• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.4
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• pp.263-270
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• 2020

This study evaluates the structural behavior of connected long-span beams applied for excavation in urban areas with a narrow street. Generally, the reliability of the connection is reduced owing to the defect of the upper flange in the connection. An improved connection part was developed to complement the defects in the connected long-span beam. A finite element analysis based on a commercial program, ABAQUS, was employed to evaluate the behavior of the improved connection part. A numerical analysis model was proposed to analyze the high-strength bolt connection and the composite behavior of steel and concrete applied to the improved connection. The suitability of the proposed numerical analysis was verified by comparing the experimental and numerical analysis results of the references. Using the proposed numerical analysis method, the improved and general connections were analyzed and compared with each other. The stress distribution and elastic-plastic behavior of the long-span beam were analyzed numerically. The analysis confirmed that 25% of the compressive stress was improved, resulting in the improvement of structural safety and performance.

• Journal of the Korean GEO-environmental Society
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• v.19 no.9
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• pp.5-12
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• 2018

The foundation of the multi-span greenhouse structures is designed with small shallow concrete foundation considering mainly the vertical load. However, recently, due to an abnormal climate such as strong wind, horizontal load and up-lift load over design strength are applied to the foundation, causing safety problems of the greenhouse foundation. In order to reasonably evaluate the safety of greenhouse foundations, rotational and pullout stiffness expressed by the ground-foundation interaction should be evaluated, which also affects the safety of the upper structural members. In this study, three representative basic foundation types were selected by classifying greenhouse standards in Korea according to the shape, and the horizontal loading tests and theoretical calculation were performed for each foundation type. As a result of the comparison and analysis of the test and calculation, it was found that rotational resistance of the foundation is different according to the ratio of the contact area between the foundation and ground when the conditions of the foundation - ground contact surface and the mechanical properties of the ground are the same.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.121-128
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• 2016

In order to suggest a reasonable design for the circular concrete filled tube steel column-foundation connection applying high-tension bolts, Overall structural behavior and characteristics according to various variables of column-foundation connection are numerically analyzed using a commercial FE analysis program, ABAQUS. To that goal, finite element analysis is conducted on the basis of the previous study replacing anchor bolts to high-tension bolts, and the analytical results are validated by comparison with experimental results. Also, the various variables(embedded depth and grade of anchor, and height and thickness of rib) involved in behavior of the column-foundation connection are selected through analyzing the current design criteria, and the characteristics of the column-foundation connection are compared and analyzed according to the various variables. In case of the anchor bolts, Applying the high-tension bolts is more advantage and securing the embedded depth beyond 0.5D is recommendable. In case of the rib, a minimum of 0.5D for rib's height and $0.4t_b$ for rib's thickness should be secured to develop the structural performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.195-200
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• 2011

KS F 2782 (for shotcrete accelerators) standard cross-section of tunnel construction or repair is a reinforcement used in the field of shotcrete accelerators as a criterion in assessing shotcrete performance. Thus, KS F 2782 by standard accelerator will determine the nature of the product of concrete accelerators that will be used to record variations in the product roles, through determination of the quality of the experimental method to identify only the quality of the many variables that exist. This evaluation standard has so far distinguished accelerator products in indoor experiments that do not meet quality standards but were mostly for an on-site accelerator mixed with the shotcrete after being quite satisfied with the level of quality in a certain number of products. This observation is derived from the results of an indoor experiment considered to verify whether the site is suitable for indoor experiments, and whether its actual location in the city is relevant to the accelerator quality, to find a way to test if it fits. This study centers on the material conditions of the shotcrete accelerator and a variety of experimental results, and used the Gilmore needle to compare the compressive strength and KS F 2782 specification of the accelerator as a means to ensure product quality conformity analysis and for further research experiments. In conclusion, a portion of KS F 2782 standard that fixes the problems that can be resolved from the ground up as a whole is not a review for the domestic reality. As an indoor experiment to ensure uniformity in the field when applied in a sufficient correlation, complement must be in place.

• Journal of the Society of Disaster Information
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• v.20 no.2
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• pp.329-338
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• 2024

Purpose: This study verified the safety of the improved box-type girder behavior by comparing and evaluating the bending behavior results of a full-scale specimen based on the analytical behavior of the splice element PSC U-shaped girder with integrated tensioning systems. Method: Based on the results of the service and strength limit state design using the bridge design standard(limit state design method), the applied load of a 40m full-scale specimen was calculated and a static loading experiment using the four-point loading method was performed. Result: When the design load, crack load, and ultimate load were applied, the specimen deflection occurred at 97.1%, 98.5%, and 79.0% of the analytical deflection value. When the design load, crack load, and ultimate load were applied, the crack gauge was measured at 0.009~0.035mm, 0.014~0.050mm, and 6.383~5.522mm at each connection. Conclusion: The specimen behaved linear-elastically until the crack load was applied, and after cracks occurred, it showed strainhardening up to the ultimate load, and it was confirmed that the resistance of bending behavior was clearly displayed against the applied load. The cracks in the dry joints were less than 25% of grade B based on the evaluation of facility condition standard. The final residual deformation after removing the ultimate load was 0.114mm, confirming the stable behavior of the segment connection.

