Effect Of Vertical Motion Research Articles

Неотектоника зоны перехода океан-континент в районе Кот д’Ивуара (Западная Африка)

Structural and geophysical indicators of neotectonics in the area of the continental margin of Côte d'Ivoire are represented in three interacting zones: oceanic, continental and transitional. Together with the time-varying gravitational field, they form a system in which neotectonic processes are enhanced due to their equatorial position. Seismicity is represented by dense clusters of events in the areas of junction of the Strakhov, Sao Paulo and Romansh oceanic transform faults with the continent and their overland continuation. Seismicity and gravity variations show the relationship of deep density changes to stress discharge in the area and the effect of volumetric forces on lithospheric blocks. Free air and isostasy anomalies along the shelf are segmented by the effects of vertical motions. Pull-apart depressions near the passive parts of transform faults indicate basement deformations in the interfault blocks and activation of shear displacements of dextral kinematics near the bend of the passive parts of the faults to the northeast from main oceanic azimuth. Segments with isostasy maxima on the shelf correspond to areas with coarser grain size granulometric composition, indicating leaching of fine sedimentary fraction from the bottom material.

Effects of Vertical Motion on Uplift of Underground Structure Induced by Soil Liquefaction

The uplift of underground structures induced by soil liquefaction can damage underground structure systems. Numerical simulations have shown that uplift is positively correlated with the energy of horizontal input motion. However, the effects of vertical input motion on uplift have not been studied comprehensively in the past. Previous studies on the vertical motion concluded that the effects of vertical motion on uplift depend on the overall characteristics of earthquake motion. These motion characteristics have only been studied separately in previous studies. A comprehensive study to explore the interactions and overall effects of these characteristics on the uplift of underground structures is essential. In this study, the FLAC program with the PM4Sand model was used as a numerical tool to explore the effects of vertical input motion on the uplift of underground structures. The numerical model was calibrated using centrifuge test results, and 48 earthquake motions were selected as input motions to study the effects of the overall characteristics of earthquake motions on the uplift of underground structures. The simulation results show that the frequency content characteristics of horizontal and vertical motion are the major factors affecting the uplift magnitude and the responses of liquefiable soils. However, most simulation cases show that the inclusion of vertical motion causes a 10% difference in the tunnel uplift, compared to cases without vertical motion.

Viscous overstability in dense planetary rings – effect of vertical motions and dense packing

ABSTRACT We investigate the linear axisymmetric viscous overstability in dense planetary rings with typical values of the dynamical optical depth τ ≳ 0.5. We develop a granular flow model which accounts for the particulate nature of a planetary ring subjected to dissipative particle collisions. The model captures the dynamical evolution of the disc’s vertical thickness, temperature, and effects related to a finite volume filling factor of the ring fluid. We compute equilibrium states of self-gravitating and non-self-gravitating rings, which compare well with existing results from kinetic models and N-body simulations. Subsequently, we conduct a linear stability analysis of our model. We briefly discuss the different linear eigenmodes of the system and compare with existing literature by applying corresponding limiting approximations. We then focus on the viscous overstability, analysing the effect of temperature variations, radial and vertical self-gravity, and for the first time the effects of vertical motions on the instability. In addition, we perform local N-body simulations incorporating radial and vertical self-gravity. Critical values for the optical depth and the filling factor for the onset of instability resulting from our N-body simulations compare well with our model predictions under the neglect of radial self-gravity. When radial self-gravity is included, agreement with N-body simulations can be achieved by adopting enhanced values of the bulk viscous stress.

