• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.189-194
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• 2001

In this study, ultimate strength of concrete deep beams with an opening is predicted by using Strut-and-Tie Model with a new effective compressive strength. First crack occurs around an opening by stress concentration due to geometric discontinuity. This results in decreasing ultimate strength of deep beams with an opening compared with general deep beams. With fundamental notion that ultimate strength of deep beam with an opening decreases as a result of reduction in effective compressive strength of a concrete strut, an equivalent effective compressive strength formula is proposed in order to reflect ultimate strength reduction due to an opening located in a concrete strut. An equivalent effective compressive strength formula which can reflect opening size and position is added to a testified algorithm of predicting ultimate strength of concrete deep beams. Therefore, ultimate strength of concrete deep beam with an opening is predicted by using a simple and rational STM algorithm including an equivalent effective compressive strength formula, not by finite element analysis or a former complex Strut-and-Tie Model

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.269-279
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• 2008

In this study, the ultimate strengths of 229 simply supported reinforced concrete deep beams tested to shear failure were evaluated by the ACI 318-05's strut-tie model approach implemented with the presented indeterminate strut-tie model and its load distribution ratio. The ultimate strengths of the deep beams were also estimated by the experimental shear equations, design codes that were based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the present strut-tie model and its load distribution ratio was examined through the comparison of the strength analysis results classified according to the prime design variables of the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.33-43
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• 2006

Pull-out strength of tie-bin used in pavement construction is not an issue because those are embedded in newly placed concrete slabs. However, sufficient pull-out strength should be secured in widening constructions because, in case, the tie-bars are inserted into drilled holes of the existing slabs with liquid filler. Insufficient pull-out strength will result in lowered load transfer efficiency between adjacent slabs in addition to poor serviceability and durability due to joint widening. The pull-out strength of the tie-bars installed by current method is evaluated and improved methods are proposed. The field pull-out strength obtained by the current method was only 42.7% of required strength. Its first counterproposal is using to insert the liquid filler into drilled holes and stoppers to prevent it from flowing out of the holes. However, this method was not judged to secure desired level of quality control. The second counterproposal which substitutes the existing type of the tie-bars by SL anchor bolts was judged to secure sufficient pull out-strength in addition to the quality control and constructibility.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.251-256
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• 1995

This paper presents an evaluation of the strength and behavior of a tested simply supported rectangular reinforced eoncrete beam and a design example of a shear wall using two-dimensional strut-tie model with finite element nonlinear analysis. Strut-tie models reflecting the actual support and loading conditions are developed for the beam and shear wall. The strut-tie model not only provides simple solutions for large number of design situations dealing with the entire range of concrete structures which appear to be rather complicated but also predicts the behavior and strength of concrete members.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.1
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• pp.21-29
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• 2017

Purpose of this study is to investigate structural behavior of the rectangular hollow column with various transverse reinforcement details. Experimental variables are diameter, arrangement details and lateral spacing of cross tie. A total of 66 column specimens have been prepared and tested under axial compressive load. Test results showed that behaviors of column specimens were different depending on the cross tie details. Specimens with cross tie wrapping longitudinal steel and transverse steel have greater strength and ductility than specimens with cross tie wrapping the longitudinal steel.

• Structural Engineering and Mechanics
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• v.44 no.2
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• pp.163-178
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• 2012

A strut-and-tie model is introduced in this paper to predict the ultimate shear strength of non-seismically detailed columns. The validity and applicability of the proposed strut-and-tie model are evaluated by comparison with available experimental data. The model was developed based on visible crack patterns observed on the test specimens. The concrete contribution is integrated into the strut-and-tie model through a concept of equivalent transverse reinforcement. To further validate the model a full-scale non-seismically detailed reinforced concrete column was tested to investigate its seismic behavior. The specimen was tested under the combination of a constant axial load, $0.30f_c{^{\prime}}A_g$ and quasi-static cyclic loadings simulating earthquake actions. Quasi-static cyclic loadings simulating earthquake actions were applied to the specimen until it could not sustain the applied axial load. The analytical results reveal that the strut-and-tie method is capable of modeling to a satisfactory accuracy the ultimate shear strength of non-seismically detailed columns subjected to reserved cyclic loadings.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.393-396
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• 2008

