scholarly journals Computer simulation of multi-storey structures subjected to ground motion

1965 ◽  
Vol 55 (2) ◽  
pp. 487-500
Author(s):  
H. S. Ward
Keyword(s):  
Ground Motion ◽  
Structural Parameters ◽  
The Other ◽  
Viscous Damping ◽  
Frequency Content ◽  
Base Shear ◽  
Shear Forces ◽  
Modes Of Vibration ◽  
Hybrid Computer ◽  
Fixed End

Abstract A hybrid computer system has been used to simulate some five-storey structures excited by ground motion. Five types of buildings were investigated to find the effect of some structural parameters on the dynamic response of the buildings. The factors that have been considered are the distribution of stiffness and mass in the structure, the type of foundation condition, and the action of viscous damping. The results indicate that it may be reasonable to calculate the base shear forces, created by ground motion, as a function of the fundamental period of the building. In the case of lightly damped structures, however, the distribution of forces through the height of the structure is also shown to be dependent on the other dynamic characteristics of the building, as well as the frequency content of the ground motion. Viscous damping considerably reduces the forces acting on a structure, and also tends to eliminate modes of vibration other than the fundamental. A pinned-end foundation condition is also shown to reduce the forces acting on the lower storeys of a building compared with the fixed-end condition.

scholarly journals Method for Robot Manipulator Joint Wear Reduction by Finding the Optimal Robot Placement in a Robotic Cell

2021 ◽  
Vol 11 (12) ◽  
pp. 5398
Author(s):  
Tomáš Kot ◽  
Zdenko Bobovský ◽  
Aleš Vysocký ◽  
Václav Krys ◽  
Jakub Šafařík ◽  
...  
Keyword(s):  
Angular Velocity ◽  
Dynamic Simulation ◽  
Robot Manipulator ◽  
The Other ◽  
Robotic Arm ◽  
Robotic Cell ◽  
Wear Reduction ◽  
Fixed End ◽  
Robot Placement ◽  
Collaborative Robot

We describe a method for robotic cell optimization by changing the placement of the robot manipulator within the cell in applications with a fixed end-point trajectory. The goal is to reduce the overall robot joint wear and to prevent uneven joint wear when one or several joints are stressed more than the other joints. Joint wear is approximated by calculating the integral of the mechanical work of each joint during the whole trajectory, which depends on the joint angular velocity and torque. The method relies on using a dynamic simulation for the evaluation of the torques and velocities in robot joints for individual robot positions. Verification of the method was performed using CoppeliaSim and a laboratory robotic cell with the collaborative robot UR3. The results confirmed that, with proper robot base placement, the overall wear of the joints of a robotic arm could be reduced from 22% to 53% depending on the trajectory.

On the mN, M Relation for Eastern North American Earthquakes

1987 ◽  
Vol 58 (4) ◽  
pp. 119-124 ◽  
Author(s):  
Gail M. Atkinson ◽  
David M. Boore
Keyword(s):  
North America ◽  
Stochastic Model ◽  
Ground Motion ◽  
Seismic Moment ◽  
The Other ◽  
Moment Magnitude ◽  
Scaling Relations ◽  
Eastern North America ◽  
Data Set ◽  
Meaningful Data

Abstract A stochastic model of ground motion has been used as a basis for comparison of data and theoretically-predicted relations between mN (commonly denoted by mbLg) and moment magnitude for eastern North America (ENA) earthquakes. mN magnitudes are recomputed for several historical ENA earthquakes, to ensure consistency of definition and provide a meaningful data set. We show that by itself the magnitude relation cannot be used as a discriminant between two specific spectral scaling relations, one with constant stress and the other with stress increasing with seismic moment, that have been proposed for ENA earthquakes.

