Formulating Seismic Intensity Scale (JMA-SIS) Using Response Spectrum: A New Approach for Structural Engineering Design

A design basis ground motion is usually defined to be compatible with a given response spectrum which is a useful measure of linear dynamic response of a structure. It has been known that the variance of maximum displacement responses to artificial ground motions in elasto-plasric region is quite large, although every artificial ground motion fits the same design response spectrum. Recently, a new synthesis method was proposed by Masuda, et al. that can generate artificial earthquake ground motions compatible with given time-frequency characteristic as well as a given response spectrum. In this paper, a group of artificial earthquake ground motions are generated, and elasto-plastic response analyses are carried out to examine variance of structural responses in elasto-plastic region. It is revealed that the variance of the structural responses to the earthquake ground motions generated by Masuda's method is less than that to the seismic ground motions by the conventional design method. And it is suggested that the given time-frequency characteristic has an effect on the variance of maximum responses.

In this paper, a number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motion as well as the given target response spectrum are generated using wavelet transform. The maximum non-dimensional displacement of elasto-plastic structures excited these artificial earthquake ground motions are calculated numerically. Displacement response, velocity response and cumulative input energy are shown in the case of the ground motion which cause larger displacement response. Under the given design response spectrum, a selection manner of generated artificial earthquake ground motion which causes lager maximum displacement response of elasto-plastic structure are suggested.

In this paper, a number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motion as well as the given target response spectrum are generated using wavelet transform. The variation of maximum displacement, velocity and acceleration responses of SDOF elasto-plastic systems by excited these artificial earthquake ground motions are evaluated numerically and theoretically. The coefficients of variation of maximum displacement, velocity and acceleration responses are shown in the case of the ground motion using the time-frequency characteristics of recently actual occurred large earthquake motions. Under the given design response spectrum, a selection manner of generated artificial earthquake ground motion which causes larger maximum displacement response of elasto-plastic structure are suggested.

A number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motions as well as the given target response spectrum are generated using wavelet transform. The Coefficient of variation (C. O. V.) of maximum displacement, maximum velocity and maximum acceleration in elasto-plastic SDOF systems excited these artificial ground motions are numerically evaluated. The C. O. V. based on different time-frequency characteristics of artificial ground motions, different input intensity and different natural periods of SDOF systems are compared. The trajectory of mass around maximum displacement and the variances of displacement with maximum displacements are shown. It is recognized that the C. O. V. become large as input intensity is large and as natural period is small. It is also recognized that the variances of displacements jump and reach the maximum value at the moment occurred plastic drift in displacement. And the fluctuation of variances of displacement fairly corresponds with the fluctuation of maximum values of displacement.

In this paper, a number of artificial earthquake ground motions compatible with non-stationary time-frequency characteristics as well as the given target response spectrum are generated using wavelet transform. The maximum displacement, velocity and acceleration responses of elasto-plastic structures by excited these artificial earthquake ground motions are calculated numerically. Displacement response, velocity response and cumulative input energy are shown in the case of the ground motion which cause larger displacement response. Under the given design response spectrum, a selection manner of generated artificial earthquake ground motion which causes larger maximum displacement response of elasto-plastic structure are suggested.

Artificial ground motion can make up for the lack of actual ground motion as ground motion input, while the previous study showed insufficient consideration of the strength envelope. This article introduces the multi-peak point strength envelope model, i.e., Amin and Ang model, and the technology of artificial ground motion considering trigonometric series stacking technology. Taking random numbers and actual ground motion phases as initial phases, the influence of the length and position of the platform on the response spectrum and the artificial acceleration time histories has been presented. The results show: (1) the fitting effect of the response spectrum varies with position of the strength envelope platform; (2) the strength envelope platform determines the position of PGA (peak acceleration of ground motion); (3) Taking phases of the strong motion record as initial phases, the response spectra are better fitted.

A number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motions as well as the given target response spectrum are generated using wavelet transform. The coefficient of variation (C. O. V.) of maximum displacement on elasto-plastic SDOF systems excited by these artificial ground motions are numerically evaluated.

A number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motions as well as the given target response spectrum are generated using wavelet transform. The coefficient of variation (C.O.V..) of maximum displacement on elasto-plastic SDOF systems excited by these artificial ground motions are numerically evaluated.

S transform is one of the effective modern time-frequency analysis techniques. A new method of applying S transform to simulate artificial near-fault ground motions is presented. The artificial near-fault ground motions are simulated by combining filtered real or artificial far-fault ground motions by time–frequency filter with equivalent pulse, which can reflect the local characteristics of site and the pulse characteristics of near-fault ground motions. Numerical analysis shows the time-frequency characteristics of artificial near-fault ground motions are similar to that of parents ground motions, and the PSD in high frequency range is compatible with a target PSD of code for seismic design of buildings of China. The PGA of artificial near-fault ground motions are identical to the PGA corresponding to earthquake intensity in this code. So the artificial near-fault ground motions presented in the paper can be used for seismic analysis of the structures in near-fault seismic zone.

Spectra-compatible artificial ground motions are used extensively in the time history analysis of nuclear power plants. Owing to reasons such as the dense controlling frequency points and stringent requirements for the number of small response points, it is difficult for the conventional matching methods to generate artificial ground motions that are highly compatible with multi-damping design spectra. In this paper, to resolve the problems of high precision and robustness, an improved hybrid method for constructing a multi-parameter adjustment curve in the time domain is proposed. Different from artificial intelligence methods, the improved hybrid method is a deterministic iterative method that combines the advantages of the simulated annealing algorithm (SAA) and the time domain adjustment method. The SAA is used to determine the optimal weights of the corrective time histories of all the damping ratios at a specific frequency, which controls the influences of the corrective time histories on the response spectra. Subsequently, based on the optimal weights, the artificial ground motion is adjusted in the time domain to reduce the fitting error of all the damping ratios at a specific frequency. Moreover, the multi-damping design spectra matching problem of frequencies and damping ratios is simplified to a one-dimensional problem of frequencies using the SAA. Numerical examples are presented to demonstrate the versatility of the proposed improved hybrid method.

The seismic response of low-energy buildings founded on a thermal insulation layer – A parametric study

The design ground motions are usually defined to be compatible with the given response spectrum which is a useful measure of the linear dynamic response of the structure. Recently, a new synthesis method was proposed by Masuda et al. that can make artificial ground motions compatible with the given time-frequency characteristics as well as the given response spectra. Because the maximum elasto-plastic deformation level depends on the nonstationary load history applied to the structure, the structural response to the ground motions designed by that method are expected to be less-variable even in the elasto-plastic region. In this paper, a number of artificial ground motions are synthesized, and elasto-plastic response analyses are carried out to examine the variance of the structural response in the elasto-plastic region. It is revealed that the variance of the structural response to the ground motions designed by Masuda's method is less than one to the ground motions by the conventional design method.

Simplified procedure for simulating artificial non-stationary multi-point earthquake accelerograms

A Multi Record Based Artificial Near Fault Ground Motion Generation Method

Bidirectional seismic response of assembled monolithic subway station-aboveground structure system under artificial bedrock ground motions