buildings with basements in medium stiffness sandy soils using a subdomain spectral element approach calibrated by micro-vibrations

This paper presents a strategy for modelling dynamic soil-structure interaction (DSSI) using the spectral element method (SEM) with a Discontinuous Galerkin approach, calibrated by micro-vibrations. The proposed methodology allows not only to adjust the vibration frequencies of the structure but also the observed vibration modes. First, models of two structural shear wall buildings with basements in medium dense sandy soils are developed to estimate empirical modal characteristics and calibrate the structural subdomain and low-strain site properties. Convenient 3D arrays of multiple seismic sensors are used to obtain the environmental vibrations measurements. Afterwards, an optimization process is conducted to calibrate volumetric models of structures. This optimization is performed by preserving the most relevant modal frequencies and shapes to achieve an equivalent dynamic response. Finally, structural models are placed into a neighbouring soil model (soil subdomain), approximating nonlinear soil behaviour by an equivalent linear strategy. Using this complete soil-structure interaction model, relevant engineering performance parameters are assessed via simulations of buildings subjected to a plane wave excitation. The results show the significant effect DSSI have in shear-wall buildings with basements and the importance of considering the flexibility of the foundation in the interpretation of the results. In general, results indicate that DSSI effects are strongly dependent on the input frequency content, which might cause a reduction of the inter-story drifts. Furthermore, a significant period lengthening of the studied structures up to 47% is found, as well as a considerable decrease in story shear up to 220% and a maximum lateral roof displacement reduction of 34% when compared against fixed base referential responses.

An analytical optimization study on the core-outrigger system for efficient design of tall buildings under static lateral loads

The location and number of outriggers in a core-outrigger lateral resisting system have a major influence on the tall buildings' performance and the design's cost efficiency. In this study, an analytical procedure was performed to produce a general equation of the top lateral displacement of a core-outrigger system (up to four outriggers) due to various static lateral loading distribution forms (uniform, triangular and parabolic). Moreover, the optimal positions of outriggers that produce the maximum top displacement reduction are determined in this research. On the other hand, this work proposes the maximum height of a tall building corresponding to displacement limit criteria, number of the outrigger and outrigger positions. For practical use, this study offers curves for use at the preliminary design stage to allocate the top displacement and the number of the required outriggers in terms of the building height and a proposed rigidity factor which shows to have a great influence on a core-outrigger system in a tall building.

Higher-order Lamb waves with quasi-zero surface displacement components on a GaAs piezoelectric plate

Higher-order Lamb waves with quasi-zero surface displacement components are reported on (100)-cut GaAs propagating along the <110> direction where the total displacement at the surface of the plate is less than 10% of the maximum total displacement. The dispersion curves and the displacement component profiles show the reduction of total displacement at the surface of the plate starting when the phase velocities of the higher-order modes are crossing the shear bulk acoustic wave velocity to the value as low as 5%. Due to the concentration of acoustic energy inside the plate, the reported quasi-zero plate acoustic waves (QZ-PAW) further reduce the radiation of acoustic energy when the plate surface is in contact with liquid. The experimental results validate the occurrence of QZ-PAW with a reduction of viscous damping insertion loss compared to previously reported quasi-longitudinal Lamb waves. The results demonstrate the potential QZ-PAW mode for emerging applications such as dual-mode PAW sensors, PAW devices with integrated sensor and actuator, thin-film and ultra-high frequency PAW sensors in highly viscous liquid media.

COMPARATIVE STUDY OF SHIP RESISTANCE ON MONOHULL AND CATAMARAN MODEL OF 15 GT FISHING BOAT

On small boats, hull design that provides a smaller value of ship resistance is usually preferred. Therefore, it is necessary to consider the selection of the hull shape provides optimum resistance. The used of multihull known as alternative to reduce ship resistance. This study investigated comparison of the resistance of fishing vessels ±15 GT. The analysis will be carried out on 4 ship hull models, U-shaped and V-shaped monohull, streamlined and asymmetrical hull catamaran. Assuming the main dimension is constant, the differences in displacement, WSA, frictional resistance and total resistance were analysed. Furthermore, a comparative analysis was carried out at several speed variations. Based on the study, it is known that the catamaran hull model provides less resistance than the monohull. The asymmetric catamaran provides the smallest ship resistance, but the reduction of ship resistance is accompanied by significant reduction in displacement. While the U-shaped monohull model shows the opposite.

