• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.50-53
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• 2006

An experimental investigation on the behavior of reinforced concrete coupling beams is presented. The test variables are the span-to-depth ratio, the ratio of flexural reinforcement and the ratio of shear rebar. The distribution of arch action and truss action which compose the mechanism of shear resistance is discussed. This study proposes the deformation model for reinforced concrete coupling beams considering the bond slip of flexural reinforcement. The yielding of flexural reinforcements determines yielding states and the ultimate states of reinforced concrete coupling beam are defined as the ultimate compressive strain of struts and the degradation of compressive strength due to principal tensile strain of struts. It is expected that this model can be applied to displacement-based design methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.349-352
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• 2004

In this study, a strut-and-tie models for the coupling beam based on deformations are presented. To design shear-dominated R/C coupling beams, it is important to consider shear strength deterioration with required deformations. This study proposes the method of estimating shear strength of the reinforced concrete coupling beams. The proposed method determines the strain states from target displacements based on the nonlinear truss analysis. The estimated horizontal strain of beam is then used in calculating the strength of the diagonal strut with compatibility conditions. The deterioration of shear strength of the coupling beam depends on the strength degradation of struts due to plastic deformations.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.639-642
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• 2004

Lately outmoded and functionally obsolete buildings are often remodelled and restored. When existing reinforced concrete(RC) apartments are remodelled, one of main reasons of the remodelling is to expand dwelling space. The experimental or theoretical research on plane expansion of RC apartments is quite scare. In this research, 9 RC slabs connected by hinged joints were tested. The test results indicated that the shear strength of the RC test slabs having various types of dowel bars was about twice that calculated by the ACI 318-02 code.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.118-126
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• 2011

The objective of this paper is to study the structural behavior of Composite Basement Wall (CBW) according to shear span-to-depth ratio through an experiment and predict the nonlinear behavior of CBW by using ADINA program widely has been being used for FE analysis. Especially, this study focuses on the part of CBW in which the Reinforced Concrete (RC) is under compression stress; At the region of CBW around each floor, RC part stresses by compressive force when lateral press by soil acts on the wall. The contact condition between RC wall and steel (H-Pile) including stud connector is main factor in the analysis since it governs overall structural behavior. In order to understand the structural behavior of CBW whose RC part is under compressive stress, an experimental work and finite element analysis were performed. Main parameter in the test is shear span-to-depth ratio. For simplicity in analysis, reinforcements were not modeled as a seperated element but idealized as smeared to concrete. All elements were modeled to have bi-linear relation of material properties. Three type of contact conditions such as All Generate Option (AGO), Same Element Group Option with Tie(SEGO-T) and Same Element Group Option with Not tie(SEGO-NT) were considered in the analysis. For each analysis, the stress flow and concentration were reviewed and analysis result was compared to test one. From the test result, CBW represented ductile behavior by contribution of steel member even if it had short shear span-to-depth ration which is close to "1". The global composite behavior of CBW whose concrete wall was under compressive stress could be predicted by using contact element in ADINA program. Especially, the modeling by using AGO and SEGO-T showed more close relation on comparing with test result.

• Journal of Korean Society of Steel Construction
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• v.15 no.5 s.66
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• pp.519-529
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• 2003

In recent years, the use of cold-formed steel roof truss has been increased in the steel houses and high-rise apartments. The design of the roof truss anchor connections has been based on the experience and decision of designers. In this paper, the structural behavior of anchor connections based on experimental and decision is described. In the tests, truss members and connection members were jointed directly with self-drilling screw fasteners and the simple shaped connection member with excellent workability and structural capacity was used to connect roof truss and sub-structure. The connecting method was selected according to the construction material of sub-structure: chemical anchor for reinforced concrete structure and welding or DX-Pin for steel structures. The pull-out tests of various type anchor connection were executed to obtain the strength and the stiffness and the result have been compared with AISI(1996) and AlSC(1989) specifications, Simple formulas for the shear strength of screw connections have been propose and compared with tests.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.231-237
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• 2008

