Displacement Analysis Research Articles

Seismic displacement of earth slopes incorporating co‐seismic accumulation of dynamic pore water pressure

AbstractThe earthquake‐induced displacement of sloping soil mass is an important indicator of co‐seismic landslide initiation. In this paper, an improved Newmark displacement model that considers the accumulation of dynamic pore water pressure (DPWP) in the soil caused by both vertical and horizontal ground motions is proposed. The model can quantitatively describe the dynamic changes of the seismic yield acceleration of near‐saturated infinite soil slopes. Three different types of ground motion time histories are selected to compare the performance of the proposed Newmark displacement model, and the influence of DPWP accumulation on the slope yield acceleration and on the seismic displacement is obtained. The seismic slope displacement analyses indicate that the weakening effect of slope yield acceleration caused by bidirectional earthquake excitation‐induced DPWP is more obvious than when only considering the horizontal ground motion, when the slip surface soils are in near‐saturated state. The effect of initial saturation (Sr0) on the DPWP accumulation caused by vertical ground motion is also investigated. Furthermore, the accumulated seismic displacement can be reasonably explained by the frequency distribution characteristics of the ground motions. Finally, the numerical results of this paper show that the seismic displacement model seldomly considering the effect of DPWP, or only considering the DPWP induced by horizontal ground motion, can significantly underestimate the displacement value when the slip surface soils are in a near‐saturated state.

THE PROBABILITY OF A STRONG (M≥6.0) EARTHQUAKE IN THE SOUTH FERGANA SEISMIC ACTIVITY ZONE IN THE COMING YEARS

There were investigated seismic mode and stress state of the Earth’s crust in the South Fergana seismic activity zone. In the central part of the zone, there was identified an area of a long-term seismic quiescence during which no earthquakes with energy class K≥12 (M≥4.5) were recorded. Along the entire length of the seismic quiescence area, there occur an activation of earthquakes of lower energy classes, as well as anomalous fluctuations of the recurrence curve slope. To localize the place of seismic activation probability, the current stress of earth’s crust in the South Fergana seismic activity zone was reconstructed according to focal earthquake mechanisms by the methods of cataclastic analysis of displacements. There were identified the areas with low values of effective confining pressure and maximum shear stresses where strong earthquakes usually occur. Taking into account the stressed state of the Earth’s crust, on the basis of the prognostic parameters of the seismic regime within the South Fergana seismic activity zone there were identified two areas in which M≥6.0 earthquakes may occur in the coming years.

A Spatial Analysis of Suicide Displacement at a High-Risk Cliff-Based Location Following Installation of a Means Restriction Initiative

Means restriction interventions are recognised as highly effective for the deterrence of suicide attempts by jumping. While such interventions can lead to significant reductions in suicide, it is unclear whether these reductions represent a displacement effect, whereby individuals are instead choosing to attempt suicide at other nearby locations which offer the same means. The potential displacement of suicides as an unintended consequence of means restriction has been relatively unexplored to date. The only studies exploring displacement effects have focused on bridges, which are relatively easily contained sites; no studies have yet explored displacement effects at cliff-based high risk suicide locations (hotspots). Using Australian coronial data for the period of 2006–2019, we undertook joinpoint and kernel density analysis of suicides by jumping at a well-known cliff-based hotspot in Sydney, Australia, to determine whether there was evidence of displacement to local and broader surrounding cliffs following the installation of a multi-component harm minimization intervention (the Gap Park Masterplan). While slight decreases were noted in the immediate area subject to the structural intervention in the post-implementation period, alongside slight increases in the surrounding cliffs, there was no evidence for statistically significant changes. While kernel density analyses did not identify the emergence of any new hotspot locations in the post-implementation period, three existing hotspot sites of concern were found in our total area of interest, with greater than expected growth in the density of one of the hotspots. While we found no persuasive evidence of displacement, ongoing monitoring of the cliff-based location where the structural interventions were implemented is needed to ensure the ongoing safety of the area.