Performance analysis of constant current heated antagonistic shape memory alloy actuator using a differential resistance measurement technique

This work presents the development of a precise, constant current heating mechanism for an antagonistic shape memory alloy (SMA) actuator. The actuator was developed using a pair of SMA wires arranged in an antagonistic configuration. SMA possesses a unique phase-dependent, resistance variation property which is called self-sensing. This phenomenon is observed during thermal phase transition. A constant heating current was employed to measure combined differential resistance (ΔR) which provides insignificant hysteresis and linear relationship with displacement. ΔR eventually helps to determine the present position of the actuator for sensorless feedback control. The aim is to remove additional external sensors, reducing actuator footprint and interface complexity using the proposed study. The performance analysis of the actuator was evaluated under constant current by the tracking trajectory of reference signals. The tracking results confirmed the improvement in operating bandwidth by a reduction in displacement. The heating module mainly consisted of a low pass filter, operational amplifier with a current sense feedback mechanism that regulates the heating current in proportion to PWM signals. The result shows a significant 21% variation in the observed value of ΔR (1.200–0.254 Ω) between the major–minor loops. The study confirms linearity and maintains similarity by highest correlation 0.9508 during open-loop, which further improves to 0.9891 in close feedback reference tracking with an error band ±0.05 mm.

Dynamic performance of soft-storey structures with gap elements at beam-column joints

Soft-storey structures are more susceptible to failure for seismic vibrations, which is well-known to the world. But, in multi-storey apartments, it is a practice to provide a parking place at the ground storey, inducing soft-storey effects. In the present study, an effort is made to reduce the soft-storey effect on the structure's dynamic performance by introducing an arrangement of gap elements at beam-column joints. To that context, a numerical assessment is carried out to check the performance of the RC structure. The gap element is modelled as a spring either in a beam or in a column or both.The research has been performed in two parts; the first part of the analysis is focused on optimizing the gap element pattern. Diagonal compressive struts replace the infill walls, and the ground storey is modelled as an open ground storey without infill walls, which is considered a soft-storey. From the first part, an optimal gap element pattern from five different arbitrary patterns is obtained from the results of linear dynamic response spectrum analysis, depending upon the comparison of various seismic parameters. The second part of the analysis involves checking the effect of the gap element's optimized pattern for four levels of structures with vertically varied aspect ratios. Response spectrum analysis is performed, and a study is conducted to compare the seismic parameters for the four levels. The models with gap elements have shown an apparent reduction in storey displacements, inter-storey drift ratios, over-turning moments, and increment in storey stiffness when compared to the conventional models, thus exhibiting constructive outcomes.

Effect of Hydrogel Rectal Spacer on Intrafraction Prostate Motion During Radiotherapy of Prostate Cancer Patients

<h3>Purpose/Objective(s)</h3> Insertion of hydrogel rectal spacer may potentially stabilize the prostate by reducing intrafraction prostate motion. The purpose of this study was to investigate the effect of hydrogel rectal spacer on intrafraction prostate motion. <h3>Materials/Methods</h3> A retrospective review was conducted of prostate cancer patients treated from September 2015 to November 2018 who underwent external beam radiation therapy (EBRT) with intrafraction motion management using implanted electromagnetic transponders. There were 87 patients (73%) who received conventional fractionation, 16 (13%) moderate hypofractionation, 10 (8%) stereotactic body radiation therapy (SBRT) and 7 (6%) EBRT plus brachytherapy. The threshold for gating was set at 4 mm for conventional fractionation, 3 mm for moderate hypofractionation, and 2 mm for SBRT. Maximum prostate motion was measured by displacement outside of the gating threshold during treatment per fraction. Independent samples t-test was performed to compare prostate motion with and without hydrogel rectal spacer. <h3>Results</h3> We identified 120 patients with a total of 4447 fractions eligible for analysis. 49 patients (41%) were treated with hydrogel spacer and 71 (59%) without hydrogel rectal spacer. Mean displacement of prostate outside of the gating threshold was 4.9 mm (range, 2.1 – 12.8) and 5.6 mm (4.1 – 14.6) anteriorly, 2.6 mm (1.1 – 7.6) and 19.4 mm (4.0 – 25.8) posteriorly, 4.7 mm (2.2 – 8.3) and 12.5 mm (4.0 – 20.8) superiorly, 3.1 mm (1.1 – 8.2) and 14.2 mm (3.7 – 22.7) inferiorly, 4.3 mm (3.0 -12.4) and 4.5 mm (4.2 -7.6) left and 3.1 mm (3.1 – 4.1) and 4.3 mm (4.1 – 11.6) right for patients treated with and without hydrogel rectal spacer, respectively. There was a significant reduction of mean displacement in the posterior (2.6 mm vs. 19.4 mm, <i>P</i> = 0.04) and inferior direction (3.1 mm vs. 14.2 mm, <i>P</i> = 0.04) in patients with hydrogel rectal spacer compared to those without hydrogel rectal spacer during "beam on time". <h3>Conclusion</h3> The use of hydrogel rectal spacer can mitigate intrafraction prostate motion in posterior and inferior directions, suggesting a potential dosimetric advantage with the use of hydrogel rectal spacer. However, longer follow-up may be needed to confirm whether this translates into significant clinical benefit outweighing potential risk.

