• Computers and Concrete
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• v.25 no.4
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• pp.355-367
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• 2020

This paper proposed a numerical investigation based on finite elements analysis (FEA) in order to study the punching shear behavior of reinforced concrete (RC) flat slabs using ABAQUS and SAP2000 programs. Firstly, the concrete and the steel reinforcements were modeled by hexahedral 3D solid and linear elements respectively, and the nonlinearity of the used materials was considered. In order to validate this model, experimental results considered in literature were compared with the proposed FE model. After validation, a parametric study was performed. The parameters include the slab thickness, the flexure reinforcement ratios and the axial membrane loads. Then, to reduce the time of FEA, a simplified modelling using 3D layered shell element and shear hinge concept was also induced. The effect of the footings settlement was studied using the proposed simplified nonlinear model as a case study. Results of numerical models showed that increase of the slab thickness by 185.7% enhanced the ultimate load by 439.1%, accompanied with a brittle punching failure. The punching failure occurred in one of the tested specimens when the tensile reinforcement ratio increased more than 0.65% and the punching capacity improved with increasing the horizontal flexural reinforcement; it decreased by 30% with the settlement of the outer footings.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.431-434
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• 2005

In the past decade, various experimental programmes were undertaken to address the lack of information on the interaction between steel coupling beams and reinforced concrete shear wall in a hybrid coupled shear wall system. In this paper, the seismic performance of steel coupling beam-wall connections in a hybrid coupled shear wall system is examined through results of an experimental research programme where three 2/3-scale specimens were tested under cyclic loading. The test variables included the reinforcement details that confer a ductile behaviour on the steel coupling beam-wall connection, i.e., the face bearing plates and the horizontal ties in the panel region of steel coupling beam-wall connections. Panel shear strength reflects enhancement achieved through mobilization of the reinforced concrete panel using face bearing plates and/or horizontal ties in the panel region of steel coupling beam-wall connections.

• Magazine of the Korea Concrete Institute
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• v.6 no.4
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• pp.161-168
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• 1994

Half-P.C. slab system is the composite structural system which utilizes precast concrete for lower portion and cast in situ concrete for upper portion slab. When the composite slab using Half P.C. slab is deformed by flexural moment, horizontal shear happened at the interface between Half P.C. slab and topping concrete. To resist horizontal shear strength a scratch method has tried. To determine ultimate interface shear strength, shear stress, and shear coefficient, high and normal strength concrete are used for topping concrete. Major variables are compressive strength of topping concrete with or without shear reinforcement, quantitative roughness of the P.C. :surface and tie or untie of the stud with welded deformed wire fabric in the P.C. member. The Icross sectional area on joints is 3,200 $cm^2$ in all specimens. Test results showed that shear stress increased, as the depth of the quantitative roughness increased. The horizontal shear strength could be resisted with safe by the quantitative roughness without shear tie. A shear coefficient determinant equation is proposed such that K = 0.025918 + 0.0068894$\cdot$R – 0.000182354${\cdot}R^2$

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.303-311
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• 1998

Ten reinforced concrete rigid frames and infilled shear wall frames were tested under both vertical and cyclic loadings. Experiments were carried out to evaluate the structural performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility etc. under load reversals. All the specimens were modeledin one-third scale size. Based on the test results reported in this study, the follwing conclusions can be made. For the rigid frame type and the fully rigid babel type shear wall specimens, the hysteresis diagrams indicate that the degradations of their strength were developed slowly beyond maximum carrying capacity. It was shown that when the hoop reinforcement ratio became higher, the energy dissipation capacity became larger and the failure mode became ductile. The specimens designed by the less hoop reinforcement for the fully rigid babel type shear wall, were mainly failed due to diagonal crack in comparison with the specimens designed by the larger hoop reinforcement ratio. Maximum horizontal resisting moment capacity of speciment designed by the fully rigid babel shear wall were increased by 5.47~7.95 times in comparison with the rigid frame type.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.04a
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• pp.75-80
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• 1991

Results of an experimental investigation of low-rise reinforced concrete shear walls with rectangular cross section under cyclic loads are discussed and evaluated. Two half scale models of test specimens with height to length ratio of 0.75 were experimented. The dimension of all walls is 1500mm wide $\times$ 950 mm high $\times$ 100 mm thick for all specimens and the section of all boundary at both ends is 100 mm $\times$ 200mm. Main variables are : horizontal shear reinforcement ratios and reinforcement details(including crossed diagonal shear reinforcements in SWR2 specimen) In SWR2 specimen, maximum strength and consequently dissipating energy index were 1.15~1.21 and 1.48 times greater than those of SWR1 specimen, respectively.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.683-691
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• 2013