Large displacement analysis of two-layer beam-columns taking into account slip and uplift

PurposeThis article presents a geometrically non-linear finite element formulation for the analysis of planar two-layer beam-columns taking into account the inter-layer slip and uplift.Design/methodology/approachThe co-rotational method is adopted, in which the motion of the element is decomposed into a rigid body motion and a small deformational one. The geometrically linear formulation can be used in the local frame and automatically be transformed into a geometrically nonlinear one. In co-rotational frame, both layers are assumed to be discretely connected at the element ends. Slips and uplifts are assumed to be small. Consequently, the condition of non interpenetration between the layers can be treated using a node-to-node contact algorithm. The resolution methods such as penalty (PM) and augmented Lagrangian method (ALM) with Uzawa updating scheme can be used.FindingsThe non-penetration condition between the layers of composite beams can be formulated by using contact law. It is found that despite a low convergence rate of augmented Lagrangian method compared to penalty method, the former prevents the unrealistic penetration. Besides, it is shown that the buckling load of the composite beam-column is largely affected by the uplift stiffness of the connectors.Originality/valueThe proposed finite element model is capable of simulating accurately the geometrically non-linear behavior of planar two-layer beam-columns taking into account the inter-layer slip and uplift. Regarding uplift, the non-penetration condition is strictly enforced by considering rigorous contact conditions at the interface. The constraint problem is solved using the penalty method or the augmented Lagrangian method with the Uzawa updating scheme.

Design of a Hierarchical Assembly at a Solid-Liquid Interface Using an Asymmetric Protein Needle.

Design and control of processes for a hierarchical assembly of proteins remain challenging because it requires consideration of design principles with atomic-level accuracy. Previous studies have adopted symmetry-based strategies to minimize the complexity of protein-protein interactions and this has placed constraints on the structures of the resulting protein assemblies. In the present work, we used an anisotropic-shaped protein needle, gene product 5 (gp5) from bacteriophage T4 with a C-terminal hexahistidine-tag (His-tag) (gp5_CHis), to construct a hierarchical assembly with two distinct protein-protein interaction sites. High-speed atomic force microscopy (HS-AFM) measurements reveal that it forms unique tetrameric clusters through its N-terminal head on a mica surface. The clusters further self-assemble into a monolayer through the C-terminal His-tag. The HS-AFM images and displacement analyses show that the monolayer is a network-like structure rather than a crystalline lattice. Our results expand the toolbox for constructing hierarchical protein assemblies based on structural anisotropy.

Compactive deformation of incoming calcareous pelagic sediments, northern Hikurangi subduction margin, New Zealand: Implications for subduction processes

Calcareous rocks are commonly found in subduction zones, but few studies have investigated the consolidation and compactive deformation of these rocks prior to subduction, and their potential effects on subduction and accretionary processes are thus poorly understood. Using drilling data obtained during International Ocean Discovery Program (IODP) Expeditions 372 and 375 combined with 2D and 3D seismic reflection data, the structure, growth history, and slip rates of normal faults identified in the incoming pelagic sedimentary sequences of the Hikurangi Margin were investigated. A seismic coherence depth slice and vertical profiles show that these faults exhibit polygonal structure that has rarely been documented at subduction margins. The polygonal faults are closely spaced and layer-bound within sequences dominated by pelagic carbonate and calcareous mudstone of Paleocene-Pliocene age. Kinematic modeling and 2D displacement analysis reveal that fault throws decrease toward the upper and lower tipline. In detail, two groups of throw profiles are defined by locations of displacement maxima, possibly reflecting lateral variations in physical properties. The polygonal fault system (PFS) likely formed by syneresis processes that involve diagenetically induced shear failure and volumetric contraction of the pelagic unit associated with fluid escape. Fault growth sequences reveal multiple, weakly correlated intervals of contemporaneous seafloor deformation and sedimentation and allow estimates of fault slip rates. We find evidence for a significant increase in typical slip rates from 0.5-3 m/Ma during pelagic sedimentation to >20 m/Ma following the onset of terrigenous sedimentation. These observations suggest that rapid loading of the pelagic sediments by the trench-wedge facies was associated with renewed and faster growth of the PFS. The PFS will eventually be transported into the base of the accretionary wedge, enhancing geometric roughness and heterogeneity of materials along the megathrust, and providing inherited zones of weakness. Selective fault reactivation may facilitate deformation and episodic vertical fluid migration in the lower wedge associated with microearthquakes, tremor, and slow slip events.

