조합하중을 받는 선체 판부재의 최종강도 상관관계 특성

백점기,이상곤,Thayamballi, Anil K 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-

선체 판부재는 일반적으로 면내 2축 방향 축력, 면내 2축 방향 굽힘, 전단 및 횡압력의 조합하중을 받으며, 최종강도 상태에 도달하기까지 복잡한 거동 특성을 보인다. 구조 부재의 최종강도 특성은 단독하중 성분이 작용할 때와 조합하중이 작용할 때는 서로 판이하게 다르며, 정밀한 구조안전성 평가와 강도설계를 위해서는 조합하중 작용시 강도 상관관계 특성을 정확하게 분석해 두는 것이 중요하다. 본 연구에서는 선체구조를 구성하는 판 및 보강판이 조합하중을 받을 때의 최종강도 상관관계 특성을 분석한다. 이를 위해 본 연구에서는 증분 에너지법과 유한요소법의 조합에 의한 간이 해석법을 적용하여 선체 판 및 보강판에 상기 6개의 하중성분이 조합하여 작용할 때의 탄소성 대처짐 거동을 해석하고, 각 하중 성분간 최종강도 상관관계 특성을 분석한다. Ship plating is normally subjected to combined loads, namely bi-axial compression/tenstion, edge shear, bi-axial in-plane bending and out-of-plane(lateral) pressure loads and shows the complex behaviro up to the ultimate limit state. It is very important to analyz the ultimate strength interaction characteristics of unstiffened and stiffened panels between the combined loads for rational design and safety assessment. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of unstiffened and stiffened panels under combined loads. Using the procedure, the ultimate strength interaction characteristics of unstiffened and stiffened panels subjected to the combined loads are examined.

복합화물열차에서 화물 배치 설계를 위한 적재 및 배치 기술 사례에 대한 고찰

신상훈(S. H. Shin),이헌규(H. G. Lee),최지영(J.Y. Choi),최용훈(Y. H. Choi),정훈(H. Jung),염병수(B.S. Yum) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.5

본 연구에서는 복합화물열차를 설계함에 있어서 화물 배치 방안을 수립하기 위하여 다양한 분야의 적재 배치 기술에 대하여 파악한다. 화물 적재 및 하역이 여객 하차 및 탑승 시간에 영향을 미치지 않기 위해 다양한 분야의 화물 적재 배치 사례를 조사하여 특징을 파악하고 복합 화물 열차에 대한 적용 시사점을 도출한다. 이를 바탕으로 복합화물열차의 화물 배치에 있어서 최적의 배치 방안을 수립할 수 있도록 도움을 준다. In this study, we survey wide range of loading/unloading operation problems. The freight loading and unloading operation time should be less than a boarding time. We find out the characteristics of wide range of freight loading studies to apply a planning of loading/unloading on the combined freight train. This study helps a planning of freight loading layout on the combined freight train operations.

수질오염총량관리 관거월류부하 변화에 따른 배출부하량 산정방법

박준대 ( Jun Dae Park ),오승영 ( Seung Young Oh ),최옥연 ( Ok Youn Choi ) 한국물환경학회 2011 한국물환경학회지 Vol.27 No.3

The quantity of a discharge load can change with changes in rainfall in the area with a combined sewer system (CSS). To evaluate the implementation appropriately in the management of total maximum daily loads (TMDLs), the effects of rainfall changes should be considered in the estimation of the discharge load. The rainfall condition for the estimation of the discharge load in a certain year should be standardized to the same rainfall condition as that of the reference year. However, the calculation process is very complicated with its potential limitations. This study investigated and developed relatively simple methods for estimating the discharge load. Load conversion method (LCM) is designed to convert the discharge load under the current rainfall condition into that of the reference rainfall conditions. Simple rainfall data method (SRDM) is to simplify the estimation process of the discharge load by the simple conversion of rainfall data. These methods were applied to calculate the discharge load and examine the estimation results. From the results of this study the application of these methods may be useful for estimating the discharge load in the TMDL process.

