Seismic Wave Input Research Articles

産業施設を対象とした免震構造の応答特性に関する研究

The nuclear power generation does not produce greenhouse gas. In addition, even an aspect of the generation cost is a superior generation method. However, seismic condition in Japan is severe. Therefore seismic design is important for nuclear power facilities. It is useful to adapt a seismic isolation system into nuclear power facility because the seismic loading can be reduced. Because of improvement of horizontal isolation characteristics and restraint of the cardinal number of laminated rubber bearing, the current laminated rubber bearings are used in the longer period and the high surface pressure. In this case, the stiffness of the laminated rubber bearing in the vertical direction decreases. As the result, the response is increased in natural frequency of the principal components. In this paper, we examined the response acceleration of the principal components in the horizontal/vertical frequency of the laminated rubber bearing. The seismic response analysis with one lumped mass model was carried out. The input seismic waves used Kashiwazaki wave and Onagawa wave. As a result of examination, we confirmed that the response amplification of the principal components of the nuclear power facilities was inhibited by using the laminated rubber bearing with the seismic isolation specification of approximately 20 Hz in the vertical frequency and approximately 2 seconds in the horizontal period.

Three-Dimensional Nonlinear Soil Response Methods Based on a Three-Component Input Wave Field

AbstractIn a previous study, three-dimensional (3D) linear and simplified nonlinear finite-element soil response methods based on a horizontal-component input seismic wave field were proposed. A seismic wave field means seismic waves propagating in a 3D medium. The method had been developed with the goal of adequately treating short-period (less than a few seconds) seismic surface waves trapped by a deep (several km) underground structure in a shallow soil model. In the present study, along with improvements of the methods, 3D linear and simplified nonlinear soil response methods based on a three-component input seismic wave field are developed, and are applied to estimate seismic soil responses in the three geotechnical zones (the reclaimed, alluvial, and hill zones) of Tokyo during two large earthquakes. The more reasonable soil responses revealed that, in a practical sense, vertical ground motions affected soil responses very little. They also clarified large effects of liquefaction in the reclaimed zo...

Damage Analysis and Evaluation of High Strength Concrete Frame Based on Deformation-Energy Damage Model

A new method of characterizing the damage of high strength concrete structures is presented, which is based on the deformation energy double parameters damage model and incorporates both of the main forms of damage by earthquakes: first time damage beyond destruction and energy consumption. Firstly, test data of high strength reinforced concrete (RC) columns were evaluated. Then, the relationship between stiffness degradation, strength degradation, and ductility performance was obtained. And an expression for damage in terms of model parameters was determined, as well as the critical input data for the restoring force model to be used in analytical damage evaluation. Experimentally, the unloading stiffness was found to be related to the cycle number. Then, a correction for this changing was applied to better describe the unloading phenomenon and compensate for the shortcomings of structure elastic-plastic time history analysis. The above algorithm was embedded into an IDARC program. Finally, a case study of high strength RC multistory frames was presented. Under various seismic wave inputs, the structural damages were predicted. The damage model and correction algorithm of stiffness unloading were proved to be suitable and applicable in engineering design and damage evaluation of a high strength concrete structure.

Study of Shaking Table Test on Seismic Performance of 750 kV Post Insulator

The applicability of seismic waves for the seismic performance estimation of 750 kV post insulator has been investigated in full-scale shaking table test. the input seismic waves comprise El Centro seismic wave, Landers seismic wave, sine beat wave and artificial standard wave. The testing results indicate that, high dynamic responses of the equipment can be obtained under artificial standard wave condition. In addition, due to comprehensive enveloping ability and gentle spectral curve, artificial standard wave is ideal for the seismic performance evaluation of 750 kV post insulator in the test. An finite element model has been developed and numerical seismic analysis has been performed. Satisfactory match between the simulated and measured results reveals the reliability of the test. The achievements obtained in this paper are helpful in choosing reasonable input wave for shaking table test, and also provide technical support on determining seismic capacity of high voltage electrical equipment.

Seismic Responses of Two RC Buildings and One Wood Building Based on an Input Wave Field

AbstractA recently proposed three-dimensional (3D) linear method for examining soil-building interactions based on an input seismic wave field is, after some improvements, applied to estimate seismic building responses in the reclaimed zone of Tokyo Bay, where ground motions include a considerable amount of surface waves, thus reconfirming the effects of the method in a different situation. A seismic wave field involves seismic waves propagating in a 3D medium. The proposed method was developed with the goal of adequately treating seismic surface waves trapped by a (several-kilometers) deep underground structure in a soil-building interaction system. Two simulations were carried out. The first simulation successfully reproduced surface, downhole, and building accelerograms that were recorded at one borehole station during two medium-sized earthquakes. In the second simulation, seismic responses of a midrise RC model building and a wood model building were favorably calculated at the other borehole station...

