• Journal of Korean Association for Spatial Structures
• /
• v.7 no.6
• /
• pp.103-110
• /
• 2007

Only horizontal seismic waves are often applied as designed load to a rectangular rigid frame because the influence of vertical seismic waves is considered small so as to be able to ignore it. But, as for the seismic responses of shell and spatial structures, the responses in the vortical direction is significantly amplified and the vertical responses are amplified even if they are subjected to the horizontal seismic wave only. And also, the horizontal and vertical seismic responses of shell and spatial structures are amplified by vortical seismic waves. An arch has been often used as the main structure component of the large spatial structures and is the mostly simple structure with the seismic response characteristics of the spatial structures. In this paper, for arches as a simple example of the shell and spatial structures, the dynamic characteristics, when the structures are subjected to the horizontal and vertical seismic wave at the same time, are studied, and the horizontal and vertical static seismic force, which have simple forms but hold the response characteristics of arches, are proposed.

• Ocean Systems Engineering
• /
• v.7 no.1
• /
• pp.1-19
• /
• 2017

This paper presents the numerical simulation results for the dynamic responses of two types of submerged floating tunnels (SFT) under wave and/or seismic excitations. Time domain simulations are conducted by the commercial program OrcaFlex (OF) and in-house CHARM3D program (CP). The dynamic performances of a short/rigid/free-end SFT section with vertical and inclined mooring lines are evaluated. The SFT numerical models were validated against Oh et al.'s (2013) model test results under regular wave conditions. Then the numerical models were further applied to the cases of irregular waves or seismic motions. The main results presented are SFT surge/heave motions and mooring tensions. The general trends and magnitudes obtained by the two different software packages reasonably agree to each other along with experimental results. When seabed seismic motions are applied to the SFT system, the dynamic responses of SFTs are small but dynamic mooring tension can significantly be amplified. In particular, horizontal earthquakes greatly increase the dynamic tension of the inclined mooring system, while vertical earthquakes cause similar effect on vertical mooring system.

• Earthquakes and Structures
• /
• v.26 no.2
• /
• pp.149-162
• /
• 2024

Aiming at the current research on the dynamic response analysis of the vehicle-bridge system under earthquake, which fails to comprehensively consider the impact of seismic wave incidence angles, terrain effects and soil-structure dynamic interaction on the bridge structure, this paper proposes a multi-point excitation input method that can consider the oblique incidence seismic P Waves based on the viscous-spring artificial boundary theory, and verifies the accuracy and feasibility of the input method. An overall numerical model of vehicle-bridge-soil foundation system in valley terrain during oblique incidence of seismic P-wave is established, and the effects of seismic wave incidence characteristics, terrain effects, soil-structure dynamic interactions, and vehicle speeds on the dynamic response of the bridge are analyzed. The research results indicate that with an increase in P wave incident angle, the vertical dynamic response of the bridge structure decreased while the horizontal dynamic response increased significantly. Traditional design methods which neglect multi-point excitation would lead to an unsafe structure. The dynamic response of the bridge structure significantly increases at the ridge while weakening at the valley. The dynamic response of bridge structures under earthquake action does not always increase with increasing train speed, but reaches a maximum value at a certain speed. Ignoring soil-structure dynamic interaction would reduce the vertical dynamic response of the bridge piers. The research results can provide a theoretical basis for the seismic design of vehicle-bridge systems in complex mountainous terrain under earthquake excitation.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.23 no.3
• /
• pp.191-199
• /
• 2019

To calculate proper seismic design load and seismic design category, the exact site class for construction site is required. At present, the average shear-wave velocity for multi-layer soil deposits is calculated by the sum of shear-wave velocities without considering of vertical relationship of the strata. In this study, the transfer function for the multi-layered soil deposits was reviewed on the basis of the wave propagation theory. Also, the transfer function was accurately verified by the finite element model and the eigenvalue analysis. Three methods for site period estimation were evaluated. The sum of shear-wave velocities underestimated the average shear-wave velocities of 526 strata with large deviations. The equation of Mexican code overestimated the average shear-wave velocities. The equation of Japanese code well estimated the average shear-wave velocities with small deviation.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.10a
• /
• pp.108-115
• /
• 2000

