• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.297-306
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• 2017

The concrete median barrier used currently in South Korea was developed the impact level of SB5-B(270kJ). However, the impact level of SB6(420kJ) should be considered in many placed with the increased accident of heavy vehicles. In order to increase the impact resistance of newly developed concrete median barrier, the computer simulation was conducted before real field test. For the accurate behavior of concrete, the parameter, such as impact vehicle, concrete cover depth and deterioration, was important. In this paper, a parametric study was conducted depending on vehicle curb weight, concrete cover depth and level of deterioration. The impact resistance of concrete median barrier was severely changed depending on vehicle curb weight and concrete cover depth. Furthermore, the impact resistance of concrete median barrier was also decreased due to deterioration of concrete, therefore the repair and rehabilitation should be conducted for damaged concrete depending on deterioration level. Therefore, vehicle curb weight, cover depth of concrete structures and deterioration level of concrete should be carefully considered for conducting analysis of concrete structure to vehicle collision.

• KIEAE Journal
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• v.10 no.3
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• pp.89-96
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• 2010

In comparison with ordinary or heavy-weight concrete, light-weight air void concrete has the good aspects in optimizing super tall structure systems for the process of design considering wind load and seismic load by lightening total dead load of buildings and reducing natural resources used. Light-weight air void concrete has excellent properties of heat and sound insulating due to its high amount porosity of air voids. So, it has been used as partition walls and the floor of Ondol which is the traditional Korean floor heating system. Under the condition of which the supply of light-weight aggregates are limited, the development of light-weight concrete using air voids is highly required in the aspects of reduced manufacturing prices and mass production. In this study, we investigated the physical properties and thermal behaviors of specimens that applied different mixing ratios of foaming agent to evaluate the possibility of use in the structural elements. We proposed the estimating equation for compressive strength of each mix having different ratio of foaming agent. We also confirmed that the density of cement matrix is decreased as the mixing amount of foaming agent increase up to 0.6% of foaming agent mixing ratio which was observed by SEM. Based on porosity and compressive strength of control mortar without foaming agent, we built the estimating equations of compressive strength for mortars with foaming agent. The upper limit of use in foaming agent is about 0.6% of the binder amount. Each air void is independent, and size of voids range from 50 to $100{\mu}m$.

• Computers and Concrete
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• v.22 no.6
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• pp.515-525
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• 2018

This paper presents a numerical study on the performance of reinforced concrete (RC) bridge structures subjected to heavy goods vehicle (HGV) collision. The objectives of this study are to investigate the dynamic response and failure modes of different types of bridges under impact loading as well as to give an insight into the simplified methods for modeling bridge structures. For this purpose, detailed finite-element models of HGV and bridges are established and verified against the full-scale collision experiment and a recent traffic accident. An intensive parametric study with the consideration of vehicle weight, vehicle velocity, structural type, simplified methods for modeling bridges is conducted; then the failure mode, impact force, deformation and internal force distribution of the validated bridge models are discussed. It is observed that the structural type has a significant effect on the force-transferring mechanism, failure mode and dynamic response of bridge structures, thus it should be considered in the anti-impact design of bridge structures. The impact force of HGV is mainly determined by the impact weight, impact velocity and contact interface, rather than the simplification of the superstructure. Furthermore, to reduce the modeling and computing cost, it is suggested to utilize the simplified bridge model considering the inertial effect of the superstructure to evaluate the structural impact behavior within a reasonable precision range.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.69-74
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• 2002

Incineration method of municipal solid waste is the general method for reduction it's quantity and weight. Municipal solid waste incineration ash is classified two general types of ash : fly ash((MWFA) and bottom ash(MWBA)). MWFA containing a high degree heavy-metal may give rise to a serious environmental trouble. Therefore, this study was carried out to examine utilization of fly ash. In this study, we tried to find the recycling method of fly ash as a environmental-friendly artificial aggregate. The artificial aggregate using fly ash was tested for the various aspects, including physical properties and environmental stability. The qualities of artificial aggregate are similar to it of lightweight aggregate, and the heavy metal leaching concentration are very lower than a limitation of KSLT and EP.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.7
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• pp.20-26
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• 2003