Failure behaviour of deep beams is largely depend on shear span to effective depth ratio(a/d). For deep beams with $a/d{\leq}1.0$, the diagonal splitting of the web and local crushing of concrete near applied loads or supports is the most common failure mode. If the beam contains sufficient web reinforcement, area of local crushing will be increased while area of diagonal splitting is decreased. When web reinforcement above purpose, web should be reinforced both in the horizontal and vertical directions or be reinforced in perpendicular direction to diagonal cracks. For deep beams with 1.0${\leq}2.5$, the increment of shear strength by the horizontal web reinforcement are hardly expected unless amount of main bars very small that the main bars should be reached yielding state when shear failure occurs. In contrast, the vertical web reinforcement prevent the beam from being transferred to tied arch mechanism, and as a result th shear strength of beam increase. In this study, formulas based on upper bound theorem of plastic theory are proposed to predict the shear strength of reinforced concrete deep beams with $a/d{\leq}1.0$. Comparisons with other experiment results are performed, and good agreement between measured and predicted value by proposed formulas is obtained.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.591-602
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• 2015

In this paper, cyclic loading test was performed to evaluate the seismic performance of the steel coupling beam and RC shear wall. The test parameter was reinforcement detail of the shear wall. For the shear wall which was designed in accordance with the current design codes, a premature bearing failure occurred at the face of the wall. On the other hand, the bearing failure of walls was prevented due to the new type of reinforcement details. Test results indicated that the vertical reinforcements were more affected to the shear strength of the coupled shear wall than the horizontal reinforcement. Based on the failure mode, concrete stress distribution above and below flanges of the embedded steel beam was proposed. Assuming proposed concrete stress distribution, load resistance was predicted and it was agree well with test data.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.198-203
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• 1995

The objective of this study is to provide the information on the techniques of manufacturing and experiment in small scale modeling of precast concrete(P.C.)large panel structures. The adopted scale was 1/5th 4types of experiments were performed : material tests for model concrete and model reinforcement, compressive test of horizontal joint, shear test of vertical joint and cyclic static test of 2-story subassemblage structure. Based on the experimental results, the following conclusions are drawn: (1)Model concrete may have in general larger compressive strength than expected. (2) Model reinforcement can show less ductility if the annealing processes were performed without using vaccuum tube. (3) Failure modes of horizontal and vertical joints were almost same for both prototype and model. But the strength of model appears to be higher than required by similitude law. (4)Hysteretic behavior of 1/5 scale subassemblage model can be made quite similar to prototype's if the ductility of model reinforcement and compressive strength of model concrete could be representative of those of prototype.

• Journal of Korean Association for Spatial Structures
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• v.17 no.1
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• pp.59-67
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• 2017

In this study, load transfer tests based on KCI-PS101 were conducted to verify the performance of spiral anchorage zone reinforcement for banded post-tensioning (PT) monostrands. With results, the compressive strength of spiral reinforcement was increased by about 20% than that of specimens with two horizontal steel bars and 8% than that of U-shaped bars. Advanced spiral reinforcement for corner increases compressive strength and can resist the spalling forces or fall-out effect at the corner by shear. The ratio of maximum load to amount of steel of the spiral reinforcement is about twice than that of U-shaped reinforcement. With increase of compressive strength capacity and improvement of constructability, the spiral reinforcement is considered to have advantages of promoting the performance of PT anchorage zone compared to conventional methods.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.399-409
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• 2015

Recently, the use of composite construction method using precast (PC) and cast-in-place (CIP) concrete is increased in modular construction. For PC members, pre-tensioning is used to improve efficiency of the structural performance. However, current design codes do not clearly define shear strength of prestressed PC-CIP composite members. In this study, 22 specimens were tested to evaluate shear strength of prestressed composite members with vertical shear reinforcement. The test variables were the area ratio of high-strength (60 MPa) to low-strength concrete (24 MPa), prestressing force of strands, shear span-to-depth ratio(a/d), and vertical shear reinforcement ratio. The test results showed the prestressing force did not completely restrain diagonal cracking of non-prestressed concrete in the web. Thus, the effect of prestress force was not insignificant in the effect for monolithic beams. The vertical shear strength and horizontal shear strength of the composite beams were compared with the strength predictions of KCI design method.