• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.61-62
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• 2011

비닐하우스는 매우 세장한 강관부재들을 교차 결합하여 조립한 철골 구조물의 한 종류이다. 현행 설계기준으로 단동 비닐하우스의 최대 구조성능은 풍하중 40m/s, 설하중 50cm에 달한다. 그러나 설계 단계에서는 부재들의 교차결합 특성 및 부재가 직접 지반에 삽입되는 기초의 특성이 적합하게 반영되지 않는 문제점이 있다. 따라서 가력시험을 통하여 반강접 특성을 갖는 부재 교차부 및 지반삽입기초 조건이 구조물의 거동에 미치는 영향을 분석하였다. 부재 교차부가 강접 조건일 경우와 비교하여 교차부가 반강접일 경우에는 재하지점의 수평강성이 최대 54% 작게 나타났으나 주변 교차절점들에서의 에너지 흡수로 인하여 재하지점과 수평으로 3m 떨어진 지점에서는 반대로 최대 39% 큰 값을 보였다. 지반삽입기초의 경우에는 고정조건과 비교하여 재하지점의 수평강성이 최대 32% 작게 나타났으며, 지점부에서는 기초 조건의 영향으로 최대 26%의 휨강성 증가 효과를 보였다. 부재 교차부와 기초 조건이 구조물의 정적거동에 미치는 영향을 확인하였으나 최대내력과 강성 산정을 통한 구조성능 평가 방법의 개발이 필요할 것으로 판단된다.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.349-359
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• 2014

Until now, wall-slab plate of steel plate concrete has been constructed by joint. But, the shear plate has problems in the workability as well as structural integrity. This study investigates the behavior and strength of rib stiffened SC wall-slab connection. Seven prototype specimens of wall-slab connections were fabricated and tested. the structural safety of the specimens was confirmed through the monotonic loading test. Based on the experimental observations, this study propose the strength formula of the joint was proposed. To enhance the reliability of the proposed strength formula, analytical verification was performed through inelastic finite element analysis. Effect of parameters, such as, load point, friction coefficient, on the joint strength was examined. The proposed formula yields a conservative value for most cases.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.1
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• pp.56-62
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• 2015

The potential impact of water temperature on sea level and air temperature rise in response to recent global warming has been noticed. To predict the effect of temperature change on river water quality and aquatic environment, it is necessary to understand and predict the change of water temperature. Air-water temperature relationship was analyzed using air temperature data at Buan and water temperature data of Shinsi, Garyeok, Mangyeong and Dongjin. Maximum and minimum water temperature was predicted by neural network and the results show a very high correlation between measured and predicted water temperature.

• Journal of Korean Society of Steel Construction
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• v.15 no.1
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• pp.25-31
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• 2003

This research aimed to experimentally and theoretically investigate the moment strength of deck plates. A moment experiment was carried out using a full-scale 14 specimen. To prevent local buckling, the point load was applied at 1/4 points. After the experiment, theoretical analysis was conducted and the differences between various codes were identified. The experimental results were compared with AISI (the American Iron and Steel Institute), EC (Euro Code) 3, and KS (Korea Standard) codes. Analysis results are summarized as follows: (1) the failure mode was influenced by local buckling at the midpoint of the beam and/or at the intermediate loading point: (2) if yielding first occurred at the tension side, the moment strength would increase as the plastic reservation of the tension zone acted: (3) the experimental results were closest to the EC3 codes in which the partial plastic reservation was considered; (4) statistical evaluation based on the EC3 Annex Z showed that the partial resistance safety coefficient calculated applying to the EC3 formula, $^{\circ}{_M}$, was placed within 1.1 which was the target value of EC3 code; and (5) the analytical power of AISI and KS codeswere expected to improve into the level of EC3 codes if the concept of plastic reservation of the tension side would be introduced to them.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.73-80
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• 2008

Experimental study has been performed in order to construct the standard test methods and appraisal criteria by investigating the influence of specimen types(property, width, layers) and loading rate on the tensile characteristics of FRP used in strengthening RC structures. The FRP composite tested in this study are the unidirectional CFRP sheet/strip and the bidirectional GFRP sheet. Test variables consist of the various width ranging from 10mm to 25mm and number of CFRP sheets plied up to 5 layers. Test results indicated that maximum tensile strength and minimum coefficient of variation are recorded at each different width according to the fiber types and weaving directions. Also, the average tensile strengths of CFRP sheets are decreased as the number of layer of CFRP sheet are increased.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.363-372
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• 2001

