• Journal of the Korean Geotechnical Society
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• v.35 no.6
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• pp.17-26
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• 2019

In this study, the statistical characteristics of the resistance bias factors were analyzed using a high-quality field load test database, and the total resistance bias factors were estimated considering the soil uncertainty and construction errors for the application of the limit state design of aggregate pier foundation. The MLR model by Bong and Kim (2017), which has a higher prediction performance than the previous models was used for estimating the resistance bias factors, and its suitability was evaluated. The chi-square goodness of fit test was performed to estimate the probability distribution of the resistance bias factors, and the normal distribution was found to be most suitable. The total variability in the nominal resistance was estimated including the uncertainty of undrained shear strength and construction errors that can occur during the aggregate pier construction. Finally, the probability distribution of the total resistance bias factors is shown to follow a log-normal distribution. The parameters of the probability distribution according to the coefficient of variation of total resistance bias factors were estimated by Monte Carlo simulation, and their regression equations were proposed for simple application.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.65-74
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• 1985

This study is an experimental analysis for local scour of the riverbed at pier. The basic equation with dimensionless elements(Pier Reynolds Number, Dimensionless Turbulence Intensity) is derived through dimensional analysis. After testing the goodness of fit of data, the coefficients are determined by multiple regression analysis. In the region where the value of the attack angle is near 20 degrees, there exists a transition region where the slope of equation with Pier Reynolds Number changes from positive to negative and that of equation with Dimensionless Turbulence Intensity changes from negative to positive adversely. As a result of testing the equation suggested on this study by using the data of the Institute of National Construction, it is found that the scour depth and width at pier can be predicted approximately.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.4
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• pp.65-81
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• 2013

Urban sprawl has been the limits of traffic accommodate and the supply road. Thus, Light Rail Transit(LRT) has been proposed as the best alternative. Owing to landscape damage from construction of LRT, landscape planning should be considered seriously in the urban planning step. This paper therefore seeks to determine landscape improvement direction of LRT pier. First, the methods in this study shared landscape improvement direction type of LRT pier through previous studies such as planting of surface(30%, 60%, 90% planting of surface), graphic(character, commercial advertising, symbol), and surface treatment type(exposed concrete, white painting, pattern dies). Next, respondent evaluated 3D simulated landscape image accordingly shared types by preference and landscape adjectives using in streetscape evaluation. As a result, visual preference was the highest in planting type of surface and the lowest in the surface treatment type. Covering 60%(4.48) in planting type of surface was the highest. Because it is similar to the golden ratio considering the visual principle, we will need to take advantage through the result of this paper. Also, most landscape improvement direction which satisfied with significant level showed a positive effect from landscape improvement. Comprehensively based on these results, it suggests desirable landscape improvement direction of LRT pier in the city for solution of landscape inhibition problem.

• Steel and Composite Structures
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• v.49 no.1
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• pp.81-89
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• 2023

A simplified calculation method of natural vibration characteristics of high-speed railway multi-span bridge-longitudinal ballastless track system is proposed. The rail, track slab, base slab, main beam, bearing, pier, cap and pile foundation are taken into account, and the multi-span longitudinal ballastless track-beam-bearing-pier-cap-pile foundation integrated model (MBTIM) is established. The energy equation of each component of the MBTIM based on Timoshenko beam theory is constructed. Using the improved Fourier series, and the Rayleigh-Ritz method and Hamilton principle are combined to obtain the extremum of the total energy function. The simplified calculation formula of the natural vibration frequency of the MBTIM under the influence of vertical and longitudinal vibration is derived and verified by numerical methods. The influence law of the natural vibration frequency of the MBTIM is analyzed considering and not considering the participation of each component of the MBTIM, the damage of the track interlayer component and the stiffness change of each layer component. The results show that the error between the calculation results of the formula and the numerical method in this paper is less than 3%, which verifies the correctness of the method in this paper. The high-order frequency of the MBTIM is significantly affected considering the track, bridge pier, pile soil and pile cap, while considering the influence of pile cap on the low-order and high-order frequency of the MBTIM is large. The influence of component damage such as void beneath slab, mortar debonding and fastener failure on each order frequency of the MBTIM is basically the same, and the influence of component damage less than 10m on the first fourteen order frequency of the MBTIM is small. The bending stiffness of track slab and rail has no obvious influence on the natural frequency of the MBTIM, and the bending stiffness of main beam has influence on the natural frequency of the MBTIM. The bending stiffness of pier and base slab only has obvious influence on the high-order frequency of the MBTIM. The natural vibration characteristics of the MBTIM play an important guiding role in the safety analysis of high-speed train running, the damage detection of track-bridge structure and the seismic design of railway bridge.

