• Title/Summary/Keyword: time-history analyses

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Vibration Analyses of the STSAT-3 Satellite (과학기술위성 3 호 진동해석)

  • Cho, Hee-Keun;Suh, Jung-Ki
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.502-507
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    • 2008
  • An entire composite structure satellite is developing for the first time in Korea. All of the structure is made of CFRP-composite faced aluminum honeycomb sandwich structure. Here the random and sinusoidal spectrum analysis of the satellite was carried out by using the finite element method. The general spectrum analysis was herein performed but also the PSD (power spectrum density) function for random vibration analysis had been transformed into equivalent time domain function and then transient analysis is conducted. The time history of displacement, acceleration, stress and velocity responses with respect to the PSD input has been achieved by the time dependent transient function transformed from frequency PDS function. It enables one to perform dynamic durability analysis and then expect the life time of the composite structure. The composite faced sandwich structure's spectrum analysis of a domestically-developed satellite, STSAT-3, has been discussed in the present study.

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Factors Associated with Underscreening for Cervical Cancer among Women in Canada

  • Schoueri-Mychasiw, Nour;McDonald, Paul Wesley
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.11
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    • pp.6445-6450
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    • 2013
  • Background: Cervical cancer is the second most common cancer among women worldwide. Failure to prevent cervical cancer is partly due to non-participation in regular screening. It is important to plan and develop screening programs directed towards underscreened women. In order to identify the factors associated with underscreening for cervical cancer among women, this study examined Pap test participation and factors associated with not having a time-appropriate (within 3 years) Pap test among a representative sample of women in Ontario, Canada using Canadian Community Health Survey (CCHS) data. Materials and Methods: Univariate analyses, cross-tabulations, and logistic regression modeling were conducted using cross-sectional data from the 2007-2008 CCHS. Analyses were restricted to 13,549 sexually active women aged 18-69 years old living in Ontario, with no history of hysterectomy. Results: Almost 17% of women reported they had not had a time-appropriate Pap test. Not having a time-appropriate Pap test was associated with being 40-69 years old, single, having low education and income, not having a regular doctor, being of Asian (Chinese, South Asian, other Asian) cultural background, less than excellent health, and being a recent immigrant. Conclusions: Results indicate that disparities still exist in terms of who is participating in cervical cancer screening. It is crucial to develop and implement cervical cancer screening programs that not only target the general population, but also those who are less likely to obtain a Pap tests.

Estimation of Applicability of Empirical Design Procedure for Predicting Seismic Response of Buried Gas Pipelines through 3D Time-history Analysis (3차원 시간이력해석을 통한 매설가스배관 종방향 지진응답 예측을 위한 경험적 설계법의 적용성 평가)

  • Kwak, Hyungjoo;Park, Duhee;Lee, Jangguen;Kang, Jaemo
    • Journal of the Korean Geotechnical Society
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    • v.31 no.9
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    • pp.53-68
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    • 2015
  • Longitudinal strain is an important component of seismic design for buried pipelines. A design procedure which determines the wavelength from site natural period and shear wave velocity of the soil layer and closed-form solutions of pipelines under a harmonic motion is typically used in design. However, the applicability of the procedure has not yet been thoroughly investigated. In this paper, displacement-time histories extracted from 1D site response analyses are used in 3D shell-spring model to accurately predict the response of pipelines. The results are closely compared to those from the design procedure. The area of interest is East Siberia. Performing a site response analysis to determine site specific displacement time history is highlighted. The site natural period may be used to predict the predominant period of the acceleration time history, but cannot be used to estimate the predominant period of the displacement time history. If an accurate estimate of the predominant period of the displacement time history is provided, it is demonstrated that the design equation can be successfully used to predict the response of pipelines.

Inelastic Behavior of Steel Frames with Buckling Restrained Braced (비좌굴가새가 설치된 골조의 비탄성거동)

  • Kim Jin-Koo;Park Jun-Hee
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2005.04a
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    • pp.97-104
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    • 2005
  • The seismic behavior of framed structure with Chevron-type bucking restrained braces were investigated and their behavior factors were evaluated following the procedure proposed in ATC-19 & ATC-34. Two types of structures, building frame systems and dual systems, with 4, 8, 12, and 16 stories were designed per the IBC 2000, the AISC LRFD and the AISC/SEAOC Recommended Provisions for BRBF. Nonlinear static pushover analyses were carried out to observe the plastic hinge formation and to identify the loads and the displacements at the yield and the ultimate states. Time history analyses were also carried out to compute the permanent displacement md the dissipated hysteretic energy. According to the analysis results, the response modification factors of model structures fumed out to be larger than what is proposed in the provision in low story structures, and a little smaller in medium-story structures. The dual systems, even though designed with smaller seismic load, showed superior static and dynamic performances.

