Bi-linear displacement response spectrum model for engineering applications in low and moderate seismicity regions

For seismic resilience-based design (RBD), a selection of recorded time histories for dynamic structural analysis is usually required. In order to make individual structures and communities regain their target functions as promptly as possible, uncertainty of the structural response estimates is in great need of reduction. The ground motion (GM) selection based on a single target response spectrum, such as acceleration or displacement response spectrum, would bias structural response estimates leading significant uncertainty, even though response spectrum variance is taken into account. In addition, resilience of an individual structure is not governed by its own performance, but depends severely on the performance of other systems in the same community. Thus, evaluation of resilience of a community using records matching target spectrum at whole periods would be reasonable because the fundamental periods of systems in the community may be varied. This paper presents a GM selection approach based on a probabilistic framework to find an optimal set of records to match multiple target spectra, including acceleration and displacement response spectra. Two major steps are included in that framework. Generation of multiple sub-spectra from target displacement response spectrum for selecting sets of GMs was proposed as the first step. Likewise, the process as genetic algorithm (GA), evolvement of individuals previously generated, is the second step, rather than using crossover and mutation techniques. A novel technique improving the match between acceleration response spectra of samples and targets is proposed as the second evolvement step. It is proved computationally efficient for the proposed algorithm by comparing with two developed GM selection algorithms. Finally, the proposed algorithm is applied to select GM records according to seismic codes for analysis of four archetype reinforced concrete (RC) frames aiming to evaluate the influence of GM selection considering two design response spectra on structural responses. The implications of design response spectra especially the displacement response spectrum and GM selection algorithm are summarized.

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Seismic performance evaluation of high-rise steel buildings dependent on wind exposures

Advances in Mechanical Engineering ◽

10.1177/1687814019835111 ◽

2019 ◽

Vol 11 (3) ◽

pp. 168781401983511

Author(s):

Seonwoong Kim

Keyword(s):

Seismic Performance ◽

Response Spectrum ◽

Slenderness Ratio ◽

Lateral Force ◽

Lateral Load ◽

Seismic Load ◽

Strong Wind ◽

Steel Buildings ◽

High Rise ◽

Moderate Seismicity

The lateral load-resisting system of high-rise buildings in regions of low and moderate seismicity and strong wind such as the typhoon in the Korean peninsula considers the wind load as the governed lateral force so that the practical structural engineer tends to skip the evaluation against the seismic load. This study is to investigate wind-designed steel diagrid buildings located in these regions and check the possibility of the elastic design of them out. To this end, first, the diagrid high-rise buildings were designed to satisfy the wind serviceability criteria specified in KBC 2016. Then, the response spectrum analyses were performed under various slenderness ratio and wind exposures. The analyses demonstrated the good seismic performance of these wind-designed diagrid high-rise buildings because of the significant over-strength induced by the lateral load-resisting system of high-rise buildings. Also, the analysis results showed that the elastic seismic design process of some diagrid high-rise buildings may be accepted based on slenderness ratios in all wind exposures.

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An Improved Source Model for Simulation Near-Field Strong Ground Motion Acceleration Time History

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.438-439.1474 ◽

2013 ◽

Vol 438-439 ◽

pp. 1474-1480

Author(s):

Ju Fang Zhong ◽

Long Wei Zhang ◽

Jun Wei Liang

Keyword(s):

Ground Motion ◽

Strong Ground Motion ◽

Response Spectrum ◽

Near Field ◽

Time History ◽

Source Spectrum ◽

Acceleration Time ◽

Acceleration Time History ◽

Spectrum Model ◽

Strong Ground

The key to near-field strong ground motion simulation based on stochastic finite fault method is to determine the spectrum of ground motion. We present an improved source spectrum model for simulation near-field strong ground motion acceleration time history. We combine Masudas source spectrum model with scaling factor Hij to keep radiation energy conservation and reflect the energy decrease with frequency at low to mid frequencies. We calculate the Fourier amplitude spectrum Fa, accelerate response spectrum Sa, velocity response spectrum Sv and displacement response spectrum Sd of simulation time histories. By comparative analysis of the laws of spectrum values (Fa, Sa, Sv, Sd) with the variation of frequency or period, we discusses the effects of sub-fault dividing scheme, the method of determining scale factor and source spectrum model on spectrum values (Fa, Sa, Sv, Sd). The results show that sub-fault dividing scheme has slightly effect on the model presented in this paper, and the model enable to reflect the sink laws of source spectrum value in mid-to-low frequencies well. We demonstrate that the improved model is superior to other commonly used models.

