• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.683-690
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• 2008

Steel-concrete composite columns are popular for superstructures of bridges, and the outside steel attached to the shaft increases the shaft resistance due to confining concrete. In this study, lateral resistance of steel-concrete composite drilled shafts was evaluated quantitatively based on numerical analysis when steel casings are used as structural elements like composite columns. Ultimate lateral resistance of composite drilled shafts with various diameters was numerically calculated through 3D finite element analysis. For that, elasto-plastic model with perfectly plasticity is involved to capture the ultimate load. A commercial FEM program, MIDAS-GTS, is used in this study. Real field conditions of the West Coast, Korea were considered to set up the ground conditions and pile lengths required for this parametric studies. Detailed characteristics of the stress and displacement distributions are evaluated for better understanding the mechanisms of the composite shaft behavior.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1195-1205
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• 2008

Composite piles have been used in ground conditions where conventional piles are unsuitable or uneconomical. They may consist of a combination of timber and concrete pile in Europe. One method of doing this was to drive a steel tube to just below water level, and a concrete pile was lowered down it and driven to the required level where corrosion was susceptible in U.K. Recently, a fiber reinforced polymer (FRP) composite pile was developed to use in many marine locations for piers and waterfront buildings in the USA(Hoy, 1995; Phair, 1997). A steel composite (SC) pile reinforced concrete spun pile with steel tube was also proposed and used for the foundation acting a high lateral earthquake load. Composite piles have been developed and researched to increase lateral resistance or to prevent corrosion in marine structures. In paper, the composite pile consisting of the steel upper portion and the concrete lower portion is proposed and are carried out several tests to confirm the capacity of the pile such as lateral load test, dynamic load tests and bending test. It is noted that the composite pile would be a economical pile being capable of increasing lateral resistance.

• Geotechnical Engineering
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• v.3 no.3
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• pp.21-30
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• 1987

Some methods are presented to estimate the ultimate lateral resistance of single active piles subjected to lateral loads above the ground surface, considering the lateral soil reaction, the pile length and the fixity condition of a pile head. The lateral soil reaction acting on a single active pile embedded in soil due to pile movement can be estimated by use of a theoretical equation which is derived by considering especially the plastic state of ground surrounding the pile and the pile- section shape. The piles are named short or long depending upon the relative magnitude of the induced bending moment to the yielding moment. As for the fixity condition of a pile head, the free head and the unrotated head are considered. Comparison with other experimental results gives that the calculated ultimate lateral resistance obtained by the author's theory is closer to experimental results than the one obtained by Brom's theory.

• Earthquakes and Structures
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• v.26 no.6
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• pp.489-499
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• 2024

Infill masonry walls are vulnerable to lateral loads, including seismic, wind, and concentrated push loads. Various strengthening metal fittings have been proposed to improve lateral load resistance, particularly against seismic loads. This study introduces the use of post-compressed wedges as a novel reinforcement method for infill masonry walls to enhance lateral load resistance. The resistance of the infill masonry wall against lateral-concentrated push loads was assessed using an out-of-plane push-over test on specimens sized 2,300×2,410×190 mm³. The presence or absence of wedges and wedge spacing were set as variables. The push-over test results showed that both the unreinforced specimen and the specimen reinforced with 300 mm spaced wedges toppled, while the specimen reinforced with 100 mm spaced wedges remained upright. Peak loads were measured to be 0.74, 29.77, and 5.88 kN for unreinforced specimens and specimens reinforced with 100 mm and 300 mm spaced wedges, respectively. Notably, a tighter reinforcement spacing yielded a similar strength, as expected, which was attributed to the increased friction force between the masonry wall and steel frame. The W-series specimens exhibited a trend comparable to that of the displacement ductility ratio. Overall, the findings validate that post-compressed wedges improve the out-of-plane strength of infill masonry walls.

• Journal of the Korean Geosynthetics Society
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• v.21 no.2
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• pp.49-56
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• 2022

This study conducted to obtain the lateral resistance of a wind power foundation reinforced with piles through an model experiment. In particular, the lateral resistance of the foundation was compared with the existing gravity-type wind power foundation by integrating the pile, the wind power generator foundation, and the rocky ground. In addition, changes in the lateral resistance and bending moment of the pile were analyzed by embeded depths of the pile. As a result, it was found that the lateral resistance increased with the depth of embedment of the piles. In particular, the pile's resistance increase ratio was 2.11 times greater in the case where the pile embedded up to the rock layer than the case where the pile was embedded into the riprap. It was found that the location of the maximum bending moment occurred at the interface between the wind turbine foundation and the riprap layer when the pile embeded to the rock layer. Through this, as the lateral resistance of the wind power foundation reinforced with piles is greater than that of the existing gravity-type wind power foundation, it is understood that it can be a more advantageous construction method in terms of safety.