Global Position Analysis during Official Elite Female Beach Volleyball Competition: A Pilot Study

The aim of this study was to quantify the physical demands of female beach volleyball competition with reference to player position, set, and match outcome. Twelve professional players were equipped with a 10 Hz GPS device (Minimax S4, Catapult Sports, Australia). Data collection occurred over 30 official matches, with a total of 50 sets. GPS output variables were related to position (e.g., Defenders and Blockers). Differences between players’ positions were found in Peak Player Load, the distance covered at different intensities, and acceleration and deceleration. Variations during the match were more pronounced for Defenders than for Blockers, with the former increasing the intensity of acceleration and deceleration, and decreasing the velocity of displacements and lower jumps. For Blockers, main variations occurred between the first and second set, with a reduction in velocity displacements and an increase in the intensity of jumps. Defender variables that contributed to victory were high deceleration, velocity, acceleration, and Peak Player Load. The characteristics of Blockers that contributed to victory were maximum velocity and high jumps. Female beach volleyball players seem to have different physiological requirements according to their position. The analysis of these variations throughout the game suggests that a specific player’s position output may be determined by proper and/or opponent tactical schemes.

Simulation of nano elastic polymer chain displacement under pressure gradient/electroosmotic flow with the target of less dispersion of transition

Since non-scattering transfer of polymer chain in nanochannel is one of the important issue in biology, in this research, the behavior study of a long polymer chain in the nanofluid in two modes of free motion and restricted motion (fixed two ends) under two different forces including constant force (pressure gradient (PG)) and variable force (electroosmotic force (EOF)) has been investigated using dissipative particle dynamics (DPD) method. Our aim is that displacement of polymer chain carries out with less dispersion. Initially, without the presence of polymer, the results have been validated in a nanochannel by analytical results for both cases (PG, EOF) with an error of less than 10%. Then, assuming 50 beads of polymer chain, the polymer chain motion in free motion and fixed two ends modes has been examined by different spring coefficients between beads and different forces including PG (0.01 DPD unite) and EOF (zeta potential = − 25 mV, electric field = 250 V/mm, kh parameter = 8). The results show that in free polymer motion-PG mode, by increasing 1.6 times of spring coefficient of the polymer, a 40% reduction in transition of polymer is achieved, which high dispersion of polymer chain is resulted for this mode. In the EOF, the spring coefficient has a slight effect on transferring of polymer and also, EOF moves the polymer chain with extremely low polymer chain scattering. Also, for fixed two ends-PG mode, a 36% reduction in displacement is achieved and in the same way, in EOF almost 39% declining in displacement is resulted by enhancing the spring coefficients. The results have developed to 25 and 100 beads which less dispersion of polymer chain transfer for free polymer chain-EOF is reported again for both circumstances and for restricted polymer chain state in two PG and EOF modes, less differences are reported for two cases. The results show that the EOF has the benefit of low dispersion for free polymer chain transfer, also, almost equal displacement for restricted polymer chain mode is observed for both cases.

