• Title, Summary, Keyword: floor response spectra

Search Result 38, Processing Time 0.051 seconds

Floor Response Spectra Analysis Including Correlations of Multiple Support Motions (층간의 상관관계를 고려한 다중 층응답스펙트럼 해석)

  • 윤정방;현창헌;공재식;윤재석
    • Computational Structural Engineering
    • /
    • v.6 no.4
    • /
    • pp.67-72
    • /
    • 1993
  • This paper deals with the response spectra analysis method of the secondary structures including the correlation effect between the nonuniform multiple support excitations. Based on the random vibration theory, the multiple floor response spectra and the cross-correlation coefficient spectra of the floor motions are derived from the design ground response spectra. The example analysis results show that the proposed method yields more accurate results than those by the conventional multiple floor response spectra method without the correlation effects of the support motions. The present method may be easily employed in the seismic design of the secondary structures in engineering practice.

  • PDF

Application of frequency domain analysis for generation of seismic floor response spectra

  • Ghosh, A.K.
    • Structural Engineering and Mechanics
    • /
    • v.10 no.1
    • /
    • pp.17-26
    • /
    • 2000
  • This paper presents a case study with a multi-degree-of-freedom (MDOF) system where the Floor Response Spectra (FRS) have been derived from a large ensemble of ground motion accelerograms. The FRS are evaluated by the frequency response function which is calculated numerically. The advantage of this scheme over a repetitive time-history analysis of the entire structure for each accelerogram of the set has been highlighted. The present procedure permits generation of FRS with a specified probability of exceedence.

Generation of Floor Response Spectra including Equipment-Structure Interaction in Frequency Domain (진동수 영역에서 기기-구조물 상호작용을 고려한 층응답스펙트럼의 작성)

  • Choi, Dong-Ho;Lee, Sang-Hoon
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.9 no.6
    • /
    • pp.13-19
    • /
    • 2005
  • Floor response spectra for dynamic response of subsystem such as equipment, or piping in nuclear power plants are usually generated without considering dynamic interaction between main structure and subsystem. This study describes the analytic method in which equipment response spectra can be obtained through dynamic analysis considering equipment-structure Interaction(ESI). In this method, dynamic response of the equipment by this method is based on a dynamic substructure method in which the equipment-structure system is partitioned into the single-degree-ol-freedom system(SDOF) representing the equipment and the equipment support impedance representing the dynamic charactenstics of the structure ai the equipment support. A family of equipment response spectra is developed by applying this method to calculate the maximum responses of a family of SDOF equipment systems with wide banded equipment frequency, damping ratio, and mass. The method is validated by comparing the floor response spectrum from this method with the floor response spectrum generated from the rigorous analysis including equipments on the containment building of a prototypical nuclear power plant. in order to Investigate ESI effect in the response of equipment, response values from the method and the conventional approach without considering ESI are compared for the equipment having the mass less than 1% of the total structural mass. Response spectra from the method showed lower spectral amplitudes than those of the conventional floor response spectra around controlling frequencies.

Numerical study on Floor Response Spectrum of a Novel High-rise Timber-concrete Structure

  • Xiong, Haibei;Zheng, Yingda;Chen, Jiawei
    • International Journal of High-Rise Buildings
    • /
    • v.9 no.3
    • /
    • pp.273-282
    • /
    • 2020
  • An innovative high-rise timber-concrete hybrid structure was proposed in previous research, which is composed of the concrete frame-tube structure and the prefabricated timber modules as main structure and substructures, respectively. Considering that the timber substructures are built on the concrete floors at a different height, the floor response spectrum is more effective in estimating the seismic response of substructures. In this paper, the floor response spectra of the hybrid structure with different structural parameters were calculated using dynamic time-history analysis. Firstly, one simplified model that can well predict the seismic response of the hybrid structure was proposed and validated. Then the construction site, the mass ratio and the frequency ratio of the main-sub structure, and the damping ratio of the substructures were discussed. The results demonstrate that the peaks of the floor response spectra usually occur near the vibration periods of the whole structure, among which the first two peaks stand out; In most cases, the acceleration amplification effect on substructures tends to be more evident when the construction site is farther from the fault rupture; On the other hand, the acceleration response of substructures can be effectively reduced with an appropriate increase in the mass ratio of the main-sub structure and the damping ratio of the substructures; However, the frequency ratio of the main-sub structure has no discernible effect on the floor response spectra. This study investigates the characteristics of the floor response spectrum of the novel timber-concrete structure, which supports the future applications of such hybrid structure in high-rise buildings.

Floor Response Spectra with Structure-Equipment Interaction Effects by a Random Vibration Approach (주구조물과 설비의 상호작용을 고려한 층 응답스펙트럼의 추계론적 작성법)

  • Yun, Chung Bang;Son, Eun Jin
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.11 no.1
    • /
    • pp.37-43
    • /
    • 1991
  • An efficient method for generating floor response spectra with the structure-equipment interaction effects is proposed. Floor response spectra are computed from a prescribed ground response spectrum by a random vibration approach. Transfer function of equipment response for earthquake excitation is constructed directly from the modal properties of the individual structures. The method also can account for the nonproportional damping characteristics of the combined system.