Detection Method for Shrinkage Cavities Inside Spheroidal Graphite Cast Iron Using Vibration Measurement by Electromagnetic Force Excitation

The inspection of shrinkage cavities formed inside spheroidal graphite cast iron during the manufacturing process of spheroidal graphite cast products, including large cast structures and machine parts, is considered to be important for quality assurance of cast products. X-ray and ultrasonic methods are generally used for this inspection. However, the former inspection method takes a long time and considerable equipment costs, the latter method requires the use of water as a contact couplant and to polish the surface of the inspection site of the cast iron. In an actual manufacturing factory, there is a demand for a simple and quick method for inspecting shrinkage cavities inside cast iron. In this research, as a simple and high-speed inspection method to evaluate shrinkage cavities inside cast iron by measuring of the vibration of the electromagnetic force is proposed. Three-dimensional electromagnetic field analysis using the finite element method and displacement analysis was performed to analyze the phenomenon, and the usefulness of this method was confirmed by verification experiments.

Generalized cyclic bond-slip model of rebar embedded in concrete under lateral pressure: Parameter calibration and numerical implementation

For some reinforced concrete members, the bond-slip between rebar and concrete is sometimes affected by the lateral pressure, e.g., the beam-column joint with the axial load induced by the column. For such cases, a cyclic bond-slip behavior taking into account the effect of lateral pressure is of great significance for seismic numerical analysis of these members/structures. So far, however, there is no available numerical approaches which can consider the cyclic bond-slip behavior of RC member under lateral pressure. Therefore, this study presents a generalized bond-slip model, which can consider the effect of cyclic loads and lateral pressure simultaneously. Based on the existing test data, the key parameters of the model are calibrated, so that the model can be used for arbitrary cyclic loading history and is easy to be implemented into existing displacement-based numerical code. Furthermore, a four-node zero-thickness bond element is developed in commercial software ABAQUS. The proposed model is implemented into the bond element and verified by the experimental results. The bond element is preliminarily applied to the force–displacement analysis of reinforcing bars in the beam-column joint, and the feasibility of the model in member-level analysis is discussed based on the numerical results.

Mathematical modelling for shield tunneling induced displacement effects on in-service tunnel: theoretical solution including shearing deformation of segment and stiffness reduction of circumferential joints

Tunneling beneath adjacent in-service tunnel can generate displacement of soil, causing adverse impact on the in-service tunnel. Many previous researches simplify the in-service tunnel as a continuous Euler-Bernoulli beam on Winkler foundation, disregarding the shearing deformation of tunnel and existence of joints. A two-stage analysis based on the Timoshenko beam model and Kerr foundation model is presented for estimating the response of in-service tunnel including the effects of segment shearing and circumferential joints stiffness reduction. Firstly, the Loganathan and Poulos solution is adopted to acquire the greenfield displacement induced by shield tunneling. Secondly, the mathematical modeling considering the interaction between shield and in-service tunnel with joint virtual forces reflects the shearing deformation of segments and discontinuity of joints. To take into full consideration for non-linearity and continuity of soil, the Kerr foundation model is employed in tunnel displacement analysis by applying the finite difference method. The accuracy of the two-stage method is then verified with three engineering cases, receiving good alignments. Finally, parametric analyses reveal that soil elastic modulus and in-service tunnel embedment depth have positive effects on tunnel displacement and internal force responses, while in-service tunnel diameter and equivalent bending stiffness have negative relationship. Equivalent shearing stiffness exhibits a complex relationship, increasing one response but decreasing another. The reduction factor has a minimal effect on tunnel displacement and segment moment, but does impact local rotation around joints.

