• Journal of the Korean Society for Railway
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• v.16 no.5
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• pp.379-385
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• 2013

In this study, partial drilled shafts (Bottom Cast-in-place Concrete pile) were applied to the pilot test site to ensure the bearing capacity; we used the skin friction force in the IGM to analyze the feasibility of the application of IGM theory. The soil characteristics were analyzed in cohesive, non-smear, and smooth conditions for the application of the IGM theory via geotechnical investigation and measurement of the disturbance and surface roughness. Static load and load transfer tests were conducted to calculate the allowable bearing capacity and the skin friction force by depth. The skin friction force increased with increase in the depth and standard settlement, showing a very high correlation. In addition, because the unconfined strength ($q_u$), which is the most important parameter in the cohesive IGM, cannot be measured in a weathered granite area, the static load and load transfer test results and the N value were used to obtain $q_u$.

• 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 Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.9-16
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• 2006

The design practice of the lateral resisting system has been traditionally dependent on the experience and know-how of a structural engineer. And the method to reflect the evaluation results of building's capacity on design process doesn't exist. The proposal of a rational design of the lateral load resisting system is based on the available full capacity $(R_{ac})$ of a building and the minimum required capacity $(R_{code})$ suggested in the code. This study suggests thai nonlinear static analysis, which is the estimation of the lateral capacity with the pushover analysis, be included in the existing design procedure of the structure. After finishing the basic structural design, the lateral resisting capacity ol a building is estimated. At the phase of nonlinear static analysis, pushover analysis is peformed to define the fully yielded baseshear $(V_Y)$. When the design wind baseshear $(V_{wind})$ is bigger than the design seismic baseshear $(V_D)$, the value is checked to determine whether or not it is smaller than the $V_Y$. After confirming that it is smaller, the $R_{ac}$ of the structure is computed. If the $V_D$ is bigger at first, only the $R_{ac}$ is computed. When the value of the estimation shows remarkable differences with the $R_{code}$, repetition of the design modification is needed for those approximate to the $R_{code}$. Application of the proposed design procedure to 2-D steel braced RC buildings has proven to be efficient.

• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.111-129
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• 2007

The standard construction manual of the SDA(Separated Doughnut Auger) piling method was proposed so that the resisting capacity of the augered piles could work effectively. 405 dynamic pile load tests and 30 static pile load tests were performed for 265 test piles, which were installed by the SDA piling method in 33 sites in Korea. The results of the pile load tests showed that the end bearing capacity of the SDA augered piles depended on the property of various soil stratums and did not agree with ones estimated by the existing formula based on several standard design codes. On the basis of the pile load test results, four formulas were presented according to bearing stratums to estimate quantitatively the unit end bearing capacity of the SDA augered piles. The formulas for the unit end bearing capacity of piles on soils or weathered rocks were related to N-value given by SPT(Standard Penetration Test), while the unit end bearing capacity on bedrock was suggested to be more than 1500 $tf/m^2$. The presented formulas were compared with the existing formulas, which were presented by several standard design codes to design the augered piles. In order to use correctly the presented formulas, the quality of Standard Penetration Test should be controlled precisely. Also it is desirable to choose a pilot construction site, where both dynamic and static pile load tests are performed.

• Structural Engineering and Mechanics
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• v.78 no.5
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• pp.623-635
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• 2021

Previous studies have suggested the maximum experimental story shear force of beam-column joint frame does not reach its theoretical value due to beam-column joint failure when the column-to-beam moment capacity ratio was close to 1.0. It was also pointed out that under a certain amount of axial force, an axial collapse and a sudden decrease of lateral load-carrying capacity may occur at the joint. Although increasing joint transverse reinforcement could improve the lateral load-carrying capacity and axial load-carrying capacity of beam-column joint frame, the conditions considering varying axial force were still not well investigated. For this purpose, 7 full-scale specimens with no-axial force and 14 half-scale specimens with varying axial force are designed and subjected to static loading tests. Comparing the experimental results of the two types of specimens, it has indicated that introducing the varying axial force leads to a reduction of the required joint transverse reinforcement ratio which can avoid the beam-column joint failure. For specimens with varying axial force, to prevent beam-column joint failure and axial collapse, the lower limit of joint transverse reinforcement ratio is acquired when given a column-to-beam moment capacity ratio.

