scholarly journals Verification of Nonlinear Numerical Analysis for Seismic Response of Single Degree of Freedom Structure with Shallow Foundation

2013 ◽  
Vol 29 (3) ◽  
pp. 29-40
Author(s):  
Yun-Wook Choo ◽  
Jin-Sun Lee ◽  
Dong-Soo Kim
Keyword(s):  
Numerical Analysis ◽  
Seismic Response ◽  
Degree Of Freedom ◽  
Shallow Foundation ◽  
Single Degree Of Freedom ◽  
Single Degree

Seismic Response Reduction Caused by Coupling Between Beam-Type and Oval-Type Vibrations of a Cylindrical Water Storage Tank Under Large Excitation

2007 ◽  
Author(s):  
Akira Maekawa ◽  
Katsuhisa Fujita ◽  
Michiaki Suzuki
Keyword(s):  
Seismic Response ◽  
Water Storage ◽  
Degree Of Freedom ◽  
Seismic Excitation ◽  
System Model ◽  
Single Degree Of Freedom ◽  
Water Storage Tank ◽  
Single Degree ◽  
Input Acceleration ◽  
Beam Type

This study describes the response reduction caused by coupling between the beam-type and the oval-type vibrations of a cylindrical water storage tank under seismic excitation. In this study, the seismic response experiment is performed by using a 1/10 reduced scale model of an actual tank and then numerical simulation is performed by the simplified model. The authors conducted the sinusoidal response experiment for the tank and reported that the coupling between the beam-type and the oval-type vibrations causes the resonance frequency of the beam-type vibration to shift to the lower frequency and the response in the beam-type vibration (the response of the tank) to reduce. The seismic response experiment of the tank model filled with water up to 95% is performed by a shaking table. The El Centro 1940 NS and the improved standard seismic wave for Japanese LWR are used as the input seismic wave. The experimental results show that the maximum response acceleration does not enlarge linearly as the maximum input acceleration increases. The dominant resonance frequency slightly shifts to the lower frequency as the maximum input acceleration increases. It is concluded that the coupling between the beam-type and the oval-type vibrations make an influence on the beam-type vibration in seismic excitation. In the meantime, the authors propose the nonlinear single-degree-of-freedom system model to explain that the vibration response of the tank reduces. This model is based on geometric nonlinearity due to the out-of-plane deformation of the side-wall of the tank caused by the oval-type vibration. The numerical simulation of the seismic response is conducted using the nonlinear single-degree-of-freedom system model proposed by the authors. The analytical results agree with the experimental results as a general trend. Therefore, it is concluded that the response reduction of the tank is generated by coupling between the beam-type and the oval-type vibrations in the seismic excitation as well as the sinusoidal excitation. In addition, the response reduction rate of the tank under much larger seismic excitation can be estimated by using the nonlinear single-degree-of-freedom system model.

scholarly journals Observation of a directed resonance in soil driven by transverse rock motion

1989 ◽  
Vol 22 (2) ◽  
pp. 81-89 ◽  
Author(s):  
W. R. Stephenson
Keyword(s):  
Seismic Response ◽  
Resonant Mode ◽  
Degree Of Freedom ◽  
Mechanical Oscillator ◽  
Ground Acceleration ◽  
Single Degree Of Freedom ◽  
Fine Grained ◽  
Single Degree ◽  
Cook Strait

One component of horizontal ground acceleration recorded on flexible soil during the 1968 November 1 Cook strait earthquake is shown to be well modelled as a single degree of freedom oscillator excited by the recorded component of transverse acceleration in nearby bed rock. This is shown to be consistent with the cellular resonant mode hypothesis of seismic response of flexible soil. The mechanical oscillator is identified as a layer of fine-grained, post-glacial alluvium of approximately 20 m thickness.

A Simplified Analysis Method for Elasto-Plastic Seismic Response Using the Energy Balance Equation of a Maximum Hysteresis Loop

2015 ◽  
Author(s):  
Gaku Nakamura ◽  
Yukihiko Okuda ◽  
Shoichi Ebato ◽  
Hiroshi Niwa ◽  
Tadashi Iijima ◽  
...  
Keyword(s):  
Energy Balance ◽  
Seismic Response ◽  
Degree Of Freedom ◽  
Integration Scheme ◽  
Analysis Method ◽  
Maximum Displacement ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Simplified Analysis ◽  
Vibration Tests

With increasing magnitude of design earthquake ground motions, it is necessary to develop methods of evaluating the seismic safety margin that are more exact than the current methods. However, a standard nonlinear analysis method requires step by step calculations of the numerical time integration scheme to obtain the seismic response. The authors present a new simplified analysis method of elasto-plastic seismic response. The proposed method is formulated by the energy balance between the input energy and the dissipated energy of an equivalent single degree of freedom model for actual equipment. Assuming the harmonic resonance of the single degree of freedom model, the maximum displacement response can be estimated conservatively. To verify the proposed method, static tests and vibration tests with cantilever-type specimens were performed. The vibration tests were conducted with sine, sweep down sine and random waves to verify the conservativeness of the proposed method. Comparisons of the maximum displacement between the tests and the proposed method show the conservative estimation of the displacement by the proposed method.

scholarly journals Functional Model to Estimate the Inelastic Displacement Ratio

2017 ◽  
Vol 13 (4) ◽  
pp. 1-11
Author(s):  
Vlad Ceangu ◽  
Dan Cretu
Keyword(s):  
Seismic Response ◽  
Functional Model ◽  
Degree Of Freedom ◽  
Similar Frequency ◽  
Single Degree Of Freedom ◽  
Inelastic Displacement ◽  
Single Degree ◽  
Ductility Factor ◽  
Displacement Ratio ◽  
Inelastic Displacement Ratio

Abstract In this paper a functional model to estimate the inelastic displacement ratio as a function of the ductility factor is presented. The coefficients of the functional model are approximated using nonlinear regression. The used data is in the form of computed displacement for an inelastic single degree of freedom system with a fixed ductility factor. The inelastic seismic response spectra of constant ductility factors are used for generating data. A method for selecting ground-motions that have similar frequency content to that of the ones picked for the comparison is presented. The variability of the seismic response of nonlinear single degree of freedom systems with different hysteretic behavior is presented.

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