제방겸용도로 건설에 따른 제방 안정성 해석에 관한 연구

김성남,이영우 한국도로학회 2008 한국도로학회논문집 Vol.10 No.3

This study analyzes the change of stability of embankment due to the construction of embankment combined used road with two different construction phases. The stabilities have been checked both in the phase of earth banking for a road construction and in the phase of the application of the traffic roads (DB-24). In both cases the factor of safety has been found higher than 1.3 which is the general criterion of the safety of an embankment. The results indicate that the safety of an embankment due to the construction of embankment combined use road is assured, and thus, it is thought that the construction of embankment combined use road can be considered for cutting down on expenses of construction sites for a road construction. However, the pre-examination of stability due to the construction should be carried out because it decreases the factor of safety of an embankment. From this study, it has been found that the factor of safety was dropped most when the water level rose in the transient flow. The result indicates that the stability analysis of a river embankment where the water level changes frequently should be carried out in the condition of transient flow. It is recommended that the inner side of an embankment should have a slope of 1:2 which is identical with the slope of the existing embankment. In addition, the factor of safety also can be decreased due to the traffic loads, and therefore, the effect should also be considered after the construction of embankment combined used road limiting the traffic loads. This study analyzes the change of stability of embankment due to the construction of embankment combined used road with two different construction phases. The stabilities have been checked both in the phase of earth banking for a road construction and in the phase of the application of the traffic roads (DB-24). In both cases the factor of safety has been found higher than 1.3 which is the general criterion of the safety of an embankment. The results indicate that the safety of an embankment due to the construction of embankment combined use road is assured, and thus, it is thought that the construction of embankment combined use road can be considered for cutting down on expenses of construction sites for a road construction. However, the pre-examination of stability due to the construction should be carried out because it decreases the factor of safety of an embankment. From this study, it has been found that the factor of safety was dropped most when the water level rose in the transient flow. The result indicates that the stability analysis of a river embankment where the water level changes frequently should be carried out in the condition of transient flow. It is recommended that the inner side of an embankment should have a slope of 1:2 which is identical with the slope of the existing embankment. In addition, the factor of safety also can be decreased due to the traffic loads, and therefore, the effect should also be considered after the construction of embankment combined used road limiting the traffic loads.

Closed-form plastic collapse loads of pipe bends under combined pressure and in-plane bending

Kim, Yun-Jae,Oh, Chang-Sik Elsevier 2006 Engineering fracture mechanics Vol.73 No.11

<P><B>Abstract</B></P><P>Based on three-dimensional (3-D) FE limit analyses, this paper provides plastic limit, collapse and instability load solutions for pipe bends under combined pressure and in-plane bending. The plastic limit loads are determined from FE limit analyses based on elastic–perfectly-plastic materials using the small geometry change option, and the FE limit analyses using the large geometry change option provide plastic collapse loads (using the twice-elastic-slope method) and instability loads. For the bending mode, both closing bending and opening bending are considered, and a wide range of parameters related to the bend geometry is considered. Based on the FE results, closed-form approximations of plastic limit and collapse load solutions for pipe bends under combined pressure and bending are proposed.</P>

비강우시 도시 합류식 하수도의 오염부하 산정을 위한 최적관측시간 산정연구

최용훈,원철희,박운지,서지연,신민환,이찬기,최중대,Choi, Yong-Hun,Won, Chul-Hee,Park, Woon-Ji,Seo, Ji-Yeon,Shin, Min-Hwan,Lee, Chan-Ki,Choi, Joong-Dae 한국농공학회 2009 한국농공학회논문집 Vol.51 No.3

Flow and pollution load were monitored at 2 combined sewer outlets (C-1 and C-2) of urban watersheds during dry weather from September, 2004 to April, 2006 for 20 months. The objectives were to investigate the diurnal variation of flow and pollutant load and to find the proper sampling time that could measure representative flow and pollutant load. Pollution load closed to the average daily load at C-1 could be measured at 00:00 hour and by the mean of 15:00 and 18:00 hour measures, and 15:00 and 21:00 hour measures, respectively. In addition at C-2, it was 21:00 hour and the mean of 15:00 and 18:00 hour measures. This study concluded that arbitrary sampling of flow and water quality could cause large errors in the estimation of urban pollution load and recommended that urban combined sewers should be monitored when flow and water quality showed daily average and concentration.

제주도내 유수하천에 대한 수질특성 및 오염부하량 산정

조은일,오윤근 한국환경과학회 1998 한국환경과학회지 Vol.7 No.6

In order to manage the water quality from the flowing streams in Cheju Island, the characteristics of water quality was investigated from August, 1996 to May, 1997 and the pollutant loadings for future were estimated from the watershed at each stream. Comparing the mean concentrations of each water quality with the criterion of water quality in river, it was under I class except for Changgo Stream, for DO, under I class at the whole station for SS and under Ⅱ class for BOD. As the pollutant loadings at each stream in 2020 is compared with those in 1996, the estimated results are as follows : 1) for BOD, 59% at Donghong Stream, 24% at Yeonoe Stream, 44% at Ohngpo Stream and 57% at Changgo Stream. 2) for T-N, 91% at Donghong Stream, 76% at Yeonoe Stream, 63% at Ohngpo Stream and 89% at Changgo Stream. 3) for T-P, 69% at Donghong Stream, 42% at Yeonoe Stream, 45% at Ohngpo Stream and 73% at Changgo Stream The point source loadings discharged through combined sewer could be treated at sewage treatment plant. However, the expected slow decreasing rate of BOD, T-N, and T-P loadings is due to the part of untreated nonpoint source loadings. Nonpoint source loading overflow typically occurs when the flow of stormwater combined with sewage exceeds the capacity of the interceptor sewers. Since most of the sewers used in Cheju Island are the combined sewers, the combined overflow sewage is bypassed into the receiving water area after a rainstorm. Therefore, a means to control nonpoint source loadings should be considered for the river and marine water quality management.