Earthquake-Response Analysis of Long-Span Cable-Stayed Bridge under Uniform and Non-Uniform Excitations

Earthquake is a kind of natural disaster which is difficult to predict and the damage degree is very great, occurrence of the strong motion often leads to the tremendous life and property loss. Bridge is very important lifeline engineering and it is very necessary to conduct the comprehensive and systemic investigation on the bridge aseismic. In this paper, the FEM model of a long-span cable-bridge was established; the dynamic characteristic and nonlinear seismic responses under uniform and non-uniform excitations of it were systematic studied. The results show that: 1) the basic cycle of it is about 8.881s. Its first mode of vibration is longitudinal floating mode, which is favorable to the earthquake-response of structures. 2) Its former 40 rank frequency are located between 0.1~2Hz which is avail to the condition of traffic condition.3) the geometric nonlinearity has much influence on the response of this kind of bridge.4) the seismic responses are sensitive to the frequency spectra of the input earthquake wave. 5) The traveling wave excitations are unfavorable to the design of tower and the main girder when considering the three orthogonal seismic wave input. In order to get correct results, artificial seismic wave of the bridge address is necessary to the time-history analysis.

Analysis on mechanism of landslides under ground shaking: a typical landslide in the Wenchuan earthquake

A high steep rock hill with two-side slopes near National Road 213 is used as a prototype in this paper. The full process from initial deformation to sliding of the slope during ground shaking is simulated by a new discrete element method—continuum-based discrete element method. Then, the seismic responses of a high steep rock hill with two-side slopes are researched from the base of time, frequency and joint time–frequency domain using Hilbert–Huang transform and Fourier Transform. The findings are: first, the stress concentration phenomenon occurs at the top of the sliding mass, and then some tension and shear failure points appear, which expand from the top toward the toe of the sliding mass along the structural plane. At the same time, the number of tension failure points gradually increases. Then the toe of the sliding mass fails, and shears out from its toe which results in the landslide. If the material parameters are under the same conditions, the landslide in the middle of the slope occurs before that at the foot of slope, and the starting time of landslide and the arrival time of the peak ground acceleration are synchronous or the former slightly lags behind the latter. The difference of distribution and dissipation of earthquake energy in the sliding body and sliding bed is the major influence factor to induce the landslide. When the accelerations are small, the instantaneous frequency of accelerations between sliding bed and sliding body is generally consistent, the energy transmittance coefficients of the sliding structural plane and the controlled frequency band of the energy all range in a limitation; with the increase of the seismic intensity, the instantaneous frequency and the energy transmittance coefficients gradually decrease, and then they are steady within the lower limitation. At the same time, the controlled frequency band also shifts gradually from high frequency band to the lower one. Based on the input seismic wave, the peak acceleration amplifies as the increase of elevation, regardless of the monitoring points on the steep slope, gentle slope side or inside of the slope. Generally speaking, amplification of the vertical peak acceleration is stronger than that of the horizontal peak acceleration, and amplification of the peak acceleration on a steep slope is stronger than that on a gentle slope, and that of inside of the slope is the weakest amplification.

Research on Seismic Displacement Response of Cable Stayed Bridge without Back Stays

Seismic displacement response of cable stayed bridge without back stays was studied in this paper. Based on the cable stayed bridge without back stays on Zhenshui Road in Xinmi City, finite element method (FEM) was applied to calculate and analyze natural vibration and peak displacement response of the structure. The results show that with regard to mid-span and consolidation of pier and main tower, uniaxial seismic wave input results in peak displacement response of corresponding direction is bigger than that of any other direction. Peak displacement response of the top of the main tower is bigger than those of mid-span and consolidation of pier and main tower in any seismic wave input cases, which indicates that the top of the tower needs to be focused in the process of design and construction. Seismic wave along triaxial direction has the biggest impact on the structure. Keywords: cable stayed bridge without back stays; seismic displacement response; seismic wave input; peak displacement response

G1010605 ケーブル諸元の影響を考慮した斜張橋の地震応答解析についての基礎検討([G101-06]機械力学・計測制御一般セッション(6))

In this study, we treat the vibration of a cable-stayed bridge, as one of a bridge supported by cables. For an analysis, we make a simple analytical model of a cable-stayed bridge composed of a girder and 4 cables, and derive equations of motion of the girder and cables. We investigate the time history response of both the girder and cables, and then estimate the coupling effects between the girder and cables. We especially treat the bridge's seismic response. As the beginning of the seismic response analysis, we focus on the effects of sag-to-span-ratio, one of parameters of a cable. We analyze the model's vibration by numerical simulation for various sag-to-span-ratio. We input seismic wave into the analytical model, and evaluate the influence of sag-to-span-ratio on the girder and cables coupled vibration behaviors.

