• Structural Engineering and Mechanics
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• 제59권4호
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• pp.703-718
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• 2016

Masonry arch bridges present a large segment of Iranian railway bridge stock. The ever increasing trend in traffic requires constant health monitoring of such structures to determine their load carrying capacity and life expectancy. In this respect, the performance of one of the oldest masonry arch bridges of Iranian railway network is assessed through field tests. Having a total of 11 sensors mounted on the bridge, dynamic tests are carried out on the bridge to study the response of bridge to test train, which is consist of two 6-axle locomotives and two 4-axle freight wagons. Finite element model of the bridge is developed and calibrated by comparing experimental and analytical mid-span deflection, and verified by comparing experimental and analytical natural frequencies. Analytical model is then used to assess the possibility of increasing the allowable axle load of the bridge to 25 tons. Fatigue life expectancy of the bridge is also assessed in permissible limit state. Results of F.E. model suggest an adequacy factor of 3.57 for an axle load of 25 tons. Remaining fatigue life of Veresk is also calculated and shown that a 0.2% decrease will be experienced, if the axle load is increased from 20 tons to 25 tons.

• 한국구조물진단유지관리공학회 논문집
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• 제22권3호
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• pp.97-102
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• 2018

기존 PSC I형 거더는 콘크리트의 자중, 정착구 및 긴장방식 등의 영향으로 장경간화의 적용성이 불리하였다. 이를 극복하기 위하여 PSC 거더의 복부에 중공을 도입하고 다단계 긴장을 도입함으로써 50~70m 경간에 적용 가능한 중공 웨브 PSC I형 거더를 개발하고 실교량으로 시공하였다. 본 연구는 중공 웨브 PSC I형 거더교 현장에서 정적재하시험을 통하여 계측을 한 결과와 대상 구조물의 유한요소해석 결과를 바탕으로 비교, 분석하여 중공 웨브 장경간 PSC 거더교의 공용내하력과 안전성을 평가하였다. 본 교량의 정적재하시험과 수치해석 결과가 유사하게 나타났으며 중공 웨브 PSC I형 거더의 거동을 잘 모사하는 것으로 나타났다. 교량의 모든 거더는 설계 활하중 하에서 충분한 내하력을 확보하는 것으로 평가되었고 안전성을 확보하여 시공 결과의 적절성을 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.359-360
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• 2009

• 한국안전학회지
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• 제25권6호
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• pp.161-168
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• 2010

A series of fatigue tests have been performed on the non-load carrying fillet welded joints in order to quantitatively assess the fatigue characteristics due to the grindings and TIG(Tungsten Inert Gas) welding treatments. From the results of fatigue tests, it has been shown that the fatigue strengths at $2{\times}106$ load cycles were improved in the case of the grinding sand TIG welding treatments, and we could know that it is satisfying fatigue strength prescribed in fatigue design standard in general. Besides, from the results of fracture mechanics approaches, the geometric shape correction factors were the most dominant factors in the initial fatigue crack growth, but as the fatigue crack develops, the finite plate correction factor were became the most dominant factor, and the fatigue life on non-load carrying fillet welded joints could be relatively exactly estimated by using the relations between fatigue crack growth rate and stress intensity factor obtained from finite element analysis and existing proposed formulae.

• Structural Engineering and Mechanics
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• 제39권2호
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• pp.287-301
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• 2011

This paper is focused on the residual capacity of steel columns, as a damage criterion. Load-Impulse (P-I) diagrams are frequently used for analysis, design, or assessment of blast resistant structures. The residual load carrying capacity of a simply supported steel column was derived as a damage criterion based on a SDOF computational approach. Dimensionless P-I diagrams were generated numerically with this quantitative damage criterion. These numerical P-I diagrams were used to show that traditional constant ductility ratios adopted as damage criteria are not appropriate for either the design or damage assessment of blast resistant steel columns, and that the current approach could be a much more appropriate alternative.

