Artificial Earthquake Waves Research Articles

Analysis of seismic damage and seismic capacity of the structure of the ultrahigh pagoda

AbstractThe Chongwen Pagoda is the tallest masonry pagoda in China, with numerous openings inside the pagoda body. It is prone to damage during earthquakes, and the patterns of damage are complex. In order to scientifically analyze the dynamic performance, earthquake damage patterns, and mechanisms of the pagoda structure, on‐site dynamic testing was conducted to obtain the dynamic characteristics of the structure. A numerical model was established using Abaqus finite element software to calculate the dynamic characteristics of the structure. The results were compared with the testing results and showed a close agreement. El‐Centro earthquake wave, Taft earthquake wave, and Lanzhou artificial earthquake wave were selected as earthquake inputs based on site conditions, simulating frequent earthquakes, fortification earthquakes, and rare earthquakes with a magnitude of 9. The dynamic response of the pagoda structure was calculated, and the relationship between acceleration amplification factor, interstorey displacement, and interstorey displacement angle with floor height was analyzed. The seismic damage to the structure and the distribution of primary tensile stresses were studied, revealing the seismic damage mechanisms and the distribution characteristics of vulnerable areas in the Chongwen Pagoda. The research results provide references for the seismic assessment of this ancient pagoda.

Pseudo-Dynamic Test on Composite Frame with Steel-Reinforced Recycled Concrete Columns and Steel Beams

Pseudo-dynamic tests were conducted on a 2/5-scaled, three-story, two-span frame with steel-reinforced recycled concrete (SRRC) columns and steel beams. The El-Centro earthquake waves, Taft earthquake waves, and Lanzhou artificial earthquake waves were considered as the main loads to study the seismic behavior. The failure modes, displacement and acceleration time history curves, hysteretic characteristics, energy dissipation, stiffness degradation, and inter-story drift capacity of the composite frame were analyzed. Results showed that the composite frame did not show plastic deformation during the whole test process, and the steel beams and columns basically did not yield. Under the action of three seismic waves, the displacement response, acceleration response, and restoring force response of the composite frame were increased with seismic intensity, while the hysteretic curves and energy dissipation were different as the seismic wave changed. The seismic response of the composite frame was greatly affected by the spectral characteristics of the loading ground motion and the hysteretic energy mainly consisted of recoverable elastic deformation energy. Under the action of Taft wave with the input peak acceleration of 400 gal (rare earthquake), the stiffness degradation of composite frame was the largest, which reduced to 47% of the initial stiffness. This indicated that the composite frame had good energy dissipation performance in the elastic and elastic-plastic stages, and still possessed good rigidity after a rare earthquake, fully achieving the design purpose of “no collapse in major earthquake”.

Generating Artificial Earthquake Wave Compatible with High-damping Target Spectra

Generating Artificial Earthquake Wave Compatible with High-damping Target Spectra

Study on Seismic Load Characteristics of Regulations and Integrity Evaluation of Wind Turbine

This paper relates to the study of load characteristics applicable to wind turbine generators induced by earthquakes. An artificial design earthquake wave generated through the target spectrum and the envelope function of Richter Magnitude Scale (ML) 7.0 as in ASCE4-98 was created. A simulation of earthquake loads were performed according to the design load cases (DLC) 9.5~9.7 of GL guidelines. Additionally, simulation of seismic loads experienced by Wind Turbines installed in the Gyeongju region were carried out utilizing artificial earthquakes of ML 5.8 simulating the real earthquakes during the Gyeongju Earthquakes of Sept. 2016.

Seismic Performance Evaluation of Steel Frame-Steel Plate Shear Wall Using Pushover and IDA

Based on the time-history analysis principle of bidirectional equivalent tension rod of steel shear wall in this paper, the theory of Incremental Dynamic Analysis (IDA) is used to investigate the real seismic behavior of steel frame-steel plate shear wall (SPSW) system under a large number of natural earthquake waves and artificial simulated earthquake waves with the gradually increased scale of seismic intensity in order to achieve the base shear-roof displacement (V-Δ) curve under each earthquake wave action. Based on the principle of unidirectional equivalent tension rod, the pushover analysis is also used to obtain the curve of base shear and roof displacement under two different loading modes of uniform distribution and inverted triangular distribution. Through the above two different methods of seismic behavior evaluation, the achieved conclusions are as follows: The most V-Δ envelope curves obtained by IDA analysis are between V-Δ envelope curves obtained by pushover analysis under these two loading modes of inverted triangular and uniform distribution. With the increase of structural storey, the effect of high order mode on seismic behavior is more and more obvious and the deviation of calculation results derived from pushover is bigger and bigger. As a result, pushover analysis is only applied to evaluate seismic performance of structure at the middle or low storey. For the pushover, the structural bearing capacity and initial stiffness is underestimated, but the structural deformation capacity is overestimated under inverted triangular loading mode, Whereas, it is the opposite situation under the uniform distribution.