Vibration of Rectangular Plates by the Ritz Method

1950 ◽  
Vol 17 (4) ◽  
pp. 448-453 ◽  
Author(s):  
Dana Young
Keyword(s):  
Ritz Method ◽  
Normal Modes ◽  
Approximate Solutions ◽  
The Other ◽  
Rectangular Plates ◽  
Elastic Plates ◽  
Modes Of Vibration ◽  
Ritz’S Method ◽  
Square Plate ◽  
Set Up

Abstract Ritz’s method is one of several possible procedures for obtaining approximate solutions for the frequencies and modes of vibration of thin elastic plates. The accuracy of the results and the practicability of the computations depend to a great extent upon the set of functions that is chosen to represent the plate deflection. In this investigation, use is made of the functions which define the normal modes of vibration of a uniform beam. Tables of values of these functions have been computed as well as values of different integrals of the functions and their derivatives. With the aid of these data, the necessary equations can be set up and solved with reasonable effort. Solutions are obtained for three specific plate problems, namely, (a) square plate clamped at all four edges, (b) square plate clamped along two adjacent edges and free along the other two edges, and (c) square plate clamped along one edge and free along the other three edges.

Robust Passive-Active Mounts for Machinery and Equipment

1997 ◽  
Author(s):  
J. Hannsen Su
Keyword(s):  
Resonant Frequency ◽  
Vibration Isolation ◽  
Vibration Suppression ◽  
Low Frequency ◽  
The Other ◽  
Resonant Frequencies ◽  
Vibration Magnitude ◽  
Fixed End ◽  
Degradation Problem ◽  
Universal Application

Abstract Conventional vibration isolation mounts are not as effective as expected on a practical foundation whose resonant frequencies normally are within the bandwidth of interest. In addition, the low frequency enhancement is a characteristic of the passive mounts. Applying inertia actuators to the bottom attachment plate of the conventional mounts overcomes these shortcomings and enhances their performance significantly. This design concept has universal application since it is applicable to any dynamic system. It requires very little power and force capacity, i.e., a small percentage of the disturbance force, from the actuators to be effective for frequencies higher than the resonant frequency of the mount itself. The effectiveness of the proposed mounts for the machinery is demonstrated on the load transmissibility reduction at the foundation support (fixed end) due to disturbance from machinery above mounts. On the other hand, the vibration magnitude reduction of equipment above mounts due to disturbance from the foundation is used for evaluating the equipment isolation effectiveness. There is no stabilty or degradation problem when a number of the passive-active mounts are used on the same foundation. Furthermore, the more of this type of mounts used on a foundation the more effective the vibration suppression and the smaller actuator force requirement for each passive-active mount.

scholarly journals Effect of the Directional Components of Earthquakes on the Seismic Behavior of an Unanchored Steel Tank

2020 ◽  
Vol 10 (16) ◽  
pp. 5489
Author(s):  
Rulin Zhang ◽  
Shili Chu ◽  
Kailai Sun ◽  
Zhongtao Zhang ◽  
Huaifeng Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Ground Motion ◽  
Seismic Behavior ◽  
Axial Stress ◽  
Ground Motions ◽  
Great Influence ◽  
Liquid Sloshing ◽  
Base Shear ◽  
Element Method

This paper investigates the effect of the multi-directional components of ground motion on an unanchored steel storage tank. Both the liquid sloshing effect and contact behavior between the foundation and tank are included in the study. A three-dimensional model for a foundation–structure–liquid system is numerically simulated using the finite element method. The Lagrange fluid finite element method (FEM) in ANSYS is used to consider the liquid–solid interaction. In the liquid–structure–foundation interaction model, the contact and target elements are adapted to simulate the nonlinear uplift and slip effects between the tank and the foundation. Three earthquake ground motions are selected for evaluating the seismic behavior of the tank. Comparisons are made on the horizontal displacement, “elephant-foot” deformation, stress, base shear and moment, sloshing of the liquid, uplift, as well as slip behavior under the application of the unidirectional, bi-directional and tri-directional components. Under the selected ground motions, the horizontal bi-directional seismic component has great influence on the liquid sloshing in the tank studied in this paper. The vertical seismic component produces high compressive axial stress, and it also makes the uplift and slide of the tank bottom increase significantly. The applicability of this conclusion should be carefully considered when applied to other types of ground motion inputs.

