• Title, Summary, Keyword: modification factor

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Seismic Capacity according to Structural System of High-rise Apartment (고층 아파트 구조시스템에 따른 내진성능 분석)

  • Lee, Minhee;Cho, So-Hoon;Kim, Jong-Ho;Kim, Hyung-Do
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.3
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    • pp.149-154
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    • 2019
  • The structural system of domestic high-rise apartments can be divided into two parts; the core wall system, which is composed of walls concentrated in the center and the shear wall system, which comprises a great number of walls distributed in the plan. In order to analyze the lateral behavior of each system, buildings with typical domestic high-rise apartment plans were selected and nonlinear static analysis was performed to investigate the their collapse mechanism. From the force-displacement relation derived from nonlinear static analysis, response modification factor was evaluated by calculating the overstrengh and ductility factor, which are important in the seismic response. The ductility of core wall system is small, but as it is governed by wind load, its overstrength is greatly estimated, and its response modification factor is calculated by the overstrengh factor. Due to a large number of walls, shear wall system has a large ductility, making the response modification factor considerably large.

Serviceability Limit State and Response Modification Factors (기능수행수준과 응답수정계수)

  • Kook, Seung-Kyu
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.2
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    • pp.149-154
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    • 2012
  • While the Earthquake Resistant Design Part of Korean Roadway Bridge Design Code provides design procedures for the No Collapse Requirement, requirements for the Serviceability Limit State are not clearly provided. The basic design method to meet the No Collapse Requirement is the spectrum analysis method using response modification factors and the Serviceability Limit State is determined by both the importance factor and the response modification factor applied in the design procedure. The importance factor can be simply applied according to the bridge importance category, however, in moderate/low seismic regions the application of the response modification factor may bring different result according to design conditions. In this study, for a typical bridge in the moderate/low seismic regions, determination procedures for the Serviceability Limit State are reviewed by carrying out earthquake resistant design and supplementary provisions for the Earthquake Resistant Design Part are identified based on the study results.

A Study on the Evaluation Methods from Probability Computation of Bridge (교량의 과하중 확률계산을 통한 상태평가 등급 산정방법에 대한 연구)

  • Kim, Doo-Hwan;Yoo, Chang-Uk
    • Journal of the Korean Society of Safety
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    • v.24 no.4
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    • pp.53-58
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    • 2009
  • The importance of process for repair and reinforcement of the bridge is increasing because of the lack of the fatigue load and stress, a lowering of the bridge load carrying capacity owing to impact and oscillation, deterioration on cultivation periods of the bridge, etc. Typically the experimenter values the bridge load carrying capacity by the real rating factor and response modification factor in bridge load rating through static load test and dynamic load test. But the error occurred in reliability of response modification factor in bridge load rating according to experience of experimenter. so tests of connecting probability theory and valuation of the bridge recently. The study is to compute the real load carrying capacity of the bridge and the rating factor and response modification factor on grade of the bridge, and calculate the probability of over-loaded truck load from Weigh In Motion(WIM) Data in FORTRAN programming applying to Monte-Carlo Simulation. At the result of this study, it is acquired that the new grade is computed for the probability of over-loaded truck load and surface inspection. The A grade is over 1.95, B grade is $1.55{\sim}1.94$, C grade is $1.26{\sim}1.54$, D grade is $1.14{\sim}1.25$, E grade is under 1.13 of rating factor, respectively.

MODIFICATIONS OF PRODUCT CONVERGENCE STRUCTURES

  • Park, Sang-Ho
    • East Asian mathematical journal
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    • v.17 no.2
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    • pp.217-224
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    • 2001
  • In this paper, we introduce the notion of some modification of given convergence structure and product convergence. Also, we find some properties which hold between the modification associated with a product of convergence structures and the product of modifications associated with the factor convergence structures.

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Profile-shifted Gears in Multi-axial Differential System (다축차동장치의 전위기어 해석)

  • Kang, Dong-Soo;Song, Chul-Ki
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.5
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    • pp.632-637
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    • 2011
  • A new tooth profile which is adjusted on the amount of addendum modification factor is proposed for reducing vibration and noise of gears. The transmission error of the new profile can be designed more uniformly than that of the standard involute profile. The basic concepts of tooth profile modification are to reduce the load in contact area and to find the appropriate profile modification factor for operation condition. In this study, gears were estimated to constructive safety of bending strength and contact strength durability by using ROMAX program, and were compared with results by design formula of AGMA standard.

The Need for Research about Buckling Strength of Arch and Beam (보와 아치의 좌굴강도에 관한 연구의 필요성)

  • Lim, Nam-Hyoung;Lee, Chin-Ok;Ryu, Hyo-Jin;Lee, Woo-Chul;Koo, So-Yeun
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.223-226
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    • 2007
  • In current specification, modification factor(B) for web-tapered beam is used to account for the stress gradient and the restraining effect for adjacent spans. However, because these effects are considered together in modification factor, this paper revaluate the accuracy of the modification factor used in current specification. Also this paper investigate the flexural torsional buckling strength of laterally fixed thin-walled arch with doubly symmetric section using the analytical and numerical method. From this investigate the concept of effective length to consider the out-of-plane boundary condition for straight column or beam is not applicate for the flexural-torsional buckling of laterally fixed arches.

