Lateral Drift Research Articles

Surface conversion of the dynamics of bacteria escaping chemorepellents

Flagellar swimming hydrodynamics confers a recognized advantage for attachment on solid surfaces. Whether this motility further enables the following environmental cues was experimentally explored. Motile E. coli (OD ~ 0.1) in a 100 µm-thick channel were exposed to off-equilibrium gradients set by a chemorepellent Ni(NO3)2-source (250 mM). Single bacterial dynamics at the solid surface was analyzed by dark-field videomicroscopy at a fixed position. The number of bacteria indicated their congregation into a wave escaping from the repellent source. Besides the high velocity drift in the propagation direction within the wave, an unexpectedly high perpendicular component drift was also observed. Swimming hydrodynamics CW-bends the bacteria trajectories during their primo approach to the surface (< 2 µm), and a high enough tumbling frequency likely preserves a notable lateral drift. This comprehension substantiates a survival strategy tailored to toxic environments, which involves drifting along surfaces, promoting the inception of colonization at the most advantageous sites.Graphical abstract

Transport and clogging dynamics of flexible rods in pore constrictions.

The transport and clogging behavior of flexible particles in confined flows is a complex interplay between elastic and hydrodynamic forces and wall interactions. While the motion of non-spherical particles in unbounded flows is well understood, their behavior in confined spaces remains less explored. This study introduces a coupled computational fluid dynamics-discrete element method (CFD-DEM) approach to investigate the transport and clogging dynamics of flexible rod-shaped particles in confined pore constrictions. The spatio-temporal analysis reveals the influence of the rod's initial conditions and flexibility on its transport dynamics through a pore constriction. The simulation results demonstrate an increase in the lateral drift of the rod upon exiting the pore that can be scaled with channel height confinement. The clogging dynamics are explored based on hydrodynamic and mechanical forces, unveiling conditions for mechanical clogging through sieving. The developed method allows for the deconvolution of the forces that contribute to particle trajectories in confined flow, which is highly relevant in particle separation processes, fibrous-shaped virus filtration, biological flows, and related applications. The method is embedded into the open-source CFDEM framework, facilitating future extensions to explore multiple particle dynamics, intermolecular forces, external influences, and complex geometries.

Post-earthquake fire performance of partially encased composite steel and concrete columns

Considering the potential severity of losses caused by post-earthquake fires compared to earthquakes alone, this study employed a three-dimensional Finite Element (FE) model established in ABAQUS to investigate the response of partially encased composite (PEC) steel and concrete columns under post-earthquake fire, serving as preliminary analysis for subsequent experimental studies. The validity of the FE model was verified using results from existing seismic and fire loading tests. In simulating the hysteresis behavior of PEC columns, this study evaluated the impacts of concrete discrete cracking and mechanical models on the simulation outcomes, thereby refining the modeling technique. A typical PEC column was selected as the focus of this investigation. Sequential earthquake-fire simulations were conducted using a data transfer technique to assess the fire resistance performance of different seismic damaged columns with different axial compression load ratios. The results indicate that the behavior of damaged PEC columns evolves based on initial damage, and the failure exhibits overall bending accompanied by local buckling of the steel flange. As the axial load ratio increases, the fire resistance time of seismic-damaged PEC columns significantly decreases. When the axial compression ratio is increased from 0.2 to 0.5, the fire resistance time of columns with damage factor D within 0.6 decreases by 59.07% on average. This sensitivity to axial pressure is particularly pronounced when earthquake damage is severe. Moreover, it finds that the lateral drift ratio under seismic action should be controlled within 2% to ensure that the post-earthquake fire resistance will not be significantly reduced.