A Self-Centering Seismic Design for Bridge with Pile-Cap Foundation

In this paper, an alternative aseismic system for bridge with pile-cap foundation called a separated pile-cap with proper material set in the gap layer was proposed. To simulate the system, a 3-dimensional finite element model for a continuous beam bridge was built. The seismic responses of the model, including behavior of the restrainer, moment at the bottom of the pier and pullout force of the piles with different restrainer lengths under 3 longitudinal artificial earthquake waves were analyzed. The results show that this system can reduce the seismic response significantly.

등가정적해석법에 의한 수계 파이프 시스템의 내진설계

In this study, seismic design in pipeline of pressurized water supply system of water extinguishing system has been carried out. This study described a generation of artificial earthquake wave compatible with seismic design spectrum, and also determined equivalent static loads to analyzed the response spectra acceleration by the simulated earthquake motion. This study constructed powerful engineering base for seismic design, and presented equivalent static analysis method for seismic design of water and gas extinguishing piping system. Also, this study readied basis that can apply seismic design and performance estimation of fire fighting system as well as pipeline of water extinguishing system from result of this research. Hereafter, if additional research by earthquake magnitude and ground kind is approached, reliance elevation, safety raising and performance based design of fire fighting system see to achieve.

Recording artificial earthquake wave signals using a detector model

No abstract

설계용 탄성응답스펙트럼으로 규준화된 인공지진동과 기록지진동의 비선형 지진응답

In the nonlinear response history analysis of building structures, the input ground accelerations have considerable effect on the nonlinear response characteristics of structural systems. As the properties of the ground motion, using time history analysis, are interrelated with many factors such as the fault mechanism, the seismic wave propagation from source to site, and the amplification characteristics of the soil, it is difficult to properly select the input ground motions for seismic response analysis. In this paper, the most unfavourable real seismic design ground motions were selected as input motions. The artificial earthquake waves were generated according to these earthquake events. The artificial waves have identical phase angles to the recorded earthquake waves, and their overall response spectra are compatible with the seismic design spectrum with 5% of critical viscous damping. It is concluded that the artificial earthquake waves simulated in this paper are applicable as input ground motions for a seismic response analysis of building structures.

Integrated Design of Structural and Semi-active Control Systems: Inverse Lyapunov Approach

An integrated design method of structural and semi-active control systems for civil structures is presented. The Vibration Control Device (VCD) that has been developed by authors is used as the semi-active control device. A new semi-active control method, which is referred to as the inverse Lyapunov approach, is proposed. In the inverse Lyapunov approach we firstly assume a bang-bang type semi-active control law based on an unknown Lyapunov function. The Lyapunov matrix that defines the Lyapunov function is optimized so that quantitative performance measures on vibration suppression of civil structures are optimized. The control design problem of the semi-active control law in the inverse Lyapunov approach results in an optimization problem of the Lyapunov matrix to construct the Lyapunov function. In the present study, in addition to the design parameters to determine the Lyapunov matrix, structural design parameters, the stiffness between neighboring two floors of the structural system itself and the parameters of the VCD, are optimized simultaneously so that the structural responses subject to recorded and/or artificial earthquake waves are optimized in the sense of the specifications on vibration suppression of civil structures. We adopt the Genetic Algorithm (GA) to get the optimal Lyapunov matrix and the structural design parameters.