Stochastic Dynamic Reliability Analysis of Seismic Response of Soft Ground Including Silt

Due to the uncertainties and randomness of earthquake loads, it is more logical that reliability method should be employed in dynamic geotechnical engineering analysis. A methodology of 2-D effective stress FEM analysis based on dynamic reliability of seismic response of soft ground including silt is proposed in this paper, Duncan-Chang and Hardin-Drnevich hyperbolic models are used for static and dynamic constitutive relations of soils, respectively. Furthermore, three stochastic dynamic reliability analysis approaches based on the cumulative damage, cyclic shear stress and pore water pressure ratio are respectively suggested. The proposed methodology was applied to the stochastic dynamic reliability analysis of ground seismic response of two typical soft soil profiles in Shanghai in terms of seismic wave input depths of 50m and 280m. Basically consistent conclusions can be drawn in the three aforementioned perspectives. In addition, the filtering effect of frequency components by deeper soil layers plays perhaps an important role in dynamic reliability analysis in view of the fact that remarkable differences of dynamic reliability analysis results exist between 50m and 280m seismic wave input depths.

Estimation of dynamic behaviors of bedrock foundation subjected to seismic loads based on FEM and DEM simulations

Seismic behavior of bedrock foundation remains as one of the most fundamental and important problems concerning the stability and safety of nuclear power plants. The dynamic FEM (Finite Element Method) is commonly utilized in analyzing the seismic responses of bedrock; while in recent decades, the DEM (Distinct Element Method) has attracted more and more attentions, which has a better capability of simulating the sliding and separation of discontinuities in dynamic simulations. In this study, the FEM and DEM were adopted to investigate the seismic behavior of the bedrock of a nuclear power plant located in Japan, and the differences between the two methods in dynamic simulations were illuminated. Simulation results using FEM and DEM models without discontinuities agree well with each other, exhibiting an amplification effect of intact bedrock on the seismic wave propagation. Numerical simulation results obtained from the models containing faults give similar responses of bedrock to the input seismic waves; however, the FEM model underestimates the weakening effect of discontinuities on the propagation of seismic waves due to that it cannot represent well the large deformational behavior of discontinuities. When large deformation happens due to large seismic loads, the DEM can be regarded as a better method in seismic response evaluations of bedrock with discontinuities.

Seismic response of submerged floating tunnel tether

A mathematical equation for vibration of submerged floating tunnel tether under the effects of earthquake and parametric excitation is presented. Multi-step Galerkin method is used to simplify this equation and the fourth-order Runge-Kuta integration method is used for numerical analysis. Finally, vibration response of submerged floating tunnel tether subjected to earthquake and parametric excitation is analyzed in a few numerical examples. The results show that the vibration response of tether varies with the seismic wave type; the steady maximum mid-span displacement of tether subjected to seismic wave keeps constant when parametric resonance takes place; the transient maximum mid-span displacement of tether is related to the peak value of input seismic wave acceleration.

Seismic analysis of a long tunnel based on multi-scale method

Seismic analysis of long tunnels is difficult due to the lack of available computing power. In this paper, a multi-scale method is used to simulate dynamic responses of a long tunnel, which involves the concurrent discretization of the entire domain with both coarse- and fine-scale finite element meshes. The method can not only capture seismic responses along the full tunnel length, but also the detail structural responses of the segment linings and joints. Both material and contact nonlinearities are considered in the multi-scale model. Effects of buried depths, spectrum characteristics of input seismic waves, non-uniform seismic excitation and flexible joints, are thoroughly investigated on seismic responses of the tunnel. Results show: (1) the seismically induced stress of the tunnel is strongly correlated with the depth and is significantly amplified when the depth is one quarter of the incident wavelength; (2) the spectrum characteristics of the given seismic input waves do affect the amplitude and distribution of tunnel ovaling deformations as well as stresses; (3) the non-uniform seismic excitation will greatly aggravate the tunnel responses compared to the uniform excitation, and the effect of spatial distribution of earthquake excitation should be considered in the design of long tunnels; and (4) it is proved that the flexible joints can slightly mitigate the stress concentration, however, especial attention should be paid to the water proof capability of the flexible joints due to the expected additional deformation. Furthermore, stress and deformation response in lining segments and their connecting bolts are investigated and analyzed within the fine-scale model, and the capacity of critical structural components such as bolts and joints is evaluated.