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Cost-Effectiveness Evaluation of Seismically Isolated Pool Structures Considering Fluid-Structure Interaction

Seismic Engineering, Volume 2 ◽

10.1115/pvp2002-1434 ◽

2002 ◽

Author(s):

Hyun-Moo Koh ◽

Kwan-Soon Park ◽

Junho Song

Keyword(s):

Cost Effectiveness ◽

Response Spectrum ◽

Mass Matrix ◽

Minimum Cost ◽

Spectral Density Function ◽

Design Variables ◽

Moderate Seismicity ◽

Seismically Isolated ◽

Function Vector ◽

The Cost

A procedure for evaluating cost-effectiveness of seismically isolated pool structures is presented. The ground motion is modeled as the spectral density function matching the response spectrum, which is specified in codes in terms of acceleration and site coefficients. Interaction between flexible walls and contained fluid is considered in the form of added mass matrix. The thickness of wall and the stiffness of isolator are used as main design variables while the minimum cost for comparison is estimated. Transfer function vector of the system is derived and spectral analysis method based on random vibration theories is used for calculating probability of failure. Evaluation results of the examples show that the cost-effectiveness of seismically isolated pool structures is relatively high in regions of low to moderate seismicity.

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A design spectrum model for flexible soil sites in regions of low-to-moderate seismicity

Soil Dynamics and Earthquake Engineering ◽

10.1016/j.soildyn.2016.09.035 ◽

2017 ◽

Vol 92 ◽

pp. 36-45 ◽

Cited By ~ 12

Author(s):

H.H. Tsang ◽

J.L. Wilson ◽

N.T.K. Lam ◽

R.K.L. Su

Keyword(s):

Design Spectrum ◽

Moderate Seismicity ◽

Spectrum Model

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A Study of Elasto-Plastic Response of Single Degree of Freedom System Using Artificial Ground Motions With Given Time-Frequency Characteristics

ASME 2010 Pressure Vessels and Piping Conference: Volume 8 ◽

10.1115/pvp2010-25381 ◽

2010 ◽

Cited By ~ 1

Author(s):

Ichiro Ichihashi ◽

Akira Sone ◽

Arata Masuda ◽

Daisuke Iba

Keyword(s):

Ground Motion ◽

Response Spectrum ◽

Ground Motions ◽

Frequency Characteristics ◽

Earthquake Ground Motion ◽

Time Frequency ◽

Displacement Response ◽

Earthquake Ground Motions ◽

Design Response Spectrum ◽

The Given

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.

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A Blade Loss Response Spectrum for Flexible Rotor Systems

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.3239683 ◽

1985 ◽

Vol 107 (1) ◽

pp. 197-204 ◽

Cited By ~ 9

Author(s):

M. Alam ◽

H. D. Nelson

Keyword(s):

Response Spectrum ◽

Damping Ratio ◽

Response Spectra ◽

Flexible Rotor ◽

Peak Displacement ◽

Rotor Systems ◽

Displacement Response ◽

Modal Damping Ratio ◽

Whirl Speed ◽

Blade Loss

A shock spectrum procedure is developed to estimate the peak displacement response of linear flexible rotor-bearing systems subjected to a step change in unbalance (i.e., a blade loss). A progressive and a retrograde response spectrum are established. These blade loss response spectra are expressed in a unique non-dimensional form and are functions of the modal damping ratio and the ratio of rotor spin speed to modal damped whirl speed. Modal decomposition using complex modes is utilized to make use of the unique feature of the spectra for the calculation of the peak blade loss displacement response of the rotor system. The procedure is applied to three example systems using several modal superposition strategies. The results of each are compared to true peak displacements obtained by a separate transient response program.

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Fully Nonstationary Spatially Variable Ground Motion Simulations Based on a Time-Varying Power Spectrum Model

Mathematical Problems in Engineering ◽

10.1155/2014/293182 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10

Author(s):

Huiguo Chen ◽

Yingmin Li ◽

Junru Ren

Keyword(s):

Power Spectrum ◽

Ground Motion ◽

Response Spectrum ◽

Power Spectra ◽

Response Spectra ◽

Simulation Method ◽

Time Varying ◽

Time Frequency ◽

Response Characteristics ◽

Spectrum Model

By analyzing the evolutionary spectrum method for multivariate nonstationary stochastic processes, a simulation method for fully nonstationary spatially variable ground motion is proposed based on the Kameda time-varying power spectrum model. This method can properly simulate nonstationary spatially variable ground motion based on a target response spectrum. Two numerical examples, in which the Kameda time-varying power spectra are calculated for different conditions, are presented to demonstrate the capabilities of the proposed method. In the first example, the nonstationary spatially variable ground motion that satisfies the time-frequency characteristics and response characteristics of the original ground motion is simulated by identifying the parameters of the given time-varying power spectrum. In the second example, the ground motion that satisfies the design response spectra is simulated by defining the parameters of the time-varying power spectrum directly. The results demonstrate that the method can effectively simulate nonstationary spatially variable ground motion, which implies that the proposed method can be used in engineering applications.

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