• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.17-20
• /
• 2006

A flat plate-column connection is susceptible to brittle punching shear failure, which may result in the necessity of shear reinforcement. In previous, experimental tests were performed to study the capacity of slab-column connections strengthened with various shear reinforcement, and the capacity of the specimens with lattice reinforcement are superior to the others. In present study, to study for effects of details of lattice reinforcement, experimental studies was performed. Main parameters are the amount of lattice shear reinforcement, arrangement of lattice and the effect of flexural re-bar. And capacity of the specimen with small amount of lattice reinforcement was higher than the capacity of other shear reinforcement.

• Journal of the Korean Society of Safety
• /
• v.34 no.5
• /
• pp.103-110
• /
• 2019

In order to reduce the accidents occurring at construction sites, it is necessary to approach with harmonious measures considering various aspects such as systems, training, facilities, and protection equipments. Suggestion of safe construction method can be a good alternative. In the previous study, the half-depth precast deck with RC rib panel was proposed as an alternative method for safe bridge deck construction, and the performance required by the design code was verified through a four-point bending test. But the actual bridge deck is subjected to the repetitive action of the wheel load rather than the bending condition due to the four-point load. In this study, fatigue test was performed by repeating the wheel load $2{\times}10^6$ cycles to verify the safety of the half-depth precast deck with RC rib panel under actual conditions. As a result, fatigue effect due to repetition of wheel load was not significant in terms of serviceability such as crack width and deflection. In the residual strength test conducted after the fatigue test, the half-depth precast deck with RC rib panel failed by punching shear which is typical failure mode of bridge decks and the residual strength was similar to the punching strength of the RC and PSC bridge decks in spite of the fatigue effects.

• Journal of the Korean Society of Safety
• /
• v.32 no.4
• /
• pp.66-72
• /
• 2017

Recently, the use of high-strength concrete is increasing due to the trend of constructing high-rise and long span structures. The benefit of using the high-strength concrete is that it increases the durability and strength while it reduces the cross-sectional area of the bridge deck slabs. Moreover, it offers more safety as these bridge deck slabs applying high-strength requires strict structural performance verification. In this study, the fatigue performance of the bridge deck slabs applying 80 MPa high-strength concrete was verified through various experiments. The experimental results showed that the specimens satisfy the conditions of flexural strength, punching shear strength, deflection and cracking. In conclusion, the bridge deck slabs designed by 80 MPa high-strength concrete are enough safe despite of its low thickness.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.2
• /
• pp.161-169
• /
• 2011

Two-way slabs reinforced with high-performance steels, which have several practical advantages of a reduction of congestion in heavily reinforced members, savings in the cost of labor and repair, the higher corrosion resistance, and a reduction of construction time, were constructed and tested. The influences of the flexural reinforcement ratio, concentrating the reinforcement in the immediate column region, and using steel fiber-reinforced concrete (SFRC) in the slab on the punching shear resistance and post-cracking stiffness were investigated, and compared with the punching shear test results of the slabs reinforced with conventional steels and GFRP bars. In addition, the strain distribution of flexural reinforcements and crack control were investigated, and the effective width calculating method for the average flexural reinforcement ratio was estimated. The use of high-performance steel reinforcement increased the punching shear strength of slabs, and decreased the amount of flexural reinforcements. The concentrating the top mat of flexural reinforcement increased the post-cracking stiffness, and showed better strain distribution and crack control. In addition, the use of SFRC showed beneficial effects on the punching shear strength and crack control. It was suggest that the effective width should be changed to larger than 2 times the slab thickness from the column faces.

• Journal of the Korean Society of Safety
• /
• v.31 no.3
• /
• pp.89-95
• /
• 2016

Lately, the high-strength concrete is often used to increase the lifespan of bridges. The benefits of using the high-strength concrete are that it increases the durability and strength. On the contrary, it reduces the cross-section of the bridges. This study conducted structural performance tests of the bridge deck slabs applying high-strength concrete. As result of the tests, specimens of bridge deck slabs were destroyed through punching shear. Moreover, the tests exposed that the high-strength concrete bridge deck slabs satisfy the flexural strength and the punching shear strength at ultimate limit state(ULS). Also, limiting deflection of the concrete fulfilled serviceability limit state(SLS) criteria. These results indicated that the bridge deck slabs designed by high-strength concrete were enough to secure the safety factor despite of its low thickness.

