• Journal of the Earthquake Engineering Society of Korea
• /
• v.3 no.2
• /
• pp.1-8
• /
• 1999

The present paper describes an approximation for estimation of earthquake-induced hydrodynamic loads in rigid storage tank which accelerated in horizontal direction. The storage tank is vertically cylindrical, and the sectional shape may be circular, rectangular or irregular. The solution for harmonic excitation is studied based on velocity potential theory, and then the time domain solution for earthquake is obtained by using design response spectrum. As a result, earthquake load is influenced primarily by the inertia force of high frequency effective mass of the storage tank, responding to the characteristics of design response spectrum, tank sectional shape, and the ratio of tank base length to depth. Earthquake-induced hydrodynamic loads in rigid storage tank can be effectively obtained by using the high frequency approximation method in case of quite large, or small ratio of the tank base length to water depth.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.6
• /
• pp.113-125
• /
• 2017

In spite of bulk literature about the tuning of TMD, the effectiveness of TMD in reducing the seismic response of engineering structures is still in a row. This paper deals with the optimum tuning parameters of a passive TMD and simulated on MATLAB with a ten-story numerical shear building. A weighted multi-objective optimization method based on computer experiment consisting of coupled with central composite design(CCD) central composite design and response surface methodology(RSM) was applied to find out the optimum tuning parameters of TMD. After the optimization, the so-conceived TMD turns out to be optimal with respect to the specific seismic event, hence allowing for an optimum reduction in seismic response. The method was employed on above structure by assuming first the El Centro seismic input as a sort of benchmark excitation, and then additional recent strong-motion earthquakes. It is found that the RSM based weighted multi-objective optimized damper improves frequency responses and root mean square displacements of the structure without TMD by 31.6% and 82.3% under El Centro earthquake, respectively, and has an equal or higher performance than the conventionally designed dampers with respect to frequency responses and root mean square displacements and when applied to earthquakes.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.6
• /
• pp.655-662
• /
• 2011

For analyzing seismic performance of long-span bridge for multi-support excitation and preparing technically and efficiently for a variety of design demands, the new module on multiple excitation was built in a reliable non-linear analysis program(RCAHEST) by using Influence Line Method, and the study on structures was performed previously. Also, the result of the analysis through RCAHEST was compared and verified with commercial finite element analysis program SAP2000 by using the feature of Multi-Support Excitation. From these results, nonlinear time history analysis considering multi-support excitation was studied after designing FE model of Incheon cable-stayed bridge. It was proved that the maximum response of horizontal displacement decreased as the time delay was increasing at all nodes of bridge. And then the serviceability of analysis model was evaluated by performing ultimate analysis under changes in maximum acceleration of seismic load data.

• Journal of Korean Association for Spatial Structures
• /
• v.6 no.1 s.19
• /
• pp.101-109
• /
• 2006

An initial member sections of steel structures is selected by experience of expert building structural designers. And appropriate member section is designed by repeat calculation through structural analysis. Therefore an initial assumption of member section is necessary for saving the time for structural design and is important to acquire safety of building structures. Also brace damper are generally used to prevent or decrease stuctural damage by its hysteretic behavior in building structures subjected to strong earthquake. Based on plastic design, the initial section of members for architectural steel structures with hysteretic damper braces is presented and seismic effect of structural behavior by the ratio of damper stiffness to structural story stiffness is estimated in this paper.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.16 no.4
• /
• pp.9-18
• /
• 2012

In this study, a shaking table test was performed for the evaluation of water extinguishing facilities. Water extinguishing facilities, such as a general pipe, a seismic pipe (Loof type) and a pump, were used in the experiment. This captured the dynamic characteristics of water extinguishing systems by earthquake records at El-Centro with a 50%, 70%, 100%, 120% level. As a result, seismic type facilities have excellent seismic performance compared to general facilities. By using the acceleration response spectrum, not only is the performance evaluation of water extinguishing facilities able to be determined, but also the deformation of facilities in low earthquake levels can be known. This proposed approach can determine the seismic performance evaluation of water extinguishing facilities and verify seismic performance criteria.

