• Journal of the Society of Disaster Information
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• v.18 no.4
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• pp.930-935
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• 2022

Purpose: The purpose of this study is to evaluate the stiffness reduction and damping ratio of reinforced concrete hollow slabs and to analyze their performance, and to study the effect of the damping effect of hollow bodies and the stiffness reduction on the serviceability of slabs. Method: Test specimen was made in a size of 0.6m^*0.21m^*3.6m to evaluate the vibration effect of the slab, and the hollow ratio was set in six steps from 0.0% to 30% to measure the change in rigidity and damping according to the change in the hollow ratio. Result: As the hollow ratio increases, rigidity decreases and the natural frequency decreases, but as the mass decreases, the natural frequency increases gradually. Since energy is hardly dissipated up to the hollow ratio of 20%, the hollow ratio should be reduced by 30%. Conclusion: It was found that the bending strength degradation of the slab with a hollow ratio of about 30% is minimized, but an appropriate natural frequency can be maintained, and a certain damping effect can be obtained.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.677-684
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• 2012

In recent years, extension of life span of buildings is becoming an important issue in our society. To improve the life span of buildings, rhamen structure construction and long-spanned structures are advantageous. And in order to achieve this goal, structural elements of buildings must be light and slender. As an alternative method, general porous slabs are used frequently domestically and internationally. But the study on the porous slabs using T-deck plate and assembly of light weight precast construction is insufficient at present. In this study, flexural and fatigue tests were performed on six specimens to verify structural performance and serviceability. The main parameters of the specimens were light weight and T-deck plate construction possibility as well as slab thickness. The test results indicated that the strength of porous slabs using T-deck plate and assembly of light weight were much better than general RC slabs and porous slabs without T-deck plate. And stiffness was much better than that of other tested slabs.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.93-98
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• 2008

Haeundae Doosan We've The Zenith project is adjacent to Suyoung-bay, now it is in the process of excavation and foundation work. The main use of the tower is residence which height is 300m and 80 floor, the highest residential reinforced concrete building through the Orient. It is comprised of 3 high- rised buildings and 1 low-rised building, the basement is 230m wide and 200m length sized mass structure. The lateral resistance system is acted effectively against the lateral load and satisfactorily against the wind vibration by the 4 direction extension of the center core wall($700{\sim}800mm$ thickness) and reinforced concrete column set around the slab. Flat-plate slab system(250mm thickness) is adjusted for the slab system and it enables effective work process and shortening the working term by minimizing the ceiling height and not needing to install perimeter beam and drop panel. The strength and serviceability of the structure is able to be monitored and estimated constantly through the health monitoring system during the construction and after the construction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.651-658
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• 2014

Notification 2013-611 of MOLIT has come into effect. It relates primarily to new standard impact source. In this study, an in-depth experimental analysis of the difference between a bang machine and an impact ball was performed via field testing of shear wall and flat plate structure at 51 sites. This paper focuses on the difference in single number quantities between a bang machine and an impact ball. At wall thicknesses of 180 and 210 mm in shear wall structure, the single number quantities exhibited differences of 3.1 and 4.5 dB, respectively, and at thicknesses exceeding 250 mm in flat plate structure, the difference was constant at 4.6 dB. With regard to flat plate structures, the single-index difference increased up to 11 dB as the thickness of the floor slab increased. In general, the highest level of contribution for the bang machine was 63 Hz, irrespective of thickness determining bandwidth. The highest level for the impact ball were 63 Hz and 125 Hz. In future research, when reviewing additional field performance measurement data, it will be necessary to consider a detailed examination instead of the current method of uniformly adding 3 dB for all thicknesses and types of structures.

• Advances in Computational Design
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• v.7 no.3
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• pp.229-251
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• 2022

In 2017, an intraplate earthquake of Mw 7.1 occurred 120 km from Mexico City (CDMX). Most collapsed structural buildings stroked by the earthquake were flat slab systems joined to reinforced concrete (RC) columns, unreinforced masonry, confined masonry, and dual systems. This article presents the simulated response of an actual six-story RC frame building with masonry infill walls that did not collapse during the 2017 earthquake. It has a structural system similar to that of many of the collapsed buildings and is located in a high seismic amplification zone. Five 3D numerical models were used in the study to model the seismic response of the building. The building dynamic properties were identified using an ambient vibration test (AVT), enabling validation of the building's finite element models. Several assumptions were made to calibrate the numerical model to the properties identified from the AVT, such as the presence of adjacent buildings, variations in masonry properties, soil-foundation-structure interaction, and the contribution of non-structural elements. The results showed that the infill masonry wall would act as a compression strut and crack along the transverse direction because the shear stresses in the original model (0.85 MPa) exceeded the shear strength (0.38 MPa). In compression, the strut presents lower stresses (3.42 MPa) well below its capacity (6.8 MPa). Although the non-structural elements were not considered to be part of the lateral resistant system, the results showed that these elements could contribute by resisting part of the base shear force, reaching a force of 82 kN.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.73-80
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• 2010