• Journal of the Korean GEO-environmental Society
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• v.14 no.11
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• pp.13-23
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• 2013

In the west coastal soft ground, the static and dynamic loading tests for PHC piles which were executed using light driving without injecting cement milk were carried out and the correlation was analyzed. Initial dynamic loading test used hydraulic hammer(ram weight 70kN) and final average penetration effect presented 3.0 to 8.0mm at 0.8m drop. Then final allowable bearing capacity using CAPWAP presented 776.4 to 1,053.6kN a pile. The static loading tests which were performed at the other piles loaded 200% of the design load dividing by eight phases. As the result, total settlement was 15.97 to 16.38mm and residual settlement was 4.48 to 5.38mm, but both yielding and ultimate load can't be estimated. Therefore, allowable bearing capacity was determined larger than 1,200kN a pile regarding maximum test load as yielding load. Thus, it showed that allowable bearing capacity of the dynamic loading test was larger than static loading test in 1.54 to 1.14 times.

• Earthquakes and Structures
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• v.22 no.2
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• pp.203-218
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• 2022

In this paper, quasi-static tests were carried out on three prefabricated reinforced concrete column-steel beam (RCS) sub-assemblages with floor slabs and one comparison specimen without floor slab. The effects of axial compression and floor slab on the seismic performance were studied, and finite element simulations were conducted using ABAQUS. The results showed that the failure of prefabricated RCS sub-assemblages with floor occurred as a joint beam and column failure mode, while failure of sub-assemblages without floor occurred due to beam plastic hinge formation. Compared to the prefabricated RCS sub-assemblages without floor slab, the overall stiffness of the sub-assemblages with floor slab was between 19.2% and 45.4% higher, and the maximum load bearing capacity increased by 26.8%. However, the equivalent viscosity coefficient was essentially unchanged. When the axial compression ratio increased from 0.24 to 0.36, the hysteretic loops of the sub-assemblages with floor became fuller, and the load bearing capacity, ductility, and energy dissipation capacity increased by 12.1%, 12.9% and 8.9%, respectively. Also, the initial stiffness increased by 10.2%, but the stiffness degradation accelerated. The proportion of column drift caused by beam end plastic bending and column end bending changed from 35% and 46% to 47% and 36%, respectively. Comparative finite element analyses indicated that the numerical simulation outcomes agreed well with the experimental results.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.145-150
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• 2002

Tubular joints having a large diameter in the offshore structure are reinforced using internal ring stiffener in order to increase the load carrying capacity. In this study, the static strengths of internally ring-stiffened tubular T-joints subjected to compressive brace loading are assessed. Nonlinear finite element analyses are used to compute the behavior of unstiffened and ring-stiffened T-joints. From the numerical results, internal ring stiffener is found to efficient in improving the ultimate capacity, and reinforcement effect are calculated. The influence of geometric parameters for members and ring is evaluated. Based on the FE results, regression analysis is performed considering practical sizes of ring stiffener, finally strength estimation formulae for ring-stiffened T-joints are proposed.

• Structural Engineering and Mechanics
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• v.33 no.6
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• pp.765-779
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• 2009

Quantitative condition assessment of structures has been traditionally using proof load test leading to an indication of the load-carrying capacity. Alternative approaches using ultrasonic, dynamics etc. are based on the unloaded state of the structure and anomalies may not be fully mobilized in the load resisting path and thus their effects are not fully included in the measured responses. This paper studies the effect of the load carried by a reinforced concrete beam on the assessment result of the crack damage. This assessment can only be performed with an approach based on static measurement. The crack damage is modelled as a crack zone over an area of high tensile stress of the member, and it is represented by a damage function for the simulation study. An existing nonlinear optimization algorithm is adopted. The identified damage extent from a selected high level load and a low load level are compared, and it is concluded that accurate assessment can only be obtained at a load level close to the one that creates the damage.

• The KSFM Journal of Fluid Machinery
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• v.20 no.2
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• pp.63-68
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• 2017

This paper predicts the rotordynamic force coefficients of tilting pad journal bearings (TPJBs) with ball-socket pivot and compares the predictions to the published test data obtained under load-between-pad (LBP) configuration. The present TPJB model considers the pivot stiffness calculated based on the Hertzian contact stress theory. Due to the compliance of the pivot, the predicted journal eccentricity agree well with the measured journal center trajectory for increasing static loads, while the early prediction without pivot model consideration underestimates it largely. The predicted pressure profile shows the significant pressure development even on the unloaded pads along the direction opposite to the loading direction. The predicted stiffness coefficients increase as the static load and the rotor speed increase. They agree excellently with test data from open literature. The predicted damping coefficients increase as the static load increases and the rotor speed decreases. The prediction underestimates the test data slightly. In general, the current predictive model including the pivot stiffness improves the accuracy of the rotordynamic performance predictions when compared to the previously published predictions.