• Journal of the Korea Concrete Institute
• /
• v.22 no.4
• /
• pp.585-593
• /
• 2010

On the basis of the strain-based shear strength model developed in the previous study, a strength model was developed to predict the direct punching shear capacity and unbalanced moment-carrying capacity of interior and exterior slab-column connections. Since the connections are severely damaged by flexural cracking, punching shear was assumed to be resisted mainly by the compression zone of the slab critical section. Considering the interaction with the compressive normal stress developed by the flexural moment, the shear strength of the compression zone was derived on the basis of the material failure criteria of concrete subjected to multiple stresses. As a result, shear capacity of the critical section was defined according to the degree of flexural damage. Since the exterior slab-column connections have unsymmertical critical sections, the unbalanced moment-carrying capacity was defined according to the direction of unbalanced moment. The proposed strength model was applied to existing test specimens. The results showed that the proposed method predicted the strengths of the test specimens better than current design methods.

• Steel and Composite Structures
• /
• v.35 no.2
• /
• pp.279-294
• /
• 2020

Foundation of a building is damaged under service loads during construction. First visit shows that the foundation has been punched at the 6 column's foot region led to building rotation. Foundation shear punching occurring has made some stresses and deflections in construction. In this study, progressing of damage caused by foundation shear punching and inverse loading in order to resolve the building rotation has been evaluated in the foundation and frame of building by finite element modeling in ABAQUS software. The stress values of bars in punched regions of foundation has been deeply exceeded from steel yielding strength and experienced large displacement based on software's results. On the other hand, the values of created stresses in the frame are not too big to make serious damage. In the beams and columns of ground floor, some partial cracks has been occurred and in other floors, the values of stresses are in the elastic zone of materials. Finally, by inverse loading to the frame, the horizontal displacement of floors has been resolved and the values of stresses in frame has been significantly reduced.

• Journal of Korean Society of Steel Construction
• /
• v.18 no.4
• /
• pp.491-502
• /
• 2006

This paper summarizes full-scale test results on CFT column-to- flat plate connections has gained wide acceptance subjected to gravity loading. CFT construction has gained wide acceptance in a relatively short time in domestic building construction practice due to its various structural and construction advantages. However, efficient details for CFT column to flat plate connections have not been proposed yet. Based on the strategies that maximize economical field construction, several connecting schemes were proposed and tested. Test results showed strength and connection stiffness exceeding those of R/C flat p late counterparts. A semi-analytical procedure is presented to model the behavior of CFT column-to-flat plate connections. The five parameters to model elastic to post-punching catenary action range are calibrated based on the limited test data of t to progressive collapse prevention design is also illustrated.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.5
• /
• pp.182-189
• /
• 2021

VPS(Void Plywood Slab System, VPS) has optimized the shape of the hollow material. In addition, it has a function to prevent the floating of the hollow material and the separation due to the working load. In this study, the punching shear capacity of flat plate was performed using Void Plywood Slab System with form work panel proposed in the previous study. As a result of the test, the strength of the VSPS specimen in which the hollow material was placed beyond 2.0 times the column width from the loading point was reduced by 9.4% compared to the reference specimen. However, the strength value was about 1.57 times higher than the design value suggested by KBC 2016. It was found that there was no change in stiffness compared to the reference specimen until shear failure occurred in the VSPS specimen in which the hollow material was placed. It can be seen that this experiment is being destroyed by shear as the flexural reinforcing bars are sufficiently reinforced.

• Journal of the Korea Concrete Institute
• /
• v.21 no.3
• /
• pp.319-326
• /
• 2009

Two parallel wide flange built-up beams are widely used as struts in resisting lateral earth pressure because of the effectiveness in structure and construction. In a certain structural system, the reinforced concrete columns are to be placed at the intersection where two perpendicular beams cross each other, the square part of the joint being filled with concrete. In the punching shear mechanism of the beam-column joint, the radial deformation caused due to shear cracking will be constrained by the spring action of the squarely encompassed beam flanges. As a result, the punching shear strength of the joint concrete can be expected to be increased. To verify this phenomenon experiments have been performed for various constraining elements and distances between columns and constraints. Test results are compared with the approximation analysis formula which has been proposed in this study, based on the code formula. The results calculated by the proposed equation show comparatively close agreement with the punching shear strength detected from the test.