Three-Dimensional Finite-Element Method for Soil-Building Interaction Based on an Input Wave Field

AbstractA three-dimensional (3D) FEM for examining the soil-building interaction based on an input seismic wave field is proposed. A seismic wave field means seismic waves propagating in a 3D medium. An input seismic wave field is employed with the goal of adequately treating seismic surface waves trapped by a deep (several kilometers) underground structure in a soil-building interaction system. As the first stage of the proposed method, a simple linear method is constructed. The linear method was applied to estimate seismic responses of low- to high-rise RC model buildings during a large earthquake at a soft-soil site in Mexico City where surface waves are dominant. At the soft-soil site, all the buildings with and without piles vibrated together with the ground, probably suppressing the pile damage. The proposed method qualitatively provided us with more realistic building responses, compared with a conventional interaction analysis based on an input base motion. When a considerable amount of surface wa...

Seismic response of poro-elastic seabed and composite breakwater under strong earthquake loading

The marine structures in offshore area, such as composite breakwater, are generally vulnerable to the strong seismic wave propagating through their seabed foundation. There are a lot of failure examples during the strong earthquake events in the world in the past 20 years. However, attention given to the seismic response of marine structures under strong seismic wave is limited. In this study, taking the dynamic Biot’s equation “u − p” as the governing equation for porous seabed foundation, the seismic response of a composite breakwater and its porous seabed foundation under the seismic wave recorded in the Japan 311 off the pacific coast of Tohoku earthquake (M L = 9.0) is investigated using a FEM numerical model. The numerical results indicate that the seismic response of composite breakwater is very strong in the earthquake process. The amplification of the input seismic wave occurs both in seabed foundation and composite breakwater; and this amplification is positively related to the buried depth of points. The horizontal seismic response is much strong than the vertical seismic response. The seismic wave induced excess pore pressure and effective stresses in seabed foundation vibrates; the vibration amplitude is also positively related to the buried depth of points. Under strong seismic loading, the surface region of seabed foundation could liquefy. The parametric study shows that the young’s modulus of seabed foundation has significant effect on the seismic response of composite breakwater.

Dynamic Responses of a Structure with Periodic Foundations

AbstractThe dynamic responses of a structure with different foundations, including the so-called periodic foundation, are studied. Based on the calculation and optimization regarding the band of frequency gap of a periodic structure, a new kind of periodic isolated foundation is designed. To test the validity of this periodic isolated foundation, the dynamic responses of a seven-storey frame structure with three different foundations are conducted and compared. The analysis assumes that seismic wave input is from the arbitrary direction. This investigation shows that the seismic waves cannot propagate in the periodic foundation without being attenuated when the frequencies of the seismic wave fall within the band of frequency gap of the foundation. Thus, the dynamic responses of the supported structure will be greatly reduced. The investigation supports this new and effective method to block seismic waves for structures in civil engineering.

Nonlinear Earthquake-Response Analysis of Wuhan Junshan Yangtze River under Uniform and Non-Uniform Excitations

Wuhan Junshan Yangtze River Bridge is an important traffic hinge on Jing-Zhu freeway, it is very necessary to conduct the comprehensive and systemic investigation on the bridge aseismic. In this paper, the FEM model of it was established; the dynamic characteristic and nonlinear seismic responses under uniform and non-uniform excitations of it were systematic studied. The results show that: 1) the basic cycle of Wuhan Junshan Yangtze River Bridge is about 8.881s. Its first mode of vibration is longitudinal floating mode, which is favorable to the earthquake- response of structures. 2) Its former 40 rank frequency are located between 0.1~2Hz which is avail to the condition of traffic condition.3) the geometric nonlinearity has much influence on the response of this kind of bridge.4) the seismic responses are sensitive to the frequency spectra of the input earthquake wave. 5) The traveling wave excitations are unfavorable to the design of tower and the main girder when considering the three orthogonal seismic wave input. In order to get correct results, artificial seismic wave of the bridge address is necessary to the time-history analysis.

