Maximum relative displacement of adjacent buildings during ground motions

2012 ◽  
Vol 18 (5) ◽  
pp. 366-371
Author(s):  
Mingqi Lu ◽  
Qingshan Yang ◽  
Na Yang
Keyword(s):  
Ground Motions ◽  
Relative Displacement ◽  
Adjacent Buildings ◽  
Maximum Relative Displacement

Effects of Lumbar Spine Assemblies and Body-Borne Equipment Mass on Anthropomorphic Test Device Responses During Drop Tests

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Daniel Aggromito ◽  
Mark Jaffrey ◽  
Allen Chhor ◽  
Bernard Chen ◽  
Wenyi Yan
Keyword(s):  
Lumbar Spine ◽  
Federal Aviation Administration ◽  
Relative Displacement ◽  
Drop Tower ◽  
Test Device ◽  
Hybrid Iii ◽  
Drop Tests ◽  
Occupant Injury ◽  
Maximum Relative Displacement ◽  
The Impact

When simulating or conducting land mine blast tests on armored vehicles to assess potential occupant injury, the preference is to use the Hybrid III anthropomorphic test device (ATD). In land blast events, neither the effect of body-borne equipment (BBE) on the ATD response nor the dynamic response index (DRI) is well understood. An experimental study was carried out using a drop tower test rig, with a rigid seat mounted on a carriage table undergoing average accelerations of 161 g and 232 g over 3 ms. A key aspect of the work looked at the various lumbar spine assemblies available for a Hybrid III ATD. These can result in different load cell orientations for the ATD which in turn can affect the load measurement in the vertical and horizontal planes. Thirty-two tests were carried out using two BBE mass conditions and three variations of ATDs. The latter were the Hybrid III with the curved (conventional) spine, the Hybrid III with the pedestrian (straight) spine, and the Federal Aviation Administration (FAA) Hybrid III which also has a straight spine. The results showed that the straight lumbar spine assemblies produced similar ATD responses in drop tower tests using a rigid seat. In contrast, the curved lumbar spine assembly generated a lower pelvis acceleration and a higher lumbar load than the straight lumbar spine assemblies. The maximum relative displacement of the lumbar spine occurred after the peak loading event, suggesting that the DRI is not suitable for assessing injury when the impact duration is short and an ATD is seated on a rigid seat on a drop tower. The peak vertical lumbar loads did not change with increasing BBE mass because the equipment mass effects did not become a factor during the peak loading event.

Shock isolation characteristics of a bistable vibration isolator with tunable magnetic controlled stiffness

2021 ◽  
pp. 1-28
Author(s):  
Bo Yan ◽  
Peng Ling ◽  
Yanlin Zhou ◽  
Chuan-yu Wu ◽  
Wen-Ming Zhang
Keyword(s):  
Damping Ratio ◽  
Excitation Amplitude ◽  
Relative Displacement ◽  
Vibration Isolator ◽  
Maximum Acceleration ◽  
Vibration Isolators ◽  
Displacement Ratio ◽  
Shock Isolation ◽  
Maximum Relative Displacement ◽  
Isolation Performance

Abstract This paper investigates the shock isolation characteristics of an electromagnetic bistable vibration isolator (BVI) with tunable magnetic controlled stiffness. The theoretical model of the BVI is established. The maximum acceleration ratio (MAR), maximum absolute displacement ratio (MADR) and maximum relative displacement ratio (MRDR) are introduced to evaluate the shock isolation performance of the BVI. The kinetic and potential energy are observed to further explore the performance of the BVI. The effects of the potential barrier, shape of potential well, damping ratio on the BVI are discussed compared to the linear vibration isolators (LVI). The results demonstrate that the intrawell oscillations and snap-through oscillations are determined by the excitation amplitude and duration time of main pulse. MADR and MRDR of the BVI are smaller than those of the LVI. The maximum acceleration peak amplitude of the BVI is far below that of the LVI, especially when the snap-through oscillation occurs. In brief, the proposed BVI has a better shock isolation performance than the LVI and has the potential to suppress the shock of space structures during the launch and on-orbit deploying process.

scholarly journals Seismic Finite Element Analysis of Lightning Arrester Combination by Casing and Pillar Insulator

2022 ◽  
Vol 2148 (1) ◽  
pp. 012044
Author(s):  
Xiaojun Zhang ◽  
Zhenlin Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Electrical Equipment ◽  
Relative Displacement ◽  
Normal Operation ◽  
Seismic Action ◽  
Peak Acceleration ◽  
Element Analysis ◽  
Maximum Relative Displacement

Abstract The seismic performance of electrical equipment in substations has a great impact on the normal operation of the whole substation. The results of the modal analysis show that the fundamental frequency of the three devices is in the range of 0.9Hz∼1.1Hz. The maximum stress of the casing for the three devices is respectively 55.43MPa, 45.39MPa, 35.26MPa, when the peak acceleration 0.4g seismic action is verified. The maximum stress of insulator is respectively 47.01MPa, 62.72MPa and 30.85MPa, and the maximum relative displacement of the top for the equipment is 617.2mm.

