• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.04b
• /
• pp.347-354
• /
• 2000

The seismic behaviors of a bridge system with several simple spans are examined to see the effects of the longitudinal stiffness degradation due to abutment-soil interaction. The abutment-backfill system is modeled as one degree-of-freedom-system with nonlinear spring and linear damper. various soil-conditions surrounding the abutment such as loose sand, medium dense sand, and dense sand are considered in the bridge seismic analysis. The idealized mechanical model for the whole bridge system is modeled by adopting the multiple-degree-of-freedom system, which can consider components such as pounding phenomena, friction at the movable supports, rotational and translational motions of foundations, and the nonlinear pier motions. The stiffness of the abutment is found to be rapidly reduced at the beginning of the earthquakes, and to be converged to constant values shortly after the displacement approaches to the Predefined critical values. It is observed that the maximum relative distanced an maximum relative displacements are generally Increased as the relative density of a soil decreases As the peak ground acceleration increases, the response ratio of the case considering stiffness degradation to the case considering constant stiffness decreases.

• Computational Structural Engineering
• /
• v.1 no.1
• /
• pp.103-112
• /
• 1988

In this study, the earthquake response of building structures with foundation uplift was investigated. The Winkler foundation model and two-spring model are widely used to represent the interaction between foundation mat and soil. While the analysis using the Winkler foundation model results in more accurate prediction, it requires a complex procedure and longer computation time. In this study, an equivalent two-spring model(S model) is proposed. The S model can represent the Winkler foundation model more accurately and the analysis using the S model is simpler and more effective. The S model is derived by simplifying the nonlinear moment-rotation relationship of foundation mat. The dynamic responses predicted by the S model gave a good agreement to those of the Winkler foundation model.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2008.04a
• /
• pp.483-489
• /
• 2008

Masonry infill walls are frequently used as interior partitions and exterior walls in low- or middlerise RC buildings In the structural design and assessment of structural behaviors of buildings, the infill walls are usually treated as non-structural elements and they are ignored in analytical models. In this study, seismic behaviors of RC frame with/without masonry infill walls were investigated. To this end, the infill walls were modeled as equivalent diagonal struts. Based on analytical results, it has been shown that masonry infill walls can increase the global strength and stiffness of a structure. Accordingly, inter-story drift ratio will be decreased but seismic forces applied to the structure were increased than design seismic load because natural period of the structure was decreased. It is also seen from the analytical results that the inelastic deformation of RC frame with soft story is concentrated on the first story columns and thus, partial damage may have possibility of collapse of system.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1993.04a
• /
• pp.148-153
• /
• 1993

The paper presents the results of shaking table test conducted on the 1/3.3 scaled large concrete panel model. The behaviors of large concrete panel structures subjected to seismic excitations are controlled by capacity of horizontal and vertical joints. To Study the seismic capacity of the large concrete panel structures, experimental researches for joints and structural assemblage are needed. Especially, since the magnitude of seismic loads are depended on the variation of time, period and accelerations, dynamic test is needed for estimating the seismic resistance of large concrete panel structures. The objective of this paper is to study the behaviors of large concrete panel structures on seismic excitations and to estimate the safety. Test results are as follows : 1) Test model was critically damaged in the first floor horizontal joint by rocking. 2) Elastic limit(0.12kg) of test model was 5times higher than that of korean seismic design code. 3) Maxium base shear of test model at the ground acceleration of 0.12g was 3.5 times higher than the result of equivalent static analysis. 4) Damping ratio of test model turned out 3.9~5.3% and the period at 0.12g was 0.065sec.

• Computational Structural Engineering
• /
• v.3 no.3
• /
• pp.141-146
• /
• 1990

This study is on a seismic analysis of absorber rod in KMRR Reactivity Control Mechanism. The model being studied is two coaxial tubes(control absorber rod and flow tube) immersed in the water and partially coupled(overlap) by water gap. The hydrodynamic mass effects by the water in each surrounding conditions are considered in the model. The natural frequencies, stresses and displacements of the system due to Safe Shutdown Earthquake are computed in the cases of in-phase modes and out-of-phase modes of two coaxial tubes. The results show that maximum stresses are well below the allowable limit but the maximum displacements at the ends of both tubes are so much that the absorber rod contacts with the flow tube(or surrounding wall).

