• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.867-870
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• 2008

Flat plate system has many advantages, story height reduction, a term of works shortening and changeableness of space, etc. However structures become a tendency of higher stories and when we use RC column, the size of column grow larger. For this reason the use of CFT column is increasing more and more. Accordingly, this study carried out the nonlinear finite element analysis. As a result of analysis moment strength of the connection increased but ductility decreased as the top reinforcement ratio in th effective width increased. And moment strength and ductility of the connection decreased as gravity load ratio decreased. In the case that shearhead length is not more than 0.27m, the effectiveness of shearhead length on the moment strength and ductility of the connection were small relatively to other variables. Initial stiffness and moment strength of connection increased as slab thickness increased

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.985-991
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• 1996

In chromatographic separation, HETP(height equivalent to a theoretical plate) is a useful quanititive parameter and it is wildely designated as column efficiency. The effects of operating conditions (sample concentration, injection volume, flow rate and mobile phase composition) on HETP were investigated in perparative liquid chromatography (PLC). Water and organic modifier of methanol were used as mobile phase. The sample of thymidine was injected into preparative C18 columns. The system was run by a isocratic mode in 1.5~5.5ml/min. The larger amounts of sample and higher flow rates of mobile phase increased HETP, which means that column efficiencies were worse. As the weight of sample injected into a chromatographic system could be prepared with different concentrations and injection volumes, for the same amount of sample, HETP was approximately increased two times with the ten-fold injection volume. HETP was mainly affected by the resistance of stationary and mobile phase mass transfer in the intraparticle section of packings at higher velocities.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.347-352
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• 2002

Recent trends in the construction of building frame feature the increase use of composite steel concrete members functioning together in what terms of mixed structural systems. One of such systems, RCS(reinforced concrete column and steel beam) system is introduced and closely examined focusing on bearing strength of the composite joint in this paper. The main objective of this study was to develope one of details to increase bearing capacity while bearing failure is one of the two primary modes of failure in RCS system. Local bearing tests with specimens about 1/3 of the actual concrete column size were performed applying uniform load through steel plate with 100$\times$110mm size. Test results show that specimens with the bearing reinforcement detail developed in this study enhanced the bearing strength by 1.71~3.02 compared to concrete cylinder strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.185-188
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• 2008

Flat plate system has structural weakness such as punching shear. Punching shear resistance can be increase by using a lager column section and effective depth, higer concrete compressive strength, and more flexural reinforcement ratio. But using a shear reinforcement is most economical, enable, workable solution in flat plate. The slab with thickness smaller than 250mm can not perform effectively due to insufficient development length of shear reinforcement in the slab. In case of proposed reinforcements, since the shear reinforcements were installed between the top bar and the bottom bar, shear elements generated slip failure before they reached yield. strength. effect of anchorage strength were effective anchorage length, concrete strength, diameter of shear element and anchorage detail. considering effect of slab thickness and concrete strength, formula of K factor propose in thin flat plate slab. by considering effect of anchorage length and concrete strength, strength of shear reinforcement will be computed correctly in thin flat plate slab.

• 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.

• Computers and Concrete
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• v.31 no.4
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• pp.337-348
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• 2023

Shear wall is commonly used as a lateral force resisting system of concrete mid-rise and high-rise buildings, but it brings challenges in providing relatively large space throughout the building height. For this reason, the structure system where the upper structure with bearing, non-bearing and/or shear walls that sits on top of a transfer plate system supported by widely spaced columns at the lower stories is preferred in some regions, particularly in low to moderate seismic regions in Asia. A thick reinforced concrete (RC) plate has often been used as a transfer system, along with RC transfer girders; however, the RC plate becomes very thick for tall buildings. Applying the post-tensioning (PT) technique to RC plates can effectively reduce the thickness and reinforcement as an economical design method. Currently, a simplified model is used for numerical modeling of PT transfer plate, which does not consider the interaction of the plate and the upper structure. To observe the actual behavior of PT transfer plate under seismic loads, it is necessary to model whole parts of the structure and tendons to precisely include the interaction and the secondary effect of PT tendons in the results. This research evaluated the seismic behavior of shear wall-type residential buildings with PT transfer plates for the condition that PT tendons are included or excluded in the modeling. Three-dimensional finite element models were developed, which includes prestressing tendon elements, and response spectrum analyses were carried out to evaluate seismic forces. Two buildings with flat-shape and L-shape plans were considered, and design forces of shear walls and transfer columns for a system with and without PT tendons were compared. The results showed that, in some cases, excluding PT tendons from the model leads to an unrealistic estimation of the demands for shear walls sit on transfer plate and transfer columns due to excluding the secondary effect of PT tendons. Based on the results, generally, the secondary effect reduces shear force demand and axial-flexural demands of transfer columns but increases the shear force demand of shear walls. The results of this study suggested that, in addition to the effect of PT on the resistance of transfer plate, it is necessary to include PT tendons in the modeling to consider its effect on force demand.

• Journal of Korean Society of Steel Construction
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• v.22 no.3
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• pp.253-260
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• 2010

The purpose of this paper is to investigate the behavior of concrete-filled tube columns for footing connections. Eight specimens were tested to investigate such structural behavior according to the column base type. The specimens consisted of concrete-filled steel tube columns (or bare steel tube columns), reinforced concrete footings, and base plates (or stud connectors). The specimens were subjected to lateral cyclic load. The cyclic load was applied according to a predetermined strength sequence. The results of the experiment indicated that the flexural strength of the stud-connector- type column base is higher than that of the base-plate-type column base. The structural behavior of the concrete-filled tube column base was similar to that of the bare steel column base.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.213-219
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• 2008

The purpose of this study is to propose frame analysis method for flat plate slabs having edge beam under lateral loads. Flat plate system is defined as the system only with slab of uniform thickness and column. However, the slab system generally incorporate edge beams at exterior connection in actual design. ACI 318 (2005) allows three methods for conducting flat plate system analysis subjected to lateral loads. There are the finite element method (FEM), the equivalent frame method (EFM), and the effective beam width method (EBWM). Among methods, the EBWM enables us to analyze practically by substituting the actual slab to beam element. In this model, the beam element has a thickness equal to that of the slab, and effective beam width equal to some fraction of the slab transverse width. However, the established EBWM was generally proposed for variables of geometry or stiffness reduction factor and seldom proposed for the effect of edge beams. This study verifies that, in the case of flat plate system having edge beams at exterior connections, the lateral stiffness is considerably larger than without edge beams. Therefore it need to analysis method for considered the effect of edge beams. In this study, an analysis model is proposed for the flat plate system having edge beams under lateral loads by considering the effect of edge beams. To verify the accuracy of proposed model, this study compared results of the proposed EBWM with results of FEM of flat plate systems having edge beams under lateral loads. Also, the proposed approach is compared with experimental results of former research.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.609-613
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• 2004

An economic analysis is one of the most dominant factors to determine the project feasibility of super tall building. In economic considerations, it is very important toadopt optimum structural floor systems because these are dependent on both the cost and the duration of construction. The economics affected by structural floor systems are more distinct athigher story. As the story increases, the construction cost of floor system. is accumulated linearly, while the cost of lateral resisting system is increased geometrically. The purpose of this study is to investigate the economical effects of super tall buildings through application of optimum structural floor systems. Three types of structural systems(RC beam-column frame, RC flat plate frame, and Steel frame) of super tall buildings having 50-stories are considered in this study and compared to RC flat plate slab with other systems. Analytical result shows that RC flat plate slab using lightweight concrete ismost effective in both the cost and the duration of construction.