• Structural Engineering and Mechanics
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• 제36권2호
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• pp.197-206
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• 2010

The purpose of this paper is to carry out both experimental and theoretical investigations of R.C. short column subjected to horizontal forces under constant compressive loading. Eight specimens with section of 40 cm ${\times}$ 40 cm, height 40 cm and 50 cm and different type hoop were used of the steel cage to detect the seismic behavior of reinforced concrete short columns. Hoop spacing of column, strength of concrete, and the axial load of experiments were the three main parameters in this test. A series of equations were derived to reveal the theory could be used on analysis short column, too. Through test failure model of R.C short column being established, the type of hoop affects the behavior R.C short column in ductility rather than in strength. And the effect of analysis by Truss Model is evident and reliable in shear failure model of short column.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.505-508
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• 1999

To evaluate the strength of square reinforced concrete shot columns, thirty specimens were manufactured and tested under monotonically increasing concentric compression. The test parameters included the volumetric ratio of transverse reinforcement($\rho$h = 0.49~2.65), and concrete compressive strength (234, 437, 704 kgf/$\textrm{cm}^2$). Test results are shown that : (1) Behavior of high -strength concrete column is improved by providing increased volumetric ratio; and (2) ACI, Eq. is not proper to evaluate HSC short column strength.

• 한국구조물진단유지관리공학회 논문집
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• 제2권4호
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• pp.201-208
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• 1998

To observe the confinement effects of Carbon Fiber Sheet(CFS) on the high-strength R/C short columns, Fifteen specimens with CFS were manufactured and tested under uni-axial compressive load. Major variables of this study are amount, spacing, type of CFS and amount of transverse steel. Increasing the amount of transverse steel and CFS, compressive strength and axial rigidity is improved. R/C columns with transverse steel and CFS exhibited less axial stress than columns with only CFS. From the test results, it is shown that the area confined with transverse steel and CFS is considerably important to evaluate axial stress of R/C short columns.

• Structural Engineering and Mechanics
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• 제21권3호
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• pp.333-350
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• 2005

This paper presents results of an experimental study to evaluate a new retrofit technique for strengthening shear deficient short concrete beams and columns. In this technique a mortar jacket reinforced with expanded steel meshes is used for retrofitting. Twelve short reinforced concrete specimens, including eight retrofitted ones, were tested. Six specimens were tested under a constant compressive axial force of 15% of column axial load capacity based on original concrete gross section, $A_g$, and the concrete compressive strength, ${f_c}^{\prime}$. Main variables were the spacing of ties in original specimens and the volume fraction of expanded metal in jackets. Original specimens failed before reaching their nominal calculated flexural strength, $M_n$, and had very poor ductility. Strengthened specimens reached their nominal flexural strength and had a ductility capacity factor of up to 8 for the beams and up to 5.5 for the columns. Based on the test results, it can be concluded that expanded steel meshes can be used effectively to strengthen shear deficient concrete members.

• Structural Monitoring and Maintenance
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• 제1권3호
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• pp.273-292
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• 2014

The effectiveness of a retrofitting method for concrete columns with particular weaknesses is experimentally evaluated and presented in this paper. Structural deficiencies namely the inadequacy of transverse reinforcement and short length of lap splices are very common in columns found in structures built prior to the 1960s and 1970s. Recent earthquakes worldwide have caused severe damages and collapses of these structures. Nevertheless, the importance of improving the load transfer capacity between the deficiently lap-spliced bars is usually underestimated during the strengthening procedures applied in old buildings, though critical for the safety of the residents' lives. Thus, the seismic performance of the enhanced columns is frequently overestimated. The retrofitting approach presented herein involves reinforced concrete jacketing of the column sub-assemblages and welding of the lap-spliced bars to prevent the splice failure and conform to the provisions of modern design Codes. The cyclic lateral loading response of poorly confined original column specimens with insufficient lap splices and the seismic behavior of the retrofitted columns are compared. Test results clearly demonstrate that the retrofitting procedure followed is an effective way of significantly improving the seismic performance of substandard columns found in old buildings.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.168-179
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• 2006

This paper summarizes full-scale test results on CFT column-to-flat plate connections subjected to gravity loading. CFT construction has gained wide acceptance in a relatively short time in domestic building construction practice due to its various structural and construction advantages. However, efficient details for CFT column to flat plate connections have not been proposed yet. Based on the strategies that maximize economical field construction, several connecting schemes were proposed and tested. Test results showed that the proposed connections can exhibit punching shear strength and connection stiffness exceeding those of R/C flat plate counterparts. A semi-analytical procedure is presented to model the behavior of CFT column-to-flat plate connections. The five parameters to model elastic to post-punching catenary action range are calibrated based on the limited test data of this study. The application of the proposed modeling procedure to progressive collapse prevention design is also illustrated.

