Variability Of Motion Research Articles

Dual-Pol VPR Corrections for Improved Operational Radar QPE in MRMS

Abstract The radar bright band is caused by melting ice crystals, and results in inflated reflectivity observations. If uncorrected, the bright band can result in large errors in radar-derived quantitative precipitation estimation (QPE). In the operational Multi-Radar Multi-Sensor (MRMS) system up to version 12.1, the effects of the bright band are corrected through the use of a reflectivity-only, tilt-based apparent vertical profile of reflectivity (tilt-VPR). This study utilizes dual-polarization (dual-pol) radar observations to improve the tilt-VPR methodology. To accomplish this, a brightband area delineation was developed within the MRMS framework and the brightband top and bottom heights were identified for individual tilts of radar data. This information was used to develop a radially dependent dual-pol VPR (dpVPR) model that can better correct reflectivity in situations of nonisotropic bright bands and low brightband events. This algorithm has been tested on 14 varying brightband events across the CONUS and compared with the tilt-VPR and the National Weather Service Weather Surveillance Radar-1988 Doppler Level-3 Digital Precipitation Rate (DPR) products. The radially dependent dpVPR correction provided a more accurate detection of brightband areas and a more effective reduction in QPE errors within and above the bright band than the tilt-VPR and DPR QPEs, especially for precipitation events with low melting layers or with strong variability of vertical motions. The brightband delineation and dpVPR methodology are also evaluated in the real-time MRMS testbed for their robustness and computational efficiency and has been transitioned into operations in 2022.

Phonological and Articulatory Deficits in the Production of Novel Signs in Children With Developmental Language Disorder.

Sign language, like spoken language, incorporates phonological and articulatory (or motor) processing components. Thus, the learning of novel signs, like novel spoken word forms, may be problematic for children with developmental language disorder (DLD). In the present work, we hypothesize that phonological and articulatory deficits in novel sign repetition and learning would differentiate preschool-age children with DLD from their typical peers. Children with DLD (n = 34; aged 4-5 years) and their age-matched typical peers (n = 21) participated. Children were exposed to four novel signs, all iconic, but only two linked to a visual referent. Children imitatively produced these novel signs multiple times. We obtained measures of phonological accuracy and articulatory motion stability as well as of learning of the associated visual referent. Children with DLD showed an increased number of phonological feature (i.e., handshape, path, and orientation of the hands) errors when compared with their typical peers. While articulatory variability did not overall differentiate children with DLD from typical peers, children with DLD showed instability in one novel sign that obligated bimanual oppositional movement. Semantic aspects of novel sign learning were unaffected in children with DLD. Deficits that have been documented in phonological organization of spoken words in children with DLD are also evident in the manual domain. Analyses of hand motion variability suggest that children with DLD do not show a generalized motor deficit, but one that is restricted to the implementation of coordinated and sequential hand motion.

Effects of trunk extensor muscle fatigue on repetitive lift (re)training using an augmented tactile feedback approach

Augmented tactile and performance feedback has been used to (re)train a modified lifting technique to reduce lumbar spine flexion, which has been associated with low back disorder development during occupational repetitive lifting tasks. However, it remains unknown if the presence of trunk extensor neuromuscular fatigue influences learning of this modified lifting technique. Therefore, we compared the effectiveness of using augmented tactile and performance feedback to reduce lumbar spine flexion during a repetitive lifting task, in both unfatigued and fatigued states. Participants completed repetitive lifting tests immediately before and after training, and one-week later, with half of the participants completing training after fatiguing their trunk extensor muscles. Both groups demonstrated learning of the modified lifting technique as demonstrated by increased thorax-pelvis coordination variability and reduced lumbar range of motion variability; however, experiencing trunk extensor neuromuscular fatigue during lift (re)training may have slight negative influences on learning the modified lifting technique.

Mesorectal motion evaluation in rectal cancer MR-guided radiotherapy: an exploratory study to quantify treatment margins