• Resources Recycling
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• v.20 no.1
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• pp.37-45
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• 2011

This study was conducted to recycle flotation tailings as non-sintered construction materials considering the economic and eco-friendly treatments. The particle size distribution( median $220\;{\mu}m$) of flotation tailings from Soon-shin mine was confirmed to be larger than that(median $140\;{\mu}m$) of tailings from Sam-kwang mine. Thus we investigated the properties of non-sintered eco-brick producted with the tailings from Sam-kwang mine and non-sintered water permeable block producted with the tailings from Soon-shin mine. Compressive strength of non-sintered water permeable block which was made with less than 25 wt% of tailings from Soon-shin mine was met with products class(over 14.70 MPa) of water permeable concrete(EL 245) from KEITL. Meanwhile, the coefficient of its permeability wasn't met with the products class( over $1.0{\times}10^{-2}\;cm/sec$). The properties of non-sintered eco-brick with less than 40 wt% of tailings from Sam-kwang mine were satisfied with third class in sintered clay brick products standard(KS L 4201). The non-sintered eco-brick as a result of leaching test on heavy metals by KSLT was verified to be environmentally stabile.

• Journal of Korean Society of Steel Construction
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• v.15 no.1
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• pp.77-85
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• 2003

The lifting and lowering supports method makes up for the weak points in the classical method and provides makes construction economical effect to construction. The application of pre-compression to continuous steel box girder bridges makes it possible to reduce the amount of steel, the height of girders and consequently, the cost consequentlyof the bridges' construction by through the process of concrete filling- up and the lifting-lowering of the inner supports. The lifting and lowering supports method is apt to cause local buckling in the lower flange and web plates by due to the process of the lifting of the inner supports. Therefore iln this study, therefore, the possibility of local buckling could be decreased, in consideration of the lifting force and the buckling strength of stiffened plates, by increasing the number of longitudinal stiffeners and the installation of extended longitudinal stiffeners on the lower flange and the web plates in the range of positive moment.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.429-437
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• 2018

The aim of the research is to analyze a feasibility of rapid evaluation method for cement fineness by the relation analysis between density measurement using hydrometer and fineness of ordinary Portland cement. Additionally, based on the commercially available cement product, relation between a series of fundamental properties of cement mortar and fineness of cement powder was analyzed. As an experimental result, the actually measured fineness value of cement powder showed a good correlation with the fineness value obtained by hydrometer while there was poor correlation with the fineness value on specification. Especially, the density measurement in three minutes showed the closest relation with cement powder fineness, thus rapid quality evaluation of cement powder can be possible by using the regression equation obtained from the three minutes density measurement. Additionally, there was a high relation between cement powder fineness with a fundamental properties of the cement mortar such as fluidity, air content, setting time, and strength development.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.1-12
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• 2006

An existing Steel pipe, Cast iron pipe and Concrete pipe is can not escaped from aging, specially Metal tube is causing many problems that the quality of water worse is concerned about many rust and mike efficient use of preservation of water. The use of Glassfiber Reinforced Plastic Pipe(GRP PIPE) should be one of the possible scheme to get over these problems. The GRP PIPE has an excellent resistance power and the life is lasting from 50 to 100 years roughly. It's to be useful as a result of high durability and a good construction work also it is a light weight therefore can be expected to short the time of construction and man power. In this research, to executed the small-scaled model test, in-situ model test using CLSM of in-situ soil and to evaluated the stress - strain of the pipe also try to estimated how useful is. From the model test in laboratory, the vertical and horizontal deformation of the GRP PIPE measured in six instance using 200mm and 300mm in diameters. The value of experimentation, theory, analysis got the same results of the test, but the vertical and horizontal deformation gauged in small and the earth pressure was almost zero using CLSM of in-situ soil..

• Journal of the Korean Geotechnical Society
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• v.29 no.11
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• pp.119-127
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• 2013

Recently, several researches on the development of new economical foundation types have been performed to support floating structures as many offshore structures have been constructed. This study focused on the evaluation of bearing capacity of group suction piles, which are connected by a concrete pile cap. The offshore floating structures are mainly subjected to horizontal loading, so the horizontal bearing capacities of the group suction piles were analyzed by performing 3-dimensional finite element analyses. The group suction piles are expected to behave as a rigid pile due to its shallow embedded depth. Therefore, the detailed soil modeling was necessary to simulate the bearing behavior of soils under low confining pressure. The modulus and the strength of soils were modelled to increase with effective confining pressure in soils. For the parametric study, the center-to-center spacing between piles was varied and two soil types of clay and sands were applied. The analyses results showed that the yielding load of the group pile increased with the increase of the pile spacing and the yielding load of the group piles with 5D spacing was about 3 times larger than that of the single pile with free rotation.