Input Earthquake Wave Research Articles

Seismic Analysis for Cross Transfer Subway Stations in Soft Soil Stratum

This paper investigates the seismic properties of a cross transfer subway station under a horizontal earthquake wave in soft soil stratum. A 3-D simulation analysis model is established considering the dimensions and soil layers of a real structure. The HS-small model is employed to simulate the non-linear stiffness of soft soil. The dynamic responses of a single station case and a cross transfer station case are explored, followed by the direction of the input earthquake wave, the type of soil reinforcement in the overlapping area, had on the dynamic response were also analyzed. The simulation results show that the subway station has better seismic response than the single station, and soil reinforcement can increase the dynamic response of the different components in the overlapping area. As soil reinforcement stiffness increases, the dynamic response increases in both the upper and bottom stations at varying degrees. The findings from this paper provide a reference to the seismic design of cross transfer stations in similar ground.

Shaking table test study on seismic performance of inclined pile foundations in liquefiable soil

Inclined pile foundations are widely used in civil engineering by virtue of sufficient horizontal stiffness, but few studies have touched upon the seismic performance of inclined piles in liquefiable soil. To better understand the performance of the inclined piles in liquefiable soil under earthquake conditions, a series of 1 g shaking table tests of inclined and vertical piles in liquefiable soil were performed. Superstructure-pile-soil dynamic interaction was considered while three types of earthquake waves with different characteristics were selected as the applied earthquake motions. The horizontal acceleration of the superstructure and the pile cap, the rotational acceleration of the pile cap, the total base shear force, and the bending moment of two types of physical models were monitored and analyzed. The results show that inclined piles in liquefiable soil can effectively reduce the horizontal vibration of the superstructure and the pile cap, and the acceleration reduction of the pile cap is about 2.5 times larger than that of the superstructure. Meanwhile, inclined piles can also reduce the total base shear force, and the extent of reduction depends on the input earthquake wave. Besides, the results suggest that the maximum bending moment of inclined piles is located at the pile head, and its value is positively correlated with the amplitude of the earthquake wave, and is affected by the type of the input earthquake wave. Overall, inclined pile foundations show satisfactory seismic performance for a superstructure-foundation-liquefiable soil system, and this study, with a rich amount of data, can serve as an important reference for the seismic design of inclined piles in liquefiable soil.

Shaking table test on flexible joints of mountain tunnels passing through normal fault

Tunnels often suffered severe seismic damage when passing through the active fault in high intensity earthquake area. The fault movement might be divided into fault movement and seismic motion under the strong earthquake action, and both of them could have the significant influence on the stability of tunnel structure. To improve the seismic performance of the mountain tunnel through fault, a design idea or method of the between sectional tunnel structures with the flexible joint were put forward to run through the active fault and verified or analyzed by using the shaking table test. Firstly, the typical seismic damage characteristics of the tunnel passing through the fault were analyzed after Wenchuan earthquake; secondly, the sectional tunnel linings with the flexible joint were designed in the active fault zone under the strong seismic motion, and the basic theory of this design method was presented in detail. Thirdly, the scaled model shaking table test was carried out to study the seismic performance of flexible joints of tunnels under the normal fault action, and some key parameters of the test was designed, including similarity relationship, boundary condition, sensor layout, input earthquake wave and flexible joint design. The test results showed that the joints between sectional linings could make structure localize damage rather than global damage, and compared to seismic motion, the fault movement suffered more serious damage for the tunnel structure. The tunnel lining at hanging wall was more susceptible to damage or destroy than that at the footwall under the normal fault action, and the flexible joint could adapt to the differential deformation of fault during the strong earthquake. Lastly, the dynamic response of the tunnel lining demonstrated that the upper-structure of the tunnel mainly suffered the severe seismic load, while the lower-structure might experiences the imposed deformation of fault movement under strong earthquake motion. So the design method of the sectional tunnel lining with the flexible joint would be applied to tunnel structure design to improve the adaptive deformation ability of tunnel structure through active fault.

Dynamic Characteristics of Metro Tunnel Closely Parallel to a Ground Fissure

Shaking table model test and numerical simulation model were conducted on scaled tunnel model to investigate the mechanism and effect of seismic loadings on metro tunnel which is closely parallel to an active ground fissure. Key technical details of the experimental test were set up; for example, similarity relations, boundary conditions, sensors layout, and modelling methods were presented. Synthetic wave, El Centro wave, and Kobe wave were adopted as the input earthquake waves. Results measured from shaking table model and numerical model were compared and analyzed. It is found that the fissure increased the dynamic response features as accelerations and strains of the tunnel, especially in the part close to the fissure. Average incremental percentage of acceleration amplifying coefficient was 8.33% from the wall close to fissure than the symmetrical one. The short distance to fissure led to serious circumferential dynamic strain, while the distance to fissure influenced the axial dynamic strain less. The numerical analysis results have a good correspondence with those of the shaking table model test. The waves at the top of tunnel have more scattering and emission effect. The fissure increases the dynamic response of the tunnel close to it.