• Structural Engineering and Mechanics
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• 제25권6호
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• pp.675-690
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• 2007

In order to study the ductility and the lateral load carrying capacity of the masonry walls strengthened with CFRPs (Carbon Fiber Reinforced Polymer sheets), three pieces of masonry walls subjected to cyclic loads with low frequency and vertical load of constant amplitude have been tested. Two different strengthening methods have been used. The strengthening efficiency is affected by the strengthening method. A simplified calculation approach has been introduced based on the experimental test results, and the theoretical results agree reasonably well with the experimental results. It is found that the critical loads, the critical displacements, the ultimate loads, the ultimate displacements and the ductile coefficients of the masonry walls strengthened with CFRPs improve remarkably (6%~57%). Therefore, the masonry structures strengthened with CFRPs are of better ductility and of better lateral load carrying capacity than the masonry structures without any strengthening measurements.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권6호
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• pp.705-719
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• 2017

Progressive Collapse Method (PCM) has been broadly applied to predict moment-carrying capacity of a hull girder, however accuracy of PCM has not been much studied. Accuracy of PCM is known to be dependent on how Load-Shortening and -Elongation (LSE) curve of a structural units are well predicted. This paper presents a new procedure to determine LSE datum based on box girder Finite Element Analyses (FEAs) instead of using finite element model of stiffened panels. To verify reliability of FEA results, the simple box girder collapse test results are compared with FEA results of same box girders. It reveals one frame-based box girder model is sufficiently accurate in terms of ultimate strengths of the box girders. After extracting LSE data from the box girders, PCM-based moment-carrying capacities are compared with those from FEAs of the box girders. PCM results are found to be equivalent to FEAs in terms of moment-carrying capacity if accurate LSE data are secured. The new procedure is applied to well-known 1/3 scaled frigate full section. Very excellent moment-carrying capacity of frigate hull section is obtained from PCM with LSE data from box girder FEAs.

• Geomechanics and Engineering
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• 제18권4호
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• pp.363-371
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• 2019

In this study, the load carrying behavior of piled rafts installed in inclined bearing rock layer was investigated for rock-mounted and -socketed conditions. It was found that settlements induced for an inclined bearing rock layer are larger than for a horizontal layer condition. The load capacity of piled rafts for the rock-mounted condition decreased as rock-layer inclination angle (${\theta}$) increased, while vice versa for the rock-socketed condition. The load capacities of raft and piles both decreased with increasing ${\theta}$ for the rock-mounted condition. When bearing rock layer was inclined, loads carried by uphill-side piles were greater than those by downhill-side piles. The values of differential settlements of rock-mounted and -socketed conditions were not significantly different whereas slightly higher for the rock-socketed condition. The values of load sharing ratio (${\alpha}_p$) and its variation with settlement were not markedly changed by the inclination of bedrock. It was shown that ${\alpha}_p$ for piled rafts installed in rock layer was not affected by ${\theta}$ whereas actual loads carried by raft and piles may vary depending on the pile installation and rock-layer inclination conditions.

• 한국터널지하공간학회 논문집
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• 제8권1호
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• pp.41-51
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• 2006

본 논문에서는 숏크리트 라이닝 충간 부착성이 숏크리트 라이닝의 하중지지력에 미치는 영향에 대한 내용을 다루었다. 이를 위해 축소 모형시험과 유한요소해석을 병행하여 더블쉘 터널 시공시 숏크리트 충간 부착성과 숏크리트 라이닝의 하중지지 특성과의 관계를 알아보았다. 연구결과 NATM의 더블쉘 구소와 같이 라이닝 층간 부착이 확보되지 않는 경우에는 이완하중 작용시 응력이 집중되는 경향을 보이는 것으로 나타났으며, 토피고 증가에 따라 그 차이가 증가하는 것으로 나타났다. 본 연구결과를 종합하여 설계와 시공시 고려하여야 할 주안점을 제시하였다.

• 대한조선학회논문집
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• 제45권1호
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• pp.87-92
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• 2008

In the load-carrying fillet weldments, which are common in ship structures, fatigue cracks can occur at the weld root, in addition to the weld toe. In particular, fatigue cracks originating from the weld root are difficult to detect and cause a significant reduction in the fatigue strength of a weldment. Therefore, it is important to note the fatigue failure mode of load-carrying fillet weldment. In this study, a series of fatigue test was carried out for the fatigue strength evaluation of longi-web connections that are typical kinds of the load-carrying fillet weldment.