Numerical analysis of the effect of a foil-shaped centerbulb on vertical motion and wake on a catamaran sightseeing boat

Internal and external factors will influence the ship’s ability to maneuver. Therefore, proper planning and calculations are needed to produce good ship comfort and performance in designing a vessel. One of them is paying attention to the quality of the movement, which is the ship’s response to the influence of the sea, such as waves and wakes which are the comparison between the planned speed and the fluid flow velocity on the propeller under water. In an effort to improve the quality of good motion, this study tries to add variations in geometry and position on the foil-shaped center bulb to see the effect of vertical motion and wake. This study solves the existing problems by analyzing them using CFD software. Based on the results of the numerical simulation. In three different ship speed conditions, it has the best response when the wave heading is 0° on the ship with the addition of a center bulb in the midship area. It can reduce the vertical motion value up to 9.35% against the vessel without a center bulb and by 8.73% at 180° wave heading. So that the shape and placement of the foil-shaped center bulb on the catamaran can improve the quality of the ship’s maneuverability.

The effect of vertical motions on damage accumulation on concrete gravity dams

AbstractThe effect of vertical ground motions on the seismic response of dams has long been a concern in the seismic design and evaluation of concrete gravity dams. The guidelines regarding the use of vertical motions in time history analysis (THA) are not clear due to the complexity of the effect as well as the large uncertainty in the motion selection process. The goal of this study is to assess the significance of vertical motions’ effects on concrete gravity dams considering the relevant variability due to ground motion, system frequency response as well as the shaking level. To this end, a carefully selected ground motion set providing realistic vertical(V)/horizontal(H) loading was used in nonlinear THAs of three different systems with different modal properties. In order to evaluate the intensity of shaking on the vertical motions’ effect, the responses were calculated at different seismic levels corresponding to operation, design, and maximum shaking levels. Along with traditional demand parameters commonly employed in assessing seismic response, cracking on the base and at the upstream face of the monolith was adopted as demand measures using a model capable of yielding discrete cracking on the system. The effect of vertical motions was quantified by comparing the response of H + V to H only shaking. The results show the vertical shaking can significantly affect upstream cracking for the operation or design level earthquakes, the effect increasing for larger dams.

Effects of Vertical Motions on Roll of Planing Hulls

AbstractRoll motion of a planing hull can be easily triggered at high speeds, causing a significant change in hydrodynamic pressure pattern, which can threaten the stability of the vessel. Modeling and investigating roll motion of a planing vessel may require a strong coupling between motions in vertical and transverse planes. In the present paper, we have used a mathematical model to analyze the roll of a planing hull by coupling surge, heave, pitch, and roll motions using 2D + T theory to study the effects of roll-induced vertical motions on roll coefficients and response. Mathematically computed forces and moments as well as roll dynamic response of the vessel are seen to be in fair quantitative agreement with experimentally measured values of previously published data. Using the 2D + T method, it has been shown that to model the roll of a planing hull at high speeds, we need to consider the effects of heave, pitch, and surge motions. Through our mathematical modeling, it is found that freedom in vertical motions increases time-dependent roll damping and added mass coefficients, especially at early planing speeds. The results of dynamic response simulations suggest that freedom in the vertical plane can decrease the roll response.

Dynamic Analysis of an Elevator Traveling Cable Using a Singularity-Free Beam Formulation

A round elevator traveling cable is modeled using a singularity-free beam formulation. Equilibria of the traveling cable with different elevator car positions are studied. Natural frequencies and the corresponding mode shapes of the traveling cable are calculated and they are in excellent agreement with those calculated by abaqus. In-plane natural frequencies of the traveling cable do not change much with the car position compared with its out-of-plane ones. Dynamic responses of the traveling cable are calculated and they are in good agreement with those from commercial multibody dynamics software recurdyn. Effects of vertical motion of the car on free responses of the traveling cable and those of in-plane and out-of-plane building sways on forced responses are investigated.

