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Experimental study of the behavior of beam-column connections with expanded beam flanges

  • Ma, Hongwei;Wang, Jiwei;Lui, Eric M.;Wan, Zeqing;Wang, Kun
    • Steel and Composite Structures
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    • v.31 no.3
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    • pp.319-327
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    • 2019
  • This paper describes an experimental study of steel beam-column connections with or without expanded beam flanges with different geometries. The objectives of this study are to elucidate the cyclic behavior of these connections, identify the location of the plastic hinge zone, and provide useful test data for future numerical simulations. Five connection specimens are designed and tested under cyclic load. The test setup consists of a beam and a column connected together by a connection with or without expanded beam flanges. A constant axial force is applied to the column and a time varying point load is applied to the free end of the beam, inducing shear and moment in the connection. Because the only effect to be studied in the present work is the expanded beam flange, the sizes of the beam and column as well as the magnitude of the axial force in the column are kept constant. However, the length, width and shape of the expanded beam flanges are varied. The responses of these connections in terms of their hysteretic behavior, failure modes, stiffness degradation and strain variations are experimentally obtained and discussed. The test results show that while the influence of the expanded beam flanges on hysteretic behavior, stiffness degradation and energy dissipation capacity of the connection is relatively minor, the size of the expanded beam flanges does affect the location of the plastic hinge zone and strain variations in these beam-column joints. Furthermore, in terms of ductility, moment and rotational capacities, all five connections behave well. No weld fracture or premature failure occurs before the formation of a plastic hinge in the beam.

Seismic Performance of PC Moment Frame with Plastic Shear Hinge (소성전단힌지를 갖는 PC 모멘트 골조의 내진성능)

  • Lim, Woo-Young;Hong, Sung-Gul
    • Journal of the Korea Concrete Institute
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    • v.27 no.4
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    • pp.353-362
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    • 2015
  • Cyclic loading tests for the PC moment frame with plastic shear hinges were performed to evaluate the seismic performance. The plastic shear hinges consisted of two steel plates were installed at the mid-length of the beam to connect the PC frames. Three shear links are existed in each steel plate. The three shear links were designed using shear force corresponding to the shear capacity of 50%, 75%, and 100% of the beam shear capacity. The proposed connections showed an efficient energy dissipation capacity and good structural performance. As a result, it is reasonable to design the plastic shear hinges using design shear capacity less than 100% of the beam shear capacity.

Quasi Static Test of Lap Spliced Shear-Flexure RC Piers Using Real Scale Models (주철근 겹침이음된 휨-전단 RC교각의 실물모형 준정적 실험)

  • 곽임종;조창백;조정래;김영진;김병석
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.203-210
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    • 2002
  • The past bridge design specifications of Korea didn't include 1imitation on the amount of lap splices in the plastic hinge zone of piers, and so do current specifications. But these specifications include just limitation on the minimal length of lap splices. Thus, a large majority of non-seismically designed bridge piers may have lap splices in plastic hinge zone. In this study, model pier was selected among existent bridge piers whose failure mode is complex shear-flexure mode. Full scaled RC pier models whose aspect ratio is about 2.67 were constructed and quasi static test according to the drift level history was implemented. From the test results, effect of the lap splices on the seismic performance of bridges piers was analyzed, and the seismic capacity of the model bridges was evaluated by capacity spectrum method.

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Evaluation on Seismic Performance of the Columns in Concrete Moment Frames (모멘트 골조 기둥의 구조 성능평가)

  • 한상환;박성일
    • Journal of the Korea Concrete Institute
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    • v.14 no.4
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    • pp.513-520
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    • 2002
  • This study is to evaluate the structural performance of columns in concrete moment frame. For this purpose the results of previous experimental studies were collected and compared. The experimental variables considered in this study are existance of lap splice within the possible plastic hinge region during an earthquake, ratio of longitudinal reinforcement axial load and the transverse reinforcement ratio. The strength, deformation, ductility capacity and the length of plastic hinge are compared in this study.

Finite Element Analysis of Exterior R.C. Beam-Column Joints Containing Headed Bars utilized for Enhanced Seismic Performance (Headed bar를 사용한 외부 철근 콘크리트 보-기둥 접합부의 강화된 내진 성능에 대한 유한요소해석)

  • Bang, Suk;Lee, Joo-Ha;Yoon, Young-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.506-509
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    • 2004
  • This paper proposes Headed bar as reinforcement of beam-column joint, and proves seismic performance and reduction of reinforcement congestion. In these case, the use of Headed bars have obvious advantages. The greatest benefit of using Headed bars is not only improved structural performance of beam-column joints, but also the ease of fabrication, construction, and placement. Three-dimensional finite element analysis model is compared with test program which was fulfilled by the proposed model with Headed bar. Also, the plastic hinge region is relocated to the center of the longitudinal beam length according to the strong column-weak beam design philosophy, so Headed bar is used as the joint reinforcement. Therefore, this paper presents results of a computer analysis of a practical solution for relocating potential beam plastic hinge regions by the placing of straight - Headed bar.