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A Comparison of Time History Analysis to UBC-88 Requirements in a Low Seismic Zone (약진지역에 있어서의 시간이력 해석과 UBC 규준 해석의 비교)

  • 김희철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1991.10a
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    • pp.90-95
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    • 1991
  • The Uniform Building Code (UBC) is the most widely used requirements for earthquake resistant design in the United States. In this paper, a mid-rise steel building is analyzed by applying 12 sets of actual strong-motion earthquake data that have been scaled to acne 2B levels. The simply extrapolated ground motion displacements are used for the dynamic loads. The results of dynamic analyses for a 10-story steel building are compared with the static and dynamic analysis requirements of UBC-88. It was found that computed lateral fortes using UBC-88 static procedure differed by about 60 percent depending on whether the natural period was computed using the UBC empirical method or the UBC recommended Rayleigh's method. The lateral fortes computed from the UBC response spectra were more than 10 times greater than those computed by UBC static procedures. The lateral forces obtained from both linear and nonlinear analyses using 1989 Loma Prieta ground mot ions compared very well with UBC response spectra results.

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Non-linear Time History Analyses of a Piloti-type Building Structure (필로티형 건물의 비선형 시간이력해석)

  • Lee, Han-Seon;Ko, Dong-Woo
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2005.03a
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    • pp.169-176
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    • 2005
  • Many RC building structures of multiple uses constructed in Korea have the irregularities of torsion and soft story at bottom stories. A typical irregular building was selected as prototype and shaking table tests were performed to investigate the seismic performance of this building. The objective of this study is to evaluate the correlation between the experimental and analytical responses of this irregular building structure subjected to the earthquake excitation by using OpenSees(Open System for Earthquake Engineering Simulation). The results of analyses simulate well the effect of axial forces on the shear force of column and axial deformation. However, some discrepancy between analytical and experimental results in the distribution of shear forces and overturning deformation were observed.

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Effect of model calibration on seismic behaviour of a historical mosque

  • Demir, Ali;Nohutcu, Halil;Ercan, Emre;Hokelekli, Emin;Altintas, Gokhan
    • Structural Engineering and Mechanics
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    • v.60 no.5
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    • pp.749-760
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    • 2016
  • The objective of the study is to investigate the effects of model calibration on seismic behaviour of a historical mosque which is one of the most significant Ottomon structures. Seismic analyses of calibrated and noncalibrated numeric models were carried out by using acceleration records of Kocaeli earthquake in 1999. In numerical analysis, existing crack zones on real structure was investigated in detail. As a result of analyses, maximum stresses and displacements of calibrated and noncalibrated numerical models were compared each other. Consequently, seismic behaviour and damage state of historical masonry Hafsa Sultan mosque was determined as more realistic in the event of a severe earthquake.

Evaluation of combination rules for multi-story buildings with asymmetric set-backs

  • Aksoylu, M. Gunhan;Durgun, Yavuz;Darilmaz, Kutlu
    • Earthquakes and Structures
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    • v.11 no.1
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    • pp.179-193
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    • 2016
  • The effectiveness of 100/30, 100/40 and SRSS directional combination rules on the response of asymmetric setback buildings is examined. Because of the irregularity in setback buildings, the maximum seismic response would be correlative with the direction of earthquake. To verify the directional combination rules of mode superposition methods, the time history analyses of setback buildings to real earthquake records are carried out. Example analyses have been used to compare the validty and accuracy of SRSS and percentage methods for frame and dual frame-wall systems.

Seismic assessment of thin steel plate shear walls with outrigger system

  • Fathy, Ebtsam
    • Structural Engineering and Mechanics
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    • v.74 no.2
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    • pp.267-282
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    • 2020
  • The seismic performance and failure modes of the dual system of moment resisting frames and thin steel plate shear walls (TSPSWs) without and with one or two outrigger trusses are studied in this paper. These structural systems were utilized to resist vertical and lateral loads of 40-storey buildings. Detailed Finite element models associated with nonlinear time history analyses were used to examine seismic capacity and plastic mechanism of the buildings. The analyses were performed under increased levels of earthquake intensities. The models with one and two outriggers showed good performance during the maximum considered earthquake (MCE), while the stress of TSPSWs in the model without outrigger reached its ultimate value under this earthquake. The best seismic capacity was in favour of the model with two outriggers, where it is found that increasing the number of outriggers not only gives more reduction in lateral displacement but also reduces stress concentration on thin steel plate shear walls at outrigger floors, which caused the early failure of TSPSWs in model with one outrigger.

Study on Seismic Responses for Base Isolated Structure Subjected to Earthquakes with Different Frequency Characteristics (주파수특성이 다른 입력지진에 대한 면진구조물의 지진응답연구)

  • Yoo, Bong;Lee, Jae-Han
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1997.04a
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    • pp.224-231
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    • 1997
  • A study on the seismic responses for a base isolated structure subjected to earthquakes with different frequency characteristics is peformed with time history analyses. Two types of seismic inputs are considered in these analyses, one is short period earthquakes such as El Centro(1940, NS), the other is long period ones such as Mexico(1985). The seismic responses of the base isolated structure depend on seismic input types and isolation frequencies. In this study the 0.5 Hz of isolation frequency for short period earthquakes remarkably reduces the acceleration responses, increases the relative displacements of isolator that are still within the proposed limits of isolator. However higher isolation frequency for long period earthquakes is more adequate to reduce the seismic responses of the base isolated structures; in the study 0.75 Hz is effective to Mexico 1985 earthquake.

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