• 한국도로학회:학술대회논문집
• /
• 2010.09a
• /
• pp.381-386
• /
• 2010

• Journal of the Earthquake Engineering Society of Korea
• /
• v.5 no.6
• /
• pp.1-10
• /
• 2001

In this study, the horizontal loading tests of 10ton and 200ton capacity of LRB(lead-rubber bearing) were performed for the evaluation of the dynamic properties of the LRB. It is noted from the test results that dynamic properties of the LRB are dependent on the loading frequency, vertical load and shear strain. A Slender bearing subjected to large deformation will tend to develop plastic hinges in the end regions of the lead plug which will cause the failure of the lead plug. It is recommended that the appropriate mechanical properties of LRB considering the level of structural response and input ground motion should be used in the design of base isolated structures.

• Magazine of the Korea Concrete Institute
• /
• v.9 no.6
• /
• pp.185-193
• /
• 1997

본 연구는 각종 제진재료를 이용하여 진동을 억제할 수 있는 콘크리트를 개발하여 각종 건설공사에서 흔히 발생할 수 있는 진동공해문제를 억제하고자 하며 아울러 폐기물의 재활용차원에서 폐자재를 이용하여 유용한 제진콘크리트를 개발하고자 하는데 그 목적이 있다. 우선, 제진재료를 이용한 압축강도 (200kg/$\textrm{cm}^2$)이상의 콘크리트 배합비를 찾기 위하여 24배치의 예비실험을 수행하였으며, 선정된 적정배합비에 따른 제진재료를 이용한9개의 진동시험체보를 제작하여 보의 구조적 및 재료적 동적특성 즉 1차 공명진동수와 동적 휨강성 및 감쇠비를 측정하여 제진효과를 조사하였다. 그리고 압축강도에 의한 각 시험체의 균열모멘트를 추정하여 재하하중과 균열모멘트비(M/Mcr)에 따른 하중단계별 동적특성값을 살펴보았다. 제진재료로서는 라텍스(Latex), 고무분말(Rubber Powder)그리고 플라스틱 레진( Plastic Resin)등을 사용하였고, 재료적, 구조적 진동감쇠효과를 파악하고자 KS F2437규정과 진동파의 속도법을 사용하였으며, 감쇠비 측정은 Frequency Spectrum 곡선에 대한 Polynomial Curvefitting 방법과 기하학적 해석방법을 이용하여 각각의 결과를 비교.분석하였다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.353-356
• /
• 2008

This study was performed to estimate the dynamic behavior for Bi Prestressed Concrete Girder(Bicon girder) which could introduce effectively prestressed forces into concrete girders. Dynamic behavior of PSC girder must be verified because it becomes not only slim but also long and a railway bridge which loaded regularly has risk of resonance especially. Forced vibration test using a vibration machine was executed for 20m railway bridge girder specimen to acquire dynamic characteristics(natural frequency, damping ratio) and test results showed the natural frequency of 6.632Hz and the damping ratio of 1.43%

• Geotechnical Engineering
• /
• v.10 no.4
• /
• pp.119-132
• /
• 1994

Undrained cyclic triaxial tests were performed on silt contained in the sand in order to investigate the effect of silt contents on the liquefaction strength and shear characterist ifs of the sand. As the result of this experiment, the weakest percentage of silt contained in the sand was 30% for all the relative density considered in the test. Also, the same bests were performed to find the effect of cyclic speed applied ranging from 0.1Hz to 5Hz on the liquefaction strength. The more the silt is contained in the sand, the greater the liquefaction strength was affected by cyclic speed, While the silt -containing sand was far less influenced by the cyclic speed than clay containing sand. These results are believed to be caused by the change of pore water pressure of the effective stress path.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.2 s.54
• /
• pp.81-94
• /
• 2007

In most experimental researches on the liquefaction phenomenon, an earthquake as a random vibration has been regraded as a sinusoidal wave or a triangular wave with an equivalent amplitude. Together with the development in the part of signal control and data acquisition, dynamic experimental equipments in the soil dynamics have also developed rapidly and further more, several real earthquakes have been simulated in the large model test such as shaking table tests and centrifuge tests. In Korea, several elementary laboratory tests to simulate the real earthquake load were performed. From these test results, it was reported that the sinusoidal wave cannot reliably reflect the soil dynamic behavior under the real earthquake motion. In this study, 4 types of dynamic motions such as the sinusoidal wave, the triangular wave, the incremental triangular wave and several real earthquake motions which were classified with shock-type and vibration-type were loaded to find something new to explain the change of the excess pore water pressure under the real earthquake load. Through the detailed investigation and comparison on all test results, it is found that the dynamic flow is generated by the soil plastic deformation and the velocity head of dynamic flow is changed the pressure head in the un-drained condition. It can be concluded that the change of the excess pore water pressure is related to the pressure head of dynamic flow. Lastly, a new hypothesis to explain such a liquefaction initiation phenomenon under the real earthquake load is also proposed and verified.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.6
• /
• pp.41-49
• /
• 2006