Path following of underactuated surface vessels based active disturbance rejection control considering lateral drift

To address the challenges posed by unmodeled dynamics, lateral drift, external disturbances, and the difficulty in measuring velocities in underactuated surface vessels (USVs) motion systems, an active disturbance rejection control (ADRC) with two linear extended state observers (LESO) is proposed for USV path following. Firstly, we employ the Backstepping technique to create a virtual heading angle while estimating lateral drift and unmodeled dynamics using LESO. Subsequently, the ADRC algorithm is employed to control the heading angle. Since measuring the velocities of USV is challenging, velocity observers are introduce to estimate surge and sway velocities. Finally, we utilize the MMG model with high precision to track straight-line and curved paths, respectively. Simulation results validate that our developed controller accurately follows the reference path even in the presence of disturbances, affirming the effectiveness of our proposed control strategy.

Experimental investigation of the infill response under the inter-story drift level for different opening location

This paper investigates the response of infilled frames associated with inter-story drift ratio considering the central and eccentric window opening under the in-plane force. The behavior of the structure was studied by experimental and numerical approach. Experimental results show that the lateral load capacity in eccentric window frame (EW) is 1.17 times of central window frame (CW due to interruption of diagonal loaded action by the central opening. The elastic condition of CW frame and EW frame is obtained at lateral drift of 0.2% and 0.4% respectively. As a result of weak mortar interaction, the diagonal action of crack distribution emerges along the corner of the panel in testing A numerical simulation was performed and validated with experimental results. As the comparison of results, the elastic limit points coincide between the two approaches of numerical and experimental. However, the slightly difference occurs at the peak point. The similarity can be seen in the range of 80% to 100% in the value of peak load and displacement at peak load. The numerical investigation revealed that the highest stress distribution occurred along the diagonal axis, aligning with the results of the experimental investigation.

Experimental study on the behavior of small-scaled circular and square RC columns under various loading conditions and corrosion effect

Reinforced concrete columns are vital load-bearing elements, responsible for transferring vertical loads and resisting lateral forces. While numerous factors govern column performance, this study pinpoints cross-sectional shape, transverse reinforcement configuration, and the corrosive threat as its primary areas of investigation. Thus, 20 small-scaled (1/8th scale) RC columns (square and circular, with ties or spirals) were tested under various loading conditions. Columns were divided into five groups. A preliminary test was conducted to determine individual axial load capacity through failure under axial compressive loading. The main test then explored their behavior under combined axial load and variable lateral drift compared to their behavior at two corrosion levels 15% and 25%. While corrosion levels were roughly achieved, uneven distribution due to the accelerated process concentrated pitting near construction joints, impacting reinforcement more than rebar. Results confirmed the efficacy of spirals in enhancing capacity, particularly for circular columns where they also increased lateral load capacity. However, spirals also amplified corrosion vulnerability in circular columns, suggesting a steeper decline in performance at higher corrosion levels. Two key models were derived from analyzing the recorded data: normalized total dissipated energy and normalized absolute peak load. Future research should prioritize exploring column behavior under a wider range of combined loads and corrosion levels to refine and validate these models.

Two-Scale Probabilistic Seismic Fragility Assessment for a Prestressed Concrete-Steel Hybrid Wind Turbine Tower with Incremental Dynamic and Multiple Stripe Analysis

ABSTRACT To evaluate the seismic performance of a prestressed concrete-steel hybrid (PCSH) wind turbine tower, the seismic fragility curves based on incremental dynamic analysis (IDA) and multiple stripe analysis (MSA) on a two-scale model are presented and compared. The peak ground acceleration (PGA) and peak lateral drift on the top of the tower are adopted as the intensity measure (IM) and engineering demand parameter (EDP) of analysis, respectively. Finally, the seismic performance of the PCSH tower subjected to seismic action at different soil is investigated. The fragility curves obtained by IDA and MSA methods are compared.