• The Korean Journal of Applied Statistics
• /
• v.36 no.4
• /
• pp.309-322
• /
• 2023

The Hawkes process is a point process with self-exciting characteristics. It has been mainly used to describe seismic phenomena in which aftershocks occur due to the main earthquake. Recently, it has been used to explain various phenomena with self-exciting properties, such as the spread of infectious diseases and the spread of news on SNS. The Hawkes process can be flexibly modified according to the characteristics of events by using various types of excitation functions. Since it is difficult to implement a maximum likelihood estimator numerically, estimation methods have been improved until recently. In this paper, the conditional intensity function and excitation function are explained to describe the Hawkes process. Then, existing examples of Hawkes processes used in seismic, epidemiological, criminal, and financial fields are described and estimation methods are introduced. I analyze earthquakes that occurred in gyeongsang-do, Korea from November 2017 to December 2022, using R package ETAS.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.1 no.1
• /
• pp.11-17
• /
• 1997

Seismic analyses of structures were carried out in the past assuming a right base and Ignoring the characteristics of foundations and the properties of the underlying soil. Resent soil-structure interaction studies show that seismic response of structure can be affected significantly by these fators. Typical effects of the soil-structure interaction are the kinematic interaction of a rigid massiess foundation and the inertial interaction between underlying soil and structure. The kinematic interaction effect is particularly important for embedded foundations and can be ignored for surface foundations with vertically propagating waves. In this study, seismic response of structure was investigated with four buildings in Mexico City considering only the inertial interaction effect and using the E-W components of the 1985 Mexico City earthquake records. The study was carried out for surface foundations and pile foundations with linear and nonlinear soil conditions, comparing the results with those of the rigid base.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.7 no.1
• /
• pp.57-63
• /
• 2003

A comparative study was performed for a suspension bridge to grasp the possible differences in seismic responses evaluated by several analytical methods. The items mainly investigated are the linear vs. nonlinear response, the response spectrum method vs. the linear dynamic analysis method, and the damping ratio and it's implementation into analysis procedures. According to the numerical example, it is found that the seismic responses are considerably affected by the damping-related parameters even though slight differences are shown depending on the response quantities and the exciting directions. On the other hand, it is also confirmed that the seismic responses are less affected by the analysis method-related parameters such as the response spectrum method vs. the linear dynamic analysis method, and the linear and nonlinear analysis method. The response spectrum method is expected to give conservative results for the examined bridge, provided that the design response spectrum in the Korean Highway Design Specification is modified according to the proper damping ratio.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.15 no.6
• /
• pp.67-80
• /
• 2011

This paper presents the results of shaking table tests on a 1:5 scale 10-story R.C. wall-type residential building model. The following conclusions are drawn based on the test results. (1) The model responded linear elastically under the excitations simulating an earthquake with a return period of 50 years, and showed a nonlinear response under the excitations simulating the design earthquake of Korea. (2) The model showed a significant strength drop under the maximum considered earthquake, with a return period of 2400 years. (3) The major portion of the resistance to lateral inertia forces came from the walls used for the elevator and stair case. (4) Finally, the damage and failure modes appear to be due to the flexural behavior of walls and slabs. A significant deterioration of stiffness and an elongation of the fundamental periods were observed under increased earthquake excitations.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.13 no.3
• /
• pp.39-50
• /
• 2009

In this paper, a method for reducing seismic responses of adjacent buildings is studied that involves connecting two buildings with energy-dissipating devices, such as MR dampers. For the vibration control of the adjacent buildings, a fuzzy control technique with semi-active MR dampers is proposed. A fuzzy controller, which can appropriately modulate the damping forces by controlling the input voltage in real time, is designed according to the proposed method. To verify the validity of the proposed method, numerical simulations are performed. In the numerical simulations, historical earthquake records with diverse frequency contents and different peak values are used. For the purpose of comparison, an uncontrolled system, a passive control system and a semi-active fuzzy control system are considered. The comparative results prove the effectiveness of the proposed control technique, i.e. the numerical results show that the fuzzy controlled semi-active MR dampers can effectively reduce the earthquake responses of the adjacent structures.