BackgroundMesorectal motion (MM) is a source of uncertainty during neoadjuvant chemoradiotherapy (nCRT) delivery for locally advanced rectal cancer (LARC). Previously published experiences using cone-beam computed tomography imaging have already described significant movement. Aim of this analysis is to assess inter-fraction MM using the higher tissue contrast provided by hybrid magnetic resonance imaging (MRI) in LARC patients (pts) treated with MRI guided radiation therapy (MRgRT).MethodsThe total mesorectum, its superior (Msup), middle (Mmid) and lower (Mlow) regions were contoured on the positioning MRIs acquired on simulation day and on each treatment day. Six PTVs were obtained adding 0.5, 0.7, 1, 1.3, 1.5 and 2 cm margin to the whole mesorectum, starting from the simulation MRI. Margins including 95% of the mesorectal structures during whole treatment in 95% of patients (pts) were considered adequate.ResultsA total number of 312 fractions of 12 consecutive pts was retrospectively analyzed. The different mesorectum regions show specific motion variability. In particular, Msup shows larger variability in left, right and anterior directions, while the Mlow in caudal and posterior ones. The anterior margin is significantly larger in the Msup than in the other regions.ConclusionDifferent mesorectal regions move differently throughout the radiotherapy treatment, with the largest MM in the Msup anterior direction. Asymmetrical margins are recommended.

Looking for Synergies in Healthy Upper Limb Motion: A Focus on the Wrist

Recent studies on human upper limb motion highlighted the benefit of dimensionality reduction techniques to extrapolate informative joint patterns. These techniques can simplify the description of upper limb kinematics in physiological conditions, serving as a baseline for the objective assessment of movement alterations, or to be implemented in a robotic joint. However, the successful description of kinematic data requires a proper alignment of the acquisitions to correctly estimate kinematic patterns and their motion variability. Here, we propose a structured methodology to process and analyze upper limb kinematic data, considering time warping and task segmentation to register task execution on a common normalized completion time axis. Functional principal component analysis (fPCA) was used to extract patterns of motion of the wrist joint from the data collected by healthy participants performing activities of daily living. Our results suggest that wrist trajectories can be described as a linear combination of few functional principal components (fPCs). In fact, three fPCs explained more than 85% of the variance of any task. Wrist trajectories in the reaching phase of movement were highly correlated among participants and significantly more than trajectories in the manipulation phase ( [Formula: see text]). These findings may be useful in simplifying the control and design of robotic wrists, and could aid the development of therapies for the early detection of pathological conditions.

A Probabilistic Dynamic Movement Primitives Framework on Human Hand Motion Prediction for an Object Transfer Scenario

Recent advancements in Human-Robot Collaboration (HRC) have opened up promising prospects for revolutionizing the current manufacturing automation. Accurate modeling of human motion patterns is crucial for enabling the robot to understand human intention and predict their future motion based on online observations. As the widely used deterministic methods often lack confidence information about the provided result to account for the possible variability of human motion, in this work, a Probabilistic Dynamic Movement Primitives (PDMP)-based framework is adopted to recognize goal-directed human movements in the reaching phase and making online predictions. The proposed framework employs PDMP based on off-line demonstrations of relevant hand movements. To avoid frame-dependency, a novel DMP formulation with rotation and magnitude scaling is used, allowing for generalization of learned motion patterns to similar tasks. The proposed framework has been validated in experiments regarding an object transfer scenario on the workbench, using a Intel RealSense camera and OpenPose system for motion capturing. Results show that this framework can offer good performance in hand motion prediction in presence of human motion variations, and can be generalized to relevant tasks beyond the limited demonstrated trajectories.

Observations on the Seismic Loading of Rigid Inclusions based on 3D Numerical Simulations

Rigid inclusions are increasingly being specified in seismic regions to transmit foundation loads to competent strata at depth due to their ability to provide excellent static performance and potential for cost-savings over other forms of ground improvement and/or deep foundations. Despite their widespread application in seismic regions, the seismic kinematic interaction of rigid inclusions is not well understood. This study presents a series of parametric numerical simulations specifically conducted to capture the kinematic soil-rigid inclusion interaction under seismic loading to identify key mechanisms that contribute to seismic performance. The effect of ground motion variability, area replacement ratio, surface crust thickness, embedment into a competent layer, liquefiable layer thickness, and steel reinforcement is systematically investigated. Although the rigid inclusion may not prevent liquefaction triggering, severe amplification associated with dilation spiking of transiently liquefied soil is mitigated and the onset of liquefaction delayed due to the soil-rigid inclusion interaction. The role of static arching to alter the geostatic stress state prior to and during shaking is shown to be responsible for significant and heretofore unknown coupled fluid-mechanical interaction that drives the performance of the rigid inclusion within the reinforced soil system. The kinematic flexural demand following the triggering of liquefaction and phase transformation associated with cyclic mobility is met through transient increases in axial load, which increases the confinement of the grout comprising the rigid inclusion, and therefore its moment capacity. The complex mechanisms identified in this work should be used to help identify which subsurface conditions may lead to responses, guide design decisions regarding selection of reinforcement and embedment, and provide a basis for assessments of the anticipated kinematic demands in view of the beneficial axial load-moment capacity interaction following soil liquefaction.

