Static Pushover Analysis Based on an Energy-Equivalent SDOF System

2011 ◽  
Vol 27 (1) ◽  
pp. 89-105 ◽  
Author(s):  
Grigorios Manoukas ◽  
Asimina Athanatopoulou ◽  
Ioannis Avramidis
Keyword(s):  
Pushover Analysis ◽  
Main Idea ◽  
Theoretical Background ◽  
Degree Of Freedom ◽  
Lateral Loads ◽  
External Work ◽  
Sdof System ◽  
New Energy ◽  
Equivalent Sdof System

In this paper, a new energy-based pushover procedure is presented in order to achieve an approximate estimation of structural performance under strong earthquakes. The steps of the proposed methodology are quite similar to those of the well-known displacement modification method. However, the determination of the characteristics of the equivalent single-degree-of-freedom (E-SDOF) system is based on a different rational concept. Its main idea is to determine the E-SDOF system by equating the external work of the lateral loads acting on the multi-degree-of-freedom (MDOF) system under consideration to the strain energy of the E-SDOF system. After a brief outline of the theoretical background, a representative numerical example is given. Finally, the accuracy of the proposed method is evaluated by an extensive parametric study which shows that, in general, it provides better results compared to those produced by other similar procedures.

Evaluation of Seismic Damage of Multi-Storey RC Frames with Damage-Based Inelastic Spectra

2009 ◽  
Vol 12 (4) ◽  
pp. 529-546 ◽  
Author(s):  
Jianwu Wei ◽  
Yong Lu
Keyword(s):  
Structural Damage ◽  
Performance Indicator ◽  
Pushover Analysis ◽  
Seismic Damage ◽  
Alternative Methods ◽  
Response Analysis ◽  
Design Environment ◽  
Sdof System ◽  
Rc Frames ◽  
Equivalent Sdof System

In the context of performance-based design, structural damage as a comprehensive measure of the seismic demand against the available capacity may be used as an effective performance indicator. Accurate methods of damage estimation usually require sophisticated dynamic response analysis and yet they do not necessarily yield the best results due to the great uncertainties involved in the seismic input. A simple and rational method based on well-constructed response spectra could be more desirable, especially in a design environment. In this paper, a methodology is developed to estimate the seismic damage of multi-storey reinforced concrete (RC) frames in terms of both the overall (global) damage and the damage distribution. The multi-storey frame is first transformed into an equivalent SDOF system, so that the damage in the equivalent SDOF system can be found from the damage-based inelastic spectra for a specified seismic intensity. Numerical investigation on a series of generic frames under a selection of real ground motions indicates that the SDOF damage and the overall damage of the actual frame correlates in a consistent manner, thus the conversion from the established SDOF damage back to the overall frame damage is rather straightforward. Two alternative methods are proposed for the prediction of the distribution of damage along the frame height, one using the modal pushover analysis, and the other based on the structural characterization using a storey capacity factor.

Kinematic and Workspace Modelling of a 6-PUS Parallel Mechanism

2018 ◽  
Author(s):  
Jérôme Landuré ◽  
Clément Gosselin
Keyword(s):  
Kinematic Analysis ◽  
Parallel Mechanism ◽  
Inverse Kinematic ◽  
Degree Of Freedom ◽  
Accurate Description ◽  
Transmission Ratio ◽  
Inverse Kinematic Problem ◽  
Jacobian Matrices ◽  
Six Degree Of Freedom

This article presents the kinematic analysis of a six-degree-of-freedom six-legged parallel mechanism of the 6-PUS architecture. The inverse kinematic problem is recalled and the Jacobian matrices are derived. Then, an algorithm for the geometric determination of the workspace is presented, which yields a very fast and accurate description of the workspace of the mechanism. Singular boundaries and a transmission ratio index are then introduced and studied for a set of architectural parameters. The proposed analysis yields conceptual architectures whose properties can be adjusted to fit given applications.