The objective of this study is to evaluate the $P-{\Delta}$ effect in the case of weak beam unbraced frames by experimental approach. To evaluate $P-{\Delta}$ effect, four specimens were tested under monotonic loading condition. The parameters of tests are the stiffness of column and the axial load ratio. The results show that the value of axial load affects frame stability because $P-{\Delta}$ effects promote the yielding of beam. The maximum lateral load increases in proportion to the increment of column stiffness and rotational stiffness of supports, The collapse mechanism of weak beam unbraced frames is stably formed in the condition of low axial load ratio. The $B_2$ factor of limit state design code does not properly consider the $P-{\Delta}$ effect in inelastic region.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.301-304
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• 2008

This paper presented an structural efficiency of steel coupling beam jointed single plate shear connections with seat and top angle. Parameters for the test specimens were are seat and top angle, reinforcing of concrete, embedded length, section loss. Steel coupling beam with angle showed excellent strength, stiffness, energy dissipation capacity. The specimen with no reinforcement around the embedded steel plate showed slightly low deformation capacity because of early failure in the precast concrete walls. However, the specimen with reinforcement around the embedded steel plate showed good deformation capacity. Deformation capacity was not decrease despite short embedded length. The specimen with section loss showed excellent deformation capacity. Because shear strength of steel coupling beam was lesser than of connections. These results showed that for workability and cost efficiency, the proposed system is promising for one of steel coupling beam.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.329-332
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• 2008

The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete structures, and the concept of the effective moment of inertia has been generally used for the estimation of beam deflections. The KCI design code adopted Branson's equation for the calculation of the effective moment of inertia, which was formulated based on the results of beam tests subjected to uniformly distributed loads. Therefore, it is worthwhile to check the applicability of the code approach on the estimation of the effective moment of inertia for the cases of beams under different loading conditions. In this study, an experimental investigation has been conducted on six beams, where primary variables were concrete compressive strengths and loading distances from supports. The test results were compared with various approaches proposed by Branson and others as well. The test results indicated that the effective moment of inertia was somewhat influenced by the moment distribution shape. Despite the different moment distribution shapes for specimens, however, the effective moment of inertia of all test beams were closely predicted by the existing methods considered in this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.64-73
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• 2014

This study proposes a load identification for the safety monitoring of the steel structure based on measured strain data. Instead of parameterizing the stiffness of structure in the existing system identification researches, the loads on a structure and a matrix (the unit strain matrix) defined by the relationship between strain and load on structure are parameterized in this study. The error function is defined by the difference between measured strain and strain estimated by parameters. In order to minimize this error function, the genetic algorithm which is one of the optimization algorithm is applied and the parameters are found. The loads on the structure can be identified through the founded parameters and measured strain data. When the loads are changed, the unmeasured strains are estimated based on founded parameters and measured strains on changed state of structure. To verify the load identification algorithm in this paper, the static experimental test for 3 dimensional steel frame structure was implemented and the loads were exactly identified through the measured strain data. In case of loading changes, the unmeasured strains which are monitoring targets on the structure were estimated in acceptable error range (0.17~3.13%). It is expected that the identification method in this study is applied to the safety monitoring of steel structures more practically.

• Journal of the Korea Concrete Institute
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• v.28 no.5
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• pp.611-620
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• 2016

In the construction of nuclear power plants, only 420 MPa reinforcing bars are allowed and, therefore, so many large-diameter bars are placed, which results in steel congestion. Consequently, re-bar works are difficult and the quality of RC structures may be deteriorated. To solve the steel congestion, 550 MPa bars are necessary. Among many items for verifying structural performance of reinforced concrete with 550 MPa bars, the 43 mm hooked bars are examined in this study. All specimens failed by side-face blowout and the side cover explosively spalled at maximum loads. The bar force was initially transferred to the concrete primarily by bond along a straight portion. At the one third of maximum load, the bond reached a peak capacity and began to decline, while the hook bearing component rose rapidly. At failure, most load was resisted by the hook bearing. For confined specimens with hoops, the average value of test-to-prediction ratios by KCI code is 1.45. The modification factor of confining reinforcement which was not allowed for larger than 35 mm bars can be applied to 43 mm hooked bars. For specimens with 70 MPa concrete, the average value of test-to-prediction ratios by KCI code is 1.0 which is less than the values of the other specimens. The effects of concrete compressive strength should be reduced. An equation to predict anchorage capacity of hooked bars was developed from regression analysis including the effects of compressive strength of concrete, embedment length, side cover thickness, and transverse reinforcement index.