Effect of spiral reinforcement on flexural-shear-torsional seismic behavior of reinforced concrete circular bridge columns

Abdeldjelil Belarbi,Suriya Prakash,Young-Min You 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.2

This paper investigates the behavior of reinforced concrete (RC) circular columns under combined loading including torsion. The main variables considered in this study are the ratio of torsional moment to bending moment (T/M) and the level of detailing for moderate and high seismicity (low and high transverse reinforcement/spiral ratio). This paper presents the results of tests on seven columns subjected to cyclic bending and shear, cyclic torsion, and various levels of combined cyclic bending, shear, and torsion. Columns under combined loading were tested at T/M ratios of 0.2 and 0.4. These columns were reinforced with two spiral reinforcement ratios of 0.73% and 1.32%. Similarly, the columns subjected to pure torsion were tested with two spiral reinforcement ratios of 0.73% and 1.32%. This study examined the significance of proper detailing, and spiral reinforcement ratio and its effect on the torsional resistance under combined loading. The test results demonstrate that both the flexural and torsional capacities are decreased due to the effect of combined loading. Furthermore, they show a significant change in the failure mode and deformation characteristics depending on the spiral reinforcement ratio. The increase in spiral reinforcement ratio also led to significant improvement in strength and ductility.

실지진 모사를 위한 조합형 정현하중의 적용성 검증

최재순 대한토목학회 2019 대한토목학회논문집 Vol.39 No.6

Since the Gyeongju earthquake in 2016 and the Pohang earthquake in 2017, the performance of various dynamic tests for seismic design has increased in Korea. However, sinusoidal load has been continuously used in the conventional laboratory tests to evaluate liquefaction potential and determine input-parameters in the numerical analysis. However, recent research results suggest that it is difficult to accurately simulate excess pore water changes of the ground under earthquake loads. In order to solve this problem, thisstudy proposes a combined sinusoidal loading and examines its applicability to the cyclic shear and triaxial test. Also, its validity is examined through performing of shaking-table test and numerical analysis based on the effective stress model. As a result, it was found that the proposed combined sinusoidal loading can more accurately simulate the change of excess pore water pressure in saturated soilsunder real earthquake load than the sinusoidal load. 2016년 경주지진과 2017년 포항지진이 발생한 이후, 우리나라 내진설계에 있어서 다양한 실내진동시험의 수행이 증가하고 있으나, 액상화 평가나 수치해석의 입력파라미터를 산정하기 위한 실내진동시험에서는 이전부터 사용해 오던 정현하중의 이용이 계속되고 있다. 그러나, 최근 정현하중으로는 지진하중으로 야기되는 지반 내 과잉간극수압의 거동을 정확하게 모사하기 어렵다는 연구결과가 발표되며 정현하중을 대신하여 동하중의 개발에 대한 논의가 주목을 받기 시작하였다. 이 연구에서는 이러한 문제를 해결하고자 조합형 정현하중을 제안하고 주문진 표준사를 대상으로 한 진동전단실험과 진동삼축압축시험을 통해 그 적용성을 검토하였으며 추가로 진동대시험과 유효응력해석모델에 기초한 수치해석을 통해 그 타당성을 검토하였다. 검토 결과, 제안된 조합형 정현하중이 정현하중보다 실지진하중 하에서의 포화지반 내 과잉간극수압의 거동변화를 잘 모사할 수 있음을 발견하였다.

A reliability-based approach to investigate the challenges of using international building design codes in developing countries

Arman Kakaie,Azad Yazdani,Mohammad-Rashid Salimi 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.6

The building design codes and standards in many countries usually are either fully or partially adopted from the international codes. However, regional conditions like the quality of construction industry and different statistical parameters of load and resistance have essential roles in the code calibration of building design codes. This paper presents a probabilistic approach to assess the reliability level of adopted national building codes by simulating design situations and considering all load combinations. The impact of the uncertainty of wind and earthquake loads, which are entirely regional condition dependent and have a high degree of uncertainty, are quantified. In this study, the design situation is modeled by generating thousands of numbers for load effect ratios, and the reliability level of steel elements for all load combinations and different load ratios is established and compared to the target reliability. This approach is applied to the Iranian structural steel code as a case study. The results indicate that the Iranian structural steel code lacks safety in some load combinations, such as gravity and earthquake load combinations, and is conservative for other load combinations. The present procedure can be applied to the assessment of the reliability level of other national codes.