Inelastic displacement spectra for Chinese highway bridges characterized by single-degree-of-freedom bilinear systems

As for the inelastic displacement demand of a single-degree-of-freedom system, previous studies usually focus on the strength reduction factor, R, or the inelastic displacement ratio, C. Only a little literature reports the direct statistical results of the mean inelastic displacement spectra, Sd. Based on 308 earthquake records selected from three types of site soil, differences between the direct mean Sd and the indirect ones that respectively derived from mean R and mean Cμ are investigated, in which Cμ refers to the constant ductility inelastic displacement ratio. It is found the indirect Sd will introduce errors for using mean R and mean Cμ, while the dispersion of the direct spectra need to be reduced before putting into practice. Two methods, the period normalized method and the spectra-matching method, are employed to address the dispersion problem, and the latter one that modified a record to make its acceleration response spectra compatible with the specified standard, Chinese highway bridge seismic design guidelines in this study, works with more acceptable performance. Finally, a comprehensive equation is proposed to characterize the spectra-matching mean Sd, the practicality and efficiency of the identified parameters in the equation are verified. It is advisable to use the proposed equation to assess the inelastic displacement demand of Chinese highway bridges characterized by single-degree-of-freedom bilinear system, and the procedures to obtain the displacement spectra can also be utilized for other corresponding researches.

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Functional Model to Estimate the Inelastic Displacement Ratio

Mathematical Modelling in Civil Engineering ◽

10.1515/mmce-2017-0010 ◽

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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Ground Motion Prediction Model for the Peak Inelastic Displacement of Single-Degree-of-Freedom Bilinear Systems

Earthquake Spectra ◽

10.1193/061517eqs118m ◽

2018 ◽

Vol 34 (3) ◽

pp. 1177-1199 ◽

Cited By ~ 2

Author(s):

Pablo Heresi ◽

Héctor Dávalos ◽

Eduardo Miranda

Keyword(s):

Prediction Model ◽

Ground Motion ◽

Degree Of Freedom ◽

Motion Prediction ◽

Ground Motion Prediction ◽

Vibration Period ◽

Single Degree Of Freedom ◽

Inelastic Displacement ◽

Single Degree ◽

Proposed Model

This paper presents a ground motion prediction model (GMPM) for estimating medians and standard deviations of the random horizontal component of the peak inelastic displacement of 5% damped single-degree-of-freedom (SDOF) systems, with bilinear hysteretic behavior and 3% postelastic stiffness ratio, directly as a function of the earthquake magnitude and the distance to the source. The equations were developed using a mixed effects model, with 1,662 recorded ground motions from 63 seismic events. In the proposed model, the median is computed as a function of the vibration period and the normalized strength of the system, as well as the event magnitude and the Joyner-Boore distance to the source. The standard deviation of the model is computed as a function of the vibration period and the normalized strength of the system. The proposed model has the advantage of not requiring an auxiliary elastic GMPM to predict the median and dispersion of peak inelastic displacement.

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Effects of human-induced load models on tuned mass damper in reducing floor vibration

Advances in Structural Engineering ◽

10.1177/1369433219843709 ◽

2019 ◽

Vol 22 (11) ◽

pp. 2449-2463

Author(s):

Jun Chen ◽

Ziping Han ◽

Ruotian Xu

Keyword(s):

Response Spectra ◽

Tuned Mass Damper ◽

Design Guidelines ◽

Degree Of Freedom ◽

Dynamic Responses ◽

Single Degree Of Freedom ◽

Load Model ◽

Load Models ◽

Single Degree ◽

Mass Damper

Dozens of human-induced load models for individual walking and jumping have been proposed in the past decades by researchers and are recommended in various design guidelines. These models differ from each other in terms of function orders, coefficients, and phase angles. When designing structures subjected to human-induced loads, in many cases, a load model is subjectively selected by the design engineer. The effects of different models on prediction of structural responses and efficiency of vibration control devices such as a tuned mass damper, however, are not clear. This article investigates the influence of human-induced load models on performance of tuned mass damper in reducing floor vibrations. Extensive numerical simulations were conducted on a single-degree-of-freedom system with one tuned mass damper, whose dynamic responses to six walking and four jumping load models were calculated and compared. The results show a maximum three times difference in the acceleration responses among all load models. Acceleration response spectra of the single-degree-of-freedom system with and without a tuned mass damper were also computed and the response reduction coefficients were determined accordingly. Comparison shows that the reduction coefficient curves have nearly the same tendency for different load models and a tuned mass damper with 5% mass ratio is able to achieve 50%–75% response reduction when the structure’s natural frequency is in multiples of the walking or jumping frequency. All the results indicate that a proper load model is crucial for structural response calculation and consequently the design of tuned mass damper device.

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