Rocking Motion of Structures under Earthquakes (Overturning of 2-DOF System)

In recent years, huge earthquakes happen, for example, The South Hyogo prefecture Earthquake in 1995, The Mid Niigata Prefecture Earthquake in 2004, The Iwate-Miyagi Nairiku Earthquake in 2008. In The Niigataken Chuetsu-oki Earthquake in 2007, hundreds of drums fell down and water spilled out. A lot of studies about rocking behavior of rigid body had been performed from 1960's. However, these studies were only for a specific condition of the structure size or input vibration characteristics. Therefore, generalizes fall condition for earthquake is required. This paper deals with the analytical and the experimental study of the rocking vibration of 1-DOF rocking system, 2-DOF vibration-rocking system and 2-DOF rocking system under earthquakes. In this study, the equation of motion for each rocking systems are developed. The numerical model of 2-DOF rocking system is evaluated by free rocking experiment. In this paper, “Overturning Map” which can distinguish whether structures falls or not is proposed. The overturning map of each rocking systems excited by the artificial earthquake wave calculated from the design spectrum is shown. As the result, overturning condition of structures is clarified.

Inverse Lyapunov Approach for semi-active control of civil structures

In the present paper an Inverse Lyapunov method in a bang-bang type semi-active control for civil structures is proposed. The vibration control device (VCD) that has been developed by authors is employed for the semi-active control. The VCD is installed between two neighboring stories of structures like general dampers and generates two types of resistance forces, i.e. an inertial force proportional to the relative acceleration and a damping force proportional to the relative velocity of the two floors. The damping coefficient of the VCD can be changed by a command signal to an electric circuit connected to the VCD. In conventional Lyapunov-based semi-active control the Lyapunov function is firstly determined, mostly it is defined as the sum of the kinetic and potential energies at every instant, and the bang-bang type control is derived so that the dissipation rate of the defined Lyapunov function (the total energy) is maximized. In this paper, conversely, we assume the simple bang-bang type control firstly and then the Lyapunov function is searched so that the high performance on vibration suppression of civil structures, e.g. small relative displacement between adjacent two floors and absolute acceleration of each storey, etc., is achieved. Genetic Algorithm is adopted for the search of the Lyapunov function. Structural responses subject to recorded and artificial earthquake waves are used in the searching process. We show the effectiveness of the proposed Inverse Lyapunov Approach with a simulation example for a 15-storey building with three VCDs. Copyright © 2010 John Wiley & Sons, Ltd.

建築構造物に対する構造系とセミアクティブ制御系の統合化設計(<特集>D&D2009)

In this paper we address an integrated design problem of semi-active controlled civil structures with Vibration Control Device (VCD) that has been developed by authors. A new semi-active control law based on a one-step-ahead prediction of the seismic response is proposed. The VCD generates two types of resistance forces, i.e., a damping force proportional to the relative velocity and an inertial force proportional to the relative acceleration between two stories. The damping coefficient of the VCD can be changed with a command signal to an electric circuit connected to the VCD. In the present paper the command signal for changing the damping coefficient of each VCD is assumed to take two values, i.e., the command to take the maximum or minimum damping coefficient. The optimal command signal is selected from all candidates of command signals so that a norm of the one-step-ahead predicted seismic response, calculated by a numerical integration, is minimized. Under the semi-active control law the stiffness distribution between neighboring two stories of the structure, design parameters of the VCDs and those in the semi-active control are optimized so that the seismic responses subject to various recorded and artificial earthquake waves are optimized. Genetic Algorithm (GA) is adopted for the optimal design. A simulation example of a fifteen-story building with three VCDs is presented. With the proposed integrated design method structural parameters and the semi-active control law that achieve the good control performance have been obtained.

High-Rise Building Seismic Vibration Control Using Large Tuned Top-Floor Mass Damper

This paper details the design of a high-rise reinforced concrete building whose top floor is isolated and used as the mass for a large-scale mass damper, describing the effect of the vibration control realized. Conventional mass dampers with additional weight at the building tops have been installed to improve environmental vibration against strong wind. Mass dampers have rarely been used, however, as measure against earthquakes. We developed large-scale vibration control using the top floor building weight to serve as a mass damper. The building is a high-rise reinforced concrete structure, 162 meters high, with 43 above-ground stories. Based on seismic response analysis using artificial earthquake waves, the natural vibration period of the mass damper was tuned to decrease story drift in the entire building. The mass damper reduced maximum story drift angle by 20%.