• Structural Engineering and Mechanics
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• 제39권2호
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• pp.207-221
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• 2011

This paper aims to study the behavior of short reinforced concrete columns confined with external glass Fiber Reinforced Polymers (GFRP) sheets under eccentric loads. The experimental part of the study was achieved by testing 9 specimens under eccentric compression. Three eccentricity ratios corresponding to e/t = 0, 0.10, 0.50 in one direction of the column were used. Specimens were divided into three groups. The first group was the control one without confinement. The second group was fully wrapped with GFRP laminates before loading. The third group was wrapped under loading after reaching 75% of failure loads of the control specimens. The third group was investigated in order to represent the practical case of strengthening a loaded column with FRP laminates. All specimens were loaded until failure. The results show that GFRP laminates enhances both failure load and ductility response of eccentrically loaded column. Moreover, the study also illustrates the effect of confinement on the first crack load, lateral deformation, strain in reinforcement and failure pattern. Based on the analysis of the experimental results, a simple model has been proposed to predict the improvement of load carrying capacity under different eccentricity ratios. The predicted equation takes into consideration the eccentricity to cross section depth ratio, the ultimate strength of GFRP, the thickness of wrapping laminate, and the time of wrapping (before loading and under loading). A good correlation was obtained between experimental and analytical results.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.203-210
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• 2005

This paper summarizes full-scale test results on CFT column to flat plate connections subjected to gravity loading. CFT construction has gained wide acceptance in a relatively short time in domestic building practice due to its various structural and construction advantages. Constructing the floor as flat plate is often regarded as being essential for both cost savings and rapid construction. However, efficient details for CFT column to flat plate connections have not been proposed yet, and their development is urgently needed. Based on some strategies that include maximizing economical field construction, several connecting schemes were proposed and tested in this study. Test results showed the proposed connection details can exhibit strength and stiffness comparable to or greater than those of R/C flat plate counterpart.

• Computers and Concrete
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• 제15권6호
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• pp.921-933
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• 2015

The aim of this study is to determine the earthquake performances of reinforced concrete (R/C) residential buildings in Turkey and to analyze the parameters that affect the performance. The performance of Turkish residential buildings, determined by their levels of damage, directly relates to their structural systems. Damage parameters observed from previous earthquakes define structural parameters selected to be used in the present study. Five different types of frame R/C buildings were modeled. For the analysis, the model buildings vary according to the number of stories, column sizes, and reinforcement and concrete strength parameters. The analyses consider gravity forces and earthquake loads through 1975 and 2007 Turkish design codes. In a total of 720 different R/C buildings were investigated for the analysis to obtain capacity curves. A performance evaluation was employed by considering the Turkish design code (TDC-2007). The current study ignores irregularities such as soft stories or short columns. The study's analysis considers a comparison of the parameters' influence on the structural performance of the model buildings.

• 한국강구조학회 논문집
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• 제18권4호
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• pp.491-502
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• 2006

본 논문은 중력하중의 지배를 받는 CFT기둥-RC 무량판 접합부의 실물대 실험결과를 요약한 것이다. CFT구조는 여러 가지 구조및 시공상의 장점으로 인하여 국내 건설 현장에서 상대적으로 짧은 시간에 폭넓게 수용되고 있다. 주차장 용도로 주로 사용되는 지하층은 철근콘크리트 무량판으로 시공하여 경제성을 도모하는 것이 국내에서 일반적으로 요구되는 시공관행이다. 그러나 CFT기둥-R C 무량판 접합부의 효율적인 디테일은 아직 국내 외적으로 제시된 바가 없어서 이 분야의 연구가 매우 필요한 실정이다. 현장 시공시 경제성을 극대화할 수 있는 몇 가지 전략을 기초로 해서, 여러가지 접합 상세를 제안하였고 실험을 통하여 검증하엿다. 실험결과 본 연구에서 제시된 CFT기둥-RC 무량판 접합 상세의 펀칭강도 및 강성이 RC 무량판 접합부와 동등하거나 이를 상회하는 것을 확인할 수 있었다. CFT기둥-RC 무량판 접합부의 초기 탄성거동에서 펀칭파괴이후 휨철근의 국부 현수작용에 이르기까지의 모델링 방안을 제시하고 본 연구의 실험결과를 기초로 5개의 모델링 변수를 캘리브레이션하였다. 또한 무량판구조의 연쇄붕괴방지 설계에 본 연구의 결과를 응용하는 방안을 사례를 통하여 예시하였다.