Equivalent linear method with complex frequency for response analyses of the ground subject to fling-step displacements

The equivalent linear (EL) method is one of the most commonly used methods for seismic ground response analyses in engineering practice. However, it cannot be used to directly calculate the displacement response of the ground subject to fling-step displacements because these are characterized by non-zero final values and ordinary Fourier transform with real frequency breaks down. This article shows that this difficulty can be overcome by introducing a complex frequency in the equivalent linear method. The technique of using complex frequency was used in existing studies for analyses of undamped structures and is known as the exponential window method (EWM). In essence, the same approach is effective for the analysis of fling-step displacement. Herein, why this works for fling-step displacements is described and an application to a vertical array record which captured near-fault fling-step displacements is shown. The reasonable agreement between the observed and synthetic time histories, both for acceleration and displacement, illustrates the applicability of the method to the response analyses of the ground subject to fling-step displacements.

Integration of multi-sensor MTInSAR and ground-based geomatic data for the analysis of non-linear displacements affecting the urban area of Chieuti, Italy

Slow instability phenomena can turn into rapid events, showing sudden accelerations and potentially developing in a threat for structures and people. In such scenarios, an in-depth understanding of the spatial and temporal evolution of the ground surface displacement field becomes essential for preventing potential catastrophes. In this work, Multi-Temporal Interferometry SAR (MTInSAR) technique based on COSMO-SkyMed and Sentinel-1 SAR acquisitions and ground measurements have been used to study an ongoing instability occurrence, affecting the urban area of Chieuti, a town located in the Southern Italy. Archives of C and X-band SAR data and geomatic monitoring observations spanning seven, five and one year, respectively, have been analyzed exploiting the complementary characteristics of these datasets. This enabled the accurate spatial-temporal characterization of the ground displacement field in the study area, the identification of sectors evidencing instability problems and a comprehensive reliability assessment of the detected displacements trends, characterized by strong non-linearities. Moreover, the multi-geometry DInSAR analysis allowed to evaluate the horizontal and vertical components of the detected motion, confirming the nature of the instability process, related to a deep landslide mechanism affecting the western slope of the town.

Investigation of differential shrinkage stresses in a revolution shell structure due to the evolving parameters of concrete

Abstract The article focuses on the influence of differential shrinkage linked by drying at the early-age displacements and strain distribution of a concrete ring specimen. Depending on the gradient of dimension changes through the thickness, tensile stress occurs near the exposed surface where drying is greater and thus results in strain gradients development. An experimental design was carried out on a concrete ring cast in laboratory conditions in order to monitor strains and displacements. Subsequently, a finite element method was used to simulate the ring’s behaviour in drying conditions. The gradient development linked by a non-uniform moisture distribution in the thickness is established by solving the non-linear partial differential drying equation with Mensi’s diffusion law. The stress and displacement analysis was modeled by three nodes curved shell FEM (CSFE-sh) based on strain approximation with the shell theory. Finally, the ring’s behaviour includes both differential shrinkage resulting in the mechanical and physical properties of gradients development in the thickness and the influence of prestressing, in which the tensile creep effects have a great influence. The comparison of experimental results with numerical simulation shows that drying and tensile creep phenomena have the most important influence on the early-age stress development in the walled ring.

