• International conference on construction engineering and project management
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• 2013.01a
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• pp.226-230
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• 2013

In the tall building construction, the slab formwork largely impacts on construction cost. Because productivity of a slab formwork is influenced by a number of and the efficiency of equipment, using the equipment-based construction method, an appropriate equipment input planning is crucial for the productivity. Meanwhile, the general equipment input planning is conducted by intuition based on experience due to the lack of equipment productivity data. Thus, this study develop a simulation model to analyze table formwork productivity and to propose an optimum equipment input plan that reflects the construction process, based on the full consideration of the economic factors. This study developed a simulation model by using CYCLONE and the data for the model was collected by measuring the duration of each unit activity in the tall building where table forms were applied. It is expected that a simulation model helps users to make better decision on the equipment input planning of slab formwork.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2A
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• pp.51-58
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• 2011

The objective of this research aims at improving the structural and economical efficiency of small and medium-span reinforced concrete bridge slab with the Inverted-T girders (hereinafter, called as IT). This IT method has an advantage over minimizing the construction process which could cause environmental pollution and traffic congestion. Especially it is thought that this new composite bridge slab with IT girders has better aesthetic view and visibility than existing old bridges, and is also a good methodology to solve labor shortage problems due to coming aging society. Therefore, this IT method should be one of very effective construction technologies to improve the constructibility and to reduce the construction cost.

• International Journal of High-Rise Buildings
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• v.9 no.2
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• pp.187-195
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• 2020

As deep decks are commonly used in construction fields and high-rise building. etc, the slim floor system is increasingly employed. But, the drawback of the slim floor system is that the use of 250 mm deep decks in a structure having a clear span of more than 6 m because of deflection and flexural buckling. This study suggests a non-support construction method where tendons are installed in the deep decks of the slim floor structure to introduce preload in order to control deflection in a structure having a clear span of 9 m. Loading tests were conducted to verify the composite effect and flexural capacity of the preloaded deep deck composite slab and evaluate the serviceability of the supportless construction method. The results showed the complete composite behavior of the preloaded deep deck composite slab with tendons. The specimens satisfied deflection limit and the working load was approximately 25% of the maximum load capacity. It is deemed that the cross-sectional area and yield strength of the deck plate should be taken into account in slab design and the yield strength and diameter of the tendon should be determined with the pre-tension taken into consideration.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.869-881
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• 1999

Inchon International Airport Elevated Road Way is located between the Passenger Terminal Building and Transportaion Center which are Inchon International Airport core construction projects. The deck of the bridge is consists of 5-span or 6-span continuous pre-stressed concrete slab. Steel form has been used to enhance the quality of texture on concrete slab. Steel form has been used to enhance the quality of texture on concrete surface, lower surface of deck slab with the two way arch has been manufactured by highly professional manner in order to get an beautiful exterior architectural looks. The prestressed concrete deck slab is mass concrete structures with a high-specified concrete strength and a varying section in the range of 0.95-2.8m thickness. Therefore high risks of thermal cracking occurrence by heat of hydration highly are expected. To resolve such problem, we adopted type 1 cement and pipe cooking method at construction site through mass concrete specimen test and 3-dimensional analysis. For Pipe cooling we used 25mm diameter stainless pipes with wrinkles. Cooling pipe with spacing 50-60cm has been installed. And continuous pipe cooling with cooling water of 15$^{\circ}C$ was conducted for 2days. In present 8 span of all 29 spans construction has been completed. No thermal cracking heat hydration has been observed yet.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.3_4
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• pp.195-203
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• 2004

VolumePro is a real-time volume rendering hardware for consumer PCs. However it cannot be used for the applications requiring perspective projection such as virtual endoscopy since it provides only orthographic projection. Several methods have been presented to approximate perspective projection by decomposing a volume into slabs and applying successive parallel projection to thou. But it takes a lot of time since the entire region of every slab should be processed, which does not contribute to final image. In this paper, we propose an efficient perspective projection method that makes the use of several sub-volumes with cropping feature of VolumePro. It reduces the rendering time in comparison to slab-based method without image quality deterioration since it processes only the parts contained in the view frustum.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.59-65
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• 2010