RECENT PROGRESS ON HEAT TRANSFER PERFORMANCE AND INFLUENCING FACTORS OF DIFFERENT MICROCHANNEL HEAT SINKS

The microchannel heat sink (MCHS) is an efficient thermal management technology widely used in various fields, including electronic equipment, automobiles, and aerospace. In this paper, the recent advances in cross-sectional shape, coolant type, flow channel shape, flow pattern, and application scenarios of the MCHS are systematically reviewed. The liquid film thickness in circular microchannels is the smallest, followed by rectangle, trapezoid, and triangle sections. Conversely, the pressure drop experienced exhibits an inverse relationship with the liquid film thickness. Comparatively, the heat transfer performance of the liquid phase surpasses that of the gas phase, and the two-phase coolant consistently outperforms the single-phase coolant. The study also investigates the impact of flow direction and shape on heat transfer performance. It is found that the implementation of wavy, fractal, and cavity structures enhances heat transfer performance at the expense of increased fluid motion variability, resulting in a loss of pressure drop. Additionally, this paper discusses the occurrence of laminar and turbulent flow phenomena within MCHSs and summarizes their respective influences on heat dissipation performance. On the basis of the aforementioned findings, four key applications of MCHSs are emphasized, accompanied by recommendations for their present utilization and future development. Future research endeavors will concentrate on striking a balance between altering the shape and material characteristics of MCHSs to optimize heat transfer performance while developing novel theoretical models continuously.

Influence of uncertainty of structural parameters on the stochastic dynamic response of asphaltic lining dam-foundation systems to non-stationary random seismic excitation

The present work aims toward the effect of uncertain structural parameters on the stochastic dynamic response of an asphaltic lining dam-foundation system subjected to stationary as well as non-stationary random excitation. Uncertain structural parameters of interest are shear modulus and mass density, modeled using the lognormal distribution. The stochastic seismic response of the dam-foundation system to the random loads with uncertain structural parameters is carried out with the Monte Carlo simulation method. The spatial variability of ground motion is considered with incoherence and wave passage effects as stationary as well as non-stationary random excitation. A time-dependent frequency response function is used throughout the study for non-stationary responses. Obtained results indicate that the variability of shear modulus and mass density can be neglected in stochastic dynamic analysis of an asphaltic lining dam-foundation system. Also, it is seen from the results that stationarity is a reasonable assumption for asphaltic lining dams to typical durations of strong shaking.

Tunnel-soil-bridge seismic interaction on soft clay

Seismic tunnel-soil-bridge interaction in high plasticity soft clays can lead to significant ground motion variability, affecting on-ground structures located next to or above underground facilities. This technical note presents a numerical study aiming at establishing tunnel-bridge seismic interaction effects on soft clays. Initially, we revised this interaction considering the impact that frequency content, intensity, and strong ground motion duration have on the interplay between incoming seismic waves reflected in the tunnel and the energy feeding back from the bridge swinging back and forth during a large earthquake. Series of three-dimensional finite difference models were developed. Seismic analyses considered both normal and subduction events with a return period of 250 years. From the results gathered in these analyses, the ground motion modification in the surrounding soil occurs in both the transverse and longitudinal components due to tunnel-bridge interaction. The tunnel underneath the bridge establishes detrimental soil-structure interaction effects for normal and subduction events.

Head movement kinematics are altered during balance stability exercises in individuals with vestibular schwannoma

BackgroundBalance stabilization exercises are often prescribed to facilitate compensation in individuals with vestibular schwannoma (VS). However, both the assessment and prescription of these exercises are reliant on clinical observations and expert opinion rather than on quantitative evidence. The aim of this study was to quantify head motion kinematics in individuals with vestibular loss while they performed commonly prescribed balance stability exercises.MethodsUsing inertial measurement units, head movements of individuals with vestibular schwannoma were measured before and after surgical deafferentation and compared with age-matched controls.ResultsWe found that individuals with vestibular schwannoma experienced more variable head motion compared to healthy controls both pre- and postoperatively, particularly in absence of visual input, but that there was little difference between preoperative and postoperative kinematic measurements for our vestibular schwannoma group. We further found correlations between head motion kinematic measures during balance exercises, performed in the absence of visual input, and multiple clinical measurements for preoperative VS subjects. Subjects with higher head motion variability also had worse DVA scores, moved more slowly during the Timed up and Go and gait speed tests, and had lower scores on the functional gait assessment. In contrast, we did not find strong correlations between clinical measures and postoperative head kinematics for the same VS subjects.ConclusionsOur data suggest that further development of such metrics based on the quantification of head motion has merit for the assessment and prescription of balance exercises, as demonstrated by the calculation of a “kinematic score” for identifying the most informative balance exercise (i.e., “Standing on foam eyes closed”).