Effects of COM Vertical Oscillation on Joint Torques During 3D Walking of Humanoid Robots

This paper proposes an analysis of the effect of vertical motion of the center of mass (COM) during humanoid walking. The linear inverted pendulum (LIP) model is classically used to deal with humanoid balance during walking. The effects on energy consumption of the COM height remaining constant for humanoid robots, or varying like human beings are studied here. Two approaches are introduced for the comparison: the LIP which offers the great advantage of analytical solving (i.e., fast and easy calculations), and a numerical solving of the IP dynamics, which allows varying the height of the center of mass during walking. The results are compared using a sthenic criterion in a 3D dynamics simulation of the humanoid robot Romeo (Aldebaran Robotics Company) and show a consequent reduction of the robot torque solicitation when the COM oscillates vertically.

Seismic Performance of Reinforced Concrete Bridge Including Effect of Vertical Motion

In recent research of seismic engineering, the damage of bridge due to vertical motion aroused wide concern. Field evidence, experimental results and numerical simulation analysis suggested that vertical ground motion can significantly impact the seismic performance of reinforced concrete (RC) bridge. In this paper, firstly, a FEM model of a continuous rigid frame bridge in China was established . Then the bridge was analyzed using time-history analysis under strong earthquake . Internal force excluding and including vertical motion are compared.Then, the incremental dynamic analysis (IDA) and fiber model are used to calculated the vertical displacement of the node in the top of pier and the sectional curvature of pier. Computational results show that vertical ground motion can increase the internal force and displacement ,as well as reduce the ductility and moment capacity of piers. It is concluded that vertical motion can't be ignored in structure design.

Nonhydrostatic granular flow over 3-D terrain: New Boussinesq-type gravity waves?

Understanding granular mass flow is a basic step in the prediction and control of natural or man-made disasters related to avalanches on the Earth. Savage and Hutter (1989) pioneered the mathematical modeling of these geophysical flows introducing Saint-Venant-type mass and momentum depth-averaged hydrostatic equations using the continuum mechanics approach. However, Denlinger and Iverson (2004) found that vertical accelerations in granular mass flows are of the same order as the gravity acceleration, requiring the consideration of nonhydrostatic modeling of granular mass flows. Although free surface water flow simulations based on nonhydrostatic depth-averaged models are commonly used since the works of Boussinesq (1872, 1877), they have not yet been applied to the modeling of debris flow. Can granular mass flow be described by Boussinesq-type gravity waves? This is a fundamental question to which an answer is required, given the potential to expand the successful Boussinesq-type water theory to granular flow over 3-D terrain. This issue is explored in this work by generalizing the basic Boussinesq-type theory used in civil and coastal engineering for more than a century to an arbitrary granular mass flow using the continuum mechanics approach. Using simple test cases, it is demonstrated that the above question can be answered in the affirmative way, thereby opening a new framework for the physical and mathematical modeling of granular mass flow in geophysics, whereby the effect of vertical motion is mathematically included without the need of ad hoc assumptions.

Dynamic response of deep soft soil deposits under multidirectional earthquake loading

The analysis of site response to earthquake is of great importance for seismic design of structure. Although it has long been recognized that the ground is simultaneously subjected to both horizontal and vertical motions during a real earthquake, the effect of vertical motion is usually ignored in most site response analyses. Moreover, some studies show that there are significant differences in site responses for saturated and unsaturated soil deposits, and site response is influenced by variation of groundwater table. Therefore, these factors should be considerably considered in the dynamic site response analysis. Based on the results of geological investigation as well as laboratory and field tests conducted in Shanghai, a deep geotechnical profile with a depth of 280 m is analyzed in this paper. By using a verified, fully coupled and inelastic finite element procedure, a series of numerical analyses is carried out for a deep soft soil profile subjected to multidirectional earthquake loadings. Parameters of the model in the procedure are calibrated by field and laboratory tests. Numerical results demonstrate that the behavior of vertical amplification is quite different from the horizontal counterpart. Furthermore, the use of a single horizontal component as seismic input in site response analysis, neglecting the other horizontal component and the vertical one, may result in considerable underestimation of site response. Variation of groundwater table brings about a profound effect on both vertical and horizontal motions, its ratio, the response spectra at ground surface, and excess pore water pressure ratio. The analysis can capture a more complete and fundamental aspects of ground response for preliminary seismic assessment.

