• Journal of the Korean GEO-environmental Society
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• v.18 no.11
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• pp.19-26
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• 2017

When narrowly excavated in the urban area, the wall of backfill space is not only symmetrical but also asymmetrical. In this case, the horizontal stress induced by backfilling depends mostly on the wall asymmetry and the wall friction angle. Therefore, in this study, the model test in the laboratory was conducted to investigate horizontal earth pressure with depth considering various boundary conditions such as base width, wall friction, relative density of backfill, and wall angle. As the wall is smoother and wall angle is lower from the bottom, the results showed higher the horizontal stresses due to the increase of vertical stresses.

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.986-992
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• 2003

We have calculated the probability of the OH formation and energy deposit of the reaction exothermicity in the newly formed OH, particularly in its vibrational motion, in the gas-surface reaction O(g) + H(ad)/Si → OH(g) + Si on the basis of the collision-induced Eley-Rideal mechanism. The reaction probability of the OH formation increases linearly with initial excitation of the HSi vibration. The translational and vibrational motions share most of the energy when the H-Si vibration is initially in the ground state. But, when the initial excitation increases, the vibrational energy of OH rises accordingly, while the energies shared by other motions vary only slightly. The product vibrational excitation is significant and the population distribution is inverted. Flow of energy between the reaction zone and the solid has been incorporated in trajectory calculations. The amount of energy propagated into the solid is only a few percent of the available energy released in the OH formation.

• Smart Structures and Systems
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• v.15 no.3
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• pp.881-896
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• 2015

The authors' research group has developed a noncontact type of sensors which directly measure the inter-story drift displacements of a building during a seismic event. Soon after that event, such seismically-induced drift displacement data would provide structural engineers with useful information to judge how the stories have been damaged. This paper presents a scheme of estimating the story cumulative plastic deformation ratios based on such measured drift displacement information toward the building safety monitoring. The presented scheme requires the data of story drift displacements and the ground motion acceleration. The involved calculations are rather simple without any detailed information on structural elements required: the story hysteresis loops are first estimated and then the cumulative plastic deformation ratio of each story is evaluated from the estimated hysteresis. The effectiveness of the scheme is demonstrated by utilizing the data of full-scale building model experiment performed at E-defense and conducting numerical simulations.

• Structural Engineering and Mechanics
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• v.44 no.6
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• pp.763-774
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• 2012

Reinforced concrete frame structures with masonry infill walls constitute the significant portion of the building stock in Turkey. Therefore it is very important to understand the behavior of masonry infill frame structures under earthquake loads. This study presents an experimental work performed on reinforced concrete (RC) frames with different types of masonry infills, namely standard and locked bricks. Earthquake effects are induced on the RC frames by quasi-static tests. Results obtained from different frames are compared with each other through various stiffness, strength, and energy related parameters. It is shown that locked bricks may prove useful in decreasing the problems related to horizontal and vertical irregularities defined in building codes. Moreover tests show that locked brick infills maintain their integrity up to very high drift levels, showing that they may have a potential in reducing injuries and fatalities related to falling hazards during severe ground shakings.

• Structural Engineering and Mechanics
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• v.36 no.4
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• pp.481-497
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• 2010

The shaking table tests were conducted on two small-scale models (Model 1 and Model 2) to examine the earthquake-induced damage of a concrete gravity dam, which has been planned for the construction with the recommendation of the peak ground acceleration of the maximum credible earthquake of 0.42 g. This study deals with the numerical simulation of shaking table tests for two smallscale dam models. The plastic damage constitutive model is used to simulate the crack/damage behavior of the bentonite-concrete mixture material. The numerical results of the maximum failure acceleration and the crack/damage propagation are compared with experimental results. Numerical results of Model 1 showed similar crack/damage propagation pattern with experimental results, while for Model 2 the similar pattern was obtained by considering the modulus of elasticity of the first and second natural frequencies. The crack/damage initiated at the changing point in the downstream side and then propagated toward the upstream side. Crack/damage accumulation occurred in the neck area at acceleration amplitudes of around 0.55 g~0.60 g and 0.65 g~0.675 g for Model 1 and Model 2, respectively.

