• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.4
• /
• pp.375-381
• /
• 2017

Recently, due to the increasing of interest about the eco-friendly concrete, it is being increased to use concretes containing by-products of industry such as fly ash, ground granulated blast furnace slag, silica fume, and etc. Especially, these are well known for improving the resistance to reinforcement corrosion in concrete and decreasing chloride ion penetration. The purpose of this experimental research is to evaluate the resistance to corrosion of reinforcement and critical chloride content of high volume fly ash concrete(HVFAC) which is replaced with fly ash for approximately 50% cement content. For this purpose, corrosion monitoring of reinforcement by half cell potential method was carried out for the cylindrical test specimens that the upper of reinforcement in concrete was exposed to detect the time of corrosion initiation for reinforcement. It was observed from the test result that the the time of corrosion initiation for reinforcement of HVFAC by the accelerated corrosion tests increased 1.2~1.3 times than plain concrete and the critical chloride contents of plain concrete and HVFAC were found to range $0.80{\sim}1.20kg/m^3$, $0.89{\sim}1.60kg/m^3$, respectively.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.43-44
• /
• 2009

3D bridge information models for a concrete box-girder bridge were built and a typical application example for the estimation linked with the 3D models was proposed. 3D geometry objects with PBS (product breakdown structure) were constructed using standard classification codes and 2D drawings. Information on the amount of materials according to the classification codes was utilized for the estimation system. A process for the estimation of concrete and rebars was developed and verified through the pilot test. Optimization of rebar fabrication was suggested as an additional function and was utilized for the cost reduction and standard fabrication.

• 레미콘
• /
• no.1 s.34
• /
• pp.29-36
• /
• 1993

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.33 no.1
• /
• pp.35-44
• /
• 2020

In the construction industry, there is a growing demand for the accurate calculation of the quantity take-off and construction budget at the design stage, and it is likewise important to grasp changes in the construction budget and quantity take-off if design alterations are made. In addition, lawsuits related to the quantity take-off and cost of construction are frequent; therefore, the calculation of these factors using building information modeling (BIM) has emerged as an alternative. However, existing 2D-based methods are still used more frequently than BIM-based methods for quantity take-offs and construction budgets. This is because of the lack of BIM experience of estimation workers and the absence of a national standard. However, from a designer's point of view, it is necessary to understand the quantity take-off and construction cost based on BIM and accurately create the design according to the budget. In this study, the quantity take-offs of concrete, rebar, and reinforced concrete structures (apartments) in Seoul and Yeongjong were compared with the quantity take-offs based on 2D and BIM methods. From the viewpoint of the designer, we aim to increase the accuracy of BIM-based quantity take-offs.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.409-412
• /
• 2008

This study were evaluated the corrosion threshold reached at steel reinforcement in latex modified concrete(LMC). Accelerated testing was accomplished to the evalate the diffusion coefficient of LMC mix, and the time dependent constants of diffusion. Also, average chloride diffusion coefficient was estimated. From the average chloride ion diffusion coefficient, the time which critical chloride contents at depth of reinforcement steel was estimated. Test results indicated that the corrosion threshold reached at reinforcement in LMC are effected on the mix proportion factor including latex content, and water-cement ratio.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.5
• /
• pp.145-152
• /
• 2019

In this study, rebar QTO(Quantity Take-Off) was quickly produced from the BIM model prepared by Revit in the early design phase, and the available premium rates were quantitatively presented. For this purpose, the amount of rebar calculated using the BuilderHub, which specializes in calculating rebar QTO, was analyzed according to various factors such as member type, rebar diameter, building size, item type, and order length, and the effect of each factor on the rebar QTO was determined. In addition, the BIM model generated on Revit was used to establish parameters and processes required to produce rebar QTO, and proposed a rebar premium rate and a stirrup/hoop premium rate based on the BuilderHub output results. Through this study, it is expected that a rapid and efficient comparative evaluation of rebar QTO will be possible according to various structural design alternatives in the early design phase.

• Korean Journal of Construction Engineering and Management
• /
• v.4 no.1 s.13
• /
• pp.114-121
• /
• 2003

The precise quantity of materials is not yet taken off by the CAD system although it has Influenced in design productivity and automatic estimate. And various estimate systems developed so far deal with the quantity take-off of building members separately, which caused to over-estimate the part of each member. Therefore, the purpose of this paper is to develop algorithms of more precise estimate than that of current estimate by solving boundary conditions of the connection parts of building members, such as column, girder, beam, wall and slab. The algorithms are proposed to take off the quantity of concrete and form work and they will be used for the estimate of building structure more precisely and automatically than ever.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.05a
• /
• pp.109-110
• /
• 2015

Estimation of rebar quantity may be used as an index to evaluate the economic feasibility of structural designs. However, when using the software to estimate the rebar quantity, there may be some limitations such as data loss caused by human errors and estimation delays caused by increased input time, since the information on arrangement of rebar is inserted manually. To solve the problems of such quantity estimation software, it is necessary to develop a method on automatic input/output of structural design information for quantity estimation and an algorithm for accurate estimation of rebar quantity. The purpose of this study is to improve the existing rebar quantity estimation by connecting with the database on information related to rebar estimation and the algorithm for rebar estimation, in order to develop an algorithm to estimate an accurate, net rebar quantity. The study result can be used as basic data for development of software for efficient structural designs and automatic framework estimation of buildings.

• Journal of the Korea Institute of Building Construction
• /
• v.10 no.2
• /
• pp.125-132
• /
• 2010

Recently, construction companies have had difficulty in managing their business due to economic hardship domestically and abroad, decreased orders, and low profitability due to intensified competition. To address these issues, construction companies need to develop or introduce construction methods that improve productivity. The purpose of this study is to investigate a re-bar construction method that reduces the high expenses of transport by folding a pre-fabricated re-bar cage. It was concluded that the application of rebar pre-fabrication would be activated and the productivity of construction sites improved by adopting the folding rebar pre-fabrication method.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.289-292
• /
• 2008

This paper studied experimentally on the structural performance and serviceability of RC beams with high-strength reinforcing bars. Following to the previous research, high-strength reinforcing bars have an negative effect on the deflection and crack depth. But, there are advantages about reducing amount of reinforcement than normal-strength reinforcing bars. So, the purpose of this paper is to analyze the effect of flexural performance on the beams with high-strength reinforcing bars. Three specimens were tested, and the main variable was the yield strength of the reinforcements; SD400, SD600 and SD700. Experimental results shows that the stiffness of members reduced when apply to high-strength reinforcement and equal reinforcement ratio. But the flexural strength of members increased to proportion to the strength and amount of reinforcement. Also, when high-strength reinforcement used, serviceability aspect do not appear to be affected because there is no change for crack number and maximum crack width.