• Journal of the Korean Geotechnical Society
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• v.28 no.8
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• pp.31-41
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• 2012

Pile foundation for transmission tower constructed in weak ground can cause the damage of the tower due to the different settlement between the foundations. In Japan and USA, connected-pile foundations whose 4 foundations are connected each other by beams were used for transmission tower (TEPCO 1988, IEEE 2001). Resistance increasing factors for connected-pile foundation signify increasing amount of resistance due to the effect of connected-pile material. In this study, we performed model lateral load tests of connected-pile foundations for transmission tower and found the resistance increasing factors for connected-pile foundation. The tests were performed in silty clay, and the resistance increasing factors were founded in various conditions that lateral load directions and height, the stiffness of beams in the connected-pile foundations were changed. The resistance increasing factors from our research were presented as a function of normal lateral loading height and normal stiffness of the connected-pile material. The resistances which were estimated from the resistance increasing factors were similar to measured values.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.71-77
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• 2008

In this study, CPT-based methodology for estimating the ultimate lateral resistance, $p_u$, is proposed and verified for lateral loaded piles in sandy soil. Preexistent methods estimating the ultimate lateral resistance, $p_u$, and the ultimate lateral capacity, $H_u$, of pile have been based on the vertical effective stress, relative density, and the coefficient of lateral earth pressure. Similarly, cone resistance $q_c$ in pure sandy soil is expressed by those essential factors. As correlation between $p_u$ and $q_c$ are normalized with average effective stress ${\sigma}_m$, estimation methodology for the lateral loaded pile of $p_u$ in sandy soil is proposed. The method is verified by calibration chamber test results in pure sand. The standard derivation of estimated $p_u$ is 0.279, and COV (Coefficient Of Variation) of estimated $p_u$ is 0.272. These results showed that the estimated pus by the method are analogous with the measured $p_us$ in calibration chamber test.

• Journal of the Korean Geotechnical Society
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• v.34 no.6
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• pp.5-16
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• 2018

In this study, the large scale laboratory model tests were executed to investigate the lateral resistance characteristics of $2{\times}2$ group pile under lateral loads according to the array method and installation angle of piles. The effect on the behavior of $2{\times}2$ group pile was also investigated through model tests varying the pile diameter and length, distance to pile top from the ground surface, center-to-center (CTC) length and surcharge etc. From these test results, it was found that the lateral resistance of $2{\times}2$ group pile of which piles were constructed slantly in both directions was greater than that of group pile of which piles were constructed vertically. And as a result of parameter tests on the lateral resistance of $2{\times}2$ group pile, it was found that the most important parameter was the pile length. As the embedment depth ratio (L/D) increased to 36.5 from 26.5, the lateral resistance increased 3~4 times or more. But the center-to-center (CTC) length, distance to pile top from the ground surface and surcharge did not affect much on the lateral resistance of group pile.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.553-556
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• 2004

This paper is to investigate the spalling and fire endurance of high performance RC column member with PP fiber and lateral confinement of metal lath and non fire resistance removal type form. According to test results, combination of PP fiber and metal lath as well as use fire resistance non removal type form had favorable fire resistance by discharging internal vapour pressure and lateral confining. After fire endurance test, compressive strength decreased markedly caused by internal expansion pressure and crack. Residual strength of plain concrete was decreased to $22\%$. The use of PP fiber and lateral confinement of metal lath and non removal type form enhanced the residual strength above $40\%$. Especially, the combination of $0.1\%$ of PP fiber and lateral confinement with the level of 2.3T exhibited more than $51\%$ of residual strength. Therefore, to improve fire endurance and spalling resistance, the combination of $0.1\%$ of PP fiber and metal lath with 2.3T can be the proper measure.

• Journal of the Korean Geotechnical Society
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• v.33 no.9
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• pp.49-60
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• 2017

The purpose of this study is to investigate the behavior of a single batter pile with repeated lateral loading through model tests. Repeated loads were applied in one direction and two directions, and lateral resistance and bending moment were analyzed by varying the relative density of the ground. As a result, lateral resistance and maximum bending moment were increased in the order of Out batter, Plumb, and In batter when one-way and two-way dynamic lateral loads were applied. The depth at the maximum bending moment was more deeper with the loading. The moments at bottom layer were decreased in the order of Out batter, Plumb, and In batter but upper moments were increased with the same order. Also, various bottom and upper moments were small when the two-way dynamic lateral load was applied compared to one-way lateral load.