Pseudo Dynamic Test and Time-History Analyses of Traditional-Style Steel Frame Structures

To study the seismic performances of steel frame structures in traditional-style buildings, the pseudo-dynamic test was carried out on a 1/2 ratio model built in the areas with a seismic design intensity of eight. The input earthquake waves included El Centro, Lanzhou and Wenchuan, and the maximum peak accelerations of these ground motions were 70, 200, 400 and 620 gal (0.7, 2, 4 and 6.2 m/s2). The seismic responses such as displacement, reaction force, acceleration were recorded. The hysteretic behavior, energy dissipation capacity, time-history curves of acceleration and displacement, bearing capacity and stiffness degradation were analyzed. The results show that the traditional-style steel frame structure stayed in the elastic stage subjected to no more than 400 gal (4 m/s2) PGA. There was no obvious pinch phenomenon in the hysteretic loops and the structural energy dissipation increased significantly with the increase of the seismic wave amplitude. When the 9-intensity seismic wave was applied, some unique members in traditional-style buildings yielded, and the spectral characteristic of the input seismic wave had a great influence on the seismic response of the structure. The modal analysis and time-history analyses were applied to the structure, the vertical deformation of the second and third modes of the steel frame was larger than that of the first modal shape, the reaction force value of finite element was a little larger than that of the test under the same loading condition. When the structure subjected to more severe earthquake, some unique members in traditional-style buildings acted as the first earthquake fortification line and dissipate most energy, and the structural most obvious reaction took place in advance or delayed a bit.

Shaking table model tests of concrete containment vessel (CCV) for CPR1000 nuclear power plant

Containment vessel of nuclear power plant is the last barrier to prevent the leakage of radioactive materials, so the seismic performance is of high importance. In order to investigate the seismic performance of the CPR1000 prestressed concrete containment vessel (PCCV) structure under design and beyond-design basis earthquake, a 1/20 scale concrete containment vessel (CCV) model was designed and constructed on the shaking table based on the similitude requirements from the Buckingham's π-Theorem. The horizontal and vertical earthquake waves generated from RG1.60 spectrum were selected as the input earthquake waves in the shaking table model test, and the earthquake waves with peak ground acceleration (PGA) 0.2g, 0.3g, 0.4g, 0.5g, 0.7g, 0.9g and 1.2g respectively were loaded step by step until the macroscopic failure occurred in the model containment vessel. The dynamic responses of the model CCV were obtained from the acceleration sensors and resistance strain gages. The model test results showed that the maximum acceleration magnification factor of the model CCV was 1.974 with PGA of 0.2g, which indicated that the CCV had a good seismic-resistant behavior under 0.2g earthquake. Until the second last test case with the horizontal peak earthquake motion of 0.9g (corresponding to 0.9g for the prototype structure), the fundamental frequency of the model CCV only decreased slightly and the maximum tensile strains at all monitoring points were much smaller than the ultimate tensile strain. It meant that the model CCV as a whole was within the elastic range. In the last case (1.2g), the model fundamental frequency decreased steeply. At the same time, the maximum tensile strains at the heel of the cylinder wall far exceeded the ultimate tensile strain and a circle of cracks occurred at the cylinder wall heel. It meant rupture failure had occurred and the cylinder wall heel of the CCV was the weak region. It agreed well with the numerical analysis results and the visual inspection and camera record at the test site. Although a circle of concrete cracks appeared around the cylinder wall foot, the model CCV still remained integral as a whole and neither cracking parts dislocation nor collapse occurred. Because the test model was a plain concrete structure and the model test results should be conservative estimation, it can be concluded that the prototype PCCV for CPR1000 nuclear power plant had sufficient seismic safety margin.

Rock toppling failure mode influenced by local response to earthquakes

Earthquake waves influence rock toppling stability, and the effects of local earthquake propagation and topographic also affect slope deformation. Detailed engineering geology conditions of slopes are obtained and a geomechanical characterization of rock topplings is performed. To study the input earthquake waves and slope interactions, a dynamic analysis is performed using the UDEC 4.0 discrete element method (DEM) numerical code under viscoplastic conditions. The earthquake signals are representative of different peak ground acceleration, Arias intensities, and frequencies, and are used in the study of different rock topplings with different height, slope angle, and strata dip angle. The derived outputs are processed for the earthquake propagation study and to assess the induced deformation mechanisms in terms of resulting displacements, plastic zone features, and deformation mode. The results prove that an interaction exists between stratigraphic and topographic effects on earthquake wave propagation, and that these effects cannot be assessed independently. The obtained results describe the effect of topography and geological settings in rock topplings, amplifying or de-amplifying earthquake ground motion, and demonstrate that the tensile state dominates at the slope surface but evolves with depth. A shear state dominates at the toe or in the deep part of rock topplings. The rock toppling deformation mode may develop into a composite of tension fractures at the crest and sliding at depth. Compared with the static scenario, under earthquake load, tensile deformation evolves over a larger area at the crest and develops a shear zone at the toe and in the substrata. The necessary earthquake-induced toppling conditions are discussed, and the UDEC 4.0 DEM method and conventional pseudostatic approach are compared. This study shows there are a broader range of deformations inside the slope.

Seismic Stability Time-Frequency Analysis Method of Reinforced Retaining Wall

The first-order differential equation of the seismic active earth pressure is established by horizontal slices analysis method, based on the elastic wave theory, with the summarized dynamic analysis model of the reinforced retaining wall and the plane of fracture assumed as linear type. And then this paper proposes a time-frequency analysis method for