Optimal curvature radius of cylindrical mirrors in linear Fresnel reflectors

The optical performance of linear Fresnel reflectors (LFRs) is heavily influenced by the curvature of their cylindrical mirrors. An innovative approach to calculating the optimal curvature radius of cylindrical mirrors in LFRs is introduced. Firstly, an optimization calculation method is proposed to determine the curvature radius of the cylindrical mirror. Then, a universal computational model for the curvature radius of cylindrical mirrors is established. Finally, a detailed analysis is conducted on the impact of optimizing the cylindrical mirrors on the optical performance of LFRs. Optical simulation results indicate that optimizing the curvature radius of the mirror significantly reduces the lateral drift of reflected rays. Increasing slope error, tracking error, and curvature radius error of the cylindrical mirrors result in decreased optical efficiency gain in the optimized LFR while improving uniformity. Furthermore, a larger transversal incidence angle yields a more pronounced improvement in the optimized gain, demonstrating a substantial enhancement in optical efficiency without compromising uniformity in LFRs. The average optical efficiency gain of the LFR is measured at 7.09 %, with an average uniformity loss of 2.10 % under all the studied conditions.

Comparative Study of RCC Structure of different types by using Shear Wall, Damper &amp; Bracing System

In seismically active places, earthquake restrictions would provide a difficulty to the majority of multistory buildings. The fundamental issue in the design of the multi-story building is lateral stability, which is required to control lateral drift and displacement, withstand lateral pressures, and avoid buckling. Reinforced concrete (RCC) structures usually utilise a damper, bracing, and shear wall system to mitigate the impacts of seismic activity. Both systems have significant structural performance. Despite the fact that both technologies are used for the same purposes, their effects and behaviour in response to seismic load differ. The G+12 storey building, shear wall and bracings will all be considered in this project's analysis. The following criteria will be used to evaluate the building's performance: base shear, storey displacement, and storey drift. This research includes dampers, shear walls, and bracings at various places, and the Etabs 2018 programme will be utilised for the entire analysis.

3D drift correction for super-resolution imaging with a single laser light.

Single-molecule localization microscopy (SMLM) enables three-dimensional (3D) super-resolution imaging of nanoscale structures within biological samples. However, prolonged acquisition introduces a drift between the sample and the imaging system, resulting in artifacts in the reconstructed super-resolution image. Here, we present a novel, to our knowledge, 3D drift correction method that utilizes both the reflected and scattered light from the sample. Our method employs the reflected light of a near-infrared (NIR) laser for focus stabilization while synchronously capturing speckle images to estimate the lateral drift. This approach combines high-precision active compensation in the axial direction with lateral post-processing compensation, achieving the abilities of 3D drift correction with a single laser light. Compared to the popular localization events-based cross correlation method, our approach is much more robust, especially for datasets with sparse localization points.

Effect of positioning of shear walls in a multi-storied building on response to earthquake

Seismic events are a matter of concern for structural engineers because of their devastating effects. These events are neither can be predicted. nor can be prevented. To mitigate its impacts on the structures several measures are taken. But none of them can be treated as 100% effective, there is a lot of scope for improvement. In this study, the dynamic behavior of structures under seismic loading was investigated, focusing on the combined influence of geometric shapes, different types of shear walls, and their position on lateral displacement and drift. Specifically, four different geometric shapes of plans of identical floor areas were taken for this study. Two types of shear walls, oupled shear walls, and core shear walls were placed in four different positions. The Static Equivalent Load method to assess the seismic response of structures is employed in this study, following the guidelines given in the Bangladesh National Building Code 2006 using ETABS software. Key findings of the study are the efficacy of shear walls in mitigating lateral displacement. The optimum results were achieved for central positions and core wall configurations. The study discloses the significance of different geometric shapes on seismic responses. This study provides a perception of effective seismic retrofitting strategies.

