• Title/Summary/Keyword: exterior beam-column joint

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An Experimental Study on Column Penetration Joint of RC Column-Steel Beam (기둥관통형 RC 기둥-철골 보 접합부에 관한 실험적 연구)

  • 김승훈;한상환;이리형
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04b
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    • pp.475-480
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    • 1998
  • The composite framed structures, consisting of RC columns and steel beams more popular in korea because of their efficiency and quality. However the force transfer mechanisms between the column and beam may by very complicated since the materials of columns and beams are different. This study develops "the column penetration joint" which the web of steel beam doesn't penetrate and which could improve the strength, deformation, and energy dissipation capacities compared to existing composite joints. It is the concrete-filled square tube joint with the exterior diaphragms and the cruciform stiffening plates. This study evaluated the strength of RC column penetration to steel beam connection by analyzing the results of partial experiments, and reviewed the applicability the strength formula through the comparison of tested results of joint experiment.

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Structural Performance of Beam-Column Connections Using 51 mm Diameter with Different Anchorage Details (51 mm 대구경 철근을 사용한 외부 보-기둥 접합부의 정착상세별 구조성능 평가)

  • Kim, Jung-Yeob;Jung, Hyung-Suk;Chun, Sung-Chul;Kim, In-Ho;Choi, Chang-Sik
    • Journal of the Korea Concrete Institute
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    • v.29 no.2
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    • pp.201-208
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    • 2017
  • In exterior beam-column joints, hooked bars are used for anchorage, but usage of high-strength and large-diameter bars increases, headed bar is preferred for solving steel congestion and difficulty in construction. To investigate the structural performance of headed bars, Six exterior beam-column joints were tested under cyclic loading. Tests parameter were the anchorage methods and concrete strength. The test results indicate that behavior of headed bar specimens shows similar performance with hooked bar specimens. All specimens failed by flexural failure of the beam. Headed bar specimens shows better performance in anchorage and joint shear. All specimens were satisfied the criteria of ACI374.1-05. Test results indicate that use of headed bar in exterior beam column joint is available.

Influence of shear deformation of exterior beam-column joints on the quasi-static behavior of RC framed structures

  • Costa, Ricardo J.T.;Gomes, Fernando C.T.;Providencia, Paulo M.M.P.;Dias, Alfredo M.P.G.
    • Computers and Concrete
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    • v.12 no.4
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    • pp.393-411
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    • 2013
  • In the analysis and design of reinforced concrete frames beam-column joints are sometimes assumed as rigid. This simplifying assumption can be unsafe because it is likely to affect the distributions of internal forces and moments, reduce drift and increase the overall load-carrying capacity of the frame. This study is concerned with the relevance of shear deformation of beam-column joints, in particular of exterior ones, on the quasi-static behavior of regular reinforced concrete sway frames. The included parametric studies of a simple sub-frame model reveal that the quasi-static monotonic behavior of unbraced regular reinforced concrete frames is prone to be significantly affected by the deformation of beam-column joints.

Improved strut-and-tie method for 2D RC beam-column joints under monotonic loading

  • Long, Xu;Lee, Chi King
    • Computers and Concrete
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    • v.15 no.5
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    • pp.807-831
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    • 2015
  • In the previous analytical studies on 2D reinforced concrete (RC) beam-column joints, the modified compression field theory (MCFT) and the strut-and-tie method (STM) are usually employed. In this paper, the limitations of these analytical models for RC joint applications are reviewed. Essentially for predictions of RC joint shear behaviour, the MCFT is not applicable, while the STM can only predict the ultimate shear strength. To eliminate these limitations, an improved STM is derived and applied to some commonly encountered 2D joints, viz., interior and exterior joints, subjected to monotonic loading. Compared with the other STMs, the most attracting novelty of the proposed improved STM is that all critical stages of the shear stress-strain relationships for RC joints can be predicted, which cover the stages characterized by concrete cracking, transverse reinforcement yielding and concrete strut crushing. For validation and demonstration of superiority, the shear stress-strain relationships of interior and exterior RC beam-column joints from published experimental studies are employed and compared with the predictions by the proposed improved STM and other widely-used analytical models, such as the MCFT and STM.

A practical model for simulating nonlinear behaviour of FRP strengthened RC beam-column joints

  • Shayanfar, Javad;Bengar, Habib Akbarzadeh
    • Steel and Composite Structures
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    • v.27 no.1
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    • pp.49-74
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    • 2018
  • Generally, beam-column joints are taken into account as rigid in assessment of seismic performance of reinforced concrete (RC) structures. Experimental and numerical studies have proved that ignoring nonlinearities in the joint core might crucially affect seismic performance of RC structures. On the other hand, to improve seismic behaviour of such structures, several strengthening techniques of beam-column joints have been studied and adopted in practical applications. Among these strengthening techniques, the application of FRP materials has extensively increased, especially in case of exterior RC beam-column joints. In current paper, to simulate the inelastic response in the core of RC beam-column joints strengthened by FRP sheets, a practical joint model has been proposed so that the effect of FRP sheets on characteristics of an RC joint were considered in principal tensile stress-joint rotation relations. To determine these relations, a combination of experimental results and a mechanically-based model has been developed. To verify the proposed model, it was applied to experimental specimens available in the literature. Results revealed that the model could predict inelastic response of as-built and FRP strengthened joints with reasonable precision. The simple analytic procedure and the use of experimentally computed parameters would make the model sufficiently suitable for practical applications.