This paper presents the experimental results on the fire performance of high strength concrete(HSC) column made with different tie spacing. Three HSC columns measuring 305${\times}$305mm in cross section were prepared to evaluate the effect of tie spacing with 150, 210, 300mm, respectively. Compressive strength was 69MPa at test. As a result, the fire performance of HSC columns was greatly influenced by tie spacing. The fire resistance increases with decreasing the tie spacing.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.540-543
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• 2004

In this study, the validity of the grid softened strut-tie model method suggested for concrete member analysis is examined through the ultimate strength evaluation of the reinforced concrete beams. The evaluated results of ultimate strength by the grid softened strut-tie model method were compared with those by the ACI 318-02 and the modified compression field theory, and European codes.

• Journal of Information Technology Services
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• v.12 no.2
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• pp.119-129
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• 2013

The degree to which people share knowledge has major impacts on the effectiveness of virtual community of practice (VCoP). As an extension to the previous study which investigated the effect of individual cooperative types (cooperator, reciprocator, and free rider) on knowledge sharing, it is investigated how much increase in the degree of cooperation will enhance knowledge sharing when there are more knowledge contributors and strong ties exist across the community. Simulation method is adopted to measure the effect of the cooperative type and tie strength on knowledge sharing. The results reveal that the tie strength positively affects knowledge contribution in VCoP and strongly tied VCoP generates equivalent level of knowledge contribution as that of weakly-tied VCoP with 5% more contributors.

• Journal of Distribution Science
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• v.14 no.5
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• pp.39-50
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• 2016

Purpose - The purpose of this study was to substantiate the relationship between on-the-job training (OJT) characteristic factors and OJT outcomes and the moderating effect of the tie strength between a trainer and a trainee on the relationship. OJT characteristic factors were composed of a unit of work to be learned, trainee's motivation, trainer's ability, OJT design, and OJT support. OJT outcomes included job satisfaction and organizational commitment in the research. The tie strength means a sense of intimacy with a trainer. All of the OJT characteristic factors, OJT outcomes, and the tie strength were defined operationally as the perceived ones by a trainee. Research design, data, and methodology - This study analyzed the data of 302 employees in a domestic travel agency as early career for seven years or less. The main methods for the analysis were multiple linear regression analysis and moderating effect analysis. The whole process of the data analysis was conducted using the SPSS 21.0 for windows. Results - The results of the study are as follows: First, every five element of OJT, including unit of work to be learned, trainee's motivation, trainer's ability, OJT design, and OJT support, showed positive influence on OJT outcomes - job satisfaction and organizational commitment. Second, the tie strength between a trainer and a trainee was positively related with OJT outcomes. Finally, the strength of ties between the trainer and the trainee was found positively to moderate the relationship of a unit of work to be learned, OJT design, or OJT support, with OJT outcomes. However, the moderating effect of the tie strength was not significant statistically between the trainee's motivation or the trainer's ability, and OJT outcomes. Conclusion - In the study, it was demonstrated that every OJT characteristic factors have a positive contribution to job satisfaction and organizational commitment for early career employees. In addition, the study showed the need to pay attention to improve the quality of relationships between trainers and trainees, in order to increase the impact of a unit of work to be learned, OJT design, and OJT support. These findings suggest the implications in the three factors as external factors that constitute OJT. The three factors are made by HRD practitioners who are involved in design and operation of the program as well as their interventions to improve the quality of the relationship between trainers and trainees. On the other hand, it was demonstrated in the research that trainee's motivation and trainer's ability, regardless of their tie strength, have a direct impact on OJT outcomes by itself. Moreover, the trainee's motivation and trainer's ability are intrinsic characteristics, rather than external factors that constitute OJT. Therefore, they are unlikely to be changed by HRD practitioners' interventions. In conclusion, it was argued in the research that the trainee's motivation and trainer's ability should be a consideration in selecting and matching partners in OJT participants before starting OJT.