  • PDF

Estimation of floor response spectra induced by artificial and real earthquake ground motions

  • Pu, Wuchuan;Xu, Xi
    • Structural Engineering and Mechanics
    • /
    • v.71 no.4
    • /
    • pp.377-390
    • /
    • 2019
  • A method for estimating the floor response spectra (FRS) of elastic structures under earthquake excitations is proposed. The method is established based on a previously proposed direct estimation method for single degree of freedom systems, which generally overestimates the FRS of a structure, particularly in the resonance period range. A modification factor is introduced to modify the original method; the modification factor is expressed as a function of the period ratio and is determined through regression analysis on time history analysis results. Both real and artificial ground motions are considered in the analysis, and it is found that the modification factors obtained from the real and artificial ground motions are significantly different. This suggests that the effect of ground motion should be considered in the estimation of FRS. The modified FRS estimation method is further applied to a 10-story building structure, and it is verified that the proposed method can lead to a good estimation of FRS of multi-story buildings.

Theoretically-based and practice-oriented formulations for the floor spectra evaluation

  • Abbati, Stefania Degli;Cattari, Serena;Lagomarsino, Sergio
    • Earthquakes and Structures
    • /
    • v.15 no.5
    • /
    • pp.565-581
    • /
    • 2018
  • This paper proposes a new analytical formulation for computing the seismic input at various levels of a structure in terms of floor response spectra. The approach, which neglects the dynamic interaction between primary structure and secondary element, is particularly useful for the seismic assessment of secondary and non-structural elements. The proposed formulation has a robust theoretical basis and it is based on few meaningful dynamic parameters of the main building. The method has been validated in the linear and nonlinear behavior of the main building through results coming from both experimental tests (available in literature) and parametric numerical analyses. The conditions, for which the Floor Spectrum Approach and its simplified assumptions are valid, have been derived in terms of specific interval ratios between the mass of the secondary element and the participant mass of the main structure. Finally, a practice-oriented formulation has been derived, which could be easily implementable also at code level.

A Study on Evaluation of Floor Response Spectrum for Seismic Design of Non-Structural Components (비구조요소의 내진 설계를 위한 기존 층응답스펙트럼의 평가)

  • Choi, Kyung Suk;Yi, Waon Ho;Yang, Won-Jik;Kim, Hyung Joon
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.17 no.6
    • /
    • pp.279-291
    • /
    • 2013
  • The seismic damage of non-structural components, such as communication facilities, causes direct economic losses as well as indirect losses which result from social chaos occurring with downtime of communication and financial management network systems. The current Korean seismic code, KBC2009, prescribes the design criteria and requirements of non-structural components based on their elastic response. However, it is difficult for KBC to reflect the dynamic characteristics of structures where non-structural components exist. In this study, both linear and nonlinear time history analyses of structures with various analysis parameters were carried out and floor acceleration spectra obtained from analyses were compared with both ground acceleration spectra used for input records of the analyses and the design floor acceleration spectrum proposed by National Radio Research Agency. Also, this study investigates to find out the influence of structural dynamic characteristics on the floor acceleration spectra. The analysis results show that the acceleration amplification is observed due to the resonance phenomenon and such amplification increases with the increase of building heights and with the decrease of structure's energy dissipation capacities.

Generation of Floor Response Spectra Considering Coupling Effect of Primary and Secondary System (부구조시스템의 연계 효과를 고려한 구조물의 층응답 스펙트럼 생성)

  • Cho, Sung Gook;Gupta, Abhinav
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.24 no.4
    • /
    • pp.179-187
    • /
    • 2020
  • Seismic qualification of equipment including piping is performed by using floor response spectra (FRS) or in-structure response spectra (ISRS) as the earthquake input at the base of the equipment. The amplitude of the FRS may be noticeably reduced when obtained from coupling analysis because of interaction between the primary structure and the equipment. This paper introduces a method using a modal synthesis approach to generate the FRS in a coupled primary-secondary system that can avoid numerical instabilities or inaccuracies. The FRS were generated by considering the dynamic interaction that can occur at the interface between the supporting structure and the equipment. This study performed a numerical example analysis using a typical nuclear structure to investigate the coupling effect when generating the FRS. The study results show that the coupling analysis dominantly reduces the FRS and yields rational results. The modal synthesis approach is very practical to implement because it requires information on only a small number of dynamic characteristics of the primary and the secondary systems such as frequencies, modal participation factors, and mode shape ordinates at the locations where the FRS needs to be generated.

A Study on Evaluation of Horizontal Force of Non-structural Components Considering Predominant Periods of Seismic Waves (지진파 탁월주기를 고려한 비구조요소의 수평설계지진력 평가)

  • Oh, Sang Hoon;Kim, Ju Chan
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.24 no.6
    • /
    • pp.267-275
    • /
    • 2020
  • In the event of an earthquake, non-structural components require seismic performance to ensure evacuation routes and to protect lives from falling non-structural components. Accordingly, the seismic design code proposes horizontal force for the design and evaluation of non-structural components. Ground motion observed on each floor is affected by a building's eigen vibration mode. Therefore, the earthquake damage of non-structural components is determined by the characteristics of the non-structural component system and the vibration characteristics of the building. Floor response spectra in the seismic design code are estimated through time history analysis using seismic waves. However, it is difficult to use floor response spectra as a design criterion because of user-specific uncertainties of time history analysis. In addition, considering the response characteristics of high-rise buildings to long-period ground motions, the safety factor of the proposed horizontal force may be low. Therefore, this study carried out the horizontal force review proposed in the seismic design code through dynamic analysis and evaluated the floor response of seismic waves considering buildings and predominant periods of seismic waves.