• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.6
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• pp.351-360
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• 2016

In regions of low-to-moderate seismicity, various types of lap splices are used for longitudinal reinforcement of columns at the plastic hinge zones. The seismic performance of such lap spliced columns, such as strength, deformation capacity, and energy dissipation, is affected by material strengths, longitudinal re-bar size, confinement of hoops, lap splice location, and lap splice length. In the present study, cyclic loading tests were performed for columns using three types of lap splices (bottom offset bar splice, top offset bar splice, and splice without offset bend). Lap splice length($40d_b$ and $50d_b$) was also considered as test parameters. Ties with 90-degree end hooks were provided in the lap splice length. The test results showed that strength, deformation capacity, and energy dissipation of columns significantly differed depending on the details and the length of lap splices. The bottom offset bar splice showed high ductility and energy dissipation but low strength; on the other hand, the top offset bar splice and the splice without offset bend showed high strength but moderate ductility and energy dissipation.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.286-289
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• 2006

Headed bars have used to the anchoring of the tension or compression longitudinal bars and of the shear reinforcing bars. Recently, lap splices of headed bars are attempted to the joints of precast concrete members and to the connections between old and new concrete members. Previous Michael's experimental research showed that confinement details had an effect on the lap splice performances of headed bars. In this study, the lap splice performances of headed bars(D25) with lap length and confinement details are evaluated through the experimental works. Four specimens, of which variables were the lap length of headed bar and the type of confine details, were tested for the performance evaluation on lap splice. Test results show that the lap length confinement reinforcement improve the performance of lap splice.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.62-71
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• 2015

KCI 2012 and ACI318-11 contains development length provisions for the use of headed deformed bars in tension and does not allow their tension lap splices. In ACI318-11, the confinement factor, such as transverse reinforcement factor, is not used to calculate the development length of headed bars. The purpose of this experimental study is to evaluate the effect of confinement details to the lap splice performance of headed deformed reinforcing bars in grade SD400 and SD500. The confinement details are stirrups and tie-down bars in lap zone. Test results showed that specimens with only stirrups had the brittle failure and could not increase lap strengths, and that specimens with composite confinements by stirrups and tie-down bars had the flexural strengths over than nominal flexural strengths. Stirrups with tie-down bars can have an effect on improvement in lap splice of headed bars in grade SD400 and SD500.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.211-219
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• 2002

This study is performed to investigate the behavior of multi-column piers and to evaluate the seismic performance. In this study, 3 types of scale model piers with 2-column are designed and tested by quasi-static load in both longitudinal and transverse directions. Each type of model consisting of 2 specimens has different reinforcement details in the lap splice of longitudinal bars and amount of transverse reinforcements. This paper reports that the ductility of the model in transverse direction is rather higher than in longitudinal direction because of formation of several plastic hinges and that the ultimate displacement and the energy absorbtion capacity are enhanced by using continuous longitudinal bars instead of lap-splice ones. And it is confirmed that relatively large amount of ductility can be achieved by providing sufficient lap-splice length and transverse reinforcements with end hook even if longitudinal bars are lap spliced in the base of pier.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.247-255
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• 2022

In this paper, a bending test was conducted on beams with two lap splice details when the effective depth of tensile high strength headed bars overlapped is the same and different. Through bending test, the lap splice performance of the high-strength headed bars was evaluated, and the applicability of the KDS-2021 design formula was evaluated. In the LS specimens with lap splice details where the high strength bars had the same effective depth, all specimens with 1.3 times or more of the development length of the KDS-2021 equation and 1 times or more of the ACI318-19 had the flexural failure mode after the ductile behavior to ensure sufficient lap splice performance. For specimens with details of lap joints between headed bars with different effective depth, when lap splice length is calculated by the KDS-2021 formula, the flexural stress may be transmitted so that the flexural strength at the cross section with the large effective depth and the cross section with the small effective depth becomes similar.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.335-340
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• 2000

The influence of lap splice of longitudinal bars in the plastic hinge zone on the nonlinear behavior characteristics of RC piers has been investigated through the scale model tests. The seismic performance of bridge piers with lap splice is found to be insufficient due to the premature bond failure. On the other hand it is confirmed that the preventing lap splice in the plastic hinge zone enhance the seismic performance considerably even without the seismic details of transverse reinforcements. Bases on these experimental results new seismic detailing concept appropriate to moderate seismicity region has been proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.131-142
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• 2021

For old piers constructed when seismic design code had not been developed, lap splices usually exist in plastic hinge region. Corrosion of rebars causes decreasement in cross-sectional area of rebar and deterioration of lap-splice behaviour, thereby reducing the seismic performance of the old piers. In this research, according to these characteristics of old piers, test specimens are designed and manufactured considering rebar corrosion, lap splice, seismic design details, and seismic reinforcement. These effects are investigated through experiments. As a result of these experiment, rebar corrosion as well as lap splice reduces displacement ductility. When seismic design details or steel-plate reinforcement are applied, sufficient displacement ductility is expressed. For non-seismically designed specimens, loosening of the lap splice of transverse rebars caused buckling of longitudinal rebars and crushing of core concrete in plastic hinge region . For seismically designed specimen, area-reducing and untying of transverse rebars due to corrosion of rebars caused buckling of longitudinal rebars and crushing of core concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.873-878
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• 2002

This study is performed to investigate the behavior of multi-column piers and to evaluate the seismic performance. In this study, 3 types of scale model piers with 2-column are designed and tested by quasi-static load in both longitudinal and transverse directions. Each type of model consisting of 2 specimens has different reinforcement details in the lap splice of longitudinal bars and amount of transverse reinforcements. This paper reports that relatively large amount of ductility can be achieved by providing sufficient lap-splice length and transverse reinforcements with end hook even if longitudinal bars are lap spliced in the base of pier. But because multi-column piers have small longitudinal stiffness, careful consideration is needed in case of multi-span continuous bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.339-342
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• 2003

The bridge columns with lap-splice reinforcements in earthquake suffered a brittle bond-slip failure due to deterioration of the lap-spliced longitudinal reinforcements without developing its flexural capacity or ductility. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP wrapping. The retrofitted columns using FRP wrapping showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the circumferential confinement effect of existing circular bridge pier strengthened with FRP wrapping for poor lap-splice details. The effects on the confinement of FRP wrapping, such as gap lengths between footing and FRP, fiber orientations, and thicknesses of FRP, were investigated by quasi-static experiments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.262-269
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• 2021

This paper conducts an evaluation of the structural performance of the lap splice detail of SD700 headed bar experiment for developing an RC beam with different depths joint details. The experiment variable is lap splice length, yield strength, and end anchorage of main reinforcements. For all specimens, a headed bar was applied to the main reinforcement of the beam with low depth (B2), and the beam with high depth (B1) was applied to the main reinforcement with two splice methods: straight headed bar and 90° hooked-headed bar. The experimental results were that specimens of applying SD500 and SD600 had the results of flexural fracture at the lap splice location, which maximum load was similar. For specimens of appling SD500, the 90° hooked-headed bar of B1, suppressed horizontal cracks in the lap splice section compared to the straight headed bar. Specimens of applying an SD 700 headed bar had the results of brittle anchorage failure. In addition, maximum load was increased with the lap splice length increasing. For specimens of applying SD700 headed bar, test for test maximum load/theoretical load for test development length/design development length were estimated to be 1.30~1.48 for the ACI 318-19 equation, and 1.14~1.30 for the KDS-2021 equation. Thus, ACI 318-19 equation had conservatively greater safety factors as estimated development lengththened.