• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.38-45
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• 2001

Numerical studies were carried out to develop the moment magnifier method for long-term behavior of flat plates, subjected to combined in-plane compressive and transverse loads. Nonlinear finite element analyses were performed for the numerical studies. Through the numerical studies, the long term behavior of the flat plate subjected to uniform or nonuniform floor load was investigated, and creep effects on the degradation of strength and stiffness of the slabs were examined. As a result, the creep factor was implemented to describe the creep effect on the flat plate. The moment magnifier method using the creep factor was developed for long-term behavior of flat plates. Also, the design examples were shown for the verification of the proposed design method.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.233-236
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• 2008

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

• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.650-661
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• 2003

During construction of reinforced concrete building, construction load two times as much as the self weight of a slab, is imposed on the slab, and strength and stiffness of the early-age concrete are not fully developed. As the result, the construction load frequently causes excessive deflection and cracking in the flat plate. The minimum thickness of flat plate specified by the current design codes does not properly address such effect of the construction load. In the present study, a simplified method was developed to calculate the deflection of flat plate affected by the construction load. The proposed method can consider the effects of a variety of design parameters such as the aspect ratio of plate, boundary condition, concrete strength, and construction load. A design equation for the minimum thickness was developed based on the proposed method.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.949-960
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• 2002

Flat plate structures under lateral load are susceptible to punching shear failure of the slab-column connection. To prevent such brittle failure, strength and ductility of the connection should be ensured. However, due to complexity in the behavior and difficulty in simulating the actual load and boundary conditions of the flat plate system, it is not easy to obtain reliable data regarding to the strength and ductility from the previous experimental studies. In the present study, a numerical study was performed for interior connections of continuous flat plate. For the purpose, a computer program for nonlinear FE analyses was developed, and the validity was verified by comparisons with the existing experimental results. Through the parametric studies, the variations of bending moment, shear, and torsional moment around the connection were investigated. Based on the findings of the numerical studies, the aspects which need to be improved in current design methods were discussed. The results of the present study will be used for developing a design method for the flat plate-column connection in the companion paper.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1-4
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• 2008

Flat plate slab has been widely used in high rise building for its remarkable advantages. However, Flat plate structures under lateral load are susceptible to punching shear of the slab-column connection. Exterior slab-column connections 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 connections is susceptible to punching shear failure. For that reason, this study compare ACI 318-05 to CEB-FIP MC 90 that is based on experiment results and existing data of flat plate exterior connections. This study shows that compared to CEB-FIP MC 90 is more exact about eccentric shear stress, unbalanced moment and Both of all are not suitable in large column aspect ratio. Considering gravity shear ratio, These are suitable but design condition only consider gravity shear ratio. So these should be considered differences from change of design condition

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.2
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• pp.121-128
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• 2014

In this study, The purpose of this study is to experimentally investigate the shear behavior of reinforced flat plate embedded with GFRP(glass fiber reinforced polymer) plate with openings. The GFRP shear reinforcement is manufactured into a plate shape with several openings to ensure perfect integration with concrete. The test was performed on 7 specimens. the parameters include the type of reinforcement and amount of the shear reinforcement., From the test, we analysed the crack, failure mode, Strain, load-displacement graph. a calculation of the shear strength of reinforced flat plate with GFRP plate based on the ACI 318-11 was compared with the test results. The results of the experiment indicate that GFRP plate is successfully applied as a shear reinforcement in the flat plate under punching shear.

• 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.

• Magazine of the Korea Concrete Institute
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• v.20 no.3
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• pp.67-74
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• 2008

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.667-675
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• 2012

Flat plate are being used more in buildings requiring a high level of technical installations or in buildings needing changeable room arrangements during their life time such as office buildings. The main problem in flat plate is its weak resistance against a punching failure at its slab-column connections. Therefore, in this research, an experimental study on full-scale interior slab-column connection was performed. Three types of shear reinforcements were tested to prevent brittle punching shear failure that could lead to collapse of the structure. A series of four flat plate specimens including a specimen without shear reinforcement and three specimens with shear reinforcements were tested. The slabs were tested up to failure using monotonic vertical shear loading. The presences of the shear reinforcements substantially increased punching shear capacity and ductility of the interior slabcolumn connections. The test results showed that a slab that did not have enough bond length failed before shear reinforcement yielded due to anchorage slip. Also, FEM analyses were performed to study an effect of slab thickness and concrete compressive strength on the flat plate slab. The analytical study results were used to propose a method to calculate performance capacity of shear reinforcement in slab-column connection.