On The Dynamics of Intermittent-Motion Mechanisms. Part 1: Dynamic Model and Response

1983 ◽  
Vol 105 (3) ◽  
pp. 534-540 ◽  
Author(s):  
Ting W. Lee ◽  
A. C. Wang
Keyword(s):  
Dynamic Models ◽  
Damping Ratio ◽  
Relative Displacement ◽  
Dynamical Response ◽  
Damping Force ◽  
Damping Material ◽  
Proposed Model ◽  
Maximum Relative Displacement ◽  
Motion Characteristics ◽  
Intermittent Motion

This paper deals with a basic problem regarding intermittent-motion mechanisms, namely, how to formulate a predicative model for the study of the dynamics of these mechanisms. A mathematical model is developed in this investigation. The model, which includes clearance, damping, material compliance, and mechanism elasticity, is basic to the determination of the dynamical response such as force amplification and motion characteristics of mechanisms with intermittent motion. A new approach in the modeling of system damping is presented. Instead of using damping ratio, which is difficult to estimate accurately, a new damping function is introduced, which characterizes the speed and load dependent nature of damping. Two types of damping functions are proposed and both of their corresponding damping forces satisfy the expected hysteresis boundary conditions, i.e., zero damping force at zero and maximum relative displacement of contact. A comparative study of the present model with conventional dynamic models is performed. It demonstrates the characteristics and the usefulness of the proposed model for the study of the dynamics of intermittent-motion mechanisms.

scholarly journals Characteristic Fatigue Life Research on the Centrifugal Impeller

2019 ◽  
Vol 8 (2S11) ◽  
pp. 2934-2938
Keyword(s):  
Maximum Stress ◽  
Structural Integrity ◽  
Fem Simulation ◽  
Relative Displacement ◽  
Estimation Methods ◽  
Centrifugal Impeller ◽  
Maximum Relative Displacement ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Better Than

The researched work quite essentially deals with the resoluteness of the safety and structural integrity of the centrifugal impeller in withstanding the forces impacted on the targeted materials Ti-6Al-4V and Au2gn. In order to counteract the effects prevalent as a result of profound instabilities such as surging, stalling and choking, the materials were subjected to an intense comparative study, undertaken with respect to primary parameters such as good strength yield, in addition to dispensing a rotational speed of 20000 rpm. The preliminary solid modeling was executed using CATIAV5. Structural Analysis is carried out using ANSYS software in order to establish their strengths together with the location of maximum stress and strain. 2D FEM simulation was done on the impeller. Furthermore the number of cycles to failure was computed using the best amongst the known strain – based life estimation methods. From the modal analysis the ubiquitous critical mode shape along with the frequency at which the maximum relative displacement occurs were obtained. Finally, Ti-6Al-4V was affirmed to be better than Au2gn.

A Novel Orthogonally Separated Isolation System and Its Seismic Performance on a Curved Concrete Bridge

2021 ◽  
pp. 2150158
Author(s):  
Ben Sha ◽  
Chenxi Xing ◽  
Junhong Xu ◽  
Hao Wang ◽  
Aiqun Li
Keyword(s):  
Seismic Response ◽  
Shear Force ◽  
Ground Motions ◽  
Time History ◽  
Relative Displacement ◽  
Analytical Models ◽  
Orthogonal Direction ◽  
Isolation System ◽  
Curved Bridge ◽  
Planar Rotation

The seismic response of curved concrete bridges is complex because of the geometric irregularity and induced planar rotation of the deck, which can magnify the displacement of the deck and deformation of the bearings. To control the planar rotation and thus the seismic response of the curved bridge, an orthogonally separated isolation system (OSIS) is proposed, which consists of the upper and lower isolation parts. With this, the planar relative displacement of the common isolation system is decomposed into the relative displacement of the upper part in one direction and the relative displacement of the lower isolation part in the orthogonal direction. Therefore, the planar rotation can be restrained and the seismic demand of the isolation bearing is decoupled. The analytical models of a curved bridge and the OSIS are established in OpenSees. A suite of 118 ground motions, of which 80 are ordinary and 38 are pulse-like, is selected as input with 24 different angles of incidence so as to consider the seismic variation. Nonlinear dynamic time-history analyses of the two models are conducted to evaluate the effectiveness of the OSIS. The results show that the OSIS can effectively decrease the deck displacement, the bearing deformation and the pier column shear force, especially under the ground motions with higher intensities, while the shear force increases slightly on the abutment.

