• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05b
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• pp.53-56
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• 2011

This study is concerned with the SL shear reinforcement that it can be installed easily in filed as product at the factory and seismic performance can be achieved. The method of study is as follows. first, we researched constructability and economy of existing method. Secondly, we made specimen and were examined structural performance tests in order to verify the performance of the shear reinforcement. Shear strength of HILL01-HILL03 specimen applied to SL shear reinforcement increased about 5-14% when compared with the applied shear stirrup reinforcing existing specimens. Also, the amount of the maximum deflection of the central sub-section of HILL01-HILL03 specimen applied to SL shear reinforcement decreased about 41-42% when compared with the applied shear stirrup reinforcing existing specimens. As a result, developed SL shear reinforcement increased in shear strength and stiffness of reinforcement, structural safety is judged to be increased.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.65-68
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• 2008

This paper verified the lateral resisting capacity of CFT column-RC flat plate connection in comparison with general RC column-flat plate connection and detected moment capacity and ductility capacity of connection according to lateral force-displacement ratio. We made and tested specimens which have different variables respectively and as a result derive a following conclusion. In CFT specimen a critical section was extended and initial stiffness and moment increased 35%, 25$^{\sim}$35% respectively in comparison to general RC column specimen. In all specimens generally shear governed behaviors and in CFT specimen complemented with seismic band, flexure behavior region of slab was extended and also ductility ratio and energy absorptance increased.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.5
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• pp.194-202
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• 2006

In the present study, stiffness prediction methodologies for flat-plate structures were evaluated in comparison with the experimental results on the full-scale slab-column connections of flat-plate structures. The methodologies are as follows: the methodology proposed by Jacob S. Grossman and the methodology proposed by Choi & Song. The former does not predict the stiffness change of the slab-column connection due to the change in the column section shape and the latter overestimates the stiffness when edge length of the column section in the loading direction is long. In the present study, the equation to calculate the effective width of slabs was modified to reflect the effect of the change in the column section shape.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.241-244
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• 2008

In general, RC flat plate frames have been used as a gravity load resisting system(GLRS) in building. This system should be constructed with lateral force resisting system(LFRS) such as shear walls and brace frames. When lateral loads such as earthquakes occur, LFRS undergo displacement by which connected gravity systems experience lateral displacement. Thus, flat plate system designed as GLRS should be predict unbalanced moments and punching failure due to lateral deformation. This study developed an analytical mode for predicting nonlinear behavior of RC slab column connection for the seismic performance evaluation of RC flat plate frames. For verifying the analytical model, the test results of two flat plate specimens having two continous spans with the difference gravity shear ratio($V_g/{\phi}V_c$) were compared with the results of analysis. The developed model can predict the failure modes and punching failures.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.141-150
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• 2005

The behavior of the concrete slabs-on-grade considering the horizontal resistance at the slab bottom, which exists due to the shear resistance of the foundation and the friction between the slab and the foundation, has been investigated when the slabs-on-grade are subjected to the vertical load. Analytical formulations have been developed to include the effect of the horizontal resistance at the slab bottom, and the solutions have been obtained in the transformed field domain using the Fourier transform. Finite element formulations have also been developed using the plate bending elements and the flat shell elements. The solutions from the analytical and numerical models have been compared and showed very good agreement. The sensitivity of the horizontal resistance to the stresses of the concrete slab has been investigated with various values of the slab thickness, elastic modulus, and vertical stiffness of the foundation. The analysis results show that the horizontal resistance at the plate bottom can significantly affect the stresses of the slab.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.271-282
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• 2006

The behavior of the concrete slabs on grade considering the horizontal resistance at the slab bottom, which exists due to the shear resistance of the foundation and the friction between the slab and the foundation, has been investigated when the slabs-on-grade are subjected to the thermal load. Analytical formulations have been developed to include the effect of the horizontal resistance at the slab bottom employing the thin plate on an elastic foundation that is widely used for the analysis of concrete slabs-on-grade and rigid pavement systems. Finite element formulations have then been developed using the plate bending elements and the flat shell elements. The solutions from the analytical and numerical models have been compared and showed very good agreement. The sensitivity of the horizontal resistance to the stresses of the concrete slab has been investigated with various values of the slab thickness, elastic modulus, and vortical stiffness of the foundation when subjected to the temperature gradient between the top and bottom of the slab and the uniform temperature drop throughout the slab depth. The analysis results show that the horizontal resistance at the plate bottom can significantly affect the stresses of the slab when the thermal loads are applied.

• Structural Engineering and Mechanics
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• v.8 no.2
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• pp.137-150
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• 1999

This paper presents a numerical study on the flat plates in deep basements, subjected to floor load and in-plane compressive load due to soil and hydraulic lateral pressure. For nonlinear finite element analysis, a computer program addressing material and geometric nonlinearities is developed. The validity of the numerical model is established by comparison with existing experiments performed on plates simply supported on four edges. The flat plates to be studied are designed according to the Direct Design Method in ACI 318-95. Through numerical study on the effects of different load combinations and loading sequence, the load condition that governs the strength of the flat plates is determined. For plates under the governing load condition, parametric studies are performed to investigate the strength variations with reinforcement ratio, aspect ratio, concrete strength, and slenderness ratio. Based on the numerical results, the floor load magnification factor is proposed.

• Computers and Concrete
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• v.22 no.4
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• pp.365-372
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• 2018

The current design codes present an equivalent frame method (EFM) for the analysis and design of two-way slab structures. However, since the EFM was developed to be suitable for two-way slab structures subjected to gravity loads only, it brings many problems in its application to the analysis of two-way slabs to which gravity and lateral loads are applied simultaneously. Therefore, authors proposed the unified equivalent frame method (UEFM) that can analyze the structural behavior of flat-plate slab systems subjected to gravity and lateral loads in their previous studies. In this study, the UEFM was modified to be applicable to the two-way slab system with beams. In addition, the accuracy of the proposed UEFM was then examined by comparing it to the lateral behaviors of the two-way slab specimens.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.126-129
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• 2006

A bending moment $M_u$ transferred at slab-column connection is resisted at the slab critical section by flexure and shear. The ACI 318-05 Building Code(1) gives an empirical equation for the fraction ${\gamma}_{\upsilon}$ of the moment $M_u$ to be transferred by shear at the slab critical section at d/2 from the column face and also the effective wide(c+3h). The equation is based on tests of interior slab-column connections without shear reinforcement. In order to investigate the data eight test specimens were examined. The test shows that increased slab load substantially reduces both the unbalanced moment capacity and the lateral drift capacity of the connection. Especially, the specimens with the bottom reinforcement existence and nonexistence, appears remarkable differences. Studies also show that the code equation for ${\gamma}_{\upsilon}$ does not apply to all cases. The purpose of this study is to compare the test results with present ACI 318-05 Building Code provisions for design of slab-column connections and with the analysis of the experimental data for a new limitation of strength equation without shear reinforcement and bottom reinforcement.