• Journal of the Korean Society of Industry Convergence
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• v.7 no.2
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• pp.181-186
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• 2004

This study presents a optimization of structure, in which constraints contain the conditions of stress and serviceability, while the sequential linear programming method (SLP) is used as a rational approach. The optimum design results contained on the limit state constraints are compared with those obtained by the only stress and ministry of construction enacted standard plans. A simple slab bridge is analysed numerically for illustration of the structural optimization. It may be asserted that serviceability constraints is very important to a structure design.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.129-136
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• 2005

The deterministic analysis method has generally used to evaluate the slope stability and it evaluates the slope stability with decision value that is a representative value of design variables. However, one of disadvantages in the deterministic approach is there is not able to consider the uncertainty of soil strength properties, even though it is the biggest influential parameter of the slope stability. On the other hand, the limit state design(LSD) can take a consideration of uncertainties and computes both the reliability index and the probability of failure. LSD method is capable of overcoming the disadvantages of deterministic method and evaluating the slope stability more reliably. In this study, both the mean value and standard deviation of the internal land's representative soil strength properties applied to process the LSD method. The major purpose of this study is to gauge the general applicability of the limit state design in soil slope and to weigh the comparative validity of the proposed partial safety factor. In order to reach the aim of this study, the partial safety factor and resistance factor which totally satisfied the slope's overall safety factor were calculated by the load and resistance safety factor design (LRFD).

• Structural Engineering and Mechanics
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• v.42 no.2
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• pp.175-189
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• 2012

This paper presents an algorithm for structural reliability with the response surface method. For this aim, an approach with three stages is proposed named as improved response surface method. In the algorithm, firstly, a quadratic approximate function is formed and design point is determined with First Order Reliability Method. Secondly, a point close to the exact limit state function is searched using the design point. Lastly, vector projected method is used to generate the sample points and Second Order Reliability Method is performed to obtain reliability index and probability of failure. Five numerical examples are selected to illustrate the proposed algorithm. The limit state functions of three examples (cantilever beam, highly nonlinear limit state function and dynamic response of an oscillator) are defined explicitly and the others (frame and truss structures) are defined implicitly. ANSYS finite element program is utilized to obtain the response of the structures which are needed in the reliability analysis of implicit limit state functions. The results (reliability index, probability of failure and limit state function evaluations) obtained from the improved response surface are compared with those of Monte Carlo Simulation, First Order Reliability Method, Second Order Reliability Method and Classical Response Surface Method. According to the results, proposed algorithm gives better results for both reliability index and limit state function evaluations.

• Structural Engineering and Mechanics
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• v.71 no.2
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• pp.165-173
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• 2019

This paper investigates the probability of failure of reinforced concrete beams for limit state of collapse for flexure and shear. The influence of randomness of the variables on the failure probability is also examined. The Indian standard code for plain and reinforced concrete IS456:2000 is used for the design of beams. Probabilistic models are developed for flexure and shear according to IS456:2000. The loads considered acting on the beam are live load and dead load only. Random variables associated with the limit state equation such as grade of concrete, grade of steel, live load and dead load are identified. Probability of failure is evaluated based on the limit state equation using First Order Reliability Method (FORM). Importance of the random variables on the limit state equations are observed and the variables are accordingly reduced. The effect of the reduced parameters is checked on the probability of failure. The results show the role of each parameter on the design of beam. Thus, the Indian standard guidelines for plain and reinforced concrete IS456:2000 is investigated with the probabilistic and risk-based analysis and design for a simple beam. The results obtained are also compared with the literature and accordingly some suggestions are made.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.2
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• pp.149-154
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• 2012

While the Earthquake Resistant Design Part of Korean Roadway Bridge Design Code provides design procedures for the No Collapse Requirement, requirements for the Serviceability Limit State are not clearly provided. The basic design method to meet the No Collapse Requirement is the spectrum analysis method using response modification factors and the Serviceability Limit State is determined by both the importance factor and the response modification factor applied in the design procedure. The importance factor can be simply applied according to the bridge importance category, however, in moderate/low seismic regions the application of the response modification factor may bring different result according to design conditions. In this study, for a typical bridge in the moderate/low seismic regions, determination procedures for the Serviceability Limit State are reviewed by carrying out earthquake resistant design and supplementary provisions for the Earthquake Resistant Design Part are identified based on the study results.

• Steel and Composite Structures
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• v.5 no.2_3
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• pp.159-168
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• 2005

Four design codes/regulations for steel structures in Japan are briefly reviewed. Some of them employ the limit state design concept while the others are still based on the allowable stress design concept. The process for revision is now in action. The directions in the development of structural design codes are also reported herein. It is noted that a current trend in this development is to employ the performance-based design concept that has been successfully implemented in some seismic design codes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.171-180
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• 2007

Reliability analysis of prestressed steel and concrete(PSSC) girders is conducted for deflection, stress and moment strength limit state. PSSC girder has strong advantages in terms of construction cost and vertical clearance for the span length of over 40 meters. In this paper, example PSSC girders with different span lengths, section dimensions and design stress levels are designed and analyzed to calculate the midspan deflection, stress and the section moment strength. Deflection limit state, stress limit state and strength limit state functions are assumed and the reliability indexes are obtained by Monte-Carlo simulation and Rackwitz-Fiessler procedure. The results show that the reliability of PSSC girder for deflection limit state is appropriately higher than the stress limit state and the reliability for moment strength is significantly conservative.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.375-382
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• 2000

This paper briefly summarizes the basic concepts and main characteristics of seismic design of New Zealand Standards(NZS) with regard to reinforced concrete(RC) structures. NZS used the concept of the capacity design and the limit state design to satisfy the requirements of serviceability and safety. Plastic mechanisms and details with respect to the limit state of safety are briefly presented in this paper. The understanding of this advanced seismic design concept will enable us to implement the basic theory of capacity design and contribute to the development of Korean seismic code in new generation,

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.351-355
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• 2019

Load resistance factors for the limit state design of vertical caisson breakwaters are presented. Reliability analysis of 16 breakwaters in nationwide ports was conducted to calculate the partial safety factors and they were converted into load and resistance factors. The final load resistance factor was calibrated by applying the optimization technique to the individually calculated load resistance factors. Finally, the breakwater was redesigned using the optimal load resistance factor and verified whether the target level was met. The load resistance factor according to the change of the target reliability level is presented to facilitate the limit state design of breakwater.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.458-464
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• 2020

Calibration of load-resistance factors for the limit state design of perforated caisson breakwaters are presented. Reliability analysis of 12 breakwaters in nationwide ports was conducted. Then, partial safety factors and load-resistance factors were sequentially calculated according to target reliability index. Load resistance factors were optimized to give one set of factor for limit state design of breakwater. The breakwaters were redesigned by using the optimal load resistance factor and verified whether reliability indices larger than the target value. Finally, some load-resistance factors were proposed by changing target reliability index.