エネルギに基づく摩擦系の応答低減マップ(機械力学,計測,自動制御)

For the past several years, seismic isolation systems have been focused in the seismic design of industrial facilities. This paper deals with the response reduction effect by friction. Friction is expected to decrease the relative displacement by dissipating the vibration energy. The relative displacement between structure and support becomes larger at long period in the case of linear system. Therefore, the response reduction effect by friction should be utilized positively in the seismic design. However, the response magnification of acceleration is used in the seismic design. The acceleration becomes larger by stick and slip motion. Therefore, the response reduction effect by friction is evaluated from the viewpoint of energy. The ratio between elastic energy and input energy is utilized. In this paper, "Response Reduction Map" based on energy for long period friction system is suggested. This map shows the range that energy response ratio is less than the ratio of the linear system. The response reduction map without complex non-linear time history calculation can easily obtain the proper parameters, such as natural period or friction force. At first in this study, the response reduction map by actual earthquake wave is shown. Next, the response reduction map by the artificial earthquake wave calculated from the design spectrum is shown.

설계용 스펙트럼에 적합한 인공지진동을 입력한 철근콘크리트 구조물의 지진응답 특성의 고찰

건축물의 지진응답해석에서 입력지진동은 구조물의 비선형 응답에 중요한 영향을 미치는 요소이다. 지진동의 특성은 표층지반의 성질과 국부적인 지반 조건에 따른 여러 가지 인자에 의해 그 특성이 결정되기 때문에 구조물의 지진응답해석에서 일반성을 갖는 입력지진동을 선정하는 것은 매우 어려운 문제이다. 본 논문은 내진설계용 스펙트럼에 적합한 인공지진동파형을 작성한 후, 작성된 인공지진동에 의한 철근콘크리트 다층 골조구조물의 탄소성 응답특성을 분석한 것이다. 여기서 작성된 인공지진동파형은 과거 비교적 큰 규모의 지진에서 얻어진 기록지진동과 동일한 위상각을 가지며, 감쇠정수 h=5%일 때의 내진설계용 스펙트럼과 거의 일치하도록 작성하였다. 입력지진동의 탄성 가속도 응답스펙트럼이 동일한반면, 각 입력지진동띄 위상특성이 다른 인공지진동을 입력하여 다자유도 골조 구조물의 지진응답을 분석하여 건축물의 내진설계용 지진동으로서 타당성을 확인하는 것이 목적이다. 본 논문에서 작성된 인공지진동은 기록지진동에 비해 지진응답치가 안정된 값을 나타내는 것을 확인할 수 있었다. 그러므로 다층 골조구조물의 비선형 지진응답해석용 입력지진동으로 타당성이 높다고 사료되며, 비선형 지진응답해석용 입력지진동의 강도를 탄성 가속도 응답스펙트럼으로 규준화 하는 것이 합리적이라고 사료된다. In seismic response analysis of building structures, the input ground accelerations have considerable effect on the nonlinear response characteristics of structures. The characteristics of soil and the locality of the site where those ground motions were recorded affect on the contents of earthquake waves. Therefore, it is difficult to select appropriate input ground motions for seismic response analysis. This study describes a generation of artificial earthquake wave compatible with seismic design spectrum, and also evaluates the seismic response values of multistory reinforced concrete structures by the simulated earthquake motions. The artificial earthquake wave are generated according to the previously recorded earthquake waves in past major earthquake events. The artificial wave have identical phase angles to the recorded earthquake wave, and their overall response spectra are compatible with seismic design spectrum with 5% critical viscous damping. The input ground motions applied to this study have identical elastic acceleration response spectra, but have different phase angles. The purpose of this study is to investigate their validity as input ground motion for nonlinear seismic response analysis. As expected, the response quantifies by simulated earthquake waves present better stable than those by real recording of ground motion. It was concluded that the artificial earthquake waves generated in this paper are applicable as input ground motions for a seismic response analysis of building structures. It was also found that strength of input ground motions for seismic analysis are suitable to be normalize as elastic acceleration spectra.

Response Reduction Map of Gap System Based on Energy

For the past several years, seismic isolation systems have been focused in the seismic design of industrial facilities. This paper deals with the response reduction effect by gap. Gap is expected to decrease the relative displacement by guide. The relative displacement between structure and support becomes larger at long period in the case of linear system. Therefore, the response reduction effect by gap should be utilized positively in the seismic design. However, the response magnification of acceleration is used in the seismic design. The acceleration becomes larger by collision. Therefore, the response reduction effect by gap is evaluated from the viewpoint of energy. The ratio between kinetic energy and input energy is utilized. In this paper, “Response Reduction Map” based on energy for long period gap system is suggested. This map shows the range that energy response ratio is less than the ratio of linear system. The response reduction map without complex non-linear time history calculation can easily obtain the proper parameters, such as natural period or gap size. At first in this study, the response reduction map by actual earthquake wave is shown. Next, the response reduction map by the artificial earthquake wave calculated from the design spectrum is shown.

