Experimental Examples for Identification of Structural Systems Using Degree of Freedom-Based Reduction Method

2017 ◽  
pp. 375-378
Author(s):  
Heejun Sung ◽  
Seongmin Chang ◽  
Maenghyo Cho
Keyword(s):  
Reduction Method ◽  
Degree Of Freedom ◽  
Structural Systems

Order Reduction of Parametrically Excited Linear and Nonlinear Structural Systems

2005 ◽  
Vol 128 (4) ◽  
pp. 458-468 ◽  
Author(s):  
Venkatesh Deshmukh ◽  
Eric A. Butcher ◽  
S. C. Sinha
Keyword(s):  
Nonlinear Systems ◽  
Order Reduction ◽  
Second Order ◽  
Degree Of Freedom ◽  
Structural Systems ◽  
Parametrically Excited ◽  
Reduced Models ◽  
Linear And Nonlinear ◽  
Time Invariant ◽  
Time Periodic

Order reduction of parametrically excited linear and nonlinear structural systems represented by a set of second order equations is considered. First, the system is converted into a second order system with time invariant linear system matrices and (for nonlinear systems) periodically modulated nonlinearities via the Lyapunov-Floquet transformation. Then a master-slave separation of degrees of freedom is used and a relation between the slave coordinates and the master coordinates is constructed. Two possible order reduction techniques are suggested. In the first approach a constant Guyan-like linear kernel which accounts for both stiffness and inertia is employed with a possible periodically modulated nonlinear part for nonlinear systems. The second method for nonlinear systems reduces to finding a time-periodic nonlinear invariant manifold relation in the modal coordinates. In the process, closed form expressions for “true internal” and “true combination” resonances are obtained for various nonlinearities which are generalizations of those previously reported for time-invariant systems. No limits are placed on the size of the time-periodic terms thus making this method extremely general even for strongly excited systems. A four degree-of-freedom mass- spring-damper system with periodic stiffness and damping as well as two and five degree-of-freedom inverted pendula with periodic follower forces are used as illustrative examples. The nonlinear-based reduced models are compared with linear-based reduced models in the presence and absence of nonlinear resonances.

Spectral Variability and Its Relationship to Structural Response Estimated from Scaled and Spectrum-Matched Ground Motions

2016 ◽  
Vol 32 (4) ◽  
pp. 2191-2205 ◽  
Author(s):  
A. E. Seifried ◽  
J. W. Baker
Keyword(s):  
Response Spectrum ◽  
Ground Motions ◽  
Structural Response ◽  
Degree Of Freedom ◽  
Structural Systems ◽  
Spectral Variability ◽  
Single Degree Of Freedom ◽  
Inelastic Response ◽  
Single Degree ◽  
Spectral Dispersion

Conditional spectral dispersion ( CSD) is a measure of response spectrum variability that implicitly characterizes the variety of spectral shapes within a suite of ground motions. It is used here to explain the discrepancy between median structural demands estimated from different suites of scaled and spectrum-matched ground motions. Performing response history analyses with spectrum-matched ground motions is known to result in unconservatively biased median demand estimates in some cases. Herein, several suites of scaled ground motions with equivalent median intensities and varying levels of CSD are selected. A single suite of spectrum-matched ground motions is also created. These records are used to analyze the responses of inelastic single-degree-of-freedom and first-mode-dominated multiple-degree-of-freedom structural systems. Collapse capacities are also examined. A consistent trend between CSD and resulting median responses indicates that the bias phenomenon can be fully explained by an asymmetric relationship between conditional spectral ordinates at periods affecting inelastic response.

TIME-SEGMENTED FREQUENCY-DOMAIN ANALYSIS FOR NON-LINEAR MULTI-DEGREE-OF-FREEDOM STRUCTURAL SYSTEMS

2000 ◽  
Vol 237 (3) ◽  
pp. 457-475 ◽  
Author(s):  
W.J. MANSUR ◽  
J.A.M. CARRER ◽  
W.G. FERREIRA ◽  
A.M. CLARET DE GOUVEIA ◽  
F. VENANCIO-FILHO
Keyword(s):  
Frequency Domain ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Degree Of Freedom ◽  
Structural Systems ◽  
Non Linear

Backstepping-based Lyapunov redesign control of hysteretic single degree-of-freedom structural systems

2013 ◽  
Vol 73 (1-2) ◽  
pp. 1165-1186 ◽  
Author(s):  
Mehdi Baradaran-nia ◽  
Ghasem Alizadeh ◽  
Sohrab Khanmohammadi ◽  
Bahman Farahmand Azar
Keyword(s):  
Degree Of Freedom ◽  
Structural Systems ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Lyapunov Redesign
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