• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.198-199
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• 2017

In this paper, the applicability of PHC piles to replace Myanmar local piles were evaluated. In Myanmar, based on the size of the building, foundation design and field applications are carried out using bored pile and square pile. As a result of the analysis, the application of PHC pile is more economical than conventional bored pile or square pile which was applied in the high rise (17-story) and middle story (12-story) buildings. However, in the low - rise (8-story) building, the application of the existing square piles was found to be more economical than PHC pile.

• Journal of the Korean Geotechnical Society
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• v.35 no.9
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• pp.15-28
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• 2019

Long-term allowable compressive Loads of PHC piles were analyzed based on qualification tests results by 17 small and medium PHC pile producing companies and product specifications by 6 major and 17 small and medium PHC pile producing companies. At the present stage, an average long-term allowable compressive load of PHC pile was designed at 70% level from current design data, and safety factor of 4.0 was applied to long-term allowable compressive loads of PHC pile despite of its excellent quality. Most quality standards of PHC pile are specified at KS F 4306. But compressive strength test method of spun concrete is specified at KS F 2454. As a result of analyzing quality test data supplied by each manufacturer, all quality test results showed higher performances than standard values. Therefore, it was considered that the capacity of PHC pile can be used up to the maximum allowable compressive load of PHC pile when PHC pile is designed.

• Journal of the Korean Geotechnical Society
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• v.35 no.9
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• pp.29-36
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• 2019

Axial compressive failure loads ($P_n$) of diameter 500 mm and diameter 600 mm A type PHC pile were calculated as 7.7 MN and 10.6 MN, respectively. In the static pile load tests, the maximum axial compressive loads of the above 2 kinds of A type pile were measured as 6.9 MN and 8.8 MN respectively, therefore these measured maximum loads were at the level of 90% and 83% of $P_n$ respectively. Long-term allowable axial compressive loads ($P_a$) of the above 2 kinds of A type pile were 1.7 MN and 2.3 MN respectively. From the bi-directional pile load test data on the prebored PHC piles, it was confirmed that the allowable axial compressive bearing resistance was estimated as 131% of the long-term allowable compressive load of the PHC pile and showed higher than the allowable bearing capacity calculated by the current design method. Therefore, it has been verified that the PHC pile can be used up to the maximum long-term allowable compressive load, and it is suggested that the ultimate pile capacity formula used in the current design for prebored PHC piles should be improved to accommodate the actual capacity.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.91-98
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• 2013

The pre-tensioned spun high strength concrete (PHC) pile has poor load carrying capacity in shear and flexure, while showing excellent axial load bearing capacity. The purpose of this study is to evaluate the flexural performance of the concrete-infilled composite PHC (ICP) pile which is the PHC pile reinforced with infilled concrete, transverse and longitudinal reinforcement for the improvement of shear and flexural load carrying capacity. The ICP pile specimen was designed to make allowable axial compression and bending moment higher load bearing capacity than those determined through the investigation of abutment design cases. The allowable axial compression and bending moment of the ICP pile was obtained using the program developed for calculating the axial compression - bending moment interaction. Then, ICP pile specimens were manufactured and flexural tests were performed. From the test results, it was found that the maximum bending moment of the ICP pile was approximately 45% higher than that of the PHC pile and the safety factor of ICP pile design was about 4.5 when the allowable bending moment was determined to be 25% of the flexural strength.

• Journal of the Korea Concrete Institute
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• v.29 no.3
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• pp.259-266
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• 2017

The purpose of this study was to contribute to the field application cost effectively and reasonably by developing the functional piles that reinforces shear force. CFP pile (Concrete Filled Pretensioned Spun High Strength Concrete Pile with Ring type Composite shear connectors) developed in this study increases the shear stress by placing composite shear connector and filling the concrete into hollow part of the pile. By placing the reinforcement (H13-8ea) and the reinforcement (H19-8ea) into hollow section inside of PHC piles, it also improves the shear strength due to increasing steel ratio. It reinforces shear strength effectively by dowel force that is generated by putting reinforcement (H13-8) into the holes of composite shear connectors for the composite behavior of filled concrete and PHC pile. The study was reviewed and compared the calculated result of the shear strength by limit state design method highway bridge design standards (2012) and experiment result of the shear strength by KS F 4306. We can design the shear strength reasonably as the safety ratio of 2.20, 2.15, 2.05 is shown comparing to design shear strength, according to design shear strength on each cross sections and the experiment results of the CFP pile.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.109-115
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• 2016

