• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.10a
• /
• pp.382-389
• /
• 2002

Recently, auger-drilled piling has been widely used in urban area to reduce the air pollution and noise. But this construction method that its basic theory was introduced from Japan may be changed depending on the each piling company and construction field condition. Therefore, the design code and management method for auger-drilled piling is not defined yet. Especially, the lack of research on the bearing capacity of auger-drilled piling leads to the absence of rational bearing capacity prediction equation. This paper presents the optimum design code and economical construction method of the auger-drilled piling by proposing the new bearing capacity prediction equation based on the site specific soil types and construction conditions. In this paper, existing bearing capacity prediction equations and current pile load tests were compared. And the end bearing capacity and skin friction characteristics were also analyzed by comparing the results of CAPWAP. From the results of analysis, a reliable bearing capacity prediction equation considered soil types is proposed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.8 s.179
• /
• pp.1940-1948
• /
• 2000

A design method for maximizing fatigue life of the deep groove ball bearing without enlarging mounting space is proposed by using a genetic algorithm. The use of gradient-based optimization methods for the design of the bearing is restricted because this design problem is characterized by the presence of discrete design variables such as the number of balls and standard ball diameter. Therefore, the design problem of rolling element bearings is a constrained discrete optimization problem. A genetic algorithm using real coding is used to efficiently find the optimum discrete design values. To effectively deal with the design constraints, a ranking method is suggested for constructing a fitness function in the genetic algorithm. Constrains for manufacturing are applied in optimization scheme. Results obtained for several 63 series deep groove ball bearings demonstrated the effectiveness of the proposed design methodology by showing that the average basic dynamic capacities of optimally designed bearings increased about 9-34% compared with the standard ones.

• Geomechanics and Engineering
• /
• v.17 no.3
• /
• pp.271-278
• /
• 2019

In recent years, the crack accidents of earth and rockfill dams occur frequently. It is urgent to study the tensile strength and tensile failure mechanism of the gravelly soil in the core for the anti-crack design of the actual high earth core rockfill dam. Based on the self-developed uniaxial tensile test device, a series of uniaxial tensile test was carried out on gravelly soil with different gravel content. The compaction test shows a good linear relationship between the optimum water content and gravel content, and the relation curve of optimum water content versus maximum dry density can be fitting by two times polynomial. For the gravelly soil under its optimum water content and maximum dry density, as the gravel content increased from 0% to 50%, the tensile strength of specimens decreased from 122.6 kPa to 49.8 kPa linearly. The peak tensile strain and ultimate tensile strain all decrease with the increase of the gravel content. From the analysis of fracture energy, it is proved that the tensile capacity of gravelly soil decreases slightly with the increasing gravel content. In the case that the sample under the maximum dry density and the water content higher than the optimum water content, the comprehensive tensile capacity of the sample is the strongest. The relevant test results can provide support for the anti-crack design of the high earth core rockfill dam.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1988.10a
• /
• pp.55-60
• /
• 1988

This paper concentrates on the development of simplified and effective algorithm for optimum reinforced concrete(RC) member design. After constructing the data base of predetermined RC sections which are arranged in the order of increasing resistant capacity. Then, the relationship between the section identification numbers and resistant capacities of sections is estabilished by regression and it can be used to obtain the initial solution(section) which satisfies the design constraints imposed. Assuming that there exists the optimum section near the initially selected one, the direct search is conducted to find the discrete optimum solution. The optimization of the entire structure is accomplished through the individual member optimization.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.03a
• /
• pp.379-386
• /
• 2001

Piled raft foundations are usually used to reduce total and differential settlements of superstructures. In the piled raft foundations, the raft is often on its own able to provide adequate bearing capacity and only few widely spaced piles are added to the foundation to keep settlements be1ow a certain limit. In this paper, experimental studies on the load sharing ratio between piles and raft are carried out. Also, for evaluating the application of optimum design technique using a genetic algorithm, optimal locations of files are compared with the results of laboratory model tests. from tile results of laboratory model tests, there are found that the load sharing ratio between files and raft is depended on the number of piles and stiffness of raft, and the optimal locations of piles became concentrated on the middle of rafts. From these results of laboratory model tests, the optimum technique using a genetic algorithm is acknowledged to the application in the piled raft.