An Experimental Analysis of the Dynamics of Lightly Damped Subcritically Excited Gear Pairs

2007 ◽  
Author(s):  
James R. Ottewill ◽  
R. Eddie Wilson ◽  
Simon A. Neild
Keyword(s):  
Angular Displacement ◽  
Relative Displacement ◽  
Spur Gears ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Input Amplitude ◽  
Numerical Integrator ◽  
Maximum Relative Displacement ◽  
The Mathematical Model ◽  
Experimental Rig

This paper investigates, through experimentation, the inherently nonlinear dynamics that meshing gear pairs display. The experimental rig consists of 1:1 ratio high-module spur gears connected to high precision encoders. The amplitude of a displacement fluctuation input is varied and the relative motion of the two gears is recorded. The experimental trajectories show at least two stable impacting regimes for each fluctuating input amplitude, differing in the magnitude of the relative angular displacement. The amplitude of motions is sometimes comparable to the backlash size, and for some parameters both noisy solutions with large relative displacement amplitudes and quieter, smaller amplitude solutions may occur. A simple single degree of freedom model is derived, based upon a combined constant velocity and fluctuating displacement input. This model is compared with experimental results in order to understand fundamental contact mechanics. Solutions to the mathematical model are generated using a numerical integrator and predict the maximum relative displacement amplitude motions accurately, but not the smaller amplitude motions. This is because the model omits and simplifies certain mechanisms such as meshing impacts and gear eccentricity, both of which will be added in future investigation.

Investigation into Central-Difference and Newmark’s Beta Methods in Measuring Dynamic Responses

2013 ◽  
Vol 831 ◽  
pp. 95-99 ◽  
Author(s):  
Behzad Mohammadzadeh ◽  
Hyuk Chun Noh
Keyword(s):  
Damping Ratio ◽  
Relative Displacement ◽  
Dynamic Responses ◽  
Dynamic Loads ◽  
Ground Acceleration ◽  
Central Difference ◽  
Earthquake Force ◽  
Central Difference Method ◽  
Require Response ◽  
Maximum Relative Displacement

Studies in the structural systems include two main approaches, design and analysis, which require response evaluation of structures to the external loads including live and dead loads. Structures behave statically and dynamically for static and dynamic loads, respectively. One of the most important dynamic loads acting on a structure is earthquake force. In order to find responses of structures subjected to earthquake, several schemes of direct integration can be used. This study deals with two methods of calculating dynamic responses of a single-degree of freedom oscillator, i.e., central difference method (CDM) and Newmarks beta method (NBM), using recorded ground acceleration for 60seconds. The maximum relative acceleration is obtained to determine maximum relative displacement by which estimation of quality and quantity of failure occurred to a structure for a given earthquake is provided. Firstly both CDM and NBM are discussed. Second, for a specific damping ratio dynamic responses are evaluated for periods of range in between 0.1sec to 1.5sec to evaluate the effects of period on responses of system. Third, the effects of damping on dynamic responses of SDOF system are evaluated by considering different damping coefficients from ζ=0 to 0.5. The results are compared and discussed to investigate the range of periods and damping factors where methods can provide a better estimation of responses.

scholarly journals Study on Earthquake-induced Structural Pounding Between Two Adjacent Building Structures with Unequal Heights

2021 ◽  
Vol 20 ◽  
pp. 196-208
Author(s):  
Pedro Folhento ◽  
Rui Carneiro De Barros ◽  
Manuel Braz-César
Keyword(s):  
Dynamic Behavior ◽  
Significant Influence ◽  
Dynamic Properties ◽  
Ground Motions ◽  
Separation Distance ◽  
Building Structures ◽  
Structural Pounding ◽  
Large Cities ◽  
Adjacent Buildings ◽  
Adjacent Building

Structural pounding has been found to have a significant influence on the dynamic behavior of building structures under earthquake excitations. This phenomenon is more probable when the buildings have insufficient separation distance and substantial different dynamic properties. In large cities, it is more common for adjacent buildings to have unequal heights, leading to different demands in the structures’ stories under earthquake-induced pounding. Hence, in this study five different buildings’ configurations with equal or unequal heights and subjected to different ground motions are considered, to study how pounding influences the dynamic behavior of the involved structures. It was found, among other results, that the peak responses tend to suffer amplifications at the stories of the taller building above the height of the shorter building.

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