• Title/Summary/Keyword: 층간변위각

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Estimation of Beam Plastic Rotation Demands for Special Moment-Resisting Steel Frames (강구조 특수모멘트골조의 보 소성변형요구량 평가)

  • Eom, Tae-Sung
    • Journal of Korean Society of Steel Construction
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    • v.23 no.4
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    • pp.405-415
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    • 2011
  • For the safe seismic design of buildings, it is necessary to predict the plastic deformation demands of the members as well as the story drift ratio. In the present study, a simple method of estimating the beam plastic rotation was developed for special-moment-resisting steel frame structures designed with strong column-weak beam behavior. The proposed method uses elastic analysis rather than nonlinear analysis, which is difficult to use in practice. The beam plastic rotation was directly calculated based on the results of the elastic analysis, addressing the moment redistribution, the column and joint dimensions, the movement of the plastic hinge, the panel zone deformation, the gravity load, and the strain-hardening behavior. In addition, the rocking effect of the braced frame or core wall on the beam plastic rotation was addressed. For verification, the proposed method was applied to a six-story special-moment frame designed with strong column-weak beam behavior. The predicted plastic rotations of the beams were compared with those that were determined via nonlinear analysis. The beam plastic rotations that were predicted using the proposed method correlated well with those that were determined from the nonlinear pushover analysis.

Experimental Study on Nonlinear Behaviors of A 1:12 Scale 10-Story Reinforced Concrete Frame with Nonseismic Details (비내진 상세를 가진 1:12축소 10층 R.C.골조의 비선형 거동에 관한 실험 연구)

  • Lee, Han-Seon;Kang, Kyi-Yong
    • Magazine of the Korea Concrete Institute
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    • v.11 no.1
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    • pp.255-266
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    • 1999
  • The objective of this experiment is to observe the elastic and inelastic behaviors of high-rise reinforced concrete frames having non-seismic details. To do this, a building frame designed according to Korean seismic code and detailed in the Korean conventional practice was selected. A 1:12 scale plane frame model was manufactured according to similitude law. A reversed lateral load test and a monotonic pushover test were performed under the displacement control. To simulate the earthquake effects, the lateral force distribution was maintained to be an inverse triangle by using a whiffle tree. From the tests, base shears, crack pattern, local rotations in the ends of critical members and the relations between interstory drift versus story shear are obtained. Based on test results, conclusions are drawn on the implications of the elastic and inelastic behaviors of a high-rise reinforced concrete frame having non-seismic details.

Experimental Study on Buckling Restrained Knee Bracing Systems using Channel Scetions (채널 형강을 이용한 비좌굴 Knee Bracing System의 내진성능에 대한 실험적 연구)

  • Lee, Jin;Lee, Ki Hak;Lee, Han Seon;Kim, Hee Cheul;Lee, Young Hak
    • Journal of Korean Society of Steel Construction
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    • v.21 no.1
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    • pp.71-81
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    • 2009
  • In this study, the seismic performance of the Buckling Restrained Knee Bracing (BRKB) system was evaluated through a pin-connected one-bay, one-story frame. The BRKB system developed in this study was composed of a steel plate as a load-resisting core member and two channel sections to restrain local and global buckling of the core plate. The main purpose of the BRKB system is to restrengthen/rehabilitate old low- and mid-rise RC buildings, which, it is assumed, were designed with non-seismic designs and details. The main variables for the test specimens were the size of the core plates and the stiffeners, and the condition of the end plates. The test results showed that the size of the core plate, which was the main element of the load-resisting member, was the most important parameter in achieving a ductile behavior under tension as well as compression until the maximum displacement exceeds twice the design drift limit.