Finite Analysis of Support Time for Tunnels in Strain-softening Rock Mass in Consideration of Fictitious Support Pressure

This study considers that the support time is quantitatively determined by the production limit of the displacement reduction factor and the support force under the extrusion conditions of the strain-softening rock mass. Therefore, the two indicators of the downlines under the support time are the displacement reduction factor of the support force and the yield limit. Based on the solution of the fictitious pressure proposed in an existing paper, the finite difference method is adopted to investigate the variations of the support force and displacement reduction factor versus the delayed distance considering different support types, initial stresses, and post-peak behaviours. The results show that on the one hand, the delay distance is suggested within 1 R0 in most tunnel cases; on the other hand, the factors have greater impact on rock-support interactions are rock mass and in-situ stress. Relatively contrast, softening and expansion behavior was not significant enough. Furthermore, it is also very important in composite support systems to assess the proportion of loads shared with the weakest part.

Age-related changes of lens stiffness in wild-type and Cx46 knockout mice

We have investigated how connexin 46 (Cx46) regulates lens stiffness by studying different Cx46 knockout (Cx46KO) mice. A modified muscle lever system was used to determine the lens stiffness of wild-type (WT) and Cx46KO mice at the C57BL/6J (B6) and the 129SvJae (129) strain backgrounds according to total lens displacement at the point of maximum force when fresh lenses were compressed with a maximum of 2 mN of force. In comparison to B6-WT controls, young and old B6-Cx46KO lenses showed 23% and 28% reductions in lens displacement, respectively. Comparing to 129-WT controls, old 129-Cx46KO lenses showed 50% reduction in the lens displacement while young 129-Cx46KO lenses displayed similar displacement. Old B6-Cx46KO and old 129-Cx46KO lenses showed almost identical lens displacement, 128 μm versus 127 μm. Morphological data revealed unique changes of peripheral fiber cell shapes in young B6-WT lenses but not in young B6-Cx46KO, 129-WT and 129-Cx46KO lenses. This work reveals Cx46 deletion increases the lens stiffness in both young and old mice at B6 strain background but only in old mice at 129 strain background which contains intermediate filament CP49 gene deletion. Cx46 impairment increases old mouse lens stiffness and may contribute to the development of presbyopia.

A review on permanent implants for prostate brachytherapy with comparison between stranded and loose seeds.

A systematic literature review to validate the conclusions with regard to stranded seeds versus loose seeds. Published data for this review were identified by searching the PubMed databases. PD90, PV100, PV150, UD30, and RV100 acquired during the perioperative period and the postoperative period were analyzed by meta-analysis. Based on these studies, in addition to the reduction of migration and displacement, stranded seeds had some dosimetric advantages, especially in dose homogeneity and coverage of target area due to its connection characteristics. We also noticed implanted seeds usually excessive both in stranded seeds group and loose seed group. Intraoperatively built custom links will prolong operation time, with the proficiency of technology, the prolonged time gradually decreases.

Dynamic response assessment of an offshore jacket platform with semi-active fuzzy-based controller: A case study

The present study investigates the dynamic responses of offshore jacket platforms using a passive and semi-active tuned mass damper (TMD, SATMD), where the control action is achieved by a fuzzy logic controller (FLC) under environmental (i.e., wind, water waves, sea currents) and seismic loadings. Since the studied structure failed to meet recent codes requirements adequately, the suppressing effect of a SATMD is considered as a way to retrofit structural performances under hydrodynamic loadings. After extraction of the dynamic properties of the jacket-type structure, simulations of an installation system with and without a TMD have been performed, and the effectiveness of TMD is quantified.In order to exploit the potential of the structure to overcome all types of excitations, the SATMD comes complete with a fuzzy-algorithm-controller, acknowledging that the use of a passive TMD is only a preliminary attempt to reduce the structure's dynamic responses. Comparison of the results indicates a significant response value reduction in acceleration, base shear, overturning moment, velocity and lateral displacement of a case study of steel jacket platforms.