EARTHQUAKE RESISTANT DESIGN OF BRIDGE CONSIDERING LATERAL MOVEMENT

In this study, the stress and deformation of a superstructure and abutment under lateral movement is examined and an adequate analytical model of these states is considered in the dynamic analysis of the whole bridge system. The improvement of the bridge’s seismic performance is inspected based on the analytical results. In this case, the input seismic wave is set as a level 2 earthquake, and two types were used. Type I (plate boundary type) has numerous repetitions at an acceleration of approximately 400 gal, while Type II (inland direct strike type) has fewer repetitions but a stronger acceleration at 800 gal. Introduction With bridges built on soft ground (clay), lateral movement of the clay, caused by the fill behind the abutments occurs, causing damage to expansion joints, supports, and other parts. In addition, abutment parapets and superstructures come into contact, causing increased axial force on the superstructures, leading to their damage. Presently, when various organizations in Japan design bridges, they investigate the potential of lateral movements (Specifications for Highway Bridges, Part IV, 2002). As such, they work to strengthen pile foundations, improve clay layers, and take other preemptive measures to reduce the occurrence of lateral movements in advance. Therefore, in the early stages of construction, lateral movements are now seldom seen. However, since the lateral movement of clay occurs over a long period of time, displacement happens gradually, a decade after construction, and negatively effects the functionality of the bridge. When this phenomenon occurs, it is handled by replacing expansion joints and supports, repairing parapets, and taking other measures. However, in Japan, which is a country with frequent earthquakes, design for massive earthquakes, including level 2 tremors on the Japanese scale, is necessary. The fill behind abutments is judged to contribute to the ability of suppressing vibrations of bridges. As such, designs anticipating the effects of this backfill are now conducted. With bridges in which lateral movements occur, the clearance with the movable side is eliminated and direct contact is made with the superstructure. Thus, it is said that earthquake resistance is enhanced since it is more likely to be affected by the backfill effect. In these ways, the lateral movement of the abutment has both positive and negative effects on bridge structures. This paper will attempt to look at the enhancement of earthquake resistance and clarify this 1 Civil Engineer, Oriental Consultants Co., Ltd, Fukuoka city in Japan 2 Professor, Dept. of Civil Engineering, University of Kyushu Kyoritsu, Kitakyushu city in Japan 3 Professor, Dept. of Civil Engineering, University of Kyushu, Fukuoka city in Japan 4 Dr, Civil Engineer, Oriental Consultants Co., Ltd, Fukuoka city in Japan

Continuum and discrete element coupling approach to analyzing seismic responses of a slope covered by deposits

Numerical analyses of earthquake effects on the deformation, stability, and load transfer of a slope covered by deposits are traditionally based on the assumption that the slope is a continuum. It would be problematic, however, to extend these approaches to the simulation of the slide, collapse and disintegration of the deposits under seismic loading. Contrary to this, a discrete element method (DEM) provides a means to consider large displacement and rotation of the non-continuum. To take the advantages of both methods of continuum and non-continuum analyses, seismic responses of a slope covered by deposits are studied by coupling a two-dimensional (2-D) finite difference method and a 2-D DEM, with the bedrock being modelled by the finite difference grids and the deposits being represented by disks. A smooth transition across the boundaries of the continuous/discontinuous domains is obtained by imposing the compatibility condition and equilibrium condition along their interfaces. In the course of computation, the same time-step value is chosen for both continuous and discontinuous domains. The free-field boundaries are adopted for lateral grids of bedrock domain to eliminate the radiation damping effect. When the static equilibrium under gravity load is obtained, dynamic calculation begins under excitation of the seismic wave input from the continuum model bottom. In this way, responses to the earthquake of a slope covered by deposits are analyzed dynamically. Combined with field monitoring data, deformation and stability of the slope are discussed. The effects of the relevant parameters of spectrum characteristic, duration, and peak acceleration of seismic waves are further investigated and explained from the simulations.

Time-frequency response spectrum of rotational ground motion and its application

The rotational seismic motions are estimated from one station records of the 1999 Jiji (Chi-Chi), Taiwan, earthquake based on the theory of elastic plane wave propagation. The time-frequency response spectrum (TFRS) of the rotational motions is calculated and its characteristics are analyzed, then the TFRS is applied to analyze the damage mechanism of one twelve-storey frame concrete structure. The results show that one of the ground motion components can not reflect the characteristics of the seismic motions completely; the characteristics of each component, especially rotational motions, need to be studied. The damage line of the structure and TFRS of ground motion are important for seismic design, only the TFRS of input seismic wave is suitable, the structure design is reliable.