Study of exterior beam-column joint with different joint core and anchorage details under reversal loading

  • Rajagopal, S.;Prabavathy, S.
    • Structural Engineering and Mechanics
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    • v.46 no.6
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    • pp.809-825
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    • 2013
  • In the present study, in reinforced concrete structures, beam-column connections are one of the most critical regions in areas with seismic susceptibility. Proper anchorage of reinforcement is vital to enhance the performance of beam-column joints. Congestion of reinforcement and construction difficulties are reported frequently while using conventional reinforcement detailing in beam-column joints of reinforced concrete structures. An effort has been made to study and evaluate the performance of beam-column joints with joint detailing as per ACI-352 (mechanical anchorage), ACI-318 (conventional hooks bent) and IS-456(full anchorage conventional hooks bent) along with confinement as per IS-13920 and without confinement. Apart from finding solutions for these problems, significant improvements in seismic performance, ductility and strength were observed while using mechanical anchorage in combination with X-cross bars for less seismic prone areas and X-cross bar plus hair clip joint reinforcement for higher seismic prone areas. To evaluate the performances of these types of anchorages and joint details, the specimens were assembled into four groups, each group having three specimens have been tested under reversal loading and the results are presented in this paper.

Seismic Response of Exterior RC Column-to-Steel Beam Connections (I. Experiment) (콘크리트 기둥-강재 보 외부 접합부의 내진성능(I. 실험))

  • 조순호
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2000.04a
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    • pp.275-282
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    • 2000
  • The seismic behavior of moment connections consisting of reinforced concrete columns and steel beams is investigated based on four 2/3 scale tests of exterior beam-column joints subject to reversed cyclic loading. The major test parameters were the number of hoops the isolated concrete contribution and the use of headed studs in the joint regions between columns and beams. Their influence on the seismic response of the connections is presented and compared. Among them the CF3 specimen containing two hoops each in the joint and column regions above and below exhibited the most favourable hysteretic response. This indicates that this type of joint details can be used in the low seismic areas such as Korea.

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Cyclic-loading Tests of 113-Scale R.C. Exterior Beam-column Joints With Non-Seismic Detailing (비내진 상세를 가진 1/3 축소 R.C. 외부 접합부의 반복 횡하중 실험)

  • 이한선;차병기;고동우;임동운
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.11a
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    • pp.179-184
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    • 2001
  • The objective of this study is to clarify the seismic capacity and the characteristics in the hysteretic behavior of RC structures with nonseismic detailing. To do this, an exterior beam-column subassemblage was selected from a 10-story RC building and 6 1/3-scale specimens were manufactured with 3 variables; ⑴ with and without slab, ⑵ upward and downward direction of anchorage for the bottom bar in beams, and ⑶ with and without hoop bars in the joint region. The test results have shown that ⑴ the existence of slab increased the strength in positive and negative moment, 25% and 62%, respectively; ⑵ the Korean practice of anchorage (downward and 25 $d_{b}$ anchorage length) caused the 8% reduction of strength and the early strength degradation when compared with the case of seismic details; and ⑶ the existence of hoop bars in the joint region does not show significant difference because the size of column is much larger than that of beam.m.

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Cyclic-Loading Test of Exterior Deep-Beam Lower-Column Joint in Upper-Wall Lower-Frame Structure (주상복합구조에서 전이보와 외부기둥 접합부의 반복횡하중 실험)

  • 이한선;김상연;고동우;권기혁;최성모
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.10b
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    • pp.851-856
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    • 2000
  • When subjected to the strong earthquake ground motion, upper-wall lower-frame structures have high possibility of the weak-story failure in the lower frame part. Sufficient strength, energy dissipation capacity and ductility should be provided at the joint between the deep beam and the lower column. In this study, a typical structure was selected for a prototype and four 1:2.5 scaled models, representing the subassemblage including the exterior column and the deep beam, were constructed. The transverse reinforcement was designed according to ACI procedure¹ and the procedure proposed by Sheikh². The inelastic behavior of the subassemblages subjected to the cyclic lateral displacement were evaluated through investigation of the ultimate strength, ductility, load-deformation characteristics. From the test of 4 specimens, it is concluded that the specimens designed according to Sheikh's procedure revealed higher ductility than that by ACI procedure.

Application of Headed Bars with Small Head in Exterior Beam-Column Joints Subjected to Reversed Cyclic Loads (반복하중을 받는 외부 보-기둥 접합부에서 작은 헤드를 사용한 Headed Bar적용)

  • Ha, Sang-Su;Choi, Dong-Uk;Lee, Chang-Ho
    • Journal of the Korea Concrete Institute
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    • v.19 no.4
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    • pp.411-420
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    • 2007
  • The applicability of headed bars in exterior beam-column joints under reversed cyclic loading was investigated. A total of ten pullout tests were first performed to examine pullout behavior of headed bars subjected to monotonic and cyclic loading with test variables such as connection type between head and bar stem (weld or no weld), loading methods (monotonic or cyclic loading), and head shape (small or large circular head and square head). Two full-scale beam-column joint tests were then performed to compare the structural behavior of exterior beam-column joints constructed using two different reinforcement details: i.e. $90^{\circ}$ standard hooks and headed bars. Both joints were designed following the recommendations of ACI-ASCE Committee 352 for Type 2 performance: i.e. the connection is required to dissipate energy through reversals of deformation into inelastic range. The pullout test results revealed that welded head to the stem did not necessarily result in increased pullout strength when compared to non-welded head. Relatively large circular head resulted in higher peak load than smaller circular and square head. Both beam-column joints with conventional $90^{\circ}$ hooks and headed bars behaved similarly in terms of crack development, hysteresis curves, and peak strengths. The joint using the headed bars showed better overall structural performance in terms of ductility, deformation capacity, and energy dissipation. These experimental results demonstrate that the headed bars using relatively small head can be properly designed far use in external beam-column joint.