A Study on the Structural Performance of the Building Exterior Panel Using the Moving Clips (이동 클립을 이용한 건축물 외장재의 구조적 성능에 관한 연구)

  • Kwak, Eui-Shin;Ki, Chang-Gun;Lee, Sang-Ho;Shon, Su-Deok;Lee, Seung-Jae
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.33 no.12
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    • pp.29-36
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    • 2017
  • A recent global trend in the increase of earthquake-related disasters has become so frequent as to cause various damages to a wide range of mid- to high-rise buildings. Particularly, more attention is being paid to the effect of horizontal load in high-rise buildings not only on the key structural elements of the structures, but also on the possibility of the secondary damages to them due to the failure of exterior panels, which are non-structural elements, but such damages are difficult to cope with as they may be caused by unexpected changes. The present study examined exterior panels using moving clips to prevent such secondary damages on the non-structural elements and analyzed the structural performance of these exterior panels through the finite element analysis and the shaking table test. The analysis results showed that the exterior panels using moving clips satisfied the structural performance against the allowable story drift of KBC2009 and the safety of the exterior panels was verified by the shake table test.

Experimental Study on the Behavior of Building Hardware with Joint Details (접합 방법에 따른 하지철물 구조물의 거동에 관한 실험적 연구)

  • Hong, Seonguk;Kim, Seunghun;Baek, Kiyoul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.1
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    • pp.190-198
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    • 2018
  • In recent years, non-welded building hardware has been installed by bolt assembly is used. The non-welded building hardware method can reduce accidents caused by welding, and can be constructed by bolt assembly, which can reduce labor costs and shorten the construction period. However, there is a need for a method to compensate for the occurrence of buckling at the time of construction. The purpose of this study is to evaluate the behavior of joints between steel pipe and fastener and to evaluate the behavior of joints of non-welded and welded hardware frame. As a result, it was found that the foundation steel structure without welded joints was deformed to a rotation angle of member much larger than the allowable interlayer displacement angle 0.01 to 0.02 required according to the seismic load rating in the seismic load resistance system.

Moment-Rotation Relationship and Effective Stiffness of Flat Plates under Lateral Load (횡하중을 받는 플랫플레이트의 모멘트-변형각 곡선과 유효강성)

  • Choi, Kyoung-Kyu;Park, Hong-Gun
    • Journal of the Korea Concrete Institute
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    • v.15 no.6
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    • pp.856-865
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    • 2003
  • Current design provisions and guide for performance-based design do not accurately evaluate seismic performance of flat plate system. In the previous companion studies, parametric studies using nonlinear finite element analyses were performed to investigate behavior of the flat plate, and based on the numerical results, design methods that can predict the bending moment-carrying capacity and the corresponding deformability of the flat plate was developed. In the present study, a generalized moment-rotation relation of the flat plate was developed based on the previous studies and the numerical analyses. The proposed method was verified by the comparisons with existing experiments. In addition, the effective stiffness of the flat plate corresponding to 0.2 percent of lateral drift that is generally regarded as the serviceability limit was proposed, so as to evaluate conveniently deflection of the structure subject to wind load.

Earthquake Simulation Tests of A 1:5 Scale Gravity Load Designed 3-Story Reinforced Concrete Frame (중력하중 설계된 1:5 축소 3층 철근콘크리트 골조의 지진모의실험)

  • 이한선;우성우
    • Magazine of the Korea Concrete Institute
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    • v.10 no.6
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    • pp.241-252
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    • 1998
  • The objective of the research stated herein is to observe the actual responses of a low-rise nonseismic moment-resisting reinforced concrete frame subjected to varied levels of earthquake ground motions. First, the reduction scale for the model was determined as 1 : 5 considering the capacity of the shaking table to be used and the model was manufactured according to the similitude law. This model was, then, subjected to the shaking table motions simulating Taft N21E component earthquake ground motions, whose peak ground accelations (PGAs) were modified to 0.12g, 0.2g, 0.3g, and 0.4g. The lateral accelerations and displacements at each story and local deformations at the critical reginos of the structure were measured. The base shear was measured by using self-made load cells. Before and after each earthquake simulation test, free vibration tests were performed to find the change in the natural period and damping ratio of the model. The test data on the global and local behaviors are interpreted. The model showed the linear elastic behavior under the Taft N21E motion with the PGA if 0.12g, which represents the design earthquake in Korea. The maximum base shear was 1.8tf, approximately 4.7 times the design base shear. The model revealed fairly good resistance to the higher level of earthquake simulation tests. The main components of its resistance to the high level of earthquakes appeared to be 1) the high overstrength, 2) the elongation of the fundamental period, and 3) the minor energy dissipation by inelastic deformations. The drifts of the model under these tests were approximately within the allowable limit.