The simple supported reinforced concrete slab bridges are analyzed by the specially orthotropic laminates theory. This method, however, may be too difficult for some practising engineers. In this paper, the result of analysis for such plate by means of the beam theory with unit width is reported. By using the "correction factor", the accurate solution for the plate can be obtained by the beam theory. By using the "correction factor", the accurate solution for the plate can be obtained by the beam theory. The plate aspect ratio considered is from 1 : 1 to 1 : 6. The result of this paper can be used for simply supported slab bridges analysis.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.88-89
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• 2015

In cold weather, the speed of concrete strength development is slow. As a result, construction speed becomes slow and it is problem for all construction site to solve this. So in this study, to shorten removing frame time after placing concrete, mix proportion using early-strength-binder(ESB) and curing method such as using heat line in concrete was considered. At first, concrete mix proportion was examined at -5℃ temperature between ordinary portland cement(OPC) and ESB. And second step, concrete, using mix proportion with OPC, was examined according to curing method(: 1) heat line used and 2) no heat line) and kinds of form (: 1) Deck slab, 2) Half PC slab and 3) SOG slab). All cases are same condition: slab thickness is 1,500mm, double-bubble sheet is used as a curing sheet after placing concrete. After the test, OPC is enough to get strength compared to ESB in special condition and 48~60 hours is needed according to form condition.

• Advances in Computational Design
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• v.8 no.4
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• pp.295-307
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• 2023

This paper presents an optimization of the reinforced concrete ribbed slab in terms of minimum CO₂ emissions and an economic justification of the final optimal design. The design variables are six geometry variables including the slab thickness, the ribs spacing, the rib width at the lower and toper end, the depth of the rib and the bar diameter of the reinforcement, and the seventh variable defines the concrete strength. The objective function is considered to be the minimum amount of carbon dioxide gas (CO₂) emission and at the same time, the optimal design is economical. Seven significant design constraints of American Concrete Institute's Standard were considered. A robust metaheuristic optimization method called improved dolphin echolocation and ant colony optimization (IDEACO) has been used to obtain the best possible answer. At optimal design, the three most important sources of CO₂ emissions include concrete, steel reinforcement, and formwork that the contribution of them are 63.72, 32.17, and 4.11 percent respectively. Formwork, concrete, steel reinforcement, and CO₂ are the four most important sources of cost with contributions of 67.56, 19.49, 12.44, and 0.51 percent respectively. Results obtained by IDEACO show that cost and CO₂ emissions are closely related, so the presented method is a practical solution that was able to reduce the cost and CO₂ emissions simultaneously.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5C
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• pp.351-358
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• 2006

The purpose of this study is to recommend the simulation method and procedure of behaviors of CFRD(Concrete Faced Rockfill Dam) concrete face slab with impoundment by centrifuge tests, to examine the effects of the flexural rigidity of the concrete face slab on the face slab deformation from the centrifuge tests, and to evaluate the effects of the stiffness of face supporting zone on the displacement and moment of face slab by numerical analysis which is verified by the centrifuge tests. In this study, the centrifuge tests on the two model dams with the concrete face slab of different flexural rigidity were carried out. Also, the centrifuge tests were simulated by numerical analysis of which input material properties were obtained by the triaxial tests on the model materials. The validity of numerical analysis was evaluated by comparison between the results of centrifuge tests and numerical simulation. The deformation pattern of the concrete face slab was examined with the various stiffness of the face supporting zone by numerical analysis. From the results of centrifuge tests, the effects of face slab thickness on the deformation of face slab were negligible. From the results of centrifuge tests and numerical analysis, it was found that the amplitude of the maximum displacement of face slab and the position where the maximum displacement was mobilized with impoundment were affected by the stiffness of face supporting zone rather than the flexural rigidity of concrete face slab.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3454-3462
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• 1996

Compared to a full three dimensional FEM, the Slab-FEM hybrid method reduces the required computation time distinctly and it can be applied to the analysis of a shape rolling process. However, the method is somewhat approximate and predictions by the method contain certain inaccuracies. In the present investigation a parameter called T-factor was introduced to compensate the inaccuracies of the method and proper values of the parameter were estimated for different widths of bars and reduction ratios. Then, the method was applied to analyze cold and hot rollings of rectangular bars and predicted results were compared to those of experiments. Nonuniform distributions of temperature in the bars were predicted by utilizing the temperature equation obtained for a semi-infinite solid under radiation and convection boundary conditions. It was found out that accuracies of spread and roll separating force predictions could be enhanced by using proper values of the T-factor.