A Study on 3D Isolation Effect on High-Rise Building Subjected to Near-Field Ground Motions

Isolation technology is widely applied in civil engineering nowadays, while it is indicated by seismic damage investigations that the effect of vertical motion on buildings under earthquake couldn’t be ignored. In order to study the 3D isolation effect on high-rise buildings subjected to near-field ground motions, the finite element analysis of an 11-story reinforced concrete frame-shear wall building is conducted, three ground motions are selected, three kinds of structural model are calculated, which are without isolation, with horizontal isolation and with three-dimensional isolation. By analyzing and comparing the seismic response results of models, the 3D isolation effect is studied, and some conclusions are obtained.

Influence of vertical earthquake motion and pre-earthquake stress on joint response of precast concrete segmental bridges

This paper investigates the seismic response of precast concrete segmental bridges using detailed, 2-D nonlinear time-history analyses and focuses on the behavior of segment-to-segment joints constructed using the balanced-cantilever method. Analytical models of full-scale precast concrete segmental bridges with geometries and characteristics similar to the Otay River Bridge in California were used in this study. 20 near-field earthquake records were used to determine the median joint response as well as to quantify the effect of vertical motion on the joint response. Four different pre-earthquake stress conditions were studied to determine whether the effects of creep, shrinkage, and temperature affect the seismic response of segment joints. Results indicated that vertical earthquake motions and the pre-earthquake stress state can significantly alter the response of segment joints.

Mesoscale Convective Vortices Observed during BAMEX. Part II: Influences on Secondary Deep Convection

Abstract Observations from the Bow Echo and Mesoscale Convective Vortex (MCV) Experiment are used to examine the role of the five mesoscale convective vortices described in Part I on heavy precipitation during the daytime heating cycle. Persistent widespread stratiform rain without deep convection occurs for two strong MCVs in conditionally stable environments with strong vertical shear. Two other MCVs in moderate-to-strong vertical shear have localized redevelopment of deep convection (termed secondary convection) on their downshear side, where conditional instability exists. The strongest of the five MCVs occurs in weak vertical shear and has widespread secondary convection, which is most intense on its conditionally unstable southeast periphery. The two MCVs with only localized secondary convection have well-defined mesoscale vertical motion couplets with downshear ascent and upshear descent above the planetary boundary layer (PBL). Although the amplitude is significantly greater, the kinematically derived vertical motion dipole resembles that implied by steady, vortex-relative isentropic flow, consistent with previous idealized (dry) simulations and diagnoses based on operational model analyses. In the other three cases with either widespread precipitation or weak environmental vertical shear, the kinematic and isentropic vertical motion patterns are poorly correlated. Vertical motions above the PBL provide a focus for secondary convection through adiabatic cooling downshear and adiabatic warming upshear of the MCV center. The MCVs occur within surface frontal zones with large temperature and moisture gradients across the environmental vertical shear vector (Part I). Thus, the effect of vertical motions on conditional instability is reinforced by horizontal advections of high equivalent potential temperature air downshear, and low equivalent potential temperature air upshear within the PBL. On average, the quadrant immediately right of downshear (typically southeast of the MCV center) best supports deep convection because of the juxtaposition of greatest mesoscale ascent, high equivalent potential temperature PBL air, and MCV-induced enhancement of the vertical shear.

