• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.677-686
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• 2005

The allowable bearing capacity of a pile, the most important factor in stability estimation, is determined by applying safety factor to the ultimate load or yield load. There are several but contradictory methods available in current design codes to estimate the allowable bearing capacity and the safety factor. This paper analyzes load-settlement curves obtained from 19 static load tests measured from 11 sites. At all tests, the load is applied until apparent failure is observed. The validity of the ultimate and yield load estimation method and load caculated from the settlement criterion is investigated through comparison with the measured data. In addition, a new procedure to estimate allowable load and safety factor is proposed. Additional data from field static load tests, such as those incorporated in this study, are needed to more reliably apply the proposed method in design practice.

• 한국지반공학회논문집
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• 제37권11호
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• pp.7-22
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• 2021

본 연구에서는 현장타설말뚝에서 실시된 양방향말뚝재하시험 자료에 대하여 역해석을 실시하였다. 그리고 실트질 점토, 실트질 모래, 모래질 실트, 모래질 자갈, 풍화암, 연암의 다양한 선단지반에 지지된 대구경 현장타설 말뚝에 대하여 수치해석을 실시하여 지지력을 분석하였다. 지지력 분석은 P-S 방법, Davisson 방법, 25.4mm 허용침하량을 이용하여 산정하였다. 3가지 방법으로 분석한 최소 허용지지력은 19.64MN ~ 24.96MN으로 나타났다. 이때, 선단지지력은 두부재하하중의 2% ~ 12%를 분담하였으며, 주면마찰력은 두부재하하중의 88% ~ 98%를 분담하였다. 선단 지반의 강도가 클수록 허용지지력이 증가하는 것으로 나타났다. 그러나 최대 허용지지력과 최소 허용지지력의 차이는 5.32MN로 선단 지반종류에 따른 허용지지력의 증가는 27%에 불과하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.173-182
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• 2000

To find axial and lateral responses of impact-driven H piles in embankment(SM), the H piles are instrumented with electric strain gages, dynamic load test is performed during driving, and then the damage of strain gages is checked simultaneously. Axially and laterally static load tests are performed on the same piles after one to nine days as well. Then load-settlement behavior is measured. Furthermore, to find the set-up effect in H pile, No. 4, 16, 26, and R6 piles are restriked about 1, 2, and 14 days after driving. As results, ram height and pile capacity obtained from impact driving control method become 80cm and 210.3∼242.3ton, respectively. At 15 days after driving, allowable bearing capacity by CAPWAP analysis, which 2.5 of the factor of safety is applied for ultimate bearing capacity, increases 10.8%. Ultimate bearing capacity obtained from axially static load test is 306∼338ton. This capacity is 68.5∼75.7% at yield force of pile material and is 4∼4.5 times of design load. Allowable bearing capacity using 2 of the factor of safety is 153∼169ton. Initial stiffness response of the pile is 27.5ton/mm. As the lateral load increases, the horizontal load-settlement behaves linearly to which the lateral load reaches up to 17ton. This reason is filled with sand in the cavity formed between flange and web during pile driving. As the result of reading with electric strain gages, flange material of pile is yielded at 19ton in horizontal load. Thus allowable load of this pile material is 9.5ton when the factor of safety is 2.0. Allowable lateral displacement of this pile corresponding to this load is 23∼36mm in embankment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.475-480
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• 1997

It is common to assum identical allowable safety factors in static strength, defined by mean stress and in fatigue, defined by stress amplitude. Under the load with asymmetrical cycles the safety factor is not the same. In this paper, with the consideration of unequal allowable safety factors a general method for estimating fatigue reliability of a machine element under a combined state of stress is derived based on the theory proposed by Prof. Kececioglu and normal distribution. The calculation of fatigue reliability for limited life is discussed with example.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(3)
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• pp.193-198
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• 1996

The effect of dynamic strain aging (DSA) on the leak-before-break (LBB) analysis was estimated through the evaluation of leakage-size-crack and flaw stability in SA106 Gr.C piping steel. Also. the results were represented as a form of "LBB allowable load window". In the DSA temperature region. the leakage-size-crack length was smaller than that at other temperatures and it increased with increasing tensile strain rate. In the results of flaw stability analysis. the lowest instability load appeared at the temperature corresponding to minimum J- R curve which was caused by DSA. The instability load near the plant operating temperature depended on the loading rate of J-R data. and decreased with increasing tensile strain rate. These are due to the strain hardening characteristic and strain rate sensitivity of DSA. In the "LBB allowable load window". LBB allowable region was the narrowest at the temperature and loading conditions where DSA occurs.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.333-338
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• 2007

The concept of "Allowable Load Set (ALS)" introduced by the author allows an easy understanding of load and strength characteristics of a structure in relation to its integrity under uncertainties. Two criteria of safety are introduced: A relative safety index denotes the distance to the boundary of the ALS and a normalized safety index is a distance in terms of functional value. They have been utilized in several examples, including multi-body mechanical systems such as a biomechanical system. Both formulations amount to robust designs in the sense that designs most insensitive to uncertainties are obtained in the context of newly defined safety indices, without using any input probability information.