Fixation lombo-sacrée avec maintien d’un fixateur externe en décubitus latéral pour le traitement des fractures pelviennes instables

Anterior external fixation (EF), as the primary treatment for unstable pelvic fractures, is performed with patients in the supine position. In most cases, however, definitive surgery for posterior fixation is performed first in the prone position without EF. We report the case of a patient with unilateral and vertically unstable pelvic fracture whom we had treated with minimally invasive spinopelvic fixation, with retention of the anterior EF in a lateral position. Reduction of the residual displacement was performed with percutaneous spinal instrumentation, and acceptable reduction was achieved. At the 13-month follow-up, the functional outcome, calculated using the Majeed Score, was 87 points. The plain radiograph showed good bone union, except for the right superior pubic ramus. The radiological outcome, measured using the Matta rating, was excellent. Thus, retaining the EF facilitates safe and accurate reduction without major surgical complications and may offer surgeons an additional management option for such fractures.

Seismic control of cable-stayed bridges with bearing uplift using tie-down rope-spring device

ABSTRACT A tie-down rope-spring device (TRD) is proposed to control bearing uplift of cable-stayed bridges under a design earthquake. The mechanical properties of TRD depict a favorable interaction between its horizontal and vertical directions, i.e. the horizontal displacement results in tie-down force. A procedure is proposed to design the TRD for a case cable-stayed bridge under longitudinal seismic excitations. Analytical results validate the effectiveness of TRDs in restricting bearing uplift of the case bridge, showing a large reduction of uplift displacement at deck end, pounding force at bearings and shear force of the crossbeam.

Simple connections retrofitted by dampers and bracket-tendon system against progressive collapse

ABSTRACT High potential for progressive collapse is one of the main weaknesses of structural frames with simple connections. Therefore, strengthening of this structural system is a necessity for both existing and new structures. In this study, the current simple connection with double web angles and one seat angle is modified by using dampers and a bracket-tendon system. The proposed methods of improvement increase the connection performance against progressive collapse due to column removal significantly, while they hardly change the stiffness and rigidity of the connections. Finite element software, ABAQUS, is used for this assessment. Vertical displacement of the modified connections after removal of the column is compared as an evaluation criterion. The results indicate that the bracket-tendon system is quite effective in reduction of vertical displacement of the connection up to 46%, and applying of dampers enhances the performance of the connections notably from 20% to 58%.

Numerical investigation of dual-row batter pile wall in deep excavation

To evaluate the performance of dual-row batter pile wall (DRBPW) in deep excavations, a three-dimensional numerical model was established. The plastic hardening (PH) constitutive model in FLAC3D was adopted, considering the hardening property of the soil. A series of parametric study was conducted to investigate the effect of different factors. By analyzing the maximum lateral displacement, the pile shaft deflection and bending moment of both the leading and trailing row, the effect of inclination angle, pile diameter, penetration depth, and row spacing on the behavior of DRBPW was determined. The following conclusions could be drawn: (1) The bearing capacity of DRBPW is quite larger than that of the dual-row vertical pile wall (DRVPW). With the increase of inclination angle, a substantial reduction of lateral displacement could be observed. However, the beneficial role of batter pile is almost negligible when the inclination angle is not larger than 5°. The recommended inclination degree of the batter pile is 10° to 15°. (2) The maximum displacement of the leading and trailing rows lies at a distance below the pile cap, while the maximum bending moment is located at a small distance below the dredging line. The maximum bending moment of the leading pile is approximately twice that of the trailing one, thereby indicating that the leading pile bear more lateral earth pressure than the trailing pile. (3) The pile diameter, penetration depth and row spacing should be maintained in a suitable range; otherwise, the DRBPW may fail earlier than expected. The slender ratios is recommend to be set not larger than 30. The penetration ratio should not be less than 0.22. The optimal row spacing for the DRBPW is four times the diameter.

Performance of Reinforced Concrete Shear Wall Equipped with an Innovative Hybrid Damper

The performance of simultaneous application of steel cantilever damper and Shape Memory Alloy (SMA) rods in the reinforced concrete (RC) shear wall was investigated. In this regard, the critical numerical validation of three full-scale experimental models were distinctly performed and the results were analyzed. Various aspects of numerical modelling, including material modelling assumptions, behavioural models, elements, and solution methods were compared with experimental results. Specimens considering SMA rods as well as steel cantilever damper were numerically investigated. The results illustrated that with increasing the SMA rod angle, the maximum force was decreased, and the residual displacement and dissipated energy was improved. Also, comparing the specimen results without the SMA rods and the specimen with the SMA rods showed that despite the positive effect of the SMA rods, which leads to an increase in maximum force and reduction of residual displacement, the dissipated energy was decreased