Atomic displacement damage energy model up to high recoil energy

Current analytical displacement damage models are derived for recoil energy below 24.9AZ4/3 keV. The present work studies the damage energy beyond this theoretical limit using SRIM Full Cascade (FC) and DART calculations. Notably, the three damage energies computed with different methods from the same SRIM simulation are not equal, whereas they are believed to be the same in principle. The method of directly subtracting the ionization energy from total recoil energy is recommended for both FC and Quick Calculation (QC) options. It is also observed that the damage energy seems to unphysically depend on the density of monatomic material in SRIM FC. While the classical analytical models imply the saturated damage energy for high recoil energy, this saturation is not observed in SRIM FC nor in the numerical solution of the Lindhard equation using reasonable electronic stopping powers.

Rethinking tourism-driven urban transformation and social tourism impact: A scenario from a CEE city

Even though research on tourism-oriented urban change is growing in number, little attention is paid to urban policy drivers of this transformation, especially in the context of Central and Eastern Europe (CEE). There is also a lack of knowledge about how such changes are perceived by long-term residents who live in ‘tourist neighborhoods’. For tourism-oriented urban change, urban regeneration and urban entrepreneurial policies have been of key importance. Furthermore, in CEE cities, tourism-driven urban change was strongly influenced by the character of the transformation of this region after the fall of the Berlin wall in 1989. In-depth interviews with long-term residents of the ‘tourist neighborhood’ (historic city center) of Kraków (Poland) have allowed to distinguish various types of tourism-related displacement in the context of a CEE tourism city. Their connections to depopulation, social changes to the neighborhood and tourism-driven financialization of historical housing have been subject to investigation. The analysis of displacement has been supplemented with the category of solastalgia, previously unused in urban studies.

Characterization of Relative Movements between Blocks Observed in a Concrete Dam and Definition of Thresholds for Novelty Identification Based on Machine Learning Models

Dam surveillance activities are based on observing the structural behaviour and interpreting the past behaviour supported by the knowledge of the main loads. For day-to-day activities, data-driven models are usually adopted. Most applications consider regression models for the analysis of horizontal displacements recorded in pendulums. Traditional regression models are not commonly applied to the analysis of relative movements between blocks due to the non-linearities related to the simultaneity of hydrostatic and thermal effects. A new application of a multilayer perceptron neural network model is proposed to interpret the relative movements between blocks measured hourly in a concrete dam under exploitation. A new methodology is proposed for threshold definition related to novelty identification, taking into account the evolution of the records over time and the simultaneity of the structural responses measured in the dam under study. The results obtained through the case study showed the ability of the methodology presented in this work to characterize the relative movement between blocks and for the identification of novelties in the dam behaviour.

Accurate Small Sized Load Bearing Components Displacement Analysis

Load bearing components with cross sections in scale of millimeters attracted popularity with the advance in material engineering. As standard size scale of load bearing structures are around 100 times bigger than millimeter sized components, classical stability analyzes may be insufficient to simulate all stress and strains in load bearing structures which may lead to fail in whole structure. In this paper, the displacement analysis of small cross-sectional load bearing metals is presented using finite element analyzes and higher order elasticity theory. To take the size effect into consideration surface elasticity theory is selected. It is obtained higher order analyzes results differs from F.E.A. results. This result reveals that classical methods are insufficient to give accurate success in millimeters scale.

Stiffening Cello Bridges with Design

In instruments of the violin family, the bridge is the part in charge of transferring the vibrational energy of the strings into the body and therefore contributes greatly to the sound of the instrument. The bridge needs to be light enough to efficiently transmit the strings’ movement yet rigid enough to support the static load of the strings. Historically, there have been several attempts at solving this problem with different designs, arriving in the early 1800s at the two current models: the French and the Belgian. Recently, in Cremona, Italy, the Amorim family of luthiers has developed a new cello bridge design. Inspired by their work, we study the influence of the shape of the legs of the cello bridge on its static and vibrational behavior through parametric modeling and simulations using the Finite Element Method. In particular, we perform displacement and modal analysis for different boundary conditions, providing in addition a detailed description of the mode shapes. We also compute and compare Frequency Response Functions for the different geometries. Our results show that shape can indeed be used to control the vibrational and static responses of the cello and consequently tune its sound.