• Journal of Ocean Engineering and Technology
• /
• v.28 no.1
• /
• pp.12-19
• /
• 2014

Tsunamis are ocean waves generated by movements of the Earth's crust. Several geophysical events can lead to this kind of catastrophe: earthquakes, landslides, volcanic eruptions, and other mechanisms such as underwater explosions. Most of the damage associated with tsunamis are related to their run-up onto the shoreline. Therefore, effectively predicting the run-up process is an important aspect of any seismic sea wave mitigation effort. In this paper, a numerical simulation of the behaviors of a floating body near a quaywall during a tsunami is conducted by using a particle method. First, a solitary wave traveling over shallow water with a slope is numerically simulated, and the results are compared with experiments and other numerical results. Then, the behaviors of floating bodies with different drafts are investigated numerically.

• Journal of Korean Society of Steel Construction
• /
• v.12 no.6
• /
• pp.681-690
• /
• 2000

Recently, a long span is often required for the spacious building. Therefore the increase of stiffness is necessary to prevent floor vibration and control deformation of the building under earthquake and wind loads. For this purpose, steel beams with stiffened ends by reinforced concrete are effective. To realize such an effective reinforcement method, the smoothening of bending and shear stress transmission at the boundaries between middle-part of the steel beam and both end-parts of the steel beam with stiffened ends by reinforced concrete is required. Therefore, the fixed plate was installed at the boundary with the view of transferring the stress smoothly. This paper evaluates the method of effective transmission of bending and shear stress through the numerical analysis that is based on advanced experimental tests.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.2
• /
• pp.329-339
• /
• 2002

This research presents a systematic design procedure for supplemental viscoelastic dampers required to satisfy the given performance objectives using capacity spectrum method. To obtain required damper size, the amount of supplemental damping was computed from effective damping minus equivalent damping and inherent damping of structure. In the case of viscoelastic damper, iterative procedure is required because of the inherent stiffness of the damper. To verify the design method proposed in this study, parametric studies were performed for single degree of freedom systems with design variables. The method was also applied to a 10-story steel framed structure and the earthquake responses were obtained. According to time history analysis result the controlled displacements turned out to be close to the target displacement regardless of the design parameters.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.9 no.5
• /
• pp.87-95
• /
• 2010

Lots of bridge structure generated the change of outward formation according to durability capability and decrepitude by long use. Especially, in case of the typhoon, snowing and earthquake is going to make rapidly more worse formation about the old structural facilitys. Also, outward formation by irregular and micro-distortion in bridge structure could not easily checked by normal diagnostics method. As a result, performance-capability of structure facility is getting to make a decline in standard of structure performance. Recently, real-time monitoring technology by wireless environment go into the study of irregular movement for structure facility. This paper presents the development of sensor to displacement checking about bridge structure. Sensing method of developed sensor put bring into the gyroscope technology using the acceleration speed and angular acceleration speed. This paper also will simulated to verified the monitoring capability of developed sensor against random vibration, frequency and distortion in simulated equipment.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.3
• /
• pp.126-126
• /
• 2002

In dynamic analyses such as seismic ground response and soil-structure interaction problems, it is very crucial to obtain accurate dynamic shear modulus of soil deposit. In this study, an extensive data base of available experimental data is compiled and reanalyzed to establish a simple empirical formula for the dynamic shear modulus reduction curve to cover wide range of strain for sandy soils. The proposed empirical equation is to represent the dynamic shear modulus degradation with strain in terms of low-amplitude dynamic shear modulus and effective mean confining Pressure, since those factors have the most significant effect on the Position and shape of the shear modulus reduction curve for nonelastic soils. If low-amplitude shear modulus is measured, degraded modulus at any shear strain amplitude can be calculated using the proposed equation.