• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.2
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• pp.129-136
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• 2005

The vehicle loading test under the strict traffic control is generally carried out as a present practice in an evaluation process of the bearing capacity of a bridge. The quasi-static load test is recently proposed to mitigate the traffic condition of test, and analyze the disturbed acceleration time-history data of free vibration due to the ambient traffic on the bridge by Fourier transform to calculate only the natural frequencies of the bridge. The calculated frequencies have some errors due to the analysis technique as well as the influence of ambient traffic loads, and in addition to it is cumbersome to obtain the free vibration data during a quasi-static load test. In this study, the wavelet transform technique using Morlet wavelet is used to analyze the acceleration data recorded during a quasi-static load test on a bridge and calculate the natural frequencies and the modal damping ratios of the bridge. The study results show that the wavelet transform technique is a reliable and reasonable method to analyze test data and obtain the natural frequencies and the modal damping ratios of a bridge regardless of the data types i.e. free or forced vibrations.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.11-20
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• 2015

An unbonded post-tensioned anchor using a 15.2 mm diameter 7-wire strand was developed based on finite element analysis and experimental testing. In order to evaluate its performance, static load tests and load transfer tests were conducted following KCI-PS101. The static load tests and additional strand tensile tests confirmed that the developed anchor had a capacity more than nominal tensile strength of a 7-wire strand without any damage or deterioration. According to the result of load transfer tests for many different reinforcing details, specimens with no additional reinforcing bars sustained at least 1.64 times the nominal tensile strength of the strand.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.192-199
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• 2000

The spot-welded automotive side member which has a hat-shaped section and a double hat shaped section has been tested on the axial static(10mm/min) and quasi-static(50mm/min) compressing load. The collapse characteristics of automotive sections have been reviews on shift on shape and in width of the spot-voiding on the flange. On the basis of the results of tests and reviews, the optimum energy absorption capacity of the structure has been studied.

• Journal of Korean Port Research
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• v.10 no.2
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• pp.69-90
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• 1996

This study is related to save the bearing capacity from using Meyerhof formula namely, static mechanics formula with the S.P.T(N value) of the soft ground and is to choose the soft ground improvement method by the using of total load for the proper method of the pile foundation and then to design the most suitable pile foundation to fit the actual circumstance. The purpose of this study is calculating the diameter of the pile foundation by static mechanics formula and introducing the optimum design condition from the result of the bearing capacity for using N value of the S.P.T obtained from the deep soft ground about the piles such as P.H.C pile, pipe and cast-in-place pile of big diameter, etc. As above-mentioned, it is considered that the use of P.H.C pile or pipe pile is advisable on the synthetical investigation and that the selection of cast-in-place pile method is desirable in terms of the constructive safety and durability.

• Tribology and Lubricants
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• v.20 no.5
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• pp.245-251
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• 2004

This paper presents the effects of the bump foil stiffness on the static and dynamic performance of the foil journal bearings. Reynolds equation is used for the static and dynamic performance analyses. To consider the deflection of top foil the top foil is modeled as a elastic beam and the bump foil is modeled as a spring. So in the static performance analysis the load capacity is compared to the various bump foil stiffness and in the dynamic performance analysis the trajectory of journal center is compared to the various bump foil stiffness.

• Computers and Concrete
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• v.12 no.4
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• pp.393-411
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• 2013

In the analysis and design of reinforced concrete frames beam-column joints are sometimes assumed as rigid. This simplifying assumption can be unsafe because it is likely to affect the distributions of internal forces and moments, reduce drift and increase the overall load-carrying capacity of the frame. This study is concerned with the relevance of shear deformation of beam-column joints, in particular of exterior ones, on the quasi-static behavior of regular reinforced concrete sway frames. The included parametric studies of a simple sub-frame model reveal that the quasi-static monotonic behavior of unbraced regular reinforced concrete frames is prone to be significantly affected by the deformation of beam-column joints.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.70-78
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• 2004

