• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.272-275
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• 2004

This study is to propose a modified equivalent frame method under lateral loading. ACI 318-02 allows the equivalent frame method to conduct slab analysis subjected to lateral loads. However, current method can not predict the behavior of the slabs particularly under lateral loading because the equivalent frame method in the ACI 318 has been developed against gravity loads. This study provides more precise model for the analysis of the flat plate slabs under lateral loading. The model reflect the force transfer mechanism of slabs, column and torsional member more accurately than the existing model. The accuracy of this model is verified by compared with finite element method analysis results.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.11-17
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• 2008

This study evaluates the seismic performance of post-tensioned flat plate structures with or without slab bottom reinforcement. For this purpose, 3 and 9 story frames were designed only considering gravity loads. This study conducts a nonlinear static pushover analysis. This study was an analytical model that is able to represent punching shear failure and fracture mechanism. The analytical results showed that the seismic performance of a post-tension flat plate is strongly influenced by the existence of slab bottom reinforcement through column. By placing slab bottom reinforcement in a PT flat plate frame, lateral strength and max drift capacity are significantly increased.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.3-10
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• 2010

This study evaluates the seismic performance of reinforced concrete (RC) flat plate structures relation to the gravity shear ratio. For this purpose, 3 and 7 story framed buildings were designed for gravity loads only. Subsequently, a nonlinear static pushover analysis and a nonlinear time history analysis for the prototype buildings were carried out. In the nonlinear analysis, newly propose analytical slab-column joint model was utilized to capture punching shear failure and fracture mechanism in the analysis. The analytical results showed that seismic performance of RC flat plate frame is strongly influenced by the gravity shear ratio. In particularly, in the RC flat plate frame with a large gravity shear ratio the lateral strength and maximum drift capacity decreased significantly.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.470-481
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• 2003

Exterior plate-column connection has an unsymmetrical critical section for eccentric shear of which perimeter is less than that of interior connection, and hence, around the connection, unbalanced moment and eccentric shear are developed by both gravity load and lateral loads. Therefore, exterior connection is susceptible to punching shear failure. Current design provision cannot accurately explain strength of existing experiments, partly due to the complexity in the behavior of exterior plate-column connection, or partly due to the theoretical deficiency of the strength analysis model adopted. In the present study, nonlinear finite element analyses were performed for exterior connections belonging to continuous flat plate. For each direction of lateral load, the behavior and strength of exterior plate-column connection were quite different. Based on the numerical result, strength prediction model for exterior connection was proposed for each direction of lateral load. Compared with existing experiments, the proposed method was verified.

• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.163-174
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• 2004

A number of experiments were performed to investigate the punching shear strength of flat plate-column connections. According to the experiments, the punching shear strength varies significantly with design parameters such as the column size of the connection, reinforcement ratio, and boundary condition. However, current design methods do not properly address the effects of such design parameters. In the present study, a theoratical approach using Rankine's failure cirterion was attempted to define the failure mechanism of the punching shear According to the study, the failure mechanism can be classified into the compression-controlled and the tension-controlled, depending on the amount of bottom re-bars placed at the connection, and the punching shear strength is also significantly affected by the flexural damage of slab. Based on the finding, a new strength model of punching shear was developed, and verified by the comparisons with existing experiments and nonlinear finite element analyses. The comparisons show that the proposed strength model addressing the effects of various design parameters can predict accurately the punching shear strength, compared to the existing strength models.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.439-450
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• 2003

Flat plate system has been adopted in many buildings constructed recently because of the advantage of reduced floor heights to meet the economical and architectural demands. Structural engineers commonly use the effective beam width model(EBWM) in practical engineering for the analysis of flat plate structures. However, in many cases, when it is difficult to use the EBWM, it is necessary to use a refined finite element model for an accurate analysis. But it would take significant amount of computational time and memory if the entire building structure was subdivided with finer meshes. An efficient analytical method is proposed in this study to obtain accurate results in significantly reduced computational time. The proposed method employs super elements developed using the matrix condensation technique and fictitious beams are used in the development of super elements to enforce the compatibility at the interfaces of super elements. The stiffness degradation of flat plate system considered in the EBWM was taken into account by reducing the elastic modulus of floor slabs in this study. Static and dynamic analyses of example structures were performed and the efficiency and accuracy of the proposed method were verified by comparing the results with those of the refined finite element model and the EBWM.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.291-299
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• 2010

Aspect-ratio-based numerical analysis is carried out to investigate the air-side convective heat transfer characteristics in compact heat exchangers with circular tubes and flat tubes-plate fins. The RNG $k-{\varepsilon}$ model is adopted for turbulence analysis. The numerical analysis is carried out for aspect ratios ranging from 3.06 to 5.44 and for Reynolds numbers ranging from 1,000 to 10,000. The calculated results indicate a correlation between the friction factor and Colburn j factor in the compact heat exchanger system for the range of aspect ratios under consideration. The results obtained for circular tubes and flat tubes-plate fins in this study can be utilized to realize the optimal design of an air conditioning system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1237-1245
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• 1993

In this study, a model of a flat plate solar collector using a heat pipe was manufactured and tested to investigate such operational characteristics of the present system of solar collector as start-up process, temperature distribution on the absorber plate and operation of the heat pipe. Moreover, collector efficiency was measured for 20-30 minutes of operation at various conditions of weather and the result was compared with that tested by Hill et. a. for a flat plate solar collector using direct circulation of coolant. Some results obtained in this study could be summarized as follows. (1) The required time for the initial start-up process was about 5-6 minutes, but the heat pipe began to operate as soon as the absorber plate was exposed to solar radiation. (2) On the absorber plate, the temperature distributions in axial direction maintained nearly constant, while temperature distributions in transversal direction showed smooth decrease with $3-5^{\cird}C$ along with solar radiation. (3) Thermal inertia of the collector system had a favorable effect to damp the turbulent variation of solar radiation. (4) The collector efficiency of the present system showed nearly the same tendency but a decrease of about 10% compared with that using direct circulation of coolant.

• International Journal of Fluid Machinery and Systems
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• v.9 no.3
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• pp.205-212
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• 2016

The performance of a prototype pump converted from that of its model pump shows an increase in efficiency brought about by a decrease in friction loss. As the friction force working on impeller blades causes partial peripheral motion on the outlet flow from the impeller, the increase in the prototype's efficiency causes also a decrease in its input power. This paper discusses results of analyses on the behavior of the theoretical head or input power of a prototype pump. The equation of friction-drag coefficient for a flat plate was applied for the analysis of hydraulic loss in impeller blade passages. It was revealed that the friction-drag of a flat plate could be, to a certain degree, substituted for the friction drag of impeller blades, i.e. as a means for analyzing the relationship between a prototype pump's efficiency increase and input power decrease.

• Solar Energy
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• v.2 no.1
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• pp.17-23
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• 1982

This paper presents the performance of a Flat-Plate Solar Collector in case of taking into account of the thermal capacitance. The relationships among energy absorption, overall heat loss coefficient and temperature distribution are studied theoretically. And the thermal capacitance of the collector is considered. Also, the results obtained are compared with those of model in which the thermal capacitance is neglected. As the results of this study, the efficiency of the collector having double glazing is higher than the other cases. It is shown that the fluid temperature in the tubes are rising close to linearly. The variations of the outlet temperature of tubes in the model neglecting the effect of thermal capacitance are tend to represent lower slope than that of considering the effect of thermal capacitance.