• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.2
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• pp.103-111
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• 2024

Due to the recent increase in domestic seismic activity and the proliferation of PC structure buildings, there is a pressing need for a fundamental study to develop and revise the design criteria for Half-PC slabs. In this study, we propose criteria for determining the rigid diaphragm based on the aspect ratio of Half-PC slabs and investigate the structural effects based on the presence of chord element installation. This study concluded that Half-PC slabs with an aspect ratio of 3.0 or lower can be designed as rigid diaphragms. When chord elements are installed, it is possible to design Half-PC slabs with an aspect ratio of 4.0 or lower as rigid diaphragms. In addition, the increase in the aspect ratio of the Half-PC slab leads to a decrease in the in-plane stiffness of the structure, confirming that the reduction effect of the maximum displacement in force direction (𝜟_max ) due to the increase in wall stiffness is predominantly influenced by flexibility.

• Steel and Composite Structures
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• v.51 no.6
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• pp.647-659
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• 2024

Given the increased interest in enhancing structural sustainability, the current study sought to apply multiobjective optimization to a footbridge with a steel-concrete composite I-girder structure. It was considered as objectives minimizing the cost for building the structure, the environmental impact assessed by CO2 emissions, and the vertical accelerations created by human-induced vibrations, with the goal of ensuring pedestrian comfort. Spans ranging from 15 to 25 meters were investigated. The resistance of the slab's concrete, the thickness of the slab, the dimensions of the welded steel I-profile, and the composite beam interaction degree were all evaluated as design variables. The optimization problem was handled using the Multiobjective Harmony Search (MOHS) metaheuristic algorithm. The optimization results were used to generate a Pareto front for each span, allowing us to assess the correlations between different objectives. By evaluating the values of design variables in relation to different levels of pedestrian comfort, it was identified optimal values that can be employed as a starting point in predimensioning of the type of structure analyzed. Based on the findings analysis, it is possible to highlight the relationship between the structure's cost and CO2 emission objectives, indicating that cost-effective solutions are also environmentally efficient. Pedestrian comfort improvement is especially feasible in smaller spans and from a medium to a maximum level of comfort, but it becomes expensive for larger spans or for increasing comfort from minimum to medium level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8408-8415
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• 2015

The purpose of this study is to propose and analyse new technology of structural elements design for Korean-style house(Hanok). Design of modern apartment building adopts many aesthetic elements from Hanok, however, these are only for the decorations of interior. In this study, projected Hanok eaves were studied in terms of the length of solar insolation. Inclined front slab system has been proposed utilizing sloping roof to an apartment building section. This system can provide the same sunshine radiation length and outside view to all levels of building to overcome the limitation of traditional hanok. It also can be applied to all residences the vertical garden concept of hanok. Inclined slab system showed 20% more efficient than flat slab system in terms of solar insolation length. This study also suggested a double deck slab system for not only reducing apartment floor impact noise but also connecting concept of traditional maru system in hanok. Double deck system reduces 66% of floor impact noise comparing with single deck slab of modern apartment buildings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.263-274
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• 2018

In this study, the applicability and external/internal stability of a MSEW abutment with a slab were investigated. Structural analysis of slab bridges between 10 ~ 20.0 m and thicknesses of 0.7 ~ 0.9 m was carried out to calculate the reaction forces due to dead and live loads acting on the bridge supports. The slab bridge with a length of 20.0 m satisfied the allowable contact pressure of 200 kPa for the true MSEW abutment. Because the external stability of the true MSEW abutment was dominated by the geometry of the MSE wall, the change in the factor of safety due to the load of the super-structure is small. Because the stiffness of the foundations is fixed and the load of the super-structure is increased, the factor of safety of the bearing capacity was reduced. As the load of the super-structure was increased, the horizontal earth pressure of the true MSEW abutment increased greatly. As a result, the pullout and fracture of the uppermost reinforcement, which are the factors of safety, did not meet the design criteria. Therefore, it is necessary to increase the pullout resistance and the long-term allowable tensile force of the reinforcement placed on the top of the reinforced soils to ensure efficient design and performance of a true MSEW abutment.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.41-50
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• 2010

Long-term floor deflection caused by excessive construction load became a critical issue for the design of concrete slabs, as a flat plate is becoming popular for tall buildings. To estimate the concrete cracking and deflection of an early age slab, the construction load should be accurately evaluated. The magnitude of construction load acting on a slab is affected by various design parameters. Most of existing methods for estimating construction load addressed only the effects of the construction period per story, material properties of early age concrete, and the number of shored floors. In the present study, in addition to these parameter, the effects of shore stiffness and concrete cracking on construction load were numerically studied. Based on the result, a simplified method for estimating construction load was developed. In the proposed method, the calculation of construction load is divided to two steps: 1)Onset of concrete placement at a top slab. 2)Removal of shoring. At each step, the construction load increment is distributed to the floor slabs according to the ratio of slab stiffness to shore stiffness. The proposed method was compared with existing methods. In a companion paper, the proposed method will be verified by the comparison with the measurements of actual construction loads.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.2
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• pp.171-183
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• 2020