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Evaluation of ductility and response modification factor in moment-resisting steel frames with CFT columns

  • Hashemi, Seyed Sh.;Sadeghi, Kabir;Vaghefi, Mohammad;Shayan, Kaveh
    • Earthquakes and Structures
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    • v.12 no.6
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    • pp.643-652
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    • 2017
  • One of the methods to strengthen the structures against the seismic lateral loading is the employment of the composite columns. A concrete-filled tube (CFT) has the cumulative advantages of steel and concrete. Concrete-filled steel tube columns have been widely used in the moment-resisting frame (MRF) structures, located in both non-seismic zones and high-risk seismic zones. In this paper, the results of studies on two important seismic parameters of ductility and the response modification factor (RMF) of the MRFs with CFT columns are submitted. While the studies are carried out, the effects of span length-story height ratio, the strength of materials and seismic behavior of MRFs are considered. In this regard, the ductility, RMF and the strength of 36 models of the steel MRFs with CFTs are analyzed. The fiber plastic hinges numerical simulation and pushover analysis method are used in the calculations. Based on the obtained results, the RMFs suitable for the 5-, 10- and 15- story frames are proposed.

Response Modification Factors for Seismic Performance Evaluation of Non-seismic School Buildings with Partial Masonry Infills (조적허리벽이 있는 비내진 학교시설의 내진성능평가를 위한 반응수정계수)

  • Kim, Beom Seok;Park, Ji-Hun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.23 no.1
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    • pp.71-82
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    • 2019
  • Most school buildings consist of reinforced concrete (RC) moment frames with masonry infills. The longitudinal direction frames of those school buildings are relatively weak due to the short-column effects caused by the partial masonry infills and need to be evaluated carefully. In 'Manual for Seismic Performance Evaluation and Retrofit of School Facilities' published in 2018, response modification factor of 2.5 is applied to non-seismic RC moment frames with partial masonry infills, but sufficient verification of the factor has not been reported yet. Therefore, this study conducted seismic performance evaluation of planar RC moment frames with partial masonry infills in accordance with both linear analysis and nonlinear static analysis procedures presented in the manual. The evaluation results from the different procedures are compared in terms of assessed performance levels and number of members not meeting target performance objectives. Finally, appropriate response modification factors are proposed with respect to a shear-controlled column ratio.

Rational Evaluation of Seismic Response Modification Factor of Steel Moment Frame Based on Available Connection Rotation Capacity (접합부 회전능력에 기초한 철골모멘트골조의 반응수정계수 산정법)

  • Lee, Cheol-Ho;Kim, Geon-Woo;Song, Jin-Gyu
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.2
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    • pp.11-17
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    • 2007
  • In current seismic design practice, the response modification factor (R-factor) is used as a factor to reduce the elastic base shear demand to the design force level. As is well-known, the R-factor is a committee-consensus factor and, as such, highly qualitative and empirical. The relationship between the R-factor and the connection rotation capacity available in a particular structural system has remained a missing link. In this paper, a rational procedure to evaluate the R-factor is proposed. To this end, the relationship between the available connection rotation capacity and the R-factor is defined and quantified using nonlinear pushover analysis. An RRS steel frame designed according to IBC 2000 was used to illustrate and verify the proposed procedure. Nonlinear time history analysis results indicated that the R-factor definition proposed in this study is generally conservative from design perspective.

Overstrength and Response Modification Factor in Low Seismicity Regions (약진지역에서의 초과강도 및 반응수정계수)

  • Lee, Dong-Guen;Cho, So-Hoon;Ko, Hyun;Kim, Tae-Jin
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.3
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    • pp.57-64
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    • 2006
  • Seismic design codes are mainly based on the research results for the inelastic response of structures in high seismicity regions. Since wind loads and gravity loads may govern the design in low seismicity regions in many cases, structures subjected to design seismic loads will have larger overstrength compared to those of high seismicity regions. Therefore, it is necessary to verify if the response modification factor based on high seismicity would be adequate for the design of structures in low seismicity regions. In this study, the adequacy of the response modification factor was verified based on the ductility and overstrength of building structures estimated from the result of nonlinear static analysis. Framed structures are designed for the seismic zones 1, 2A, 4 in UBC-97 representing the low, moderated and high seismicity regions and the overstrength factors and ductility demands of the example structures are investigated. When the same response modification factor was used in the design, inelastic response of structures in low seismicity regions turned out to be much smaller than that in high seismicity regions because of the larger overstrength of structures in low seismicity regions. Demands of plastic rotation in connections and ductility in members were much lower in the low seismicity regions compared to those of the high seismicity regions when the structures are designed with the same response modification factor.