• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4D
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• pp.483-489
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• 2009

The endurance of expansion joint manufactured the Fe-Mn damping alloy reducing noise and vibration is analyzed into FEM (Finite Element Method) and fatigue test. The fatigue test have been performed using the expansion joint manufactured Fe-Mn damping alloy and the hydraulic actuator (25tonf). And the results of fatigue test show that the maximum strength is 237.6 MPa. Also that is 56.6 percent of Fe-Mn damping alloy yield strength (420 MPa). The loading plate size is prepared $57.7cm{\times}23.1cm$ and the loading plate's set position is located on expansion joint. The expansion joint manufactured the Fe-Mn damping alloy had not presented breaking behavior against 2,000,000 times fatigue test and identified the fatigue endurance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.665-672
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• 2008

In the study herein, the fatigue test was conducted on the fillet welds of the load carrying cruciform joint, which is frequently used in the steel structures such as bridges, ships, etc. In addition, the fatigue strength was analyzed with respect to the different post-weld treatment. The treatment methods used include Toe Grinding, TIG Dressing, and Weld Profiling. The fatigue test was under constant amplitude with repeated load for these test specimens. In the load carrying full penetration fillet welded joints, regardless the conduction of the post-weld treatment or not, they all secured the fatigue strength of category "F", which exceeds the fatigue design specifications of BS Code. In the comparison of the fatigue strength upon the post-weld treatment, the fatigue strength tends to increase according to the order: Toe Grinding, TIG Dressing, and Weld Profiling.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.317-328
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• 2010

The method to evaluate the flexural capacity of steel fiber-reinforced ultra high strength concrete beams was proposed in this study. An experimental program was set up and fourteen beams have been tested. Test results were compared with predictions by design code and by the proposed method, respectively. It was found that predictions by using ACI 544 Committee recommendations considerably underestimate the flexural capacity. Underestimation of flexural capacity resulted from that of tensile stress block. Three-point bending test data of notched prism specimens and their inverse analysis results were incorporated into modeling of tension stress block. The ratio of the predicted to the experimental flexural capacity was in the range of 0.98 to 1.14. The present study represents that the proposed method allows more realistic prediction of flexural capacity of steel fiber-reinforced ultra high strength concrete beams.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2D
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• pp.295-303
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• 2009

The purpose of present study is to examine the effect of guideway characteristics on runnability of low and medium speed maglev vehicle. Dynamic governing equation for 2-dof vehicle and optimal feedback control scheme are developed. And then the effect of vehicle speed, rail roughness, guideway deflection, continuity of spans, each span length on dynamic response of the UTM-01 maglev vehicle are investigated. From the numerical simulation, it is found that the gap between bogie and guideway does not increase greatly within design velocity of the vehicle. The response of vehicle are mostly affected by the guideway deflection rather than rail roughness. As a result of the present study, the runnability of maglev vehicle can be improved by reducing the maximum deflection of guideway and adopting the continuous girder systems.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.75-83
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• 2023

As part of a study to analyze the excessive camber occurring in prestressed concrete railway bridges, this paper presents a calculation method and analysis results for the creep coefficient which defines the increase in camber of a concrete structure over time. Using the creep coefficient formula of the design code, the coefficient is obtained by applying the climatic conditions (relative humidity and temperature) of 12 regions in Korea. The effects of differences in climatic conditions by region and starting time of load on the creep coefficient are analyzed. In order to properly calculate the creep, most of which occurs in the early stages of loading, a detailed analysis is performed by applying a time step analysis method to consider varying climate conditions through loaded period. The creep coefficient obtained by applying the average climate conditions of the region is similar to the average of the creep coefficients obtained by time step analysis. Through time step analysis, it is shown that the offset and overlap effects of relative humidity and temperature on the creep coefficient and the climate effect at the time of initial loading can be appropriately represented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.61-69
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• 2024

An ultra-high strength prestressed prismatic beam of 100 MPa in compressive strength was developed by increasing the water-tightness of concrete by utilizing centrifugal molding processes without adding expensive admixtures. The centrifugal prismatic PSC beam developed as the superstructure of the avalanche tunnel was constructed on a rahmen bridge in a small local river. In this study, the centrifugal prismatic beam was compared and analyzed based on the results of measurements made through static load tests and the results of numerical analysis of the target structure. The common load-carrying capacity and safety of the rahmen bridge were evaluated. The static·dynamic load tests and finite element analysis results of this bridge were similar, and it was confirmed that the behavior of the centrifugal prismatic beam was well simulated. All centrifugally formed square beams that make up the composite rahmen bridge were evaluated to secure sufficient load carrying capacity under the design live load, and structural reliability was proven by ensuring safety.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.173-182
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• 2006