• 한국농공학회지
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• 제39권2호
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• pp.124-133
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• 1997

Pile load test is good for estimating pile bearing capacity, but using this method is limited by time and cost required. Dynamic and static method is more convenient and economical, but confidence of estimated value by dynamic and static method are lower than that of pile load test. After being compared pile bearing capacity data obtained from pile load test with those of other two methods, the results from this study were summarised as follows. For allowable bearing capacity values greater than 175t per pile, bearing capacity acquired from static method was higher than that acquired from pile load test, whereas bearing capacity acquired from pile load test was higher than that acquired from static method for values under 175 per pile. It was that variance of bearing capacity was large when bearing capacity obtained by dynamic method was higher than 250t. Also bearing capacity based on dynamic method was higher than that based on pile load test. Allowable bearing capacity get from dynamic method suggested that carefull precautions are necessary in application for allowable bearing capacity values higher than 2S0ton per pile.

• 복합신소재구조학회 논문집
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• 제4권1호
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• pp.33-39
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• 2013

Structural insulated panels, structurally performed panels consisting of a plastic insulation bonded between two structural panel facings, are one of emerging products with a viewpoint of its energy and construction efficiencies. These components are applicable to fabricated wood structures. In Korea, there are few technical documents regulated structural performance and engineering criteria in domestic market. This study was conducted to identify fundamental performance of both monotonic load and quasi static cyclic load for SIPs in shear wall application. Static test results showed that maximum load was 44.3kN, allowable shear load was 6.1kN/m, shear stiffness was 1.23 M N/m, and ductility ratio was 3.6. Cyclic test was conducted by two kinds of specimens : single panel and double panels. Cyclic test results, which were equivalent to static test results, showed that maximum load was 45.42kN, allowable shear load was 6.3kN/m. Furthermore the accumulated energy dissipation capability for double panels was as 2.3 times as that for single panel. From performance of structural tests, it was recommended that the allowable shear load for panels was at least 6.1kN/m.

• Steel and Composite Structures
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• 제14권6호
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• pp.587-604
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• 2013

There are few technical documents regulated structural performance and engineering criteria in domestic market for Structural insulated panels in Korea. This paper was focused to identify fundamental performance under monotonic loading and cyclic loading for SIPs in shear wall application. Load-displacement responses of total twelve test specimens were recorded based on shear stiffness, strength, ultimate load and displacement. Finally energy dissipation of each specimen was analyzed respectively. Monotonic test results showed that ultimate load was 44.3 kN, allowable shear load was 6.1 kN/m, shear stiffness was 1.2 MN/m, and ductility ratio was 3.6. Cyclic test was conducted by two kinds of specimens: single panel and double panels. Cyclic loading results, which were equivalent to monotonic loading results, showed that ultimate load was 45.4 kN, allowable shear load was 6.3 kN/m. Furthermore the accumulated energy dissipation capability for double panels was as 2.3 times as that for single panel. Based on results of structural performance test, it was recommended that the allowable shear load for panels should be 6.1 kN/m at least.

• Tribology and Lubricants
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• 제36권2호
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• pp.82-87
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• 2020

In thrust bearings, the thrust collar and bearing surface need to be parallel to each other to ensure that all pads share the same load. In rotating machines, the shaft system cannot achieve perfect alignment. Misalignment of the thrust collar results in some pads supporting a higher load than others and excessive loads being placed on some pads. Consequently, high loads and high temperatures may occur in the bearing. Thus, in this study, we aim to analytically evaluate the performance of a misaligned non-equalizing direct lubricated tilting pad thrust bearing. We define the oil film thickness of the misaligned thrust bearing using the Byrant angle. Additionally, we calculate the pressure distribution and temperature distribution of the thrust bearing using the generalized Reynolds equation and energy equation. The design limit of the thrust bearing is defined by the load and temperature. Therefore, we evaluate the allowable misalignment angle as the limit of the maximum load and temperature. The analysis results demonstrate that an increase in the speed and load corresponds to a smaller allowable misalignment angle. However, as this is not the same for all thrust bearings, evaluating the allowable misalignment angle at each thrust bearing is essential.