1995 Fiscal Year Final Research Report Summary
Seismic Reliability Assessment of a Structure with Elasto-Plastic Hysteresis
| Project/Area Number |
06650279
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Dynamics/Control
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
KIMURA Koji Tokyo Institute of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (70143675)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHARA Hiroki Tokyo Institute of Technology, Faculty of Engineering, Research Associate, 工学部, 助手 (90226910)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Theory of Vibration / Aseismic Engineering / Random Vibration / Earthauake Response / Hystereris / Parametric Vibration / Reliability |
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| Research Abstract |
An approximate analytical technique is developed for obtaining the nonstationary response of a single-degree-of-freedom mechanical system with bilinear hysteresis subjected to amplitude modulated nonwhite random excitations. The hysteretic behavior is described by introducing an additional state variable and nonlinear functions. The equivalent linear coefficients and also the moment equations of the equivalent linear systems are derived using a non-Gaussian probability density function which is composed of a truncatd Gaussian probability density function and a couple of delta functions. The mean square responses and the mean dissipated hysteretic energy are calculated by solving the moment equations and are compared with the corresponding digital simulation results.
An experiment is conducted by using a lead cantilever beam with a mass in order to examine the random vibrations of a hysteretic system. Power spectra and root mean square values of the stationary responses to two types of r
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andom excitation, i.e., white noise, and nonwhite noise with a dominat frequency, are measured. A theoretical analysis is carried out by assuming a bilinear hysterersis model and using the moment equations approach. A fairly good agreement is found between the theoretical and experimental results. It is shown that the effect on the response of energy dissipation due to hysteresis is observed even in the case of low input level.
Parametric vibration of the liquid surface in a partially filled circular cylindrical tank is investigated. The tank is subjected to horizontal, vertical and pitching excitations. Nonlinearity of the liquid surface oscillation is considered in the response analysis of the sloshing motion. The nonlinear and parametric ordinary differential equations, governing the axisymmetric liquid surface oscillation and including the higher order radial modes, are derived by applying Galerkin's method. It is confirmed that the vertical excitation causes the parametric excitation. In addition, it is noted that the pitching excitation also causes the parametric excitation when the pitching axis does not intersect the symmetrical axis of the circular cylindrical tank. An experiment was conducted using a model tank. Good agreement was found between the theoretical and experimental results.
The stochastic response spectrum approach is presented for predicting the dynamic behavior of structures to earthquake excitation expressed by a random process, one of whose sample functions can be regarded as a recorded strong-motion earthquake accelerogram. The approach consists of modeling recorded ground motion by a random process and the rms response analysis of a single-degree-of freedom system by using the moment equations method. The stochastic respone spectrum is obtained as a plot of the maximum rms response versus the natural period of the system and is compared with the conventional response spectrum. Less
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