高速旅客船の乗り心地評価に関する研究 (第1報)

The purpose of this study is to establish an evaluation method of ride comfort of high-speed passenger craft. For the conventional displacement-type ships, vertical acceleration was used to be analysed so as to estimate ride quality of vessels or the motion sickness incidence (MSI) which represents the percentage of a group who will vomit during the voyage. This is because the principal vertical motion of most ships is close to 0.2 Hz where motion sickness sensitivity is considered to be at a maximum. Various types of stabilizer have been designed to reduce the rolling motions of ships. However, it is pointed out that lateral acceleration cannot be negligible for evaluating ride comfort of especially high-speed catamaran. Effect of vertical motion might be rather small because oscillatory frequencies of vertical motion are somewhat higher. Sway motion of high-speed crafts therefore comes to be a research subject overseas too. The authors have conducted experiment on ride comfort of a high-speed craft. Ship motion and subjects' psychological and physiological responses were measured in a high-speed craft running across the Bay of Osaka. The present paper deals with analysis of ship motion and proposes an evaluation method introducing the concept of the “frequency weighting” defined in ISO 2631-1 (1997).

Effects of Low Frequency Vibration on Train Motion Sickness

In order to identify the vibrational characteristics influencing motion sickness experienced on trains, a poll of approximately 4,000 commercial passengers was carried out and vibration measurements taken on each train involved. When the results were summarized, it was revealed that the ratio of passengers who felt motion sickness on tilting trains was higher than that on non-tilting trains. Low frequency lateral motions in the range 0.25 to 0.32 Hz highly influenced the degree of motion sickness. Unlike seasickness, vertical motion effects were not apparent and there was a wide variation in susceptibility to motion sickness, with data from women and young people showing them to be more susceptible. Traditional frequency weighting curves for evaluating vibrational discomfort were ineffective for motion sickness evaluation. Consequently, a new frequency weighting curve needed to be proposed.

Reappraisal of vertical motion effects on soil liquefaction

INTRODUCTION Ground motion induced by an earthquake is in general characterised by a vector with its components along the vertical and two horizontal directions. In current practice and research, the effect of vertical ground motion is often disregarded while attention is focused mainly on the horizontal ground motion. Two primary reasons have been accepted for neglect of the vertical seismic motion. First, engineering structures are considered to have adequate resistance to dynamic forces induced by the vertical ground motion, which is generally much smaller than its horizontal counterparts. If the effect of vertical motion is explicitly included in design, it is typically assumed that the ratio of vertical to horizontal (V/H) response spectra will not exceed two-thirds (International Code Council, 1996). Second, the vertical ground motion is considered to have negligible influence on soil liquefaction because it induces almost purely compressive stresses, which cannot cause changes in the effective stress in the subsoil (Ishihara, 1996). However, there are repeated observations from recent earthquakes, such as those in Northridge, California, in 1994 and Kobe, Japan, in 1995 (Bardet et al., 1997; NCEER, 1997), that the rule-of-thumb ratio of two-thirds is a poor descriptor of vertical ground motions. The (V/H) spectral ratios may substantially exceed two-thirds in the near field of moderate and large earthquakes and at short periods. A typical case comes from the three-dimensional borehole array recordings obtained at Port Island, Kobe, during the 1995 Kobe earthquake (Yang & Sato, 2000), which indicated that the peak vertical acceleration was twice as high as the peak horizontal acceleration at the ground surface (Fig. 1). An integrated study of this case history (Yang & Sato, 2000; Yang et al., 2000) has revealed that both the horizontal and the vertical ground motions were closely related to the liquefied soil layers and, particularly, the condition of partial saturation in the near-surface soils played a crucial role in the amplification of vertical motion. Partial saturation conditions may occur in certain situations as a result of fluctuating groundwater tables associated with natural or man-made processes. They may also exist in offshore sites or marine sediments. Thus considerable interest arises in reappraising the effect of vertical ground motion on soil liquefaction and, especially, in clarifying whether or not this effect is dependent on the saturation condition. Aimed at this goal, analyses have been conducted by means of a verified, fully coupled numerical procedure for a model deposit subjected to a variety of combinations of loading and saturation conditions. A significant finding of the analyses is that the current understanding that the effect of vertical motion on liquefaction is negligible may not always hold true; rather, the effect is dependent on the saturation condition. This paper presents the main results and the related mechanisms. Implications of the results for dynamic model testing in the geotechnical laboratory are also addressed briefly.