Near-source ground motion estimation for assessing the seismic hazard of critical facilities in central Italy

We apply the Probabilistic Seismic Hazard Analysis (PSHA) and compute Physics-Based Simulations (PBS) of ground motion for three dams in the Campotosto area (Central Italy). The dams, which confine an artificial water reservoir feeding hydroelectric power plants, are located in an active seismic zone between the areas that experienced the 2009 L’Aquila and 2016–2017 Central Italy seismic sequences. The probabilistic disaggregation estimated for a return period of 2475 years, corresponding to the collapse limit state for critical facilities, indicates that the most dangerous fault is associated with a maximum magnitude of 6.75 ± 0.25 within a distance of 10 km. This fault is used in PBS to emulate the Maximum Credible Earthquake scenario. To capture the ground motion variability, we input a pseudo-dynamic source model to encompass spatial and temporal variations in the slip, rise time and rupture propagation, heavily affecting the near-source ground motion. Indeed, the ground motion above the rupture volume is mainly influenced by the epistemic uncertainties of rupture nucleation and slip distribution. The computed broadband seismograms are consistent with the near-source shaking recorded during the 2016 MW 6.6 Norcia earthquake and constrain the upper bound of the simulated ground motion at specific sites. Our modelling reinforces the importance of considering vertical ground motion near the source in seismic design. It could reach shaking values comparable to or larger than those of the horizontal components. This approach can be applied in other areas with high seismic hazard to evaluate the seismic safety of existing critical facilities.

A closed form solution for the internal stability of landfills considering spatial variability of the input seismic motion

The scope of this paper is to develop a calculation method of a closed form solution for the internal stability of the landfill considering spatial variability of the input seismic motion based on log-spiral combined sliding surface. A calculation method for multi-point seismic load of the log-spiral combined sliding surface landfill was proposed, which used to establish the multi-point seismic stability calculation model of the log-spiral combined sliding surface landfill. The calculation results for a typically shaped landfill of this method showed a lower result comparing with the method considering pseudo-static seismic action and translational slip surface. Thus, the coupling effect of the internal sliding of the landfill and multi-point seismic action should not be ignored in the seismic design of landfills.

Variability of Inter-Fraction Target Motion during Hypofractionated Lung Radiation Therapy

<h3>Purpose/Objective(s)</h3> Pre-treatment 4D-CTs are used in planning for motion management of lung RT. The target excursion (E) at the time of planning may differ between planning and treatment. Additionally, the tumor excursion can change between fraction deliveries. The objective of this study is to investigate patterns of excursion variability (∆E) during hypofractionated radiotherapy (HRT) and the clinical factors that correlate with ∆E. <h3>Materials/Methods</h3> 41 patients with primary or metastatic lung tumors underwent HRT. For each patient, planning was performed on 4D-CT imaging. Patients underwent daily pre- and post- treatment 4D-CBCT for setup conformation and motion assessment. Respiration-induced excursion (E) was quantified in the planning 4D-CT, and in each daily excursion 4D-CBCT. All excursion values were measured in 3 dimensions: AP, LR, and SI. ∆E was calculated as the difference between daily 4D-CBCT excursion values and the planning 4D-CT excursion value. The clinical statistics and excursion statistics were evaluated for all fractions. Finally, Pearson correlation was performed to associate clinical factors with ∆E. <h3>Results</h3> 377 4D-CBCTs were analyzed. ∆E was largest in the SI direction, with ∆E_avg in the SI, LR, and AP directions being 0.16, 0.05, and 0.08 cm respectively. Only 7.1% of all 4D-CBCT's displayed ∆E ≥ 4mm. The average age of patients with ∆E ≥ 4mm was 58.63 y/o, and that of patients with ∆E<4mm was 71.73 y/o (P<0.001). The average baseline weight of patients with ∆E ≥ 4mm and ∆E<4mm were 84.94 kg and 72.82 kg respectively (P<0.001). 71.1% of males and 28.9% of females gave ∆E ≥ 4mm (P=0.003). 58.3% of tumors with ∆E ≥ 4mm were in the right lower lobe (RLL) and 20.8% of tumors with ∆E ≥ 4mm were in the left lower lobe (LLL) (P<0.001). An average AP planning excursion of 0.34cm gave ∆E<4mm and that of 0.53 cm gave ∆E ≥ 4mm (P =0.008). The average Charlson Comorbidity Index (CCI) was 3.58 for tumors with ∆E<4mm, and 5.17 for tumors with ∆E ≥ 4mm (P=0.004). Pearson correlation between the left and right lungs didn't yield statistically significant results (P=0.76). <h3>Conclusion</h3> Large ∆E seems predictable, with ∆E ≥ 4mm seen more in young patients with higher baseline weight, male gender, tumors in the lower lobes, and with large 4D-CT excursion displayed in the AP direction. There was no correlation found between ∆E and right versus left lung. Additionally, CCI did not correlate with excursion variability. Finally, the largest degree of ∆E is displayed in the SI direction.