Subassemblage test and width-thickness design limit for steel built-up box columns subjected to axial load and cyclic lateral drift

This study investigates the behavior of first-story columns under reversed cyclic lateral loading and constant axial loading by using a full-scale, one-and-a-half story subassemblage testing scheme. Four subassemblages were designed with steel beams at the second floor and a moderately ductile built-up box column with a width-thickness ratio (b/t) of either 16.2 or 20.5, which are between the highly ductile (=12.9) and moderately ductile (=23.5) requirements in AISC 341 (2016). All built-up box columns were made by SM570MB steel with a nominal yield stress, Fy= 420 MPa. A high axial load (=4200–8000 kN, corresponding to 0.2–0.4 times the axial yield strength Py) was applied to the one-and-a-half story subassemblage column before cyclic lateral drifts. The second-floor beams and column provide rotational flexibility at the top end of first-story columns in the subassemblages, significantly changing column’s stiffness, moment distribution, and inflection point location observed from typical column testing. The subassemblage column and the isolated column had a similar maximum moment at the first cycle of 0.04 rad drift, but the later showed larger strength degradation in the following cycles due to larger fixity at the column top end. An experimental solution that relates the column width-thickness ratio to the moment strength deterioration was developed to obtain design b/t limits for highly and moderately ductile built-up box columns under combined high axial load (0.3–0.4Py) and cyclic lateral drift.

Study on the hysteretic characteristics of FRP-reinforced concrete shear wall with innovative friction dampers

FRP-reinforced concrete shear walls (FRCWs) are able to achieve satisfactory residual deformation and corrosion resistance compared with steel reinforced concrete walls (SRCWs). However, in the FRCWs, the failure of the plastic hinge region brings great challenges to the post-earthquake repair of the structure. Therefore, this paper designed one SRCW and two FRCWs with innovative friction dampers (FDs) at the feet, and steel truss and steel plate were embedded at the plastic hinge region of the two FRCWs respectively to supplement the weakened shear strength. Then pseudo-static tests were carried out twice before and after repairing the two FRCWs with FDs. Experimental results showed that compared with the SRCW at the same lateral drift, the damage of the FRCW was reduced by installing FDs at the feet, and the energy dissipation capacity was enhanced; the repaired FRCWs with FDs could still have acceptable seismic performance. Subsequently, the Park-Ang damage indices of wall webs of the FRCWs with FDs were calculated, which proved that the FRCWs with FDs could meet the four-level seismic fortification objective. In the end, two orthogonal tests were designed based on the established OpenSees models to evaluate the impact of the damper friction and FRP reinforcement ratio on the seismic behaviours of the FRCWs with FDs. It was recommended to adopt larger longitudinally distributed FRP reinforcement ratio to obtain satisfactory self-centering ability and hysteresis performance of the FRCW with FDs.

System effects in T‐shaped timber shear walls: Effects of transverse walls, diaphragms, and axial loading

AbstractThis paper investigates the effects of transverse shear walls (TSWs), out‐of‐plane bending stiffness of diaphragms (FDIA), and axial loading (AXL) on the lateral response of strong wood‐frame shear walls (SWs) used for multistory light frame timber buildings (LFTBs) located in highly active seismic zones. Experimental tests were conducted to understand the requirements for SW‐to‐TSW connections to achieve desirable TSW effects in non‐planar SWs and to characterize the lateral cyclic response of T‐shaped SW assemblies with and without diaphragms and axial load. Both slotted and screwed connections were evaluated as SW‐to‐TSW connections, and both showed sufficient stiffness and strength to achieve TSW effects. However, the slotted connection is preferred because it has a more ductile failure mode. Tests on T‐shaped SW assemblies with and without diaphragms and axial load revealed that TSWs significantly enhance the lateral stiffness and strength but reduce the deformation capacity with respect to that of planar SWs. FDIA and AXL effects further influence the stiffness and strength, overcoming the limitation of smaller deformation capacity in T‐shaped SWs without diaphragms. Diaphragms also make the T‐shaped SW response more symmetrical and improve the evolution of the secant stiffness, the cumulative dissipated energy, and the equivalent viscous damping over increasing levels of lateral drift. Numerical analyses of a theoretical building model with T‐shaped SWs show significant reductions in lateral drift (up to 46%) and uplift (up to 100%) compared to the case with planar SWs only, emphasizing the importance of considering system effects in the seismic design of LFTBs.