원전기기의 면진을 위한 진동대 실험 II : FPS

본 연구에서는 원전기기의 내진안전성을 증가시키기 위해 면진장치를 적용한 기기의 진동대 실험을 수행하였다. 원전구조물과 유사한 진동수 특성을 가지는 실험모형을 제작하여 실험에 사용하였으며 구조물 내부의 기기를 모형화 하기 위하여 400kg의 강체를 사용하였다. 탁월주파수 특성이 상이한 3종류 지진파를 이용하여 진동대 실험을 수행하였다. 면진장치로는 마찰진자형 베어링(FPS)을 사용하였다. 입력지진의 최대가속도를 0.1g, 0.2g, 0.25g의 3단계로 변화시키면서 실험을 수행하였고 또한 1방향, 2방향 및 3방향 가진에 의한 거동을 분석하였다. 실험결과 지진파의 연직성분이 FPS의 면진성능에 영향을 미치는 것을 알 수 있었으며 펄스타입의 속도성분이 큰 근거리 지진인 경우 면진효과가 감소하는 것을 알 수 있었다. This paper presents the results of experimental studies on the equipment isolation effect in the nuclear containment. For this purpose, shaking table tests were performed. The purpose of this study is enhancement of seismic safety of equipment in the Nuclear Power Plant. The isolation system, known as Friction Pendulum System (FPS), combines the concepts of sliding bearings and pendulum motion was selected. Peak ground acceleration, bidirectional motion, effect of vertical motion and frequency contents of selected earthquake motions were considered. As a result, these are founded that the vertical motion of seismic wave affect to the base isolation and the isolation effect decreased in case of near fault earthquake motion.

Effect of Vertical Motions on Seismic Response of Highway Bridges

Results of a parametric study of the effects of vertical motions on the seismic response of typical highway bridges are presented. Six different bridges covering a variety of types and geometry are subjected to a suite of ground motions representing events with magnitudes of 6.5 and 7.5 at both rock and soil sites, and with fault distances of 1, 5, 10, 20, and 40 km. Response spectrum analyses are performed on all six bridges for all ground motion parameters. Response results excluding and including vertical motions are compared, with the effect of the vertical motion expressed as a ratio of the dead load actions. Three of the bridges are also analyzed using linear time history analysis to validate the response spectrum results. Analysis of one bridge is extended to incorporate nonlinear behavior of the piers. Recommendations are made for including the effects of vertical ground motions in a code format, and will be considered for adoption by AASHTO in May 2003.

Analytical and Experimental Seismic Studies of Transformers Isolated with Friction Pendulum System and Design Aspects

This paper presents the results of analytical and experimental studies on the use of an advanced technology for seismic rehabilitation and design of substation transformers. The isolation system, known as Friction Pendulum System (FPS), combines the concepts of sliding bearings and pendulum motion. Discussion of formulation is followed by an extensive parametric study using a typical transformer. Among parameters are peak ground acceleration, bidirectional motions, effect of vertical motion, and isolation radius. Inertia reduction and the maximum displacement of the system are the criteria used in evaluating the seismic response and the effectiveness of FPS bearings. Using the results of the parametric study, charts that can be used in design are developed for each criterion. Furthermore, two commonly used response combination rules, namely SRSS and CQC, are evaluated, and recommendations are made with regard to the suitability of each method in estimating the total responses under orthogonal motions. Finally, the results of an experimental study, which considers 1-D, 2-D, and 3-D responses of fixed and base isolated transformer models supporting a bushing, are presented. Experimental results are consistent with the analytical results and further support the effectiveness of FPS bearings in reducing inertia forces, thus, providing a suitable procedure to mitigate the seismic hazard of substation transformers.