• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.477-492
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• 2001

About half of bridges in United States are considered to be deficient and therefore are in need of repair or replacement. Half of these are functionally obsolete, and others do not have required strength For these bridges repairs and replacements are needed To avoid the high cost of rehabilitation the bridge rating must corectly report the present load-carrying capacity Rating engineers use Allowable Stress Design(ASD) Load Factor Design(LFD), and Load Resistance Factor Design(LRFD) to evaluate the bridge load carrying capacity In this paper the load rating methods are introduced and bridge load test data are collected. The reasons that make the difference between test results and analytical results are explained for each bridge load test And load rating methods are applied to real bridge. The rating factors from each method are compared.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.89-96
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• 2018

Bridge structures are a socially important infrastructure and safety management of bridges during the public service period is important. Steel box girder bridges, which account for a large percentage of road bridges, have been designed by allowable stress design method(ASD) and load carrying capacity have been evaluated using ASD. Although design specification has recently been changed to limit state design method(LSD), in most cases, ASD is still used for load carrying capacity evaluation. In this study, the two design methods were used to compare the results of a load rating factor evaluation on a number of bridges, and we are going to find out how to convert the existing rating factor by ASD into rating factor by LSD. The results of this study are expected to can be used as a basis for determining the need for reinforcement and evaluating load carrying capacity by LSD in bridge maintenance.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.7
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• pp.36-45
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• 2002

Most of rural bridges have passed 30 years of age since they were built, which have to support unexpected overload caused by changed design load and excessive amount of transportation. For these rural bridges, repairs and replacements are needed. Even though there have been attempt to estimate the safety of existing bridges deteriorated with major defects, those approaches must rely on the observable damage and subsequent decisions are made subjectively. To avoid the high cost of rehabilitation, the bridge rating must correctly represent the present load-carrying capacity. Rating engineers use a methods such as Allowable Stress Design (ASD), Load Factor Design (LFD), and Load Resistance Factor Design (LRFD) to evaluate the bridge load carrying capacity. In this paper, the load rating methods are introduced, and it is illustrated how to use the load test data from literature survey. Load test is conducted to the bridge that was built 30 years ago in rural area. From load test results, new maintenance method is suggested instead of the bridge replacement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.125-134
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• 2003

In order to rate current bridge load carrying capacity, typically two methods are used. These are Allowable Stress Rating (ASR) and Load Factor Rating (LFR). Using the rating factors, there are many attempts to make a connection between rating factors and probability concept. The main purpose of the paper is computing the probability of overload using rating factors and probability concept. In this paper, the load rating methods are briefly explained, and the probability concept is connected to rating factors by using live load from Weigh-in-Motion (WIM). Based on the live load model and rati ng factor, the computation procedure of the probability of overload is explained.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.61-68
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• 1988

This study is intended to propose an approach to reliability-based safety evaluation as well as LRFR(Load and Resisitance Factor Rating) type capacity classification of military or civilian bridges based on the limit state models which are delived by incorporating all the uncertainties of resistance and load random variables including deterioration, and are used in a practical AFOSM (Advanced First Order Second Moment) method. The proposed methods for the assement of safety and load carrying capacity are applied for the evaluation of rating and classifications of several practical bridges against the crossing of military vehicles. Based on the observation of the numerical results, it can be concluded that the current NATO classification method which is based on the traditionl allowable stress concept can not provide real load carrying capacity but results in nominal classification, and therefore the reliability-based safety evaluation and LRFR-classification method or the corresponding rational allowable stress method proposed in this paper may have to be introduced into the classification practice.

• Journal of the Society of Disaster Information
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• v.17 no.3
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• pp.454-464
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• 2021

Purpose: There is a need to construct an evacuation passageway for the 2-Arch tunnel, which has been constructed and is in operation. Therefore, it aims to analyze tunnel and center wall behaviour and stability due to excavation of the center wall. Method: We describe the theoretical background of 2-Arch tunnel and evacuation passageway, and focused on analyzing the behaviour of tunnel and wall using 3-dimensional finite element analysis. Parametric analysis according to rock rating was performed with various ground conditions, and the displacement and stress of the center wall were intensively analyzed. Result: With the center wall excavation, the largest amount of settlement was shown in the center of the opening, and the stress was greatest during the first excavation. In addition, it was shown that stress concentration occurred at the top of both openings, and stability reviews considering the concept of allowable stress showed that it exceeded the allowable stress. Conclusion: Although the displacement of the tunnel has secured stability within the allowable standard, the generated stress is found to exceed the allowable standard, so it is necessary to prevent sudden stress release by applying appropriate reinforcement methods during construction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.239-249
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• 2003

The bridges, which were built between 20 and 30 years ago in rural area, have to support unexpected overload caused by excessive amount of transportation. For these rural bridges, repairs and replacements are needed. To avoid the high cost of rehabilitation, the bridge rating must correctly report the present load-carrying capacity. Rating engineers use Allowable Stress Design (ASD), Load Factor Design (LFD), and Load Resistance Factor Design (LRFD) to evaluate the bridge load carrying capacity. In this paper, the load rating methods are introduced, and it is illustrated how to use the load test data from literature survey. Load test is conducted to the bridge that was built 30 years ago in rural area. From load test results, new maintenance strategy is suggested instead of the bridge replacement.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.108-115
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• 2003

Bridges are rated at two levels by either Load Factor Design (LFD) or Allowable Stress Design (ASD). The lower level rating is called Inventory Rating and the upper level rating is called Operating Rating. To maintain bridges effectively, there is an urgent need to assess actual bridge loading carrying capacity and to predict their remaining life from a system reliability viewpoint. The lifetime functions are introduced and explained to predict the time-dependent failure probability. The bridge studied in this paper was built 30 years ago in rural area. For this bridge, the load test and rehabilitation were conducted. The time-dependent system failure probability is predicted with or without rehabilitation. As a case study, an optional rehabilitation is suggested, and fir this rehabilitation, load rating is computed and the time-dependent system failure probability is predicted. Based on rehabilitation costs and extended service lifes, the optimal rehabilitation is suggested.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.1
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• pp.37-45
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• 2021

The construction of the tunnel portal should be careful because cover depth is shallow and it is difficult to exhibit the arching effect. Tunnel stability may be reduced with additional embankment above the portal of tunnel. In this study, in order to examine the stability of the tunnel according to additional embankment above the portal of tunnel, numerical analysis was performed while changing the ground conditions and height of embankment. As a result of the numerical analysis, it was found that the allowable flexural compressive stress of shotcrete and allowable axial force of rockbolts were exceeded when the height of additional embankment was 12 m in rock mass rating V. When considering the displacement, the range of the plastic region and the behavior of the support materials, the tunnel stability seems to be greatly reduced if the height of additional embankment above the portal of tunnel exceeds 10 m.