• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.41-49
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• 2006

Through the 1982 Urahawa-ohi and the 1995 Kobe earthquakes, a number of bridge columns were observed to develop a flexural-shear failure due to the bond slip as a consequence of premature termination of the column longitudinal reinforcement. Because the seismic behavior of RC bridge piers is largely dependent on the performance of the plastic hinge legion of RC bridge piers, it is desirable that the seismic capacity of RC bridge pier is to evaluate as a curvature ductility. The provision for the lap splice of longitudinal steel was not specified in KHBDS(Korea Highway Bridge Design Specification) before the implementation of 1992 seismic design code, but the lap splice of not more than 50%, longitudinal reinforcement was newly allowed in the 2005 version of the KHBDS. The objective of this research is to investigate the distribution and ductility of the curvature of RC bridge column with the lap splice of longitudinal reinforcement in the plastic hinge legion. Six (6) specimens were made in 600 mm diameter with an aspect ratio of 2.5 or 3.5. These piers were cyclically subjected to the quasi-static loads with the uniform axial load of $P=0.1f_{ck}A_g$. According to the slip failure of longitudinal steels of the lap spliced specimen by cyclic loads, the curvatures of the lower and upper parts of the lap spliced region were bigger and smaller than the corresponding paris of the specimen without a lap splice, respectively. Therefore, the damage of the lap spliced test column was concentrated almost on the lower part of the lap spliced region, that appeared io be failed in flexure.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.535-546
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• 2010

Recently, the probability of collision accident between vehicles or vessels and infrastructures are increasing at alarming rate. Particularly, collision impact load can be detrimental to sub-structures such as piers and columns. The damaged pier from an impact load of a vehicle or a vessel can lead to member damages, which make the member more vulnerable to impact load due to other accidents which. In extreme case, may cause structural collapse. Therefore, in this study, the vehicle impact load on concrete compression member was considered to assess the quantitative design resistance capacity to improve, the existing design method and to setup the new damage assessment method. The case study was carried out using the LS-DYNA, an explicit finite element analysis program. The parameters for the case study were cross-section variation of pier, impact load angle, permanent axial load and axial load ratio, concrete strength, longitudinal and lateral rebar ratios, and slenderness ratio. Using the analysis results, the performance based resistance capacity evaluation method for impact load using satisfaction curve was developed using Bayesian probabilistic method, which can be applied to reinforced concrete column design for impact loads.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.343-358
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• 2008

Piles of a bridge pier are connected with a column through a pile cap(footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. This difference causes a change of the design method. Connection methods between pile heads and the pile cap are divided into two groups ; rigid connections and hinge connections. KHBDC(Korea Highway Bridge Design Code) has specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However some specifications prescribe that conservative results through investigations for both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which have very good quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) are unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the very large diameter drilled shaft and the pile cap for Incheon Bridge which will the longest bridge in Korea were investigated through the full modeling for rigid connection conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.102-111
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• 2022

The aim of this study is to assess the seismic performance of octagonal hollow cross section reinforced concrete bridge pier, and to investigate the effect of longitudinal reinforcement ratios on the failure behavior. Four octagonal hollow section RC bridge columns of small scale model were tested under a quasi-static cyclically reversed horizontal load with constant axial load. The volumetric ratio of transverse spiral hoop of all specimens was maintained constant(0.206%), the ratios of longitudinal reinforcement were varied(2.36 ~ 4.71%). Failure behavior and seismic performance were investigated. Three specimens with the exception of lap spliced specimen showed flexure-shear failure at final stage. The test results with the exception of lap spliced specimen showed that the displacement ductility factor and accumulated energy dissipation decreased in inverse proportion to the ratio of longitudinal steel.

• Journal of the Korean Geotechnical Society
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• v.25 no.4
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• pp.69-75
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• 2009

The load distribution and deformation of pile-bent structures are investigated using a numerical study. A numerical analysis that takes into account the effects of varying cross-sectional area was performed for different pier diameters, loading steps, and soil conditions. Through the comparison study, it is shown that the location of maximum bending moment is almost the same per each loading step, regardless of varying cross-sections. However, the member force (i.e., stress of pile material) has the largest value at the ground surface when the cross-section is changed. Based on the results obtained, it is found that the location of maximum member force influences highly the behavior of pile-bent structure with varying cross-sections for repair works.

• Journal of the Korean Geotechnical Society
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• v.24 no.7
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• pp.61-73
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• 2008

Piles of a bridge pier are connected with the column through the pile cap (footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. Connection methods between pile heads and the pile cap are divided into two groups : rigid connections and hinge connections. Domestic design code has been specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However, some specifications prescribe that conservative results through investigations of both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which has high-quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) is unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the large diameter drilled shaft and the pile cap for Incheon Bridge which will be the longest bridge of Korea were investigated through the full modeling for rigid connection conditions.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.77-88
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• 2006

In this study, the lateral behavior of Pile-Bent structures subjected to lateral loading was evaluated by a load-transfer approach. An analytical method based on the Beam-Column model and nonlinear load transfer curve method was proposed to consider material non-linearity (elastic and yielding) and $P-{\Delta}$ effect. Special attention was given to the lateral deflection of Pile-Bent structures depending on different soil properties, lateral load, slenderness ratio based on pier length and reinforcing effect of casing. From the results of the parametric study, it is shown that the increase of lateral displacement in a pile is much less favorable for an inelastic analysis than for an elastic analysis. It is found that for inelastic analysis, the maximum bending moment is located within a depth approximately 3.5D(D: pile diameter) below ground surface, but within 1.5D when $P-{\Delta}$ effect is considered. It is also found that the magnitude and distribution of the lateral deflections and bending moments on a pile are highly influenced by the inelastic analysis and $P-{\Delta}$ effect, let alone soil properties around an embedded pile.