Charts for Permanent Displacement-Based Seismic Design of Cantilever Retaining Walls

ABSTRACT This study proposes seismic design charts to predict the permanent displacements in cantilever retaining walls. These charts are developed considering the realistic v-shaped mechanism in the backfill. It captures the aleatory uncertainty of earthquake motions by incorporating numerical analysis results for 152 earthquake ground motions. Conventionally, the charts developed for slopes and gravity walls have been adopted by practitioners for cantilever retaining walls assuming an imaginary vertical plane through the wall heel and considering the soil above as a part of the wall itself. Using these conventional charts of slopes with a single wedge assumption may lead to misleading predictions, which is one of the motivations behind developing charts specifically for the cantilever retaining walls. It also provides an estimation for the resulting subsidence in the backfill that may induce distress in the overlying structures. Unlike conventional charts, 5% − 20% probability of exceedance curves besides upper-bound curves have been developed accounting for earthquake motion variability. Non-dimensional equations have been proposed to estimate the minimum heel-length of the wall with and without shear key for the design values of PGA and PGV.

Probability-based residual displacement estimation of unbonded laminated rubber bearing supported highway bridges retrofitted with Transverse Steel Damper

Predicting the post-earthquake residual displacement of isolated bridges is crucial in deciding their operational and recovery strategies after a seismic event. This study proposes a probability-based approach to estimate the residual displacement of a trilinear hysteretic system representing the unbonded laminated rubber bearing (ULRB) supported highway bridge retrofitted with transverse steel dampers (TSDs), considering the uncertainty of structural parameters and the variability of ground motions. To this end, this study systematically derives the quasi-static residual displacement of a trilinear hysteretic system, and presents the statistical distribution model for the related structural parameters, especially for the pier height and the TSD model parameters. After that, the dynamic residual displacement property of the ULRB supported highway bridge retrofitted with TSDs is investigated considering the uncertainty of various parameters, including model parameters of TSD and ULRB, the mass of superstructure, the height of piers, as well as the ground motions with and without pulse. The maximum possible residual displacement of the trilinear hysteretic system is then related to its quasi-static residual displacement and peak displacement demand. Finally, an innovative probability-based approach is developed in this study to estimate the conditional probability of the dynamic residual displacement of the trilinear system exceeding a threshold at the given ground motion intensity, and this innovative approach is further validated by comparing it with the incremental dynamic analysis (IDA) method. Results show that the dynamic residual displacement of the TSD retrofitted ULRB supported highway bridge system is random, and the ratio between the dynamic residual displacement and the maximum possible residual displacement approximately satisfies a uniform distribution bounded by zero and one. The probability-based approach can obtain a close result with the IDA method and significantly reduce computational efforts. This research represents a first step toward developing a rapid post-earthquake assessment approach for seismically isolated bridges and the seismic design of these bridges considering the residual displacement.

Mechatronic acoustic research system for generating real large-scale dynamic datasets

To support spatial audio research, we aim to take recordings from complex acoustic environments with moving sources and microphones, however we observe a lack of research tools that can accomplish this. Past approaches recorded people engaging in various tasks, which produces rich data that unfortunately lacks repeatability. We propose using robots to recreate dynamic scenes without the inherent variability of human motion. To be useful, this Mechatronic Acoustic Research System must be remotely accessible, offer concise representations of dynamic scenes, support a variety of robot and audio devices, and synchronize robot motion. In this talk, we show how we solved these challenges. Remote experimentation is facilitated by our virtual interface, which uses a simple GUI to describe robot motion and audio playback/recording. A digital twin physical simulation is used for visualization and validation of motion paths. We propose using the Robot Operating System for multi-robot coordination so that networked robots can be incorporated with little overhead. We use MARS to run experiments where a cable-driven parallel robot moves a loudspeaker along a 3D path while being recorded from distributed Matrix Voice microphone arrays. We evaluate the measured audio to show repeatability of the system, justifying its use in research.

