• KCI Concrete Journal
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• 제12권2호
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• pp.45-54
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• 2000

Precast R.C. slabs are being used widely for the construction of bridge structures due to their simplicity in construction processes. However, one of the disadvantages in precast R.C. slabs is the existence of transverse joints between two precast slabs. The transverse joints are structurally fragile and the task of strengthening the joints is difficult one due to their structural discontinuity. The aim of this study was to improve the behavior of transverse joints between precast R.C. slabs by introducing prestress with external cables. Three steel-concrete composite bridge specimens, which were prestressed with the external cables anchored on steel girders, were fabricated in the laboratory. Both pretension and post-tension methods were applied to introduce prestressing on the concrete slab with a straight tendon arrangement. Static tests were conducted at service load and ultimate load test was performed to evaluate punching shear capacity of the transverse joint. In this paper, two prestressing methods were tested and their effects were evaluated with respect to the elastic behavior and ultimate loading capacity of the transverse joints.

• 한국강구조학회 논문집
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• 제8권4호통권29호
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• pp.3-17
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• 1996

The purpose of this paper is to investigate experimentally and theoretically the strength and deformation of K-joints in welded Warren-type square hollow structural section truss. There are 2 types in K-joints in K-joints having one compression bracing member and one tension bracing member. One type is KP-series that brae members are rotated to $45^{\circ}$, another type is KS-series that are not rotated. Principal parameters are the ratio of the chord width to thickness (D/T=33.3, 25, 16.7), the ratio of brace width to chord width(d/D=0.4, 0.5, 0.67, 0.83, 1.0) and the ratio of eccenticity to chord height (e/D=0.25, 0.125, 0, -0.125, -0.25, -0.375, -0.5). The important results obtained from the experiments are as follow ; The strength of K-joints increase proportionally as the D/T ratio decreases, and the d/D ratio increases. But the e/D ratio has no correlation with the strength of K-joints. Generally the strength and ductility ratio of KP-series increase more than a current type(KS-series) in full ${\beta}$range.

• Steel and Composite Structures
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• 제33권1호
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• pp.143-162
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• 2019

A number of desirable characteristics concerning excellent durability, aesthetics, recyclability, high ductility and fire resistance have made stainless steel a preferred option in engineering practice. However, the relatively high initial cost has greatly restricted the application of stainless steel as a major structural material in general construction. This drawback can be partially overcome by introducing composite stainless steel-concrete structures, which provides a cost-efficient and sustainable solution for future stainless steel construction. This paper presents a preliminary numerical study on stainless steel-concrete composite beam-to-column joints with bolted flush endplates. In order to ensure a consistent corrosion resistance within the whole structural system, all structural steel components were designed with austenitic stainless steel, including beams, columns, endplates, bolts, reinforcing bars and shear connectors. A finite element model was developed using ABAQUS software for composite beam-to-column joints under monotonic and symmetric hogging moments, while validation was performed based on independent test results. A parametric study was subsequently conducted to investigate the effects of several critical factors on the behaviour of composite stainless steel joints. Finally, comparisons were made between the numerical results and the predictions by current design codes regarding the plastic moment capacity and the rotational stiffness of the joints. It was concluded that the present codes of practice generally overestimate the rotational stiffness and underestimate the plastic moment resistance of stainless steel-concrete composite joints.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.362-367
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• 1994

In Precast Concrete Structure, safety of structure depends on strength of joint. Asa result, there exists a necessity to review the effects of elements consisting joints, since these elements are important factors for evalaution of joint strength. However, there elements are different for construction methods and may be changed even during construction. Obviously, the change of elements can cause the change of joint strength; yet, the effects of the variables are not clearly defined. The behavior of the joints are complicated and evaluated only through experiments. Consequently, the main objective of this paper is to review effects of components consisting Precast Joints, I order to keep higher joint strength than specified in the design code.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.871-876
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• 2022

In the construction industry, fatal accidents related to scaffolds frequently occur. To prevent such accidents, scaffolds should be carefully monitored for their safety status. However, manual observation of scaffolds is time-consuming and labor-intensive. This paper proposes a method that automatically analyzes the installation status of scaffold joints based on images acquired from a Unmanned Aerial Vehicle (UAV). Using a deep learning-based object detection algorithm (YOLOv5), scaffold joints and joint components are detected. Based on the detection result, a two-stage rule-based classifier is used to analyze the joint installation status. Experimental results show that joints can be classified as safe or unsafe with 98.2 % and 85.7 % F1-scores, respectively. These results indicate that the proposed method can effectively analyze the joint installation status in UAV-acquired scaffold images.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.259-260
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• 2023

This study attempted to derive an appropriate application range by reviewing the integration performance of joints according to the application range of SRA concrete. As a result, it was confirmed that the integration performance was improved even if SRA concrete was placed only by 75mm, which is 0.5 times the thickness of the member.