In order to increase the load carrying capacity of tubular structures, the joints of tubular members are usually reinforced with various reinforcement system. A stiffening method with internal ring stiffeners is effectively used for the steel tubular joint with a large diameter. In this study, the behavior of internally ring-stiffened tubular T-joints subjected to axial loading is assessed. For the parametric study, nonlinear finite element analyses are used to compute the static strength on non-stiffened and ring-stiffened T-joints. Based on the numerical results, an internal ring stiffener is found to be efficient in improving the static strength. The influence of geometric parameters has been determined, and the reinforcement effect are evaluated. Based on the FE results, regression analises are performed considering the practical size of ring stiffener. Finally strength estimation formulas for ring-stiffened tubular T-joints are proposed.

• KIEAE Journal
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• v.10 no.5
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• pp.151-157
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• 2010

This study is connected with evaluation of the progressive collapse resisting capacity for sustainable RC super tall building design. As the progressive collapse is not considered in current design codes in Korea, differences between linear static and dynamic analysis based on the GSA guidelines was analyzed for better evaluation, and the analysis model of flat plate system was determined. Finally, the progressive collapse resisting capacity was evaluated for structural system of super tall building. According to this study, the results by linear dynamic analysis were underestimated than the results by linear static analysis. Thus, the dynamic coefficient value of 2 provides conservative approach. The Effective Beam Width's model, currently used in field, is useful for the analysis about lateral force, but this model does not consider the effect of load redistribution by the slab. Hence, finite element analysis considering slab element will be needed for progressive collapse resisting capacity of the flat plate system. Finally, analysis model of 80-story building designed based on KBC(Korea Building Code) shows the weakness against progressive collapse because the DCR value is over 2. Thus, the countermeasure for alternative loading path such as installment of spandrel beam and reinforcements around slab is required to prevent the progressive collapse.

• Smart Structures and Systems
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• v.3 no.3
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• pp.281-298
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• 2007

The load carrying capacity of a bridge needs to be properly assessed to operate the bridge safely and maintain it efficiently. For the evaluation of load carrying capacity considering the current state of a bridge, static and quasi-static loading tests with weight-controlled heavy trucks have been conventionally utilized. In these tests, the deflection (or strain) of the structural members loaded by the controlled vehicles are measured and analyzed. Using the measured data, deflection (or strain) correction factor and impact correction factor are calculated. These correction factors are used in the enhancement of the load carrying capacity of a bridge, reflecting the real state of a bridge. However, full or partial control of the traffic during the tests and difficulties during the installment of displacement transducers or strain gauges may cause not only inconvenience to the traffic but also the increase of the logistics cost and time. To overcome these difficulties, an alternative method is proposed using an excited response part of full measured ambient acceleration data by ordinary traffic on a bridge without traffic control. Based on the modal properties extracted from the ambient vibration data, the initial finite element (FE) model of a bridge can be updated to represent the current real state of a bridge. Using the updated FE model, the deflection of a bridge akin to the real value can be easily obtained without measuring the real deflection. Impact factors are obtained from pseudo-deflection, which is obtained by double-integration of the acceleration data with removal of the linear components on the acceleration data. For validation, a series of tests were carried out on a steel plategirder bridge of an expressway in Korea in four different seasons, and the evaluated load carrying capacities of the bridge by the proposed method are compared with the result obtained by the conventional load test method.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.481-486
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• 1998

In this paper, elastic and inelastic behavior of exterior joint of moment-resisting R.C frame with non-seismic detail subjected to reversed cyclic lateral load such as earthquake excitations was investigated. 1/2-scals subassemblage exterior beam-column joint including slab was manufactured based on similitude law. Then, pseudo static test under the displacement control was performed. The results of 1)crack pattern and failure mode, 2)degradation stiffness and strength, energy dissipation capacity from load-displacement hysteresis curve, 3)strain of steel were analysed.