A demand of high bearing capacity of piles to resist heavy static loads has been increased. For this reason, the utilization of large diameter PHC piles including a range from 700 mm to 1,200 mm have been increased and applied to the construction sites in Korea recently. In this study, in order to increase the flexural strength capacity of the PHC pile, the large diameter composite PHC pile reinforced by in-filled concrete and reinforcement was developed and manufactured. All the specimens were tested under four-point bending setup and displacement control. From the strain behavior of transverse bar, it was found that the presence of transverse bar was effective against crack propagation and controlling crack width as well as prevented the web shear cracks. The flexural strength and mid-span deflection of LICPT specimens were increased by a maximum of 1.08 times and 1.19 times compared to the LICP specimens. This results indicated that the installed transverse bar is in an advantageous ductility performance of the PHC piles. A conventional layered sectional analysis for the pile specimens was performed to investigate the flexural strength according to the each used material. The calculated bending moment of conventional PHC pile and composite PHC pile, which was determined by P-M interaction curve, showed a safety factor 1.13 and 1.16 compared to the test results.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.53-63
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• 2013

Bored pre-cast piles using PHC piles is widely used in foundation of building structures constructed in urban areas because noise and vibration due to pile installation are low. However, since slime is formed at the base of borehole and the density of bearing stratum surrounding the base of borehole is decreased due to stress relaxation in drilling process of bored pre-cast pile method, the base load capacity of bored pre-cast piles is very low compared to the strength of bearing stratum. In this study, a new type of PHC pile, which short steel pipe with the same diameter as the PHC pile is attached to the pile tip, is developed to increase the base load capacity of bored pre-cast piles. In order to check the effect of the use of new PHC pile on the base load capacity of bored pre-cast piles, field pile load tests are performed for bored pre-cast piles using the new and existing PHC piles. Results of the pile load tests show that the new PHC pile gives higher base load capacity to bored pre-cast piles than the existing PHC pile, since the tip of new PHC pile is penetrated to undisturbed bearing stratum passing through the slime at the base of borehole and the loosened bearing stratum under the slime by pile driving using light hammer.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.06a
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• pp.1-13
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• 1992

본 연구에서는 일반 PC 말뚝과는 달리 제작시 실리카(silica) 재료를 사용하고 중기양생후 고온,고압의 추가양생(autoclave curing)을 실시 함으로써 말뚝자체의 강성을 높인 PHC 말뚝의 항타 시공성을 컴퓨터 프로그램을 이용하여 파악하였다. 일반적으로 임의의 지반조건, 항타장비에 따른 컴퓨터 프로그램의 실행결과는 PHC 말뚝이 PC 말뚝에 비해 항타장비에 의해서 발휘되는 타격에너지에 대해 보다 큰 저항력을 가지므로 설계지지력을 크게 얻을 수 있으며 항타장비의 선정에 있어서도 보다 큰 효율을 지닌 장비의 선정이 가능하여 경제적인 항타작업을 수행하는데 유리함을 보였다. 이와같은 결과를 실제 현장에서의 말뚝 항타시공을 실시한 후 항타기록 및 재하시험 결과와 비교검토 하였는데 본 연구결과와 재하시험 결과가 잘 일치함을 보였다.

• Land and Housing Review
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• v.3 no.3
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• pp.279-286
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• 2012

The limit states design method is replacing the allowable stress design method worldwide, e.g. the design code of ISO and various construction codes of Korea are adopting the reliability based limit state method. This paper proposed LRFD design value which is one of limit states design method for the PHC bored pile used as building foundation. This paper analysed 81 load test results and the bearing design(Meyerhof method & SPT-CPT conversion method), and proposed LRFD value for each design reliability Index 2.33 and 3.0 for PHC bored pile. LRFD value of PHC bored pile represents 0.36~0.44 for Meyerhof method and 0.24~0.31 for SPT-CPT conversion method according to the deign reliability index.

• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.5-16
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• 2016

New PHC piles, where short steel pipes are attached to the pile toe, are developed to increase the base load capacity of bored pre-cast piles embedded in weathered rock. In this study, new bored pre-cast piles using the new PHC piles are installed at 7 test sites with different soil conditions, and static and dynamic pile load tests are performed to investigate quantitative characteristics on the base load capacity of new bored pre-cast piles. In addition, based on the static pile load test results, a new empirical equation for estimating the base load capacity of new bored pre-cast piles is proposed. A comparison between predicted and measured base load capacities shows that the proposed empirical equation produces conservative predictions for the new bored pre-cast piles. However, the existing design criterion significantly underestimates the base load capacity of new bored pre-cast piles.