scholarly journals The physical basis of the fission wave reactor

2008 ◽  
Vol 23 (2) ◽  
pp. 3-15 ◽  
Author(s):  
Volodymyr Pavlovych ◽  
Volodymyr Khotyayintsev ◽  
Olena Khotyayintseva
Keyword(s):  
Diffusion Equation ◽  
Main Idea ◽  
Stationary Wave ◽  
Short Review ◽  
Nuclear Fission ◽  
Stationary Processes ◽  
Wave Parameters ◽  
Nuclear Burning ◽  
Fission Wave

The main idea of slow nuclear fission wave reactor is discussed and short review of the existing works is also presented. The aim of this paper is to clarify the physics of processes, which define the stationary wave of nuclear burning, and to develop the approaches determining the wave parameters. It is shown that the diffusion equation for fluence can be used to describe the stationary and non-stationary processes in the nuclear fission wave. Two conditions of stationary wave existence are first formulated in the paper. The rule of determination of wave velocity as the eigenvalue of boundary problem is also formulated.

scholarly journals The determination of the specific heat of superheated steam by throttling and other experiments

1905 ◽  
Vol 76 (509) ◽  
pp. 185-205 ◽  
Keyword(s):  
Specific Heat ◽  
Atmospheric Pressure ◽  
Superheated Steam ◽  
Electrical Energy ◽  
Total Heat ◽  
Saturated Steam ◽  
External Work

In October, 1898, the author commenced experiments, having for their object the determination of the specific heat of superheated steam. At first an attempt was made to obtain this end by measuring the rise in temperature produced in a known quantity of steam by supplying a definite amount of heat in the form of electrical energy, but the experimental difficulties experienced in satisfactorily preventing radiation, in maintaining the rate of flow of steam uniform and in securing a steam supply sufficiently homogeneous and constant as to temperature, proved so great that the attempt on these lines was given up for a time, but returned to later. Then another method was adopted, that of allowing dry saturated steam to expand without doing external work, and observing the resulting change in temperature. This method had been used in preliminary experiments on this subject by Professor Ewing and Mr. Dunkerley, who found that the specific heat of superheated steam at atmospheric pressure, as deduced by this method from Regnault’s values of the "total heat,” was not a constant, as had been previously supposed, but increased with temperature.

A Comparison of the Effects of Nonlinear Damping on the Free Vibration of a Single-Degree-of-Freedom System

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Bin Tang ◽  
M. J. Brennan
Keyword(s):  
Free Vibration ◽  
Equations Of Motion ◽  
Nonlinear Damping ◽  
Degree Of Freedom ◽  
Damping Force ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Single Degree ◽  
Dependent Term ◽  
Quadratic Damping

This article concerns the free vibration of a single-degree-of-freedom (SDOF) system with three types of nonlinear damping. One system considered is where the spring and the damper are connected to the mass so that they are orthogonal, and the vibration is in the direction of the spring. It is shown that, provided the displacement is small, this system behaves in a similar way to the conventional SDOF system with cubic damping, in which the spring and the damper are connected so they act in the same direction. For completeness, these systems are compared with a conventional SDOF system with quadratic damping. By transforming all the equations of motion of the systems so that the damping force is proportional to the product of a displacement dependent term and velocity, then all the systems can be directly compared. It is seen that the system with cubic damping is worse than that with quadratic damping for the attenuation of free vibration.

Determination of the Workspace of 6-DOF Parallel Manipulators

1989 ◽  
Author(s):  
C. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Geometrical Properties ◽  
Cartesian Space ◽  
Six Degree Of Freedom

Abstract This paper presents an algorithm for the determination of the workspace of parallel manipulators. The method described here, which is based on geometrical properties of the workspace, leads to a simple graphical representation of the regions of the three-dimensional Cartesian space that are attainable by the manipulator with a given orientation of the platform. Moreover, the volume of the workspace can be easily computed by performing an integration on its boundary, which is obtained from the algorithm. Examples are included to illustrate the application of the method to a six-degree-of-freedom fully-parallel manipulator.

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