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Employing a fiber-based finite-length plastic hinge model for representing the cyclic and seismic behaviour of hollow steel columns

  • Farahi, Mojtaba;Erfani, Saeed
    • Steel and Composite Structures
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    • v.23 no.5
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    • pp.501-516
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    • 2017
  • Numerical simulations are prevalently used to evaluate the seismic behaviour of structures. The accuracy of the simulation results depends directly on the accuracy of the modelling techniques employed to simulate the behaviour of individual structural members. An empirical modelling technique is employed in this paper to simulate the behaviour of column members under cyclic and seismic loading. Despite the common modelling techniques, this technique is capable of simulating two important aspects of the cyclic and seismic behaviour of columns simultaneously. The proposed fiber-based modelling technique captures explicitly the interaction between the bending moment and the axial force in columns, and the cyclic deterioration of the hysteretic behaviour of these members is implicitly taken into account. The fiber-based model is calibrated based on the cyclic behaviour of square hollow steel sections. The behaviour of several column archetypes is investigated under a dual cyclic loading protocol to develop a benchmark database before the calibration procedure. The dual loading protocol used in this study consists of both axial and lateral loading cycles with varying amplitudes. After the calibration procedure, a regression analysis is conducted to derive an equation for predicting a varying calibrated modelling parameter. Finally, several nonlinear time-history analyses are conducted on a 6-story steel special moment frame in order to investigate how the results of numerical simulations can be affected by employing the intended modelling technique for columns instead of other common modelling techniques.

Proposal of a New Design Method of the Pile-Bent Structure Considering Plastic Hinge (단일 현장타설말뚝의 소성힌지를 고려한 최적설계법 제안)

  • Ahn, Sang-Yong;Jeong, Sang-Seom;Kim, Jae-Young
    • Journal of the Korean Geotechnical Society
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    • v.27 no.2
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    • pp.91-101
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    • 2011
  • In this study, a new design method of Pile-Bent structure considering plastic hinge was proposed on the basis of the beam-column model. To obtain the detailed informations, the optimized cross-section ratio between column and pile was analyzed to induce the plastic hinge at the joint section between the pile and column. Base on this study, the optimized diameter ratio of pile and column can be obtained below the inflection point of the bi-linear curve depending on the relations between column-pile diameter ratio ($D_c/D_p$) and normalized lateral cracking load ratio ($F/F_{Dc=Dp}$). Moreover, through comparisons with field cases to find out in-depth limit in which minimum concrete-steel ratio could be applied, in-depth limits ($L_{As=0.4%}$) normalized by the pile length ($L_p$) proportionally decrease as the pile length ($L_p/D_p$)increases up to $L_p/D_p=17.5$, and beyond that in-depth limit converges to a constant value (${\simeq}0.3$).

Plastic collapse of tapered, tip-loaded cantilevered beams

  • Wilson, James F.;El-Esnawy, Nayer A.
    • Structural Engineering and Mechanics
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    • v.9 no.6
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    • pp.569-588
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    • 2000
  • The plastic collapse loads and their locations are predicted for a class of tapered, initially curved, and transversely corrugated cantilevered beams subjected to static tip loading. Results of both closed form and finite element solutions for several rigid perfectly plastic and elastic perfectly plastic beam models are evaluated. The governing equations are cast in nondimensional form for efficient studies of collapse load as it varies with beam geometry and the angle of the tip load. Static experiments for laboratory-scale configurations whose taper flared toward the tip, complemented the theory in that collapse occurred at points about 40% of the beams length from the fixed end. Experiments for low speed impact loading of these configurations showed that collapse occurred further from the fixed end, between the 61% and 71% points. The results may be applied to the design of safer highway guardrail terminal systems that collapse by design under vehicle impact.

Evaluation on elastic-plastic fracture resistance curve of SA508C-3 and aluminum alloy steels by load-ratio method (Load-ratio 법에 의한 SA508C-3와 알루미늄 합금의 탄소성 파괴저항 곡선평가)

  • Yoon, H. K.
    • Journal of Ocean Engineering and Technology
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    • v.10 no.2
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    • pp.98-105
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    • 1996
  • A method is proposed to evaluate the elastic-plastic fracture resistance curve only with load displacement records without the crack length measurement in CT specimen. This method is based on the idea that the effect of plastic deformation and the crack growth can be measured only by using a load-displacement record. If we know the reference-load curve representing the hardening of specimen, then the crack extension can be calculated by the elastic compliance determined from the load ratio. The results of this proposed method were compared to those of the elastic-plastic fracture resistance curve for the ASTM standard unloading compliance method. The experimental results for two kinds of ductile materials showed that the proposed method well simulates the material J-R curves. This method is currently applied for CT specimens. but it can be extended to the other specimen geometries.

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Cyclic behavior of steel I-beams modified by a welded haunch and reinforced with GFRP

  • Egilmez, O. Ozgur;Alkan, Deniz;Ozdemir, Timur
    • Steel and Composite Structures
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    • v.9 no.5
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    • pp.419-444
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    • 2009
  • Flange and web local buckling in beam plastic hinge regions of steel moment frames can prevent beam-column connections from achieving adequate plastic rotations under earthquake-induced forces. Reducing the flange-web slenderness ratios (FSR/WSR) of beams is the most effective way in mitigating local member buckling as stipulated in the latest seismic design specifications. However, existing steel moment frame buildings with beams that lack the adequate slenderness ratios set forth for new buildings are vulnerable to local member buckling and thereby system-wise instability prior to reaching the required plastic rotation capacities specified for new buildings. This paper presents results from a research study investigating the cyclic behavior of steel I-beams modified by a welded haunch at the bottom flange and reinforced with glass fiber reinforced polymers at the plastic hinge region. Cantilever I-sections with a triangular haunch at the bottom flange and flange slenderness ratios higher then those stipulated in current design specifications were analyzed under reversed cyclic loading. Beam sections with different depth/width and flange/web slenderness ratios (FSR/WSR) were considered. The effect of GFRP thickness, width, and length on stabilizing plastic local buckling was investigated. The FEA results revealed that the contribution of GFRP strips to mitigation of local buckling increases with increasing depth/width ratio and decreasing FSR and WSR. Provided that the interfacial shear strength of the steel/GFRP bond surface is at least 15 MPa, GFRP reinforcement can enable deep beams with FSR of 8-9 and WSR below 55 to maintain plastic rotations in the order of 0.02 radians without experiencing any local buckling.