In the design of curved girder bridges, the engineer is faced with a complex stress situatiorl. since these types of mutiple-I girder. mono-box girder and twin-box girder are subjected to both bending and torsional force. In general, the torsional forces consist of two part, St. venant's and warping. Thus the procedure for determining the induced stresses in a curved girder is difficult. The transfer matrix method is extensively used for the structural analysis because its merit in the theoretical background and applicability. The technique is attractive for implementation on a numerical solution by means of a computer program coded in Fortran language with a few elements. To demonstrate this fact. it gives good results which compare well with finite difference method. Therefore, in this paper, to clarify the range where the torsional warping stress can be approximated by pure torsional analyzed a critical value of relationships between the torsional stress ratio and torsional ratio.

• 주택과사람들
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• no.54 s.71
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• pp.185-206
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• 1996

1.건설제도의 국제화와 경쟁기반 구축 $\bullet$건설산업을 기획$\cdot$설계$\cdot$시공$\cdot$감리$\cdot$사후관리 등 전 분야에 걸쳐 경쟁력 있는 산업으로 육성-기획$\cdot$설계$\cdot$시공$\cdot$감리$\cdot$유지관리 등 건설산업 전반에 관한 기본사항을 법제화-대규모 공사의 경우 발주자를 대신하여 건설공사의 기획$\cdot$설계$\cdot$발주$\cdot$감리$\cdot$시공관리 등 업무의 전부 또는 일부를 종합적으로 조정$\cdot$관리하는 $\lceil$건설사업관리$\rfloor$제도를 도입 $bullet$건설공사 $\lceil$현장실명제$\rfloor$도입을 통한 하도급제도의 정비-전문건설업자로부터 하도급, 위탁, 고용 등의 형태로 공사에 참여하는 현장근로자를 신고 받아 권익을 보호하고 시공책임도 부과하는 $\lceil$현장실명제$\rfloor$도입 $\bullet$공사완성보증제, 손해배상보증제도를 도입하고, 신용상태 $\cdot$시공능력에 따라 보증 요율 등을 차등화 하여 부실업체를 배제 $\bullet$건설공사관련 각종 계약서와 시방서 등 제기준을 정비하여 발주자$\cdot$시공자 등 건설주체간의 역할과 책임을 명확화$\bullet$건설분쟁을 신속하고 객관적으로 조정$\cdot$중재하기 위하여 $\lceil$건설분쟁중재원$\rfloor$으로 확대 개편 2. 건설인력의 육성과 고용안정$\bullet$경쟁력 제고의 관건인 우수인력 확보를 위하여 대학교육 제도의 개선을 포함한 건설 인력 수급대책을 추진 - 대학의 건설관련 학과 정원을 2000년까지 매년 일정규모로 증원하여 고급기술 인력을 배출 현재 50$\%$에 불과한 건설관련 국가기술자격자를 2000년에 70$\%$까지 제고 - 감리 등 전문인력을 양성하고, 선진외국 감리 회사를 활용하여 국내 업계와의 경쟁을 유도 $\bullet$건설현장의 최일선에서 품질을 담당하고 있는 건설기능공의 고용안정과 복지향상을 위한 획기적인 대책을 마련 - 건설기능공의 자긍심과 사회적 책임의식을 고취하기 위해 기능공이 여러 현장을 전전하여 근무하더라도 경력관리, 공제금 등의 합산 관리가 가능하도록 $\lceil$건설 근로자 복지카드$\rfloor$제도를 도입 *$\lceil$건실시연구단$\rfloor$을 구성$\cdot$구체적인 운영방안을 수립 - 건설 업체 실정에 맞는 현장위주의 기능검정제도 도입 $\cdot$자격증이 현장에서 요구되는 기능수준과 숙련도를 제대로 반영할 수 있도록 검정방법을 현장 실기위주로 개선하고 자격검정업무도 건설협회 등의 자격 검정능력을 향상시켜 위탁$\cdot$시행하는 방안을 검토 3. 공사시행기관의 전문성과 책임성 제고 $\bullet$시장이 개방되어 건설공사가 국제적인 관행에 따라 이루어질 것에 대비하여 시행기관에 계약$\cdot$공사관리 등 전문직공무원을 집중 교육하여 양성 $\bullet$ 조달청이 대행하여 공사계약을 하는 경우라도 설계변경은 발주기관이 자체적으로 할 수 있도록 허용 $\bullet$ 기술직 공무원의 기술향상을 위하여 관련 공무원의 확충, 해외연수, 현장교육 강화 등을 지속적으로 추진 $\bullet$ 충분한 사전조사를 거쳐 사업계획을 수립하도록 $\lceil$건설공사 시행절차$\rfloor$를 규정 $\bullet$ 공사기간 3년 이상의 공사에 대하여는 최대한 계속비사업으로 편성토록 계속비제도의 운영을 활성화 4. 건설현장의 품질관리체제 구축 $\bullet$ 현장배쳐플랜트 설치를 확대하여 레미콘의 품질관리를 일원화하고 현장에서 레이콘을 배합하는 건식공법을 채택 - 현장레미콘생산시설(B/P)설치 확대로 콘크리트 하자에 대한 책임한계 일원화 유도 - 레미콘 재료인 골재$\cdot$시멘트$\cdot$물을 공장에서 혼합하여 공급하는 현행 습식배합 대신에 물만을 현장에서 혼합하는 건식 배합방식을 도입 $\bullet$철강재$\cdot$철구조물의 품질을 보증하기 위하여 일정기술을 갖춘 공장에서만 제작토록 하는$\lceil$공장인증제$\rfloor$를 도입 - 제작시설과 품질관리 등을 심사하여 제작공장을 등급화하고 등급에 따라 철강재 등의 제작업무 범위를 차등화 $\bullet$시설물에 대하여도 시공업체가 제작공장을 등급화하고 등급에 따라 철강재 등의 제작업무 범위를 차등화 $\bullet$시설물에 대하여도 시공업체가 사후관리를 일괄 책임질 수 있도록 $\lceil$시공 및 유지관리 일괄계약제도$\rfloor$를 도입 - 대형교량$\cdot$소각로$\cdot$하수처리장 등 유지관리에 전문성이 요구되는 분야부터 시범적으로 도입 $\bullet$건설자재의 표준화$\cdot$정보화사업을 조속히 추진 5. 건설업체에 대한 지원 강화 $\bullet$일부 공공사업자의 경우 관행화되어 있는 대금일부의 어음 또는 채권지급방법을 단계적으로 축소 $\bullet$매월 감독이나 감리원의 기성확인에 의하여 시공자에게 공사대금을 직접 지급토록 하는 등 대금 지급절차를 간소화 6. 민간 건축물에 대한 안전확보 $\bullet$충실한 설계가 이루어지도록 제도를 개선 - 설계도서 작성기준을 제정하고 다중이용시설에 대하여는 건축심의단계에서 구조검토 등 설계심의를 의무화 $\bullet$대형다중이용시설에 대한 감리 강화 - 감리전문회사 수준의 감리체제로 전환하고 감리대가도 공공수준으로 인상하고 적용요율대로 지도$\cdot$감독 강화

