• Title/Summary/Keyword: beam-column subassemblage

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Cyclic-Leading Tests of RC Exterior Beam-Column Joints with Non-Seismic Detailing (비내진 상세를 가진 RC 외부접합부의 반복 횡하중 실험)

  • Cha, Byung-Gi;Ko, Dong-Woo;Woo, Sung-Woo;Lee, Han-Seon
    • Journal of the Korea Concrete Institute
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    • v.15 no.1
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    • pp.11-16
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    • 2003
  • The objective of this study is to clarify the seismic capacity and the characteristics in the hysteretic behavior of RC structures with non-seismic detailing. To do this, an exterior beam-column subassemblage was selected from a ten story RC building and six 1/3-scale specimens were manufactured with three variables; (1) with and without slab, (2) upward and downward direction of anchorage for the bottom bar in beams, and (3) with and without hoop bars in the joint region. The test results have shown that (1) the existence of slab increased the strength in positive and negative moment, 25% and 52%, respectively; (2) the Korean practice of anchorage (downward and 25 $d_{b}$ anchorage length) caused the 8% reduction of strength and the early strength degradation in comparison with the case of seismic details; and (3) the existence of hoop bars in the joint region shows significant role in preventing the pull-out.t.

Design of MR dampers to prevent progressive collapse of moment frames

  • Kim, Jinkoo;Lee, Seungjun;Min, Kyung-Won
    • Structural Engineering and Mechanics
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    • v.52 no.2
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    • pp.291-306
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    • 2014
  • In this paper the progressive collapse resisting capacity of steel moment frames with MR dampers is evaluated, and a preliminary design procedure for the dampers to prevent progressive collapse is suggested. Parametric studies are carried out using a beam-column subassemblage with varying natural period, yield strength, and damper force. Then the progressive collapse potentials of 15-story steel moment frames installed with MR dampers are evaluated by nonlinear dynamic analysis. The analysis results of the model structures showed that the MR dampers are effective in preventing progressive collapse of framed structures subjected to sudden loss of a first story column. The effectiveness is more noticeable in the structure with larger vertical deflection subjected to larger inelastic deformation. The maximum responses of the structure installed with the MR dampers designed to meet a given target dynamic response factor generally coincided well with the target value on the conservative side.

Stability analysis of semi-rigid composite frames

  • Wang, Jing-Feng;Li, Guo-Qiang
    • Steel and Composite Structures
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    • v.7 no.2
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    • pp.119-133
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    • 2007
  • Based on stability theory of current rigid steel frames and using the three-column subassemblage model, the governing equations for determining the effective length factor (${\mu}$-factor) of the columns in semirigid composite frames are derived. The effects of the nonlinear moment-rotation characteristics of beam-to-column connections and composite action of slab are considered. Furthermore, using a two-bay three-storey composite frame with semi-rigid connections as an example, the effects of the non-linear moment-rotation characteristics of connections and load value on the ${\mu}$-factor are numerically studied and the ${\mu}$-factors obtained by the proposed method and Baraket-Chen's method are compared with those obtained by the exact finite element method. It was found that the proposed method has good accuracy and can be used in stability analysis of semi-rigid composite frames.

Repair of seismically damaged RC bridge bent with ductile steel bracing

  • Bazaez, Ramiro;Dusicka, Peter
    • Steel and Composite Structures
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    • v.26 no.6
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    • pp.745-757
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    • 2018
  • The inclusion of a ductile steel bracing as means of repairing an earthquake-damaged bridge bent is evaluated and experimentally assessed for the purposes of restoring the damaged bent's strength and stiffness and further improving the energy dissipation capacity. The study is focused on substandard reinforced concrete multi-column bridge bents constructed in the 1950 to mid-1970 in the United States. These types of bents have numerous deficiencies making them susceptible to seismic damage. Large-scale experiments were used on a two-column reinforced concrete bent to impose considerable damage of the bent through increasing amplitude cyclic deformations. The damaged bent was then repaired by installing a ductile fuse steel brace in the form of a buckling-restrained brace in a diagonal configuration between the columns and using post-tensioned rods to strengthen the cap beam. The brace was secured to the bent using steel gusset plate brackets and post-installed adhesive anchors. The repaired bent was then subjected to increasing amplitude cyclic deformations to reassess the bent performance. A subassemblage test of a nominally identical steel brace was also conducted in an effort to quantify and isolate the ductile fuse behavior. The experimental data from these large-scale experiments were analyzed in terms of the hysteretic response, observed damage, internal member loads, as well as the overall stiffness and energy dissipation characteristics. The results of this study demonstrated the effectiveness of utilizing ductile steel bracing for restoring the bent and preventing further damage to the columns and cap beams while also improving the stiffness and energy dissipation characteristics.

Exterior Joint Behavior of Low-Rise Reinforced Concrete Frame with Non-Seismic Detail (비내진 상세를 가진 저층 R.C조의 외부접합부 거동)

  • 김영문;기찬호;장준호;이세웅;김상대
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04b
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    • pp.481-486
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    • 1998
  • In this paper, elastic and inelastic behavior of exterior joint of moment-resisting R.C frame with non-seismic detail subjected to reversed cyclic lateral load such as earthquake excitations was investigated. 1/2-scals subassemblage exterior beam-column joint including slab was manufactured based on similitude law. Then, pseudo static test under the displacement control was performed. The results of 1)crack pattern and failure mode, 2)degradation stiffness and strength, energy dissipation capacity from load-displacement hysteresis curve, 3)strain of steel were analysed.

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Analytical Simulation of Reversed Cyclic Lateral Behaviors of R.C. Shear Wall Subassemblages Using PERFORM 3D (PERFORM 3D를 이용한 RC 벽식 부분구조의 반전 횡하중 거동에 대한 해석적 모사)

  • Lee, Han-Seon;Jeong, Da-Hun;Hwang, Kyung-Ran;Park, Hong-Gun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.6
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    • pp.23-31
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    • 2010
  • It is necessary to develop reliable but simple analytical models to predict the nonlinear response of reinforced concrete wall structures. In this study, experimental results on the cyclic reversed lateral behaviors of reinforced concrete shear wall assemblages are simulated analytically by using the wall, beam, and column models available in the PERFORM 3D program. Through the comparison of experimental and analytical results, the reliability and limitations of the analysis are evaluated. In addition, the information, which could not be obtained experimentally, such as the internal flow of force, the contribution of the flange walls, and the resisting mechanism of the walls with the contribution of the coupling beam, is provided.

Hysteretic Damage Model for Reinforced Concrete Joints Considering Bond-Slip (부착-슬립을 고려한 철근콘크리트 접합부의 이력 손상 모델 개발)

  • Kim, Do-Yeon;Choi, In-Kil
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.4A
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    • pp.517-528
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    • 2008
  • This paper presents a hysteretic damage model for reinforced concrete (RC) joints that explicitly accounts for the bond-slip between the reinforcing bars and the surrounding concrete. A frame element whose displacement fields for the concrete and the reinforcing bars are different to permit slip is developed. From the fiber section concept, compatibility equations for concrete, rebar, and bond are defined. Modification of the hysteretic stress-strain curve of steel is conducted for partial unloading and reloading conditions. Local bond stress-slip relations for monotonic loads are updated at each slip reversal according to the damage factor. The numerical applications of the reinforcing bar embedded in the confined concrete block, the RC column anchored in the foundation, and the RC beam-column subassemblage validate the model accuracy and show how including the effects of bond-slip leads to a good assessment of the amount of energy dissipation during loading histories.