• 한국건축시공학회지
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• 제21권2호
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• pp.129-139
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• 2021

신축 공동주택 보급률이 상승하면서 입주민 개인별 자산의 관리적 측면과 함께 품질에 관한 관심이 높아져 공동주택 품질과 관련된 분쟁이 급격하게 증가되고 있는 실정이다. 이에 본 연구에서는 분쟁을 저감할 목적으로 관리주체가 제소하는 집단하자보수비 청구 소송을 확인하여 가장 빈번하게 분쟁이 발생된 콘크리트의 층간이음부와 관련하여 각 사건별로 층간이음부가 차지하는 비중과 쟁점을 분석하였다. 그 결과 분쟁 발생의 원인에는 첫째, 표준시방서가 부재한 점, 둘째, 보수공법에 대한 표준이 없는 점, 셋째, 공동주택의 공통적인 사항이나 법원에서는 이를 관대한 개념에서 배상 범위를 인정하고 있는 점에 있음이 확인되었다. 이에, 하자예방을 위해서는 첫째, 층간이음부 시공에 대한 국토교통부의 표준시방서가 개정되어야하고, 둘째, 표준시방서 이행 여부에 따라 하자판정이 진행되어야 하며, 셋째, 하자로 판정 시 명확한 하자보수공법이 적용될 수 있는 제도개선이 필요한 부분임을 확인할 수 있었다.

• Advances in concrete construction
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• 제4권3호
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• pp.161-172
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• 2016

An experimental investigation was carried out on the strength and behavior plain and fiber reinforced geopolymer concrete beam column joints and the results were compared with plain and steel fiber reinforced conventional concrete beam column joints. The volume fraction of fibers used was 0.5%. A total of six Geopolymer concrete joints and four conventional concrete joints were cast and tested under reversed cyclic loading to evaluate the performance of the joints. First crack load, ultimate load, energy absorption capacity, energy dissipation capacity stiffness degradation and moment-curvature relation were evaluated from the test results. The comparison of test results revealed that the strength and behavior of plain and fiber reinforced geopolymer concrete beam column joints are marginally better than corresponding conventional concrete beam column joints.

• Steel and Composite Structures
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• 제32권3호
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• pp.337-346
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• 2019

The present paper tries to contribute fill the gap of application of the component method to tubular connections. For this purpose, one typical joint configuration in which just one component can be considered as active has been studied. These joints were selected as symmetrically loaded welded connections in which the beam width was the same as the column width. This focused the study on the component 'side walls of rectangular hollow sections (RHS) in tension/compression'. It should be one of the main components to be considered in welded unstiffened joints between I beams and RHS columns. Many experimental tests on double-sided I-beam-to-RHS-column joint with a width ratio 1 have been carried out by the authors and a finite element (FE) model was validated with their results. Then, some different analytical approaches for the component stiffness and strength have been assessed. Finally, the stiffness proposals have been compared with some FE simulations on I-beam-to-RHS-column joints. This work finally proposes the most adequate equations that were found for the stiffness and strength characterization of the component 'side walls of RHS in tension/compression' to be applied in a further unified global proposal for the application of the component method to RHS.

• Steel and Composite Structures
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• 제22권5호
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• pp.1019-1038
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• 2016

The use of high-strength concrete (HSC) in precast concrete segmental bridges (PCSBs) can minimize the superstructure geometry and reduce beam weight, which can accelerate the construction speed. Dry joints between the segments in PCSBs introduce discontinuity and require special attention in design and construction. Cracks in dry joints initiate more easily than those in epoxy joints in construction period or in service. Due to the higher rupture strength of HSC, the higher cracking resistance can be achieved. In this study, shear behavior of dry joints in PCSBs was investigated by experiments, especially focusing on cracking resistance and shear strength of HSC dry joints. It can be concluded that the use of HSC can improve the cracking resistance, shear strength, and ductility of monolithic, single-keyed and three-keyed specimens. The experimental results obtained from tests were compared with the AASHTO 2003 design provisions. The AASHTO 2003 provision underestimates the shear capacity of single-keyed dry joint C50 and C70 HSC specimens, underestimates the shear strength of three-keyed dry joint C70 HSC specimens, and overestimates the shear capacity of three-keyed dry joint C50 HSC specimens.