Wind-induced vibration is one of the important structural design factors for serviceability of tall buildings. In order to evaluate the reliable wind-loads and wind induced-vibration, it is necessary to obtain the exact natural period of buildings. The discrepancy in the natural period estimation often results in the overestimation of wind loads. In this study, the effectiveness of lateral stiffness estimation method for tall buildings with flat plate system is evaluated. For this purposed, the results of finite element analysis of three recently constructed buildings are compared with those obtained from field measurement. For the analysis, factors affecting on the lateral resistance such as cracked stiffness of vertical members, elastic modulus of concrete, effective slab width, and cracked stiffness of link beam are considered. Form the results, it is found that the use of non-cracked stiffness and application of dynamic modulus of elasticity rather than initial secant modulus yields closer analysis result to the as-built period.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.1
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• pp.34-40
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• 2013

The 1st assessment(performance test) was applied to assure the floor impact sound performance for developing the dry double-floor with the change of rubber hardness of the upper panel's support and the ceiling structure of the sub-floor. Depends on the change of the rubber hardness in sub-structure, the heavy-weight sound impact value is improved up to 3 dB, and the light-weight sound impact value is moved up to 21 dB, comparing with the bare-slab. Also, the improved value for the floor impact sound conjugating with the sub-floor's ceiling was 5 dB. Based on this result, the 2nd assessment(performance test) was made the state that the rubber hardness of the sub-floor support was ranged between 50 and 70 for considering the stability of walking patients. In addition to this process, the assessment was carried out with a variety of ceiling structure applied to the dry double-floor structure with the air flow system on the sub-floor's ceiling. The result for the 2nd assessment proved that TYPEII-3 had the better sound reduction performance in the heavy-weight impact sound test than other types, and also for the light-weight impact sound TYPEII-3 had the 29 dB sound reduction performance overall. Henceforth, based on the result the research for the sound reduction performance from the floor impact sound shall be ongoing process as well as the development of a double-dry floor and a sound reduction ceiling to suitable on the field.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.5 s.51
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• pp.49-61
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• 2006

The floor impact sound insulations are installed frequently for reducing the floor impact sound into the floor slab of the residential buildings in recent years. Therefore the analytical FE model considering the insulation is needed for the sound and vibration analysis of the floor and it is necessary to use a refined finite element model fer considering the large number of modes involved dynamic responses. So it is very difficult to use FE model because of the tiresome task for constructing the FE model, taking a lot of times for analysis and the impossibility of using the proportional damping. The efficient analysis and modeling method are proposed to the dynamic analysis for the floor with damping layer in this study. The floor slabs and finished layers are modeled individually and the spring elements that mean damping layers used to connect two parts. The dynamic analysis by the $Newmark-{\beta}$ method is performed to solve the non-proportional damping problem due to the damping coefficient of insulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.280-285
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• 2012

The 1st assessment (performance test) was applied to assure the floor impact sound performance for developing the dry double- floor with the change of rubber hardness of the upper panel's support and the ceiling structure of the sub-floor. Depends on the change of the rubber hardness in substructure, the heavy-weight sound impact value is improved up to 3 dB, and the light-weight sound impact value is moved up to 21 dB, comparing with the bare-slab. Also, the improved value for the floor impact sound conjugating with the sub-floor's ceiling was 5dB. Based on this result, the 2nd assessment (performance test) was made the state that the rubber hardness of the sub-floor support was ranged between 50 and 70 for considering the stability of walking patients. In addition to this process, the assessment was carried out with a variety of ceiling structure applied to the dry doublefloor structure with the air flow system on the sub-floor's ceiling. The result for the 2nd assessment proved that TYPE-11 had the better sound reduction performance in the heavy-weight impact sound test than other types, and also for the light-weight impact sound TYPE-11 had the 29 dB sound reduction performance overall. Henceforth, based on the result the research for the sound reduction performance from the floor impact sound shall be ongoing process as well as the development of a double-dry floor and a sound reduction ceiling to suitable on the field.

• Elastomers and Composites
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• v.35 no.2
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• pp.138-148
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• 2000

In order to investigate the possibility of EPDM micro cellular pad (MCP) as an impact sound insulation product, we studied static/dynamic properties and vibration transfer characteristics of EPDM MCP depending on shape, thickness, degrees of foaming by using material test system (MTS) and lab scale mock-up test apparatus. Static/dynamic rigidity is increased when shape is simple. thickness and degrees of foaming low. We could see that dynamic stiffness is proportional to the transmissibility of EPDM MCP. When dynamic stiffness is increased, characteristic peak at transmissibility curve moves high frequency range or snows increase of maximum value of transmissibility. For lab scale mock-up test and finite element method, EPDM MCP shows low vibration velocity and superior mode shape to just concrete plus slab structure. We could confirm that possibility of EPDM MCP as a impact sound insulation product is high.