Evaluation of Axial Strains of Reinforced Concrete Columns (철근콘크리트 기둥의 축방향 변형률 평가)

  • Lee, Jung-Yoon;Kim, Min-Ok;Kim, Hyung-Beom
    • Journal of the Korea Concrete Institute
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    • v.25 no.1
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    • pp.19-28
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    • 2013
  • The longitudinal axial strain in the plastic hinge region of reinforced concrete (RC) columns influences on the structural behavior of RC structures subjected to reversed cyclic loading. This strain decreases the effective compressive strength of concrete and increases the lateral displacements between stories by causing the elongation of member length. This paper investigated the effects of the axial force on the elongation of a RC member by using a sectional analysis of RC members. The analytical and experimental results indicated that the axial force decreased the axial strain in the plastic hinge region of RC columns. In this study, a model was proposed to predict the axial strain of RC columns. The proposed model considering the effects of axial force ratio consisted of three path types ; Path 1-loading region, Path 2-unloading region, and Path 3-reversing cyclic loading region. The axal strains predicted by the proposed model were compared with the test results of RC columns with various axial force ratios, and agreed reasonably with the observed longitudinal strains.

Seismic Analysis of Mid Rise Steel Moment Resisting Frames with Relative Stiffness of Connections and Beams (접합부와 보의 상대강성을 고려한 중층 철골 모멘트 골조의 내진해석)

  • Ha, Sung-Hwan;Kang, Cheol-Kyu;Han, Hong-Soo;Han, Kweon-Gyu;Choi, Byong-Jeong
    • Journal of Korean Society of Steel Construction
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    • v.23 no.5
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    • pp.595-606
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    • 2011
  • This study was conducted to investigate the seismic behavior of steel member resisting frames considering the relative stiffness of the connection and beams. Six-story steel moment frames were designed to study the seismic behavior. The connections were classified into Double Web-Angle connections (DWAs), Top- and Seat-angles with double Web-angles (TWSs), FEMA-Test Summary No. 28, Specimen ID: UCSD-6 (SAC), and Fully Restrained (FR). The rotational stiffness of the semi-rigid connections was estimated using the Three-Parameter Power Model adopted by Chen and Kishi. The relative stiffness, which is the ratio of the rotational stiffness of the connections to the stiffness of the beams, was used. Push-over, repeated loading, and time history analysis were performed for all the frames. The seismic behavior of each frame was analyzed with the story drift, plastic hinge rotation, and hysteretic energy distribution.

Correlation of Experimental and Analytical Inelastic Responses of A 1:12 Scale 10-Story Reinforced Concrete Frame with Non-seismic Details (비내진 상세를 가진 1:12축소 10층 R.C.골조의 비선형 거동에 대한 실험과 해석의 상관성)

  • Lee, Han-Seon;Kang, Kyi-Yong
    • Magazine of the Korea Concrete Institute
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    • v.11 no.1
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    • pp.267-277
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    • 1999
  • The pushover analysis technique is now attracting the world-wide interest for the prediction of elastic and inelastic behavior of structures in the seismic evaluation of existing buildings. However, the reliability of this analysis technique has not been fully checked by the test results in the case of structures with nonseismic details. The objective of this study is to verify the correlation between the experimental and analytical responses of a 1:12 scale 10-story reinforced concrete frame with non-seismic details by using DRAIN-2DX program and the test results performed previously. It is concluded from this comparison that the overall responses such as the relations between story shear versus interstory drift and the local deformations such as plastic rotations can be predicted with quite high reliability.