• Explosives and Blasting
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• v.21 no.3
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• pp.23-35
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• 2003

An analytical diffusion model for flood routing with backwater effects and lateral flows is developed. The basic diffusion equation is linearized about an average depth of (H + h), and is solved using the boundary conditons which take into account the effects of backwater and lateral flows. Scouring phenomenon around pier which affects on the support function of pier and the stabilization if river bed is a complex problem depending on flow properties and river bed state as well as pier geometry. therefore, there is no uniting theory at present which would enable the designer to estimate, with confidence, the depth of scour at bridge piers. The various methods used in erosion control are collectively called upstream engineering, HEC-RAS Model, underwater blasting. They consist of reforestation, check-dam construction, planting of burned-over areas, contour plowing and regulation of crop and grazing practices. Also included are measures for proper treatment of high embankments and cuts and stabilization of streambanks by planting or by revetment construction. One phase of reforestation that may be applied near a reservoir is planting of vegetation screens. Such screens, planted on the flats adjacent to the normal stream channel at the head of a reservoir, reduce the velocity of silt-laden storm inflows that inundate these areas. This stilling action causes extensive deposition to occur before the silt reaches the main cavity of the reservoir.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.221-224
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• 2008

Recently various types of prefabricated pier has been developed. In this paper, prefabricated composite columns with core steel elements embedded in concrete were proposed, which has no prestressing. Based on the previous research on composite columns with low steel ratio, the column were designed. A simple bolt connection detail between a footing and a pier element were also suggested. In order to investigate the seismic performance of the composite columns, several tests on concrete encased composite columns, which are prefabricated, were performed. Quasi-static tests were carried out and their performance was evaluated and compared with the results from the tests on CIP composite piers. In the case of precast piers, the end part of the pier needs to be carefully reinforced and related recommendations on details were derived.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.121-124
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• 2008

Fast construction of bridge substructures is a new trend of bridge design. A precast pier system with bonded prestressing bars was proposed. In this paper, quasi-static tests on precast prestressed piers were conducted to evaluate the seismic behavior of the precast piers with bonded prestressing bars. In order to strengthen the shear strength of the joints between column segments, steel tubes filled with mortar were used. Displacement ductility and energy dissipation capacity of the precast piers were evaluated. The suggested precast pier system showed better seismic performance than the required ductility. Based on the research results, an example bridge pier for light-railway lines was designed and design considerations were discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.237-240
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• 2008

Today, some bridges or highways are becoming superannuated in Korea. Also, in this section, rehabilitation, replacement and expansion are necessary to increasing traffic volumes these days. Bridge reconstruction is major problem because it has relation to civil application, economical loss and loss of vehicles made a detour while this work. Many precast components and methods of construction are developed for this issue. Many research of various precast components and new materials are being performed owing to apply to prefabrication bridges. The present paper represents experimental studies on the performance of precast CFFT pier model. Also, stay-in-place RC pier and stay-in-place CFFT pier are made an experiment on due to comparing test results. Hysteretic responses of all columns are obtained through the test. Compared with the displacement ductility factors, conclusions of seismic performances can be made.

• Journal of Korea Port Economic Association
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• v.25 no.1
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• pp.29-46
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• 2009

According to construction work of No. 2 Lotte world, the alternative pier is under construction in Dongsam-dong Yeongdo-gu to accommodate small boats. As a result of that, in order to procure route of small boats passage,0-2 Anchorage used to bunkering or waiting for berth should be reduced, 220m. It is expected that the risk of passage and congestion around the anchorage could be increased because of the traffic of small boat using the alternative pier. Therefore, it is needed to enlarge the O-2 Anchorage 250m toward to inner breakwater. According to result of analyzing traffic circumstance and weather condition of anchorage near the Busan inner fairway, and to procure of alternative anchorage in order to resolve the problem caused by reduction of O-2 Anchorage, no problems incurred. In conclusion, reduction & enlargement of area of new O-2 Anchorage is expected to resolving of congestion & reducing of risk of traffic at O-2 Anchorage, and to operating O-2 Anchorage, efficiently.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.10a
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• pp.135-139
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• 1991

The Seoul expressway is designed with prestressed concrete box girders. As a construction method, Precast Free Cantilever Method (P.F.C.M) is used which is introduced to Korea first time. Especially, the end spans in each bridge are designed to be constructed by cantilever method using temporary cantilever tendons. And pier and pierhead are prestressed vertically and horizontally.