• Steel and Composite Structures
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• 제23권1호
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• pp.17-29
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• 2017

The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.

• Structural Engineering and Mechanics
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• 제61권1호
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• pp.77-90
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• 2017

Glazed curtain walls are façade systems frequently chosen in modern architecture for mid and high-rise buildings. From recent earthquakes surveys it is observed the large occurrence of non-structural components failure, such as storefronts and curtain walls, which causes sensitive economic losses and represents an hazard for occupants and pedestrians safety. In the present study, the behavior of curtain wall stick systems under seismic actions has been investigated through experimental in-plane racking tests conducted at the laboratory of the Construction Technologies Institute (ITC) of the Italian National Research Council (CNR) on two full-scale aluminium/glass curtain wall test units. A finite element model has been calibrated according to experimental results in order to simulate the behavior of such components under seismic excitation. The numerical model investigates the influence of the interaction between glass panels and aluminium frame, the gasket friction and the stiffness degradation of aluminium-to-glass connections due to the high deformation level on the curtain walls behavior. This study aims to give a practical support to researchers and/or professionals who intend to numerically predict the lateral behavior of similar façade systems, so as to avoid or reduce the need of performing expensive experimental tests.

• Steel and Composite Structures
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• 제38권6호
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• pp.617-635
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• 2021

This paper numerically investigated the behavior of built-up square concrete-filled steel tubular (CFST) columns under combined preload and axial compression. The finite element (FE) models of target columns were verified in terms of failure mode, axial load-deformation curve and ultimate strength. A full-range analysis on the axial load-deformation response as well as the interaction behavior was conducted to reveal the composite mechanism. The parametric study was performed to investigate the influences of material strengths and geometric sizes. Subsequently, influence of construction preload on the full-range behavior and confinement effect was investigated. Numerical results indicate that the axial load-deformation curve can be divided into four working stages where the contact pressure of curling rib arc gradually disappears as the steel tube buckles; increasing width-to-thickness (B/t) ratio can enhance the strength enhancement index (e.g., an increment of 1.88% from B/t=40 to B/t=100), though ultimate strength and ductility are decreased; stiffener length and lip inclination angle display a slight influence on strength enhancement index and ductility; construction preload can degrade the plastic deformation capacity and postpone the origin appearance of contact pressure, thus making a decrease of 14.81%~27.23% in ductility. Finally, a revised equation for determining strain εscy corresponding to ultimate strength was proposed to evaluate the plastic deformation capacity of built-up square CFST columns.

• 한국전산구조공학회논문집
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• 제29권3호
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• pp.219-227
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• 2016

이 연구에서는 현장타설 캔틸레버공법(free cantilever method)을 적용한 PSC(prestressed concrete) 교량에 콘크리트의 장기거동을 고려한 시공 중 계측분석 방법을 제안하였다. 콘크리트 박스 거더의 장기 거동에 따른 응력을 확인하기 위해 온도센서와 변형률계를 함께 설치하고 계측된 데이터를 이용하여 크리프계수를 산출하였다. 또한 크리프계수를 적용한 콘크리트 박스 거더의 시공 중 응력을 분석하고 설치된 온도 센서의 변화 데이터를 비교하여 세그먼트 시공에 따른 연직변위를 분석하였다. 연구결과, 교량의 장기 거동을 고려한 FCM 교량의 시공 중 계측은 레이저 변위계나 처짐계를 사용하지 않고 온도와 변위 데이터만을 이용하여 효율적인 분석이 가능한 것으로 나타났다.

• 한국건설안전학회 논문집
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• 제6권1호
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• pp.1-6
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• 2024

본연구는 건설근로자 대상으로 실시되는 안전교육을 가상체험과 실물체험식 안전교육으로 진행되면 교육에 오락적, 일탈적, 심미적 요소가 더해진 학습효과로 건설업 안전사고는 현저히 감소함을 분석하였다. 연구결과 체험교육에 대한 판별타당도 분석에서는 C.R=0.925327>0.7로 충족되었고, AVE= 0.716226>0.5로 수렴되어 신뢰도가 높음을 알 수 있었다. 근로자의 행동 의도에 대한 MC 시뮬레이션 분석과 베이지안 구조방정식에서 근로자 행동변화는 여러 가지 요인으로 달라질 수 있지만, 교육의 정도에 따라 행동이 변화됨을 알 수 있었고, 의도된 안전에 대한 확률밀도분포 분석결과 실물체험의 경험이 낮을수록 안전행동 보다 불안전 행동이 높고, 사고 위험이 증가함으로 체험식 안전교육이 근로자 행동변화와 건설 안전문화 개선에 실질적인 효과가 검증되었다. 후속 연구에서도 체험교육 이수 근로자에 대한 2~3년 추적관리 연구를 기대한다.