• Journal of the Korean GEO-environmental Society
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• v.21 no.12
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• pp.29-34
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• 2020

Reinforced earth retaining walls were developed in France in the 1970s and began to be applied in earnest to Korea in the 1990s. And now, about 1,300 reinforced soil retaining walls support the embankment of highways and bridge connections. The reinforced earth retaining wall construction technology has evolved day by day, and in recent years the reinforced earth retaining wall itself has been developed and introduced as a demonstration. However, various damages are constantly occurring in the reinforced earth retaining walls constructed throughout the highway. The cause of this was analyzed as minor defects in the design, construction, and maintenance stages. The solution for this is a change in perception of the importance of each individual process, but this does not form overnight. In this study, 30 years have passed since the introduction of the reinforced soil retaining wall on the highway, the damage cases were analyzed and categorized that have occurred in the reinforced soil retaining wall so far, and attempted to present a confrontation. As a result, the damage occurring on the reinforced soil retaining wall was divided into 10 types, and the causes and countermeasures in the design, construction, and maintenance stages for each were derived.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.691-697
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• 2015

In this paper, an embedded EM sensor was researched to estimate prestressing force of PS tendon in PSC girder. Recent methodologies for managing prestressing force loss were staying on verifying a applying prestressing force under construction, namely the loss management can not be controlled after construction. To estimate the tensile force of PS tendon during lifetime of PSC girder, this research proposed a bobbin-type embedded EM sensor that can be embedded in PSC girder is designed and fabricated considering the shape properties of anchorage zone and sheath. To verify the proposed sensor, a small PSC girder test was performed. The embedded EM sensor was connected to a sheath and anchor block, and the concrete was poured. After curing, the change of the permeability of PS tendon under tensile forces of 200, 710, 1070, 1300kN was measured using embedded EM sensor. The permeability of PS tendon had decreased according to the increment of applied tensile force. Also it is confirmed that the change of permeability due to applied tensile force could resolve the applied tensile force values. As a result, proposed embedded EM sensor could be embed into the PSC girder and it could be used to estimate the tensile force variation during lifetime of PSC girder.