Bed-material entrainment in a mountain river affected by hydropeaking

Hydropeaking, by artificially generated flow peaks, influences hydro-sedimentary dynamics on rivers and, consequently, affects bed material entrainment and transport. This study examines the onset of motion of sediment particles in four sections of a Pyrenean gravel-to-cobble bed river exposed to frequent hydropeaking (once per day, on average). Five criteria of particle entrainment have been used to assess the prediction of the initiation of grain motion at-a-section scale. Theoretical entrainment conditions were validated using real observations of mobility by means of tracers. It was found that the maximum flow discharged by the hydropower plant mostly affects the furthest downstream section, located almost 17 km downstream, in which the finer fractions of the bed are entrained. The mobile grain sizes include up to coarse gravels (≈ 30 mm). Differences in sediment supply (imposed by tributaries), the value of the bed slope and the structure of the coarse surface layer decisively control the downstream variability of incipient particle motion between sections. Results from a 17 km study segment indicated that hydropeaking generate partial transport, that is, a partially size-selective transport that occurs downstream from the hydropower plant and winnows the sand and small gravel further downstream, increasing armouring and depleting fine sediments.

Selection of Ground Motion Intensity Measures in Fragility Analysis of a Mega-Scale Steel Frame Structure at Separate Limit States: A Case Study

Selecting an appropriate ground motion intensity measure (IM) to estimate the aleatory uncertainty produced by ground motion variability is the first and crucial step in fragility analysis. The choice of IM is influenced not only by the structural system type itself but also by the limit state of the structural damage. In this study, an investigation of the selection of IM in fragility analysis with respect to different limit states is developed for a 48-story mega-scale steel frame structure with buckling restrained braces. A comparative study of the efficiency of 27 IMs is conducted at four structural damage limit states, i.e., negligible, light, moderate, and severe, through the lognormal standard deviation estimated in fragility equations. In addition, for the purpose of considering the influence of different earthquake characteristics, two completely different sets of ground motions are selected, namely near-field pulse-like and far-field earthquakes. The research shows that the ground motion characteristics and structural damage limit states have nonnegligible effects on the flexibility of intensity measures. For combination-type IMs, the number of combined terms and the combined power index have a significant impact on their performance; thus, an optimized dual-parameter combination-type intensity measure is recommended.

Loss estimation of curved bridges considering the incidence angle and spatial variability of earthquake ground motion

The consideration for the angle of seismic incidence (ASI) is critical for the seismic design of curved bridges. Previous studies indicate that the effect of ASI weakens as the damage develops throughout the structure. Since curved bridges often extend over long distances and cross varied geological conditions, the spatial variability of earthquake ground motions (SVEGMs) may significantly affect their responses. However, the concurrent effects of ASI and SVEGM on the system performance of curved bridges have yet to be explored, and there are currently few reliable methodologies for conducting relevant research. To this end, this study takes the monetary repair costs as the metric for representing the entire performance of the bridge, and the impact of ASI on the total loss of long multi-span curved bridges considering the spatially variable nature of earthquake ground motions is investigated in a probabilistic manner. A multi-directional loss assessment approach is derived based on the extension of an existing loss methodology, and an already constructed, 638-m-long, twelve-span prestressed concrete curved bridge is selected as the test-bed. Twenty non-stationary and spectrum-compatible spatially variable earthquake ground motion (SVEGM) pairs are generated based on the Eurocode 8 (EC8) design spectrum and soil conditions of the bridge site for each ASI. Three seismic input motion scenarios are assumed according to the characteristics of SVEGMs, and variabilities of bridge loss with respect to the ASI under the scenario earthquakes are investigated for each excitation case. On these bases, the original ground motion records are amplified by 2 and 4 times, respectively, and 4320 (3 earthquake intensity levels × 3 excitation scenarios × 24 ASIs × 20 ground motion pairs) nonlinear response-history analyses (NRHAs) are implemented to identify the influence induced by the ground motion intensity on the loss variability. Results indicate that the impacts of ASI and SVEGMs weaken as the ground shaking intensity increases and the damage accumulates in the structure.