• Title, Summary, Keyword: modification factor

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Application for a BWIM Algorithm Using Density Estimation Function and Average Modification Factor in The Field Test (밀도추정함수와 평균보정계수를 이용한 BWIM 알고리즘의 현장실험 적용)

  • Han, Ah Reum Sam;Shin, Soobong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.2
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    • pp.70-78
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    • 2011
  • The paper aims at developing a more reliable and accurate BWIM(Bridge Weigh-In-Motion) algorithm using measured strain data and examining its efficiency with various tests on bridges. It proposes a BWIM algorithm using density estimation function and average modification factor for moment-strain relationship. Density estimation function has been proved to be reliably applied when multiple axle loads are estimated. An average modification factor is applied to minimize overall error that can be encountered between theoretically computed moments and measured strains at multiple locations in a bridge. The developed algorithm has been successfully examined through numerical simulations, laboratory tests, and also by field tests on a multi-girder composite bridge.

A Study of the Modification Factor(B) in the AISC Specification for Elastic Buckling of Web-Tapered Beams (웨브 변단면보의 탄성좌굴에 대한 AISC 기준의 수정계수(B)에 관한 연구)

  • Ryu, Hyo-Jin;Lim, Nam-Hyoung
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.2
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    • pp.45-49
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    • 2008
  • This paper investigated the accuracy of the current design formulae for the elastic buckling strength of web-tapered I-beams in AISC-LRFD specification. The basic concept is to replace a tapered beam by an equivalent prismatic beam with a different length, but with a cross section identical to that of the smaller end of the tapered beam. The modification factor, B, is used to account for the stress gradient within the unbraced length and the lateral restraining effects offered by the adjacent segments. The modification factor(B) suggested in AISC-LRFD specification was compared with the finite element method(FEM) results. This paper presented a redefined method to calculate the modification factor(B).

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.

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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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.

Force-based seismic design of steel haunch retrofit for RC frames

  • Ahmad, Naveed
    • Earthquakes and Structures
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    • v.20 no.2
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    • pp.133-148
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    • 2021
  • The paper presents a simplified force-based seismic design procedure for the preliminary design of steel haunch retrofitting for the seismic upgrade of deficient RC frames. The procedure involved constructing a site-specific seismic design spectrum for the site, which is transformed into seismic base shear coefficient demand, using an applicable response modification factor, that defines base shear force for seismic analysis of the structure. Recent experimental campaign; involving shake table testing of ten (10), and quasi-static cyclic testing of two (02), 1:3 reduced scale RC frame models, carried out for the seismic performance assessment of both deficient and retrofitted structures has provided the basis to calculate retrofit-specific response modification factor Rretrofitted. The haunch retrofitting technique enhanced the structural stiffness, strength, and ductility, hence, increased the structural response modification factor, which is mainly dependent on the applied retrofit scheme. An additional retrofit effectiveness factor (ΩR) is proposed for the deficient structure's response modification factor Rdeficient, representing the retrofit effectiveness (ΩR=Rretrofitted /Rdeficient), to calculate components' moment and shear demands for the retrofitted structure. The experimental campaign revealed that regardless of the deficient structures' characteristics, the ΩR factor remains fairly the unchanged, which is encouraging to generalize the design procedure. Haunch configuration is finalized that avoid brittle hinging of beam-column joints and ensure ductile beam yielding. Example case study for the seismic retrofit designs of RC frames are presented, which were validated through equivalent lateral load analysis using elastic model and response history analysis of finite-element based inelastic model, showing reasonable performance of the proposed design procedure. The proposed design has the advantage to provide a seismic zone-specific design solution, and also, to suggest if any additional measure is required to enhance the strength/deformability of beams and columns.

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.

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.

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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