scholarly journals Dynamic reduction method for frame structures

2013 ◽  
Vol 35 (2) ◽  
pp. 113-129
Author(s):  
Buntara S. Gan ◽  
Kien Nguyen-Dinh ◽  
Mitsuharu Kurata ◽  
Eiji Nouchi
Keyword(s):  
Dynamic Analysis ◽  
Reduction Method ◽  
Reduction Process ◽  
Degree Of Freedom ◽  
Frame Structures ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Dynamic Condensation ◽  
Dynamic Analyses ◽  
Dynamic Reduction Method

This paper proposes a new method for reducing MDOF (Multi Degree of Freedom) system of frame structures into SDOF (Single Degree of Freedom) system and recovering back the results of dynamic analysis from the SDOF to the MDOF system.In most of dynamic condensation methods, the reduction of MDOF into an SDOF system is usually done by means of modal analysis. As a result, simplification against the MDOF is made forward-wise and not reversible. In other words, after the responses of SDOF system evaluated by the modal and dynamic analyses, then it is not possible to recover back the responses of the other condensed degree of freedoms accurately. In the new Strain Reduction Method, displacement and rotational DOFs of all nodal points in the frame structures except an arbitrarily selected representative node are transformed into their strains field before the reduction process. By adopting previous authors’ work in improving the dynamic reduction method, small order in magnitude of strains field can be separated as secondary DOFs, hence leaving the representative node as an SDOFsystem. After conducting dynamic analysis to the SDOF system, the time historical responses of the SDOF system can be used to recover back the time historical responses in the MDOF system of frame structures with negligible error.

scholarly journals An approach to quantify the influence of ground motion uncertainty on elastoplastic system acceleration in incremental dynamic analysis

2017 ◽  
Vol 20 (11) ◽  
pp. 1744-1756 ◽  
Author(s):  
Peng Deng ◽  
Shiling Pei ◽  
John W. van de Lindt ◽  
Hongyan Liu ◽  
Chao Zhang
Keyword(s):  
Dynamic Analysis ◽  
Ground Motion ◽  
Earthquake Engineering ◽  
Structural Response ◽  
Incremental Dynamic Analysis ◽  
Degree Of Freedom ◽  
Maximum Acceleration ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Performance Based Earthquake Engineering

Inclusion of ground motion–induced uncertainty in structural response evaluation is an essential component for performance-based earthquake engineering. In current practice, ground motion uncertainty is often represented in performance-based earthquake engineering analysis empirically through the use of one or more ground motion suites. How to quantitatively characterize ground motion–induced structural response uncertainty propagation at different seismic hazard levels has not been thoroughly studied to date. In this study, a procedure to quantify the influence of ground motion uncertainty on elastoplastic single-degree-of-freedom acceleration responses in an incremental dynamic analysis is proposed. By modeling the shape of the incremental dynamic analysis curves, the formula to calculate uncertainty in maximum acceleration responses of linear systems and elastoplastic single-degree-of-freedom systems is constructed. This closed-form calculation provided a quantitative way to establish statistical equivalency for different ground motion suites with regard to acceleration response in these simple systems. This equivalence was validated through a numerical experiment, in which an equivalent ground motion suite for an existing ground motion suite was constructed and shown to yield statistically similar acceleration responses to that of the existing ground motion suite at all intensity levels.

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.

Ground mobile Bennett mechanism

2019 ◽  
Vol 43 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Zhirui Wang ◽  
Yan-an Yao ◽  
Chao Liu
Keyword(s):  
Weight Distribution ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Dynamic Analyses ◽  
Constant Direction ◽  
Moving Direction ◽  
Series Of Experiments

This paper presents a novel application of the well-known single degree of freedom Bennett mechanism. By optimizing the link’s shape and the weight distribution of the Bennett mechanism, we put forward a ground mobile mechanism that can move in a constant direction and change its moving direction with only one actuator. A type of tumbling gait is proposed and kinematic and dynamic analyses of the gait are carried out. Finally, a series of experiments are performed on a manufactured prototype. The results verify the tumbling gait and functionality of the mobile mechanism.

Dynamic analysis of single-degree-of-freedom systems (DYANAS): A graphical user interface for OpenSees

2018 ◽  
Vol 177 ◽  
pp. 395-408 ◽  
Author(s):  
Georgios Baltzopoulos ◽  
Roberto Baraschino ◽  
Iunio Iervolino ◽  
Dimitrios Vamvatsikos
Keyword(s):  
User Interface ◽  
Dynamic Analysis ◽  
Graphical User Interface ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree

scholarly journals Experimental investigation of a single-degree-of-freedom system with Coulomb friction

2020 ◽  
Vol 99 (3) ◽  
pp. 1781-1799
Author(s):  
Luca Marino ◽  
Alice Cicirello
Keyword(s):  
Experimental Investigation ◽  
Degree Of Freedom ◽  
Experimental Results ◽  
Systematic Observation ◽  
Stick Slip ◽  
Friction Forces ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Single Degree ◽  
Set Up

AbstractThis paper presents an experimental investigation of the dynamic behaviour of a single-degree-of-freedom (SDoF) system with a metal-to-metal contact under harmonic base or joined base-wall excitation. The experimental results are compared with those yielded by mathematical models based on a SDoF system with Coulomb damping. While previous experiments on friction-damped systems focused on the characterisation of the friction force, the proposed approach investigates the steady response of a SDoF system when different exciting frequencies and friction forces are applied. The experimental set-up consists of a single-storey building, where harmonic excitation is imposed on a base plate and a friction contact is achieved between a steel top plate and a brass disc. The experimental results are expressed in terms of displacement transmissibility, phase angle and top plate motion in the time and frequency domains. Both continuous and stick-slip motions are investigated. The main results achieved in this paper are: (1) the development of an experimental set-up capable of reproducing friction damping effects on a harmonically excited SDoF system; (2) the validation of the analytical model introduced by Marino et al. (Nonlinear Dyn, 2019. https://doi.org/10.1007/s11071-019-04983-x) and, particularly, the inversion of the transmissibility curves in the joined base-wall motion case; (3) the systematic observation of stick-slip phenomena and their validation with numerical results.

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