Numerical analysis of slop stability is presented using seismic displacement, response seismic coefficient, and earthquake response analysis methods. In seismic displacement and response seismic coefficient methods, horizontal static seismic force is considered as 0.2g while vertical static seismic force is not considered in analysis. For earthquake response analysis Hahinoha-wave is applied, It is found from result that analysis using response seismic coefficient method is much more conservative than that using seismic displacement method Also, analysis result using earthquake response analysis method is somewhat less conservative about 25% when compared with that using seismic displacement method.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.193-200
• /
• 2000

Numerical analysis of slope stability is presented using slice method, static seismic analysis methods, and earthquake response analysis methods. Static seismic force is considered as 0.2g while vertical static seismic force is not considered in analysis. For earthquake response analysis, Hachinohe-wave is applied. Safety factor calculated using slice method for failure surface. Calculating methods are Bishop's method and Janhu's method. Static seismic analysis was applied using Mhor-Coulomb model and earthquake response analysis was applied using non-linear elastic model.

• Geophysics and Geophysical Exploration
• /
• v.9 no.3
• /
• pp.193-206
• /
• 2006

Among various borehole seismic testing techniques for determining body wave velocity, crosshole seismic method has been known as one of the most suitable technique for evaluating reliably geotechnical dynamic properties. In this study, to perform successfully the crosshole seismic test for rock as well as soil layers regardless of the groundwater level, multi-purposed spring-loaded source which impact horizontally a subsurface ground in vertical borehole was developed and applied at major facility sites in Korea. The geotechnical dynamic properties were evaluated by determining efficiently the body wave velocities such as shear wave velocity and compressional wave velocity from the horizontally impacted crosshole seismic tests at study sites, and were provided as the fundamental parameters for the seismic performance evaluation and seismic design of the target facilities.

• Geomechanics and Engineering
• /
• v.3 no.4
• /
• pp.255-266
• /
• 2011

Knowledge of seismic earth pressure against rigid retaining wall is very important. Mononobe-Okabe method is commonly used, which considers pseudo-static approach. In this paper, the pseudo-dynamic method is used to compute the distribution of seismic earth pressure on a rigid cantilever retaining wall supporting dry cohesionless backfill. Planar rupture surface is considered in the analysis. Effect of various parameters like wall friction angle, soil friction angle, shear wave velocity, primary wave velocity, horizontal and vertical seismic accelerations on seismic earth pressure have been studied. Results are presented in terms of tabular and graphical non-dimensional form.

• Earthquakes and Structures
• /
• v.13 no.1
• /
• pp.67-77
• /
• 2017

Oil storage tanks are vital life-line structures, suffered significant damages during past earthquakes. In this study, a numerical model for an unanchored vertical vaulted-type tank was established by ANSYS software, including the tank-liquid coupling, nonlinear uplift and slip effect between the tank bottom and foundation. Four actual earthquakes recorded at different soil sites were selected as input to study the dynamic characteristics of the tank by nonlinear time-history dynamic analysis, including the elephant-foot buckling, the liquid sloshing, the uplift and slip at the bottom. The results demonstrate that, obvious elephant-foot deformation and buckling failure occurred near the bottom of the tank wall under the seismic input of Class-I and Class-IV sites. The local buckling failure appeared at the location close to the elephant-foot because the axial compressive stress exceeded the allowable critical stress. Under the seismic input of Class-IV site, significant nonlinear uplift and slip occurred at the tank bottom. Large amplitude vertical sloshing with a long period occurred on the free surface of the liquid under the seismic wave record at Class-III site. The seismic properties of the storage tank were affected by site class and should be considered in the seismic design of large tanks. Effective measures should be taken to reduce the seismic response of storage tanks, and ensure the safety of tanks.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.6C
• /
• pp.241-253
• /
• 2010

For seismic design of a vertical shaft, three-dimensional Finite Element (FE) analyses were performed to evaluate the accurate response of a vertical shaft and to apply a Response Displacement Method (RDM). Special attention is given to the evaluation of seismic base and response displacement of surrounding soil, estimation of load and loading method. Based on the result, it was found that shear wave velocity of seismic base greater than 1500m/s was appropriate for the seismic design. It was also found that double cosine method which evaluates a response displacement of surrounding soil was most appropriate to consider the characteristic of multi-layered soil. Finally, shape effect of the structure was considered to clarify the dynamic behavior of vertical shaft and it would be more economical vertical shaft design when a vertical shaft was analyzed by using RDM.