A hybrid physical data informed DNN in axial displacement prediction of immersed tunnel joint

ABSTRACT Due to complex interactions between immersed tunnel and surrounding environment, it is difficult to apply theoretical analysis for axial displacement (DIS) of immersion joints. To develop a generalised model for DIS prediction, Deep Neural Network (DNN) could be considered. However, the spatial generalisation of black-box DNN models is not always convincible for small data. In this study, we proposed a novel hybrid physical data (HPD) informed DNN model with improved spatial generalisation for prediction of DIS. The physical mechanism of DIS is firstly analysed by correlation between DIS and other monitoring data. The HPD is then created based on the physical analysis and contributes to the DNN as a substituting feature rather than an additional feature. Three DNN models fed with different groups of features are compared, while the proposed HPD-DNN has outperformed others in terms of both prediction generalisation as well as accuracy. The permutation feature importance analysis reveals that HPD has effectively enhanced physical interpretation of DNN, which supports the results stated in physical analysis. The application of HPD is further verified to enhance the spatial generalisation of prediction for not only DNN but also other black-box models, which is promising for insufficient data problems in geotechnical engineering.

Isogeometric Analysis of Longitudinal Displacement of a Simplified Tunnel Model Based on Elastic Foundation Beam

Serious uneven settlement of the tunnel may directly cause safety problems. At this stage, the deformation of the tunnel is predicted and analyzed mainly by numerical simulation, while the commonly used finite element method (FEM) uses low-order continuous elements. Therefore, the accuracy of tunnel settlement prediction is not enough. In this paper, a method is proposed to study the vertical deformation of the tunnel by using the combination of isogeometric analysis (IGA) and Bézier extraction operator. Compared with the traditional IGA method, this method can be easily integrated into the existing FEM framework, and ensure the same accuracy. A numerical example of an elastic foundation beam subjected to uniformly distributed load and an engineering example of an equivalent elastic foundation beam of the tunnel are given. The results show that the solution of the IGA method is closer to the theoretical solution of the initial-parameter method than the FEM, and the accuracy and reliability of the proposed model are verified. Moreover, it not only provides some theoretical support for the longitudinal design of the tunnel, but also provides a new way for the application and popularization of IGA in tunnel engineering.

Комплекс методик для снижения токсичности лучевой терапии при местнораспространённом раке прямой кишки

In order to reduce the incidence of acute radiation toxicity during chemoradiation therapy in patients with rectal cancer, we proposed a prone position for patient on the treatment table using a BellyBoard fixation device. The data on 156 patients with rectal cancer who underwent radiation therapy were analyzed, 108 patients were treated in prone position, 48 patients were treated in supine position. We obtained data on the reduction of small intestine volumes treated with the calculated dose of 35, 40 and 45 Gy (V35, V40 and V45) when positioning in the prone position compared to positioning in the supine position when contouring the volume of the small intestine in a single block (bowelbag). Treatment in the prone position using a BellyBoard fixation device significantly reduced acute urogenital toxicity (by 30%) and significantly reduced the incidence of grade 2 cystitis by 4 times (from 12% to 3%) compared with treatment of the patient in supine position. Treatment in the prone position using a BellyBoard significantly reduced the incidence of grade 3 enterocolitis by 5 times (from 10% to 2%) compared with treatment of the patient in supine position. Despite a number of objective advantages of using a BellyBoard fixation device, treatment in prone position is associated with a decrease in the reproducibility of patient positioning compared to supine position. The main source of error when using a BellyBoard is the unstable position of its aperture relative to the patient's anatomy. Treatment in prone position, planning using intensity-modulated radiation therapy (IMRT) and volume-modulated arc radiation therapy (VMAT), determining the indents during the conversion from the clinical target volume (CTV) to the planned target volume (PTV) based on the analysis of interfractional displacements, determining the optimal multiplicity of visual control may help to reduce the acute toxicity of chemoradiotherapy in patients with local advanced rectal cancer.