• Advances in concrete construction
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• 제10권5호
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• pp.455-462
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• 2020

This study investigated the effect of horizontal casting joints on the mechanical properties and structural behavior of sustainable self-compacting reinforced concrete beams (SCRCB). The experimental research consisted of two stages. The first stage used four types of concrete mixtures which were produced to indicate the effects of cement replaced with cement waste at 0%, 5%, 10%, and 15% by weight of cement content on fresh concrete properties of self-compacting concrete (SCC) such as, passing ability, filling ability, and segregation resistance. In addition, mechanical properties such as compressive, tensile, and flexural strength were also studied. The second stage selected the best mixture from the first stage and studied the effect of horizontal casting joints on the structural behavior of sustainable SCRCBs. The effect of horizontal casting joints on the mechanical properties and structural behavior were at the 25%, 50%, 75%, and 100% of sample height. Load deflection, failure mode, and theoretical analysis were studied. Results indicated that the incorporation of replacement with cement waste by 5% to 10% led to economic and environmental advantages, and the results were acceptable for fresh and mechanical properties. The results indicated that delaying the time for casting the second layer and increasing the cement waste in concrete mixtures had a great effect on the mechanical properties of SCC. The ultimate load capacity of horizontal casting joints reinforced concrete beams slightly decreased compared with the control beam. The maximum deflection of casting joint beams with 75% of samples height is similar with the control beam. The experimental results of reinforced concrete beams were substantially acceptable with the theoretical results. The failure modes obtained the best forced casting joint on the structural behavior at 50% height of casting in the beam.

• 대한안전경영과학회지
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• 제15권3호
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• pp.19-28
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• 2013

While the reduction of industrial accidents has been stagnant, many researchers have been studying and focusing on safety behaviors including safety perception, attitude and safety culture as a new solution as well as a turning-point of this issue. However, we do not pay attention to those studies and researches in Korean construction. Therefore, this study is to introduce preceding researches and case studies in other countries and suggest a new direction to Korean construction. This study found out the current situation and problems in Korean construction studies after tracing the safety perception, attitude and safety culture in Korea and reviewing the background and trend of overseas studies and researches with regard to safety behaviors. Fundamental researches and systematic studies must be conducted in Korean construction with the reference and research data of this study.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 봄 학술발표회 논문집
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• pp.13-18
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• 1994

Most widened bridges have been constructed by the joining-construction method that makes new and existing bridge structurally single structure. However, joing-construction method has several problems in design and construction viewpoint. Therefore, this study is conducted in order to investigate structural behavior of widened RC slab and traffic-induced vibration of existing bridge during placing and curing of new concrete by the prototype flexural fatigue test. From the results of this study, it is shown that stress-concentration and slip occur between concrete and reinforcing rod at joint section but the reduction of load carrying capacity and of fatigue strength is negligible according to the traffic-induced vibration as well as the difference of construction method. A reasonable construction method for the bridge widening which takes into account the effects of the traffic-induced vibration and S-N curve for the widened bridge are also proposed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.583-588
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• 2005

In this study, a concrete faced rockfill dam constructed by stages was numerically analyzed, and the numerical results were compared with in situ measurements. The simple incremental elastic and isotropic hyperbolic model was employed to characterize the nonlinear deformation behavior of rockfill material and computational procedure followed construction sequence. A series of large triaxial tests for rockfill material were carried out to obtain mechanical input parameters. According to the analysis results, relative great additional deformation was introduced at the surface of stage-I dam body due to the loading by stage-II construction. The results reveal that numerical analysis can effectively simulate the construction processes, and some meaningful insights about the behavior of CFRD during construction were gained.

• 한국공간구조학회논문집
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• 제23권2호
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• pp.45-52
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• 2023

Modular construction is an economical and efficient construction that reduces time and costs by manufacturing units in factories and constructing them on site. Currently, the demand for modular construction is increasing not only abroad but also domestically. As the demand for modular construction increases, a lot of development and research on connections between modular units are being conducted. Connections between modular units should be quick and simple to assemble when assembling units on site, and should be in a form that allows each unit to be connected regardless of direction. In addition, it must be able to exert sufficient strength against external loads. In this study, a connection between modular units using connecting steel plates and bolts was proposed, and the nonlinear behavior of the connection to external lateral force was analyzed through finite element analysis, and resistance performance was evaluated.