The ultra-lightweight high strength polymer concrete could be used for the drain structures under severe condition. In this study, materials used were unsaturated polyester resin, heavy calcium carbonate, artificial lightweight coarse aggregate and perlite. In the test results, the unit weight of the ultra-lightweight high strength polymer concrete was 946 kg f/$\textrm{m}^3$ and the compressive strength was appeared in 34.5 MPa. The compressive strength, splitting tensile strength, flexural strength, acid resistance and weather resistance were shown in excellently than that of the normal cement concrete. The draining trench had 1m length, 0.24 m width, 0.02 m thickness and 0.07 m height. The developed trench could be effectively used at the draining structures.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.671-676
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• 1999

Because of relatively heavy dead weight of concrete itself and unavoidable heat of massive concrete in bridge piers, circular hollow columns are widely used in Korean highway bridges. Since the occurrence of 1995 Kobe earthquake, there have been much concerns about seismic design for various infrastructures, inclusive of bridge structures. It is, however, understood that there are not much research works for nonlinear behavior of circular hollow columns subjected to earthquake motions. The ultimate of this experimental research is investigate nonlinear behavior of circular hollow reinforced concrete bridge piers under the quasi-static cyclic load, and then to enhance their ductility by strengthening the plastic hinge region with glassfiber sheets. It is concluded from quasi-static tests for 7 bridge piers that energy dissipation capacity and curvatures for a given displacement ductility factor $\{\mu}=frac{\Delta}{\Delta_y}$are about 20% higher for the seismically designed columns and about 70% higher for the retrofitted piers than the nonseismically designed columns in a conventional way.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.651-657
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• 2010

Previous experimental results performed by many researchers for a couple of decades in South Korea have shown that an absorbing sheet inserted in a conventional floating slab system for thermal insulation or vibration absorption may amplify the vibration of the slab system at specific frequency ranges depending on the material properties of the sheet. The amplified vibration, consequently, results in the heavy weight floor impact noise exceeding the sound level limit for an apartment house, 50 dB. In this study, the amplification mechanism is examined through numerical analysis and a new slab system is proposed to reduce the amplification and control the noise. The new slab system consists of studs connecting the base slab and upper concrete finishing yielding the dramatically increased stiffness of the slab. The numerical simulation is performed to investigate the effect of the slab system with studs on the vibration and noise control. The results show that the performance of the slab is sensitive to the number and location of studs, and the heavy weight floor impact noise can be reduced up to 6~7 dB compared to the conventional slab system at the optimal stud location.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.92-95
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• 2005

In this study, Heavy-weight floor impact sound and vibration in concrete structures with different slab thickness have been measured in a test building. It was found that natural frequency increased according to increases of slab thickness, and acceleration level decreases. Results also show that the measurements in the 210 and 240mm slab structures are complied with the result from finite element analysis but the In and 180mm slab structures are not because the structures are constrained to the ground. Therefore, in modelling process the condition of sub-structures should be examined in relation to the boundary conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.486-491
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• 2002

Auditory experiments based on subjective responses were undertaken for the standard heavy and light weight impact noise. Relations between noise levels and subjective evaluations were also investigated. As a result, it was shown that the noise class was rated with the range of sensible satisfaction by investigating the various social responses for the floor impact noise. The rate classification for the heavy weight impact noise is suggested as a design guide for concrete slabs which satisfy the residents' requirements in various sound insulation capacities of multistory residential buildings.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1160-1168
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• 2005

Floor impact noise isolation performance of reinforced concrete floors was investigated through new measurement method using impact bail. Strong impact force in Bow frequency band below 63 Hz of bang machine is not similar to human impact source and causes some problem in evaluating heavy-weight Impact noise but heavy-weight impact noise measurement and evaluation using impact ball which is very similar to human impact is more reliable than bang machine. Correction value on the background noise and sensitivity of residents should be considered on the floor impact noise evaluation classes.