• 저자: 임종진, 엄태성

• Abstract: The compression behavior of octagonal concrete-filled thin-walled tube (OCFT) columns was investigated. Eight OCFT columns with different tube sections were tested under monotonic compressive loading. The tests showed that the thin-walled tubes underwent elastic or inelastic local buckling, and the slenderness ratio (or width-to-thickness ratio) and section shape of the tubes significantly affected their buckling modes. Despite such local buckling, the load-deformation behavior of the OCFT columns all was highly ductile, due to confinement to the infilled concrete. The design strengths of AISC 360-16 agreed well with the test strengths. In this study, effective stress–strain relationships of the tube and infilled concrete were proposed to account for the local buckling and confinement. The maximum strength and post-buckling behavior were estimated through the strain-compatibility analysis, and the results were compared with the tests.

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• 콘크리트 충전 팔각 강관합성기둥의 압축강도평가(Evaluation of Compression Strengths of Octagonal Concrete-Filled Tube Columns)

• 저자: 임종진, 엄태성

• Abstract: In this study, the axial compression behavior of concrete-filled octagonal tube columns (OCFT columns) was experimentally investigated. Eight OCFT column specimens designed as the slender and noncompact sections using thin-walled tubes were prepared for the compression test. The wall thickness, fabrication detail, and section shape of the thin-walled tubes were considered as the test parameters. The test results showed that the buckling mode of the tubes and the compressive strength of the columns were affected by the test parameters. By using the thick tube wall and section geometry close to a circle, the local buckling of the tube wall was delayed and thus the column strengths were increased. The theoretical strengths of the OCFT columns computed in accordance with the provisions for filled composite columns specified in KBC 2016 and AISC 360-16 were compared with the test strengths.

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• 콘크리트 충전 박판강관기둥을 위한 볼트이음에 대한 실험연구(Experimental Investigation of Bolted Splice for Concrete-Filled Thin-Walled Tube Columns)

• 저자: 임종진, 이창남, 엄태성

• Abstract: In
  this study, the results of the experimental investigation of the bolted splice for concrete-filled thin-walled tube columns are presented. For the connection of the column tube, the bolted lap plate joint was used at each tube wall and non-planar ribbed plates were used as the lap plate at the joint in order to improve the connection performance such as strength and slip resistance. To investigate the connection strength and failure mode, five full scale column specimens with different lap joint details were tested. The tests showed that the ribbed lap plates were beneficial to increasing the strength and slip resistance of the joint as the ribbed portion provided additional resistance. The failure modes of the joint were net section fracture and block shear rupture of the lap plate or tube wall. The force transfer mechanism at the joint via the bolts and ribbed lap plates was also investigated based on strain measurements. Finally, a plastic stress distribution method to estimate the connection strength of the column splice was proposed.