• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.709-717
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• 2004

The existing AASHTO Standard Specification have some inadequacies in expressing wheel load distribution of bridge which has specific shape of curved bridge instead of straight bridge. Thus, this research presented the finite element analysis and modelling technique of prestressed concrete girder bridge having curved slab and the expression of wheel load distribution was suggested as the ratio of bending moment utilizing the result of finite element analysis of prestressed concrete girder bridge having cowed slab. The considered parameter of girder distribution expression is the curvature of slab, span length, girder space, cross beam space and number of lanes. Though the suggested girder distribution expression is generally underestimated below AASHTO Standard Specification, once the curvature of slab increases, the suggested expression gets larger than AASHTO LRFD Standard Specification.

• Journal of the Korean Society of Safety
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• v.30 no.6
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• pp.102-109
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• 2015

In this study, on the basis of the results of the field survey and the theoretical consideration for Korean Standard Specification for concrete durability and maintenance, the following conclusions are derived. From the survey, the prediction equation of carbonation depth for the southwest region in Korea is experimentally proposed, $y_p=5.865{\sqrt{t}}$, which predicts about 60mm of the carbonation depth for the concrete structures of 100 years, a 1st class of target endurance period, under a combined deterioration environment like a marine environment. Considering that the marginal value for a carbonation depth limitation under very severely marine environment is 25mm, in accordance with the Specification, it is found that the predicting carbonation depth for the concrete cover depths, 100mm and 60mm are 63mm and 29.4mm, respectively. In conclusion, according to the equation and the Specification, it is strongly required that the reinforced concrete structures with the cover depth under 100mm have to make a protection from combined deterioration factors by any methods like a surface coating, an increment of cover depth or an application of a special concrete.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.10-27
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• 1999

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.5-9
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• 1999

• Magazine of the Korea Concrete Institute
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• v.22 no.1
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• pp.26-28
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• 2010

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.749-756
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• 2006

Because of the orthotropic elastic properties and significant two-way bending action, orthotropic plate theory may be suitable for describing the behavior of concrete filled grid bridge decks. Current AASHTO LRFD Bridge Design Specification(2004) has live load moment equations considering flexural rigidity ratio between longitudinal and transverse direction, but the Korea highway bridge design specification(2005) doesn't. The Korea highway bridge standard specification LRFD(1996) considers an orthotropic plate model with a single load to estimate live load moments in concrete filled grid bridge decks, which may not be conservative. This paper presents live load moment equations for truck and passenger car, based on orthotropic plate theory. The equations of truck model use multiple presence factor, impact factor, design truck and design tandem of the Korea highway bridge standard specification LRFD(1996). The estimated moments are verified through finite-element analyses.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.131-132
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• 2023

In this paper, standard specification of heat curing section of cold weather concrete between Korea and China were compared. First, Korea concrete specification (KCS 14 20 40) stipulates that the application period is less than 4℃ per day or less than 0℃ per day right after pouring, but in China, the outdoor daily average temperature is less than 5℃ for five consecutive days. This is believed to be due to the difference in temperatures between Korea and China in winter. Next, in the case of Korea, KCS do not show that the concrete temperature in curing should be 5℃ or higher to prevent early frost damage and obtain the minimum required compressive strength. On the other hand, in the case of China, the specificaion does not show that the curing method is selected based on the concrete surface coefficient after considering the outdoor temperature. In addition, in Korea and China regulation, the temperature of the space during thermal curing was shown to be similar.

• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.1
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• pp.60-70
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• 2013

This study focused on analyzing classification system, technique methods, quality levels of periodic amendment characteristics in planting of standard specification. Through analyzing the above and comparing with foreign case study, this study suggests the improvement directions. The results improvement directions are as follows. 1. Many kinds of new construction were set up through the amendments of Landscape Standard Specification, but there are still needs to combine some construction categories because of mismatches between upper and lower categories. 2. Although the Landscape Standard Specification was revised to be more concrete, the contents there remains an ambiguous expression. So, standard specification is needed to revise a depth of earth ball or strength of support materials and quantify collect period of topsoil and application time. In addition, standards about following supervisor's instruction should be more detailed or deleted. 3. The standard specification has not been specified despite enactment and amendments reflecting the periodical paradigm and the needs of users, so it is still needed to revise. In addition, quality levels, planting periods, size of earth ball and performance criteria of tree materials are needed to revise. Each specific classification and construction methods were made by amendments of standard specification, but some standards are not clear and concrete. Therefore, the standard specification is needed to revise the classification system, technique methods, and problem deduction of quality levels and proposal of improvement. This study will be reference material when Landscape Standard Specification is revised.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.4
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• pp.419-426
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• 2001

Concrete mix proportioning is a process of selecting the right combination of many materials such as cement, fine aggregates, coarse aggregates, water, and admixtures to make concrete satisfying for specification and cost. In determining proportioning of concrete mixes, code information, specification, and the experience of experts are needed. However, all factors regarding mix proportioning factor cannot be considered. Therefore, the final acceptance depends on concrete quality control test results. The proportioning of concrete mixes and the adjustments are somewhat complicated, time-consuming, and uncertain tasks. In this paper, as a tool to predict the factor of the proportioning of concrete mixes, an artificial neural network is used. To consider the varieties of material properties, the standard mixed table of two companies of ready mixed concrete are used. The results show that neural net works is successfully applied to the prediction of concrete mix proportioning factor.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.143-144
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• 2023

The compressive strength of concrete varies depending on various factors. Among them, based on the curing temperature, the KCS 14 20 10 Standard Specification for General Concrete calculates the nominal strength by applying the temperature correction value (Tn) based on the compressive strength of the standard cured concrete at 20±2℃ when designing the formulation strength. However, Tn is a correction value that considers only the temperature, and the correction of strength difference due to heat of hydration is not applied. Therefore, in this study, one-component and two-component concrete are mixed in the summer, structural concrete are manufactured, standard concrete specimen are manufactured, and coring is performed on the central and boundary parts of the structural concrete to calculate the correction value applied to the nominal strength by comparing the compressive strength of standard cured concrete on the 28th day of curing and the compressive strength of structural concrete on the 91st day of curing.