A Study on the Variations in Lateral Loading Imapcats Between Medium and High-rise Buildings Under Diverse Enviromental Conditions

-This thesis investigates the lateral loading effects on medium and high-rise buildings and compares their responses under different loading conditions. The study aims to provide insights into the behavior of these structures and aid in designing safer and more efficient buildings. The research methodology comprises analytical and numerical simulations of both medium and high-rise buildings subjected to various lateral loads. The analytical approach involves the use of hand calculations and mathematical models to determine the response of the building under different loading scenarios. The numerical simulations utilize computer software to model the structural behavior of the buildings and predict their response to lateral loads. The study focuses on four main lateral load types: wind loads, seismic loads. The loading conditions are applied to the buildings individually, and their responses are compared in terms of their lateral displacement, drift, and acceleration. The results show that both medium and high-rise buildings are susceptible to lateral loads, and their response depends on various factors such as building height, stiffness, and load duration. The lateral displacement of the high-rise building is more significant than the medium-rise building under all types of loading conditions. The results also show that the acceleration of the high-rise building is more significant under seismic loads than wind load. The study provides valuable insights into the behavior of medium and high-rise buildings under different lateral loading conditions. The findings of the study can be used to improve the design of these structures and enhance their resilience to lateral loads. The study recommends that designers should pay close attention to the building's lateral load resisting system and consider the impact of structural irregularities to ensure the building's safety and stability.

Numerical Study on Seismic Performance of Rocking Self-Centering (RSC) Bridge Piers Under Bidirectional Excitation

To study the seismic performance of rocking self-centering (RSC) bridge piers, a numerical model of RSC pier is established based on the OpenSees platform. The model is verified by experimental results. The seismic performance of RSC piers is analyzed under quasi-static and seismic loads, respectively, in terms of peak lateral drift, residual deformation, compressive zone height of the cross-section and tendon stress. Far-field, near-field without pulse and near-field pulse-like ground motion records are selected for the time-history analysis. The effects of prestressing tendon reinforcement ratio, energy-dissipating bar ratio and axial load are examined, respectively. The results show that the strength of the RSC pier, the depth of the compressive zone of the cross-section and the self-centering capacity increase with increasing prestressing tendon reinforcement ratio. When the energy-dissipating reinforcement ratio exceeds 1%, the boost of seismic performance of the pier becomes insignificant. The increasing axial load can increase the lateral strength of the pier. However, it could lead to premature yielding of the prestressing tendons.

Quantitative assessment of earthquake-induced building damage at regional scale using LiDAR data

Regional-scale assessment of the damage caused by earthquakes to structures is crucial for post-disaster management. While remote sensing techniques can be of great help for a quick post-event structural assessment of large areas, currently available methods are limited to the detection of severely-damaged buildings. Furthermore, remote sensing-based assessment methods typically provide only qualitative results, as they lack integration with information on the building’s behaviour in response to seismic-induced ground shaking. In this study, we developed a new methodology that uses airborne Light Detection And Ranging (LiDAR) data in combination with structural indicators of building response to provide a quantitative assessment of earthquake-induced damage at a regional scale. LiDAR datasets collected before and after an earthquake are used to measure residual displacements of building roofs. The resulting lateral drift estimations are used to quantify the level of damage for a specific building typology. Application to the LiDAR datasets collected before and after the 2014 earthquake in Napa Valley, California, demonstrates the capability of the proposed method to detect moderate levels of structural damage, proving its potential for faster and more accurate support to post-disaster management.