This study was performed to evaluate joint behavior of prestressed concrete(PSC)-steel mixed girders through the flexural test of 14 beams according to embedded length, amount of reinforcing steel, stud arrangement, and prestressing force. All test beams were failed by turns of desertion of reinforcing steel, stud, and steel plate. From test results, prestressing force was more effective on performance of connection than stud arrangement and reinforcing steel. And the spacing of stud is also more effective than embedding length. This paper also presented 3D nonlinear analysis considering the slip of composite section as well as the static load tests of PSC-steel mixed girders. According to the slip modulus, the nonlinear analysis showed that the behavior of hybrid girders could be divided into three parts as full-composite, partial-composite and non-composite. However, the experimental results showed that the PSC-steel hybrid girders with shear connectors took the part of partial composite action in ultimate load stage. In addition, it was founded that stud shear connectors and welded reinforcements were contributed to improve the ultimate strength of hybrid girders for about 20%.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.737-744
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• 2012

Hysteretic steel damper has been applied mainly to steel buildings. However, the usage in RC buildings is rapidly increasing recently. In order to apply the steel hysteretic damper in RC buildings, supporting elements of the damper should have sufficient strength and stiffness suitable for transferring damper forces to beams and walls. But due to the inevitable damage in reinforced concrete elements due to cracking, identification of the load transfer mechanism from damper to supporting element and hysteretic characteristics of the supporting element are extremely important in evaluating the damper behavior. Experiments were carried out on connection details between RC walls and supporting elements of the steel plate typed damper such as EaSy damper. The test results showed that fracture patterns of all specimens were almost identical except in the crack number and pattern associated with shear loading condition. Among the specimens, HD-3 shoed a well distributed cracks patterns along with good performance with respect to energy dissipation capacity, stiffness deterioration, and strength degradation.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.99-106
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• 2001

The main objective of this study is to develop a continuity of double tee slab with two modified dap-ends to solve the problems of excessive moment, slab depth, deflection, and joint cracking in the original simply supported double tee slab systems. The modified joint is produced in a combination with two slabs with modified dap and one rectangular beam. The modified joint can be justified as following different merits. The span capacity for a design load is increased, while the deflection of the slab is decreased due to the decrease of positive moment at the center span of the slab. The joint cracking between slab and beam, which occur frequently in the original slab systems of double tee will be reduced. No more additional form work is needed to cast topping concrete for continuity. Three point loading tests are performed on the specimens with a variable of an amount of main longitudinal reinforcement to evaluate flexural and shear behavior. Following conclusions are obtained from the experimental investigation. The continuity of double tee slab effectively is provided by placing longitudinal steel reinforcement in the topping concrete over the connection, and generally leads to an increase in span capacity of double tee slabs with reduced deflection. It is more effective to control the initial cracking at the connection than that of some simply supported double tee slab systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.521-529
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• 2017

In this study, analyzed the effective width of concrete unfilled composite steel grid deck which has different shear connector details from that of composite bridge. The effective width of concrete unfilled composite steel grid deck according to effective width calculation method, load size and main bearing bar spacing-span ratio was evaluated. As a result of analysis, it is analyzed that the effective width is calculated to be nearly equal to the actual effective width by idealizing the stress shape as a trapezoidal shape. In addition, shear hole penetration reinforcing bars applied to increase the shear strength is shown to increase the effective width. From the results of the analysis of the effective width according to main bearing bar spacing-span ratio, proposes the correction factor that can calculate the effective width ratio of the unfilled steel composite steel grid deck.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.55-63
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• 2015

Prefabrication technologies are making bridge construction safer and less disruptive to the environment and traveling public, making bridge designs more constructible and, improving the quality and durability by shifting site work to a more controllable environment. Modular bridge substructures with concrete-filled steel tube (CFT) piers and composite pier caps were suggested to realize accelerated bridge construction. The precast segmental pier cap consists of a composite pier table and precast prestressed segments on the table. The pier table has embedded steel section to mitigate stress concentration at the connection by small tubes. Each bridge pier has four or six CFT columns which connect to the pier cap. Shear strength of the pier cap was obtained by extending vertical reinforcing bars from the table to the precast segment. Transverse prestressing was introduced to control tensile stresses by service loadings. Structural performance of the proposed modular system was evaluated by static tests. Design requirements of the composite pier cap were satisfied by continuous reinforcing bars and prestressing tendons. Standardized modular substructures can be effectively utilized for the fast replacement or construction of bridges.