The purpose of this study is to analyze in advance the problems and improvements that may occur during the construction of intermediate slabs and the loading of intermediate slabs through the preliminary structural safety evaluation of intermediate slabs for Test bed structures in deep depth tunnels. The Test bed construction can verify and confirm the results of the design and construction technology development of large depth double deck tunnel through the process, and can also be used as a learning site for engineers and the general public to speed up the time of underground space development. There will be an opportunity to do this. In particular, the design load of middle slab built inside the circular deep-depth double-sided tunnel cross-section varies depending on the construction method and the construction equipment load used. Class 3 truck load of KL-510 assumed to be common load to upper and middle slab during loading and installation is loaded on upper and lower slab with different working position for each load combination Analyzed.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.331-340
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• 2004

This paper presents a feasibility study of a fresh air load reduction system by using an underground double floor space. The fresh air is introduced into the double slab space and passes through the opening bored into the footing beam. The air is cooled by the heat exchange with the inside surface of the double slab space in summer, and heated in winter. This system not only reduces sensible heat load of the fresh air by heat exchange with earth but also reduces latent heat load of the fresh air by ad/de-sorption of underground double slab concrete. In this paper, we used a model for evaluation of fresh air latent heat load reduction by hygroscopic of air to earth exchange system taking into account coupled heat and moisture transfer of underground double floor space. In conclusion it shows the validity of the proposed method for a design tool and the quantitative effect of the system.

• Steel and Composite Structures
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• v.15 no.3
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• pp.323-342
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• 2013

In the case of seismic-resistant composite dual moment resisting and eccentrically braced frames, the current design practice is to avoid the disposition of shear connectors in the expected plastic zones, and consequently to consider a symmetric moment or shear plastic hinges, which occur only in the steel beam or link. Even without connectors, the real behavior of the hinge may be different from the symmetric assumption since the reinforced concrete slab is connected to the steel element close to the hinge locations, and also due to contact friction between the concrete slab and the steel element. At a larger level, the structural response in the case of important seismic motions depends directly on the elasto-plastic behavior of elements and hinges. The numerical investigation presented in this study summarizes the results of elasto-plastic analyses of several steel frames, considering the interaction of the steel beam with the concrete slab. Several parameters, such as the inter-story drift, plastic rotation requirements and behavior factors q were monitored. In order to obtain accurate results, adequate models of plastic hinges are proposed for both the composite short link and composite reduced beam sections.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.100-110
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• 2000

In practical design of girder bridges or reinforced concrete slab bridges with T-type piers, it is usually assumed that vertical movements of superstructures are completely restrained at the locations of bearings(shoes) on a cap beam of the pier, The resulting vertical reactions are applied to the bearing for the calculation of bending moments and shear forces in the cap beam. However, in reality, the overhang parts of the cap beam will deform under the dead load of superstructures and the live load so that it may act as an elastic foundation. Due to the settlement of the elastic foundation, the actual distribution of the reactions at the bearings along the cap beam may be different from that obtained under the assumption that the vertical movements are fixed at the bearings. In the present study, investigated is the effects of elastic deformations of the T-type pier on the distribution of reactions at the bearings along the cap beam through 3-dimensional finite element analysis. Herein, for this purpose the whole structural system including the superstructure and piers as well is analyzed. It appears that the conventional practice which neglects the elastic deformations of the cap beam exhibits considerably different distributions of the reactions as compared with those obtained from the present finite element analysis. It is, therefore, recommended that in order to assess the reactions at bearings correctly the whole structural system be analyzed using 3-dimensional finite element analysis.

• Computational Structural Engineering
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• v.3 no.2
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• pp.89-95
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• 1990

As modern industry go further, a rigid concrete pavement has been widely constructed. The load carrying capacity of the flexible asphalt pavements is brought about by a layered system, distributing the load over the subgrade, rather than by the bending action of the slab. On the other hand, the rigid pavement, because of its rigidity and high modulus of elasticity, tends to distribute the traffic load over wide subbases, and its capacity of the strength is supplied by the slab itself. Thus, it is necessary to study the structural behavior of concrete slab under the variations of temperature changes and applied traffic loads. It reguires the development of finite element analysis program for the concrete highway pavement, which provides better understanding of concrete pavement behavior and effective design data to highway engineers.