• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.561-566
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• 2002

Recently, high quality exposed concrete is needed to achieve high quality surface for outer wall of the building. In this study, to solve above characteristic of the exposed concrete we selected self compacting concrete(SCC) and compared with normal concrete. So, we developed the SCC mix design and performed the semi mock-up test. Through this result, we performed the pilot test and mock-up test to check surface of outer wall and to measure formwork pressure As a result because SCC is better than normal concrete with respect to flowability and seggregation resistance SCC is suit to a exposed concrete needed high quality surface for outer wall of the building.

• Computers and Concrete
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• v.26 no.5
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• pp.377-384
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• 2020

A two-dimensional particle flow cod (PFC) is used to study the effect of missile impact on the concrete target. For this purpose firstly calibration of numerical model was performed so that tensile strength of numerical models and experimental sample were the same. Secondly, a concrete model was built. The number of concrete layers and the angle of concrete layers related to horizontal axis were changed. Their numbers were 1, 2, 3 and 4. The angles were 0°, 15°, 30°, 45°, 60°, 75° and 90°. A semi-circle missile was simulated at top of the concrete layers. Its velocity in opposite side of Y direction was 100 m/s. three measuring circles were situated at the below the missile in the model to receive the applied force. The load in the missile and measuring circles together with failure pattern were registered at the beginning of the impaction. The results show that concrete layers number and concrete layers angle have important effect on the failure load while the failure pattern was nearly constant in all of the models.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.555-560
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• 2002

The structure of Chosun-ilbo Boopyung factory was desined as exposed concrete. The self compacting concrete(non-vibrating concrete) must be applied to this case because the exposed concrete wall is very thin(200mm) and high(6m), Laboratory tests and semi mock-up test were performed for optimum mix design of the self compacting concrete. As a result, the optimum mixes were observed at the 3-component types(ope, fly-ash, slag powder) that Vp$\geq$0.175, Vw/Vp$\geq$0.95, W=170~175$kgf/m^3$ and B=500~540$kgf/m^3$ Based on this result. we make plan that the pilot productions of batcher plant, the full-scale mock up tests and site application.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.783-788
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• 2001

Voids created with concrete construction or deterioration result in serious weakness from the aspects of both structural and durable function. Ultrasonic method using image processing technique was used for detecting pattern of voids in concrete in this study Experimental investigation was carried out for three types(patterns) of void in concrete. The effect of curing period of concrete and ultrasonic measurement method was also investigated. As a result it has been verified that the semi-direct measurement method is more effective than the other methods for detecting pattern of voids in concrete in ultrasonic method using image processing technique. The longer the curing period of concrete is, the better the detection accuracy of void pattern can be obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.811-816
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• 2000

The joint treatment of concrete is one of the technical problems in top down construction method. Joints created with the top down construction result in serious weakness from the aspects of both structural and water-barrier function. Ultrasonic method was used for the inspection of top down construction joints of column in SRC structure in this study. As a result it has been verified that the semi-direct measurement method is more effective than the other methods for detecting the voids of construction joints.

• Structural Engineering and Mechanics
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• v.24 no.6
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• pp.683-698
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• 2006

The accurate dynamic analysis of concrete arch dams relies heavily on employing a three-dimensional semi-infinite fluid element. The usual method for calculating the impedance matrix of this fluid hyper-element is dependent on the solution of a complex eigen-value problem for each frequency. In the present study, an efficient procedure is proposed which simplifies this procedure amazingly, and results in great computational time saving. Moreover, the accuracy of this technique is examined thoroughly and it is concluded that efficient procedure is incredibly accurate under all practical conditions.

• Steel and Composite Structures
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• v.1 no.2
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• pp.159-170
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• 2001

The Millennium Tower is situated to the north of the center of Vienna. With a height of 202 m it is the highest building in Austria. Realization was improved by new methods. The tower is a typical example of mixed building technology, combining composite frames with a concrete core. Special attention has been paid to the moment connections between the slim floors and the column tubes resulting in a drastically reduced construction time and thin slabs. The semi-continuity has been considered in the design at ultimate and serviceability limit states.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.173-176
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• 2006

Concrete has been considered as a semi-permanent structural material, because its excellent durability. But concrete durability is affected by carbon dioxide, chloride, water, etc. This study is about surface protection materials-one materials is silane type and the other silicate type for the promoting of concrete durability. As a results, Silane type could protect affection of chloride(Cl-), water(H2O), carbon dioxide(CO2). Also silicate type could improve the abrasion of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.189-190
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• 2010

Yeoju-Bo is a large massive concrete structures that require the reduction of working period of construction. In this study, we optimized the mix proportion of internal/external concrete and physical properties like compressive strength, semi adiabatic temperature rise in laboratory. And we also performed thermal analysis to verify the thermal cracking. Lastly we measured the hydration heat and the thermal cracking in site to verify the safety of massive concrete structure.

• Computers and Concrete
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• v.9 no.3
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• pp.227-244
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• 2012

A theoretical model for shear strength evaluation of fibrous concrete beams reinforced with stirrups is proposed. The formulation is founded on the theory of plasticity and the stress field concepts, generalizing a known plastic model for calculating the bearing capacity of reinforced concrete beams, to the case of fibrous concrete. The beneficial effect of steel fibres is estimated taking into account the residual tensile strength of fibrous concrete, by modifying an analytical constitutive law which presents a plastic plateau as a post-peak branch. Around fifty results of experimental tests carried out on steel fibrous concrete beams available in the literature were collected, and a comparison of shear strength estimation provided by other semi-empirical models is performed, proving that the numerical values obtained with the proposed model are in very good agreement with the experimental results.