scholarly journals A simplified method for seismic analysis of rooftop telecommunication towers

2007 ◽  
Vol 34 (10) ◽  
pp. 1352-1363
Author(s):  
Rola Assi ◽  
Ghyslaine McClure
Keyword(s):  
Seismic Analysis ◽  
Seismic Excitation ◽  
Base Shear ◽  
Shear Forces ◽  
Modal Superposition ◽  
Dynamic Analyses ◽  
Simplified Method ◽  
Excitation Dynamic ◽  
Telecommunication Towers ◽  
Definition Of

A simplified method is presented in this paper for the estimation of forces at the base of telecommunication towers mounted on building rooftops due to seismic excitation. Although some codes and standards propose simplified methods for the evaluation of base shear forces for towers founded on ground, no method yet exists for the evaluation of overturning moments. The proposed simplified method is based on numerical simulations using truncated modal superposition, which is widely used for seismic analysis of linear structures. The method requires the prediction of input seismic acceleration at the building–tower interface, the definition of an acceleration profile along the building-mounted tower, and the determination or evaluation of the mass distribution of the tower along its height. The method was developed on the basis of detailed dynamic analyses of three existing towers assumed to be mounted separately on three buildings. It was found that the method yields conservative results, especially for the overturning moments.Key words: self-supporting towers, earthquake, horizontal excitation, dynamic analysis, acceleration, modal superposition.

Effects of Adjacent Ground Treatment on Site Seismic Response

2011 ◽  
Vol 90-93 ◽  
pp. 1576-1580
Author(s):  
Gang Ge ◽  
Jian Min Liu
Keyword(s):  
Ground Motion ◽  
Single Layer ◽  
Soil Improvement ◽  
Soil Reinforcement ◽  
The Other ◽  
Acceleration Response ◽  
Horizontal Acceleration ◽  
Ground Treatment ◽  
Single Block ◽  
Adjacent Soil

The effect of adjacent soil improvement on ground motion is studied using finite element method, when seismic wave is introduced from the single layer on bedrock. The influence of ground motion on soil reinforcement is analyzed; the impacts of the reinforcement zone width, depth, elastic modulus, and the soil improvement interval on response of the ground motion are also investigated. Study shows: for the same site, when the distance between two adjacent foundation consolidation interval is less than 3 to 4 times the width of the reinforcement area, the interaction acceleration response amplitude of various points on the surface of the two adjacent reinforcement area increased significantly than the single block; within the interval , increasing one of the two adjacent foundation’s width, depth, and the other foundation surface, the horizontal acceleration response will Subsequently enlarged; when the interval between the reinforcement area is greater than the range, this effect is negligible.

Acoustic Non-Reciprocal Band Structure in a Passive, Nonlinear, 1D Material

2019 ◽  
Author(s):  
Lezheng Fang ◽  
Amir Darabi ◽  
Alexander F. Vakakis ◽  
Michael J. Leamy
Keyword(s):  
Numerical Study ◽  
The Other ◽  
Signal Frequency ◽  
Strong Nonlinearity ◽  
Frequency Content ◽  
Minimal Distortion ◽  
Shape Structure ◽  
Band Pass ◽  
Path Dependent ◽  
Mechanical Devices

Abstract Acoustic non-reciprocity, referring to the phenomenon of path-dependent propagation, has diverse applications in mechanical devices. This paper presents a numerical study on a periodic triangle-shape structure that breaks reciprocity in a passive manner over a broad range of frequency and energy. The proposed structure contains strong nonlinearity and geometric asymmetry, which contributes to a direction-dependent dispersion relationship. When the signal frequency falls in the band pass in one direction, and band gap in the other, a unidirectional wave propagation results. The system achieves giant non-reciprocity with minimal distortion in the frequency content of the signal.

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