Cyclic performance of non‐ductile reinforced concrete columns retrofitted by partial steel plate jacketing: Experiment and numerical analysis

AbstractThis paper investigates the strengthening of non‐ductile reinforced concrete (RC) columns using partial steel‐plate jacketing to enhance ductile capacity. Quasi‐static cyclic loading tests were conducted on three rectangular RC columns with varying shear‐span‐to‐depth ratios, evaluating the effectiveness of steel‐plate jacketing. Results show improved ductile flexural response, high drift capacity, and maintained gravity‐loading capacity under high lateral displacements. A numerical investigation, adopting a multi‐spring fiber section model, predicted cyclic lateral strength, drift ratio, and failure mode, accurately simulating reinforcement behavior and capturing the shear‐strength enhancement due to steel‐plate jacketing. Numerical results demonstrated good agreement with experimental findings. Based on these outcomes, a simple design procedure for retrofitted concrete columns, applicable to design engineers, has been developed and reported in this paper. This study contributes valuable insights into the practical applications of steel‐plate jacketing for non‐ductile RC column retrofitting, offering a comprehensive approach to predicting their seismic performance.

Seismic Performance Evaluation of Reinforced Concrete Building Structure Retrofitted with Self-Centering Disc-Slit Damper and Conventional Steel Slit Damper

To meet the recent requirements of low-damage design, there is a growing need to retrofit building structures with a self-centering dissipation system. This system serves a dual purpose: reducing lateral drift and providing supplemental damping to enhance the seismic performance of buildings. This research focuses on assessing the efficiency in seismic response of structures retrofitted with an innovative self-centering hysteretic damper called a Self-Centering Disc Slit Damper (SC-DSD). The SC-DSD consists of four slit dampers and pre-compressed Belleville disc springs that provide self-centering and energy dissipation capabilities. This study investigates the SC-DSD’s working mechanism, theoretical formulation, and design method of SC-DSD dampers for their application in multistory building structures. A reinforced concrete (RC) structure is selected as a case study building that is retrofitted with SC-DSDs and conventional slit dampers. Subsequent seismic performance assessments are conducted using detailed pushover to evaluate the global behavior and capacity of the structure used for the design of the damping system. Nonlinear time history analysis is performed to simulate the dynamic behavior of the retrofitted structure under a variety of seismic excitations. This analysis considers a range of ground motion records to capture different intensity levels and frequency content. Comparing these analyses reveals that the designed SC-DSDs effectively reduce seismic responses while minimizing residual displacement up to 95% when contrasted with both the bare structure and the structure retrofitted with conventional steel slit dampers.

Optimal energy dissipation ratio of base-rocking walls

Base-rocking walls (BRWs) were excellent in maintaining enhanced post-earthquake serviceability and decreasing repair costs and downtime. However, little research has been aimed at finding the optimal range of energy dissipation ratio for designing BRWs. In this study, an approach was developed first for designing BRWs to obtain an intended level of energy dissipation capacity. Using the proposed approach, fifteen BRWs with different heights (i.e., 16, 25.6, and 38.4 m) and energy dissipation ratios (i.e., 0, 0.25, 0.50, 0.75, and 1.00) were designed and modeled using experimentally validated numerical models. Conducting nonlinear time history analyses using far-field (FF), near-field no-pulse (NFnP), and pulse-like (NFP) ground motions, the walls’ response features (RFs), including residual and transient lateral drifts, story acceleration, energy dissipation capacity, post-tensioning (PT) tendons strain, and structural demand were estimated and compared to the existing criteria. Proposing a desirability index (DI), the extent of criteria exceedance for the walls RFs was investigated to find the optimal range of energy dissipation ratio. The results showed that the walls designed by the developed approach could achieve the pre-assumed energy dissipation capacity. Increasing the energy dissipation ratio increases the lateral residual drift while decreasing the transient lateral drift, PT tendon strain, and wall demand. Increasing the wall height increases dissipated energy, exacerbating the adverse effects of higher modes while decreasing PT tendon strain. The obtained residual and transient drifts and PT tendon strain for NFP records are higher than those for FF and NFnP records. Moreover, the peak moment occurred at the lower wall height for NFP records. The adverse effects of higher modes are more evident in FF records. In general, for designing BRWs, the optimal energy dissipation ratio range was 0.50–0.75.