109 エネルギーによる高固有振動数機械構造物の耐震性評価 : 第2報:人工地震波の場合

High Seismic safety reliability is required for nuclear power plant. Usually equipment and piping installed in nuclear power plant are assumed to be rigid, and are designed by using static seismic load. However seismic load is cyclic load, thus it is very important to grasp dynamic vibration characteristics. In this paper, forced vibration experiment by artificial earthquake wave is carried out then experimental results are evaluated from the viewpoint of the Energy Balance that is varied method for dynamic evaluation.

설계용 스펙트럼에 적합한 인공지진파에 의한 비선형 응답 특성의 분석

건축구조물의 비선형 지진응답해석에서 입력지진동은 구조물의 탄소성 지진응답을 좌우하는 중요한 요소이다. 지진동파형은 지진발생과 전파경로에 따른 여러 가지 인자에 의해 그 특성이 결정되기 때문에 구조물의 지진응답해석에서 일반성을 갖는 입력지진동을 선정하는 것은 매우 어려운 문제이다. 본 논문은 내진설계용 스펙트럼에 대응하는 인공지진동파형을 작성한 후, 작성된 인공지진동에 대한 탄소성 응답스펙트럼 특성을 분석한 것이다. 여기서 작성된 인공지진동파형은 과거의 지진에서 얻어진 기록지진동파형을 이용하여 기록지진동과 동일한 위상각을 가지며, 감쇠정수 h=5%일 때의 내진설계용 스펙트럼과 거의 일치하도록 작성되었다. 작성된 인공지진동은 원 기록지진동과 동일한 위상각을 가지며, 주기 <TEX>$T=0.02{\sim}10.0sec$</TEX> 범위에서 설계용 스펙트럼과 매우 근접하게 작성되었다. 인공지진동을 입력한 1자유도계의 탄성 및 탄소성 지진응답해석을 수행하여 탄소성 응답스펙트럼 및 탄소성 응답특성을 분석하였다. 본 논문에서 작성된 인공지진동은 건축구조물의 탄소성 지진응답해석용 입력지진동으로 충분히 타당성이 있다고 사료된다. In seismic response analysis of building structures, the input ground accelerations have considerable effect on the nonlinear response characteristics of structures. The characteristics of soil and the locality of the site where those ground motions were recorded affect on the contents of earthquake waves. Therefore, it is difficult to select appropriate input ground motions for seismic response analysis. This study describes a generation of artificial earthquake wave compatible with seismic design spectrum, and also evaluates the nonlinear response spectra by the simulated earthquake motions. The artificial earthquake wave are generated according to the previously recorded earthquake waves in past earthquake events. The artificial wave have identical phase angles to the recorded earthquake wave, and their overall response spectra are compatible with seismic design spectrum with 5% critical viscous damping. Each simulated earthquake wave has a identical phase angles to the original recorded ground acceleration, and match to design spectra in the range of period from 0.02 to 10.0 seconds. The seismic response analysis is performed to examine the nonlinear response characteristics of SDOF system subjected to the simulated earthquake waves. It was concluded that the artificial earthquake waves simulated in this paper are applicable as input ground motions for a seismic response analysis of building structures.

진동시험에 의한 154kV 변압기 부싱의 동특성 분석 및 내진성능 평가

The power supply system is one of the most important infrafacilities which should maintain their inherent function during and after earthquakes. This study was performed to analyze dynamic characteristics and seismic performance of Korean typical 154kV transformer porcelain bushing. For the purpose of this study, actual 154kV porcelain bushings were selected and tested on the shaking table. The vibration tests consist of modal identification tests, seismic performance tests, and fragility tests. The sine sweep waves, artificial earthquake waves, and continuous resonant sine waves were used as shaking table motions. This paper describes the test specimens, shaking facilities, and test methods. Natural frequencies and damping ratios of the bushing have been evaluated from the experimental data. The failure mode and the performance level of the Korean transformer bushing have been first identified in this study.