• Geomechanics and Engineering
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• v.7 no.1
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• pp.87-103
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• 2014

This study investigated the effect of soil-structure interaction (SSI) on the response of base-isolated buildings. Seismic isolation can significantly reduce the induced seismic loads on a relatively stiff building by introducing flexibility at its base and avoiding resonance with the predominant frequencies of common earthquakes. To provide a better understanding of the movement behavior of multi-story structures during earthquakes, this study analyzed the dynamic behavior of multi-story structures with high damping rubber bearing (HDRB) behavior base isolation systems that were built on soft soil. Various models were developed, both with and without consideration of SSI. Both the superstructure and soil were modeled linearly, but HDRB was modeled non-linearly. The behavior of the specified models under dynamic loads was analyzed using SAP2000 computer software. Erzincan, Marmara and Duzce Earthquakes were chosen as the ground motions. Following the analysis, the displacements, base shear forces, top story accelerations, base level accelerations, periods and maximum internal forces were compared in isolated and fixed-base structures with and without SSI. The results indicate that soil-structure interaction is an important factor (in terms of earthquakes) to consider in the selection of an appropriate isolator for base-isolated structures on soft soils.

• Geomechanics and Engineering
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• v.7 no.1
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• pp.55-73
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• 2014

The theoretical predictions of ground movements induced by tunnelling are usually based on the assumptions that the subsoil has the same soil densities. The theoretical prediction does not consider the impact of different sand soil types on the surface settlement due to tunnelling. The finite elements analysis (FEA) considers stress and strength parameters of the different sand soil densities. The tunnel construction requires the solution of large soil-structure interaction problem. In the present study, the FEA is used to model soil-tunnel system performance based on a case study to discuss surface displacement due to tunnelling. The Greater Cairo metro tunnel (Line 3) is considered in the present study as case study. The surface displacements obtained by surface displacement equation (SDE) proposed by Peck and Schmidt (1969) are presented and discussed. The main objective of this study is to capture the limitations of the parameters used in the SDE based on the FEA at different sand soil densities. The study focuses on the parameters used in the SDE based on different sand soil densities. The surface displacements obtained by the FEA are compared with those obtained by the SDE. The results discussed in this paper show that the different sand soil densities neglected in the SDE have a significant influence on the surface displacement due to tunnelling.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.1
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• pp.3-12
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• 2002

This research work is to investigate influences of the Opera House in Arts Center caused by the twin tunnel construction. The Opera House of 3D structural feature with various type of foundations and adjacent twin tunnels are modeled in 3-Dimensional mesh for FEM analysis. Confirmation of safety is essential for this particular type of structure, and attention level and warning level of control criteria are examined for the protection of the Opera House by means of the analytical results.

• International Journal of Railway
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• v.6 no.3
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• pp.95-106
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• 2013

Earthborne vibrations are induced by construction operation such as pile driving, roadbed compaction, and blasting and also by transit activities such as truck and trains. The earthborne vibration creates the stress waves traveling outward from the source and can structurally damage nearby buildings and structures in the forms of direct damage to structure and damage due to dynamic settlement. The wave propagation characteristics depends on impact or vibration energy, distance from the source, and soil characteristics. The aim of this paper is to provide a comprehensive review on the mechanistic of earthborne vibration and the current practice of vibration control and mitigation measures. The paper describes the state of knowledge in the areas of: (1) mechanics of earthborne vibration, (2) damage mechanism by earthborne vibration, (3) calculation, prediction of ground vibration, (4) the criteria of vibration limits, (5) vibration mitigation measures and their performance, and (6) the current practice of vibration control and mitigation measures.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1675-1679
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• 2003

The photodynamics of excited-state intramolecular proton transfer reaction of 1-hydroxyanthraquinone (1-HAQ) and 1-deuterioanthraquinone was investigated in toluene with time-resolved emission and femtosecond transient transmittance techniques at room temperature. The temporal profiles of transient transmittance of 1-HAQ could be well described with multi-decaying time constants. The ultrafast time constant within ca. 260 fs reflects the dynamics of proton transfer. The decay component of 2 ps is assigned to an additional proton translocation process induced by the intramolecular vibrational relaxation, whereas the decay component of 18 ps is assigned to the vibrational cooling process, while the long component (200 ps) can be explained in terms of the relaxation from excited-state keto-tautomer to its ground state. Time-resolved anisotropy decay dynamics and isotope effects on the photodynamics reveals that the ESIPT from enol-tautomer to keto-one of 1-HAQ is barrierless reaction and coupled to a vibrational relaxation process.