• Earthquakes and Structures
• /
• v.23 no.2
• /
• pp.139-150
• /
• 2022

In most self-center braces, decreasing residual deformation is possible only by increasing pretension force, which results in lower energy dissipation capacity. On the other hand, increasing energy dissipation capacity means higher values of residual deformation. The goal of this research was to find the best design for a self-centering buckling restrained brace (SC-BRB) system by balancing self-centering capability and energy dissipation. Three, six, and nine-story structures were investigated using OpenSees software and the TCL programming language to achieve this goal. For each height, 62 different SC-BRBs were considered using different values for the pretension force of cables, the area of the buckling restrained brace (BRB) core plate, and the yield stress of the core plate. The residual deformation and dissipated energy of all the models were calculated using nonlinear analyses after cyclic loading was applied. The optimum design for each height was determined among all the models and was compared to the structure equipped with the usual BRB. The residual deformation of the framed buildings was significantly reduced, according to the findings. Also the reduction of the energy dissipation was acceptable. The optimum design of SC-BRB in 6-story building has the most reduction percent in residual deformation, it can reduce residual deformation of building 83% while causing only a 57% of reduction in dissipated energy. The greatest reduction in residual deformation versus dissipated energy reduction was for the optimum SC-BRB design of 9-story building, results indicated that it can reduce residual deformation of building 69% while causing only a 42% of reduction in dissipated energy.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2012.06a
• /
• pp.388-389
• /
• 2012

Current offshore wind power towers are made of steel. As the capacity of wind power increases, the tower structures become higher. Steel structures have buckling problem and their increased slenderness ratios make them weak against buckling and vibration. In this study, double skinned composite tubular (DSCT) offshore wind power tower was proposed and its optimum design method was suggested. Fiber reinforced polymer (FRP) and steel were considered as material of the tubes. And both materials satisfied the required capacity.

• Computers and Concrete
• /
• v.24 no.2
• /
• pp.117-123
• /
• 2019

Optimization is an important subject which is widely used in engineering problems. In this paper, an analytical method is developed for optimum design of reinforced concrete beams considering both flexural and shear effects. A closed-form formulation is derived for optimal height and rebar of beams. The total material cost of steel and concrete is considered as the objective function which is minimized during the optimization process. The ultimate flexural and shear capacities of the beam are considered as the main constraints. The ultimate limit state is considered for deriving the relations for flexural capacity of the beam. The design requirements are considered according to the item 9 of the Iranian National Building. Analytical formulas and some curves are proposed to be used for optimum design of RC beams. The proposed method can be used to perform the optimization of RC beams without the need of any prior knowledge in optimization. Also, the results of the studied numerical example show that the proposed method results in a better design comparing with the other methods.

• Korean Chemical Engineering Research
• /
• v.55 no.6
• /
• pp.745-753
• /
• 2017

In this study, a design strategy is proposed to restore the distorted urban water cycle to the natural water cycle through the LID facility. This is accomplished by determining the optimal LID facility design capacity through which flow duration curves remain the same before and after urban development. A part of the Noksan National Industrial Complex in Busan was selected as the study area and EPA SWMM was constructed to simulate long-term stormwater for various land use scenarios and LID facility design capacity. In the case that the study area was assumed to be a forest area or an agricultural area before urban development, it was found that it was necessary to allocate 7.3% or 5.5% of the impervious area to the area of the bio-retention in order for the flow duration curve to remain the same as before urban development. As a result of the sensitivity analysis of the bio-retention design capacity according to regional rainfall characteristics, the design capacity of 3.8~5.5% of impervious area is needed for the development of agriculture area. Therefore, it can be seen that the optimum capacity can be significantly different according to regional rainfall characteristics. On the other hand, as a result of analyzing the sensitivity of the design capacity according to the variation of the depth of each layer constituting the bio-retention and the size of contributing catchment area, the sensitivity of the optimal design capacity with respect to the design specifications of the bio-retention and the size of contributing catchment area was not significant.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.10a
• /
• pp.656-660
• /
• 2000

In general, the silo blender is composed of silo, blending cone and vane. This study is to develop the blending system for resin of industrial materials produced in the chemical plant By examining closely the How states at the six flow zones of different geometry in the blender due to the gravity of resin, it is possible to develop the silo blender by the optimum design through the sin and the capacity change.