This paper deals with development and dissipation of excess pore pressure induced by the cyclic load. Cyclic triaxial tests on reconstituted samples of weathered residual soils, which were widely used as construction materials in Korea, were performed. Test results showed that excess pore pressures developed under undrained condition increased with the increase of cyclic loads and confining pressures. And a new concept based on modified excess pore pressure ratio (MEPPR) was proposed for simply estimating excess pore pressures in terms of the number of cyclic load, irrespective of cyclic loads and confining pressures. Also, it was proposed that excess pore pressure ratio (EPPR) could be effectively utilized to estimate volumetric strains during dissipation which decreased as confining pressures increased. Consequently, concept and method to effectively estimate settlements under non-liquefied condition, induced by dynamic loads such as earthquake loads were evaluated based on laboratory test results for reconstituted weathered residual soils.

• Journal of the Korean Geotechnical Society
• /
• v.31 no.3
• /
• pp.63-72
• /
• 2015

This paper describes the correlation and relationship between elastic moduli measured by three stiffness measurement methods with different mechanical characteristics to evaluate the compaction characteristics of subgrade soils. The Soil Stiffness Gauge (SSG) with very small strain (${\approx}0.001%$) ranges, static Plate Loading Test (PLT) with mid-level strain (${\approx}0.01{\sim}0.1%$) ranges, and Dynamic Cone Penetrometer (DCP) using penetration resistance were implemented to measure the elastic modulus. To use the elastic modulus measured by different measurement methods with a wide range of strain in practice, it is required to identify the correlation and relationship of measured values in advance. The comparison results of the measured elastic moduli ($E_{SSG}$, $E_{PLT}$, $E_{DCP}$) using the three measurement methods for domestic and overseas subgrade soils under various conditions indicate that the evaluated elastic modulus relies on the types of soils and the level of stress condition. The correlation analysis of the measured elastic moduli except the data of cement treated soils indicates that the static elastic modulus ($E_{PLT}$) is evaluated as about 60 to 80% of the dynamic elastic modulus ($E_{SSG}$). Unusual soils such as cement treated soils are required to be corrected by the stress correction during the correlation analysis with typical soils, because these types of soils are sensitive to the stress condition when measuring the static elastic modulus ($E_{PLT}$) of soils. In addition, when considering the use of DCP data for the evaluation of the elastic modulus ($E_{DCP}$), the measured data of the elastic modulus less than 200 MPa show more reliable correlation.

• Journal of the Korean Geotechnical Society
• /
• v.38 no.11
• /
• pp.55-67
• /
• 2022

This study applied the dynamic cone penetrometer test (DCPT) and light-weight deflectometer test (LWDT) to the quality control of subgrade base by performing DCPT, LWDT, and plate load test (PLT) at two earthwork sites. Although DCPT and LWDT were performed under the same conditions, the results showed significant variation with the test location. Because the measured value at the time of the initial blow, which varies depending on the test location, significantly influenced the test result. Thus, it was appropriate to ignore the first two blows as preliminary blows and use subsequent measurements as quality control indicators. In addition, DCPT, LWDT, and PLT results showed a high correlation under the same conditions. Especially regression analyses using averaged data for each experiment condition tended to yield significantly improved R² values over individual point data sets. This indicates that average DCPT and LWDT values at various adjacent locations are better quality control indicators for subgrade bases than individual point values.

• International Journal of Highway Engineering
• /
• v.8 no.1 s.27
• /
• pp.119-130
• /
• 2006

The behavior of continuously reinforced concrete pavement (CRCP) and the effect of the steel ratio on the behavior under moving wheel loads were investigated in this study. The CRCP sections having different steel ratios of 0.6, 0.7, and 0.8% were considered to evaluate the load transfer efficiency (LTE) at transverse cracks and to investigate the strains in CRCP when the system is subjected to moving vehicle loads. The LTEs were obtained by conducting the falling weight deflectometer (FWD) tests and the tests were performed at three different times of a day to find the curling effect due to the daily temperature changes in CRCP. The strains in the concrete slab and the bond braker layer of the CRCP system under moving vehicle loads were obtained using the embedded strain gages. The results of this study show that the LTEs at transverse cracks are very high and not affected by the time of testing and the steel ratio. The strains in CRCP under vehicle loads become smaller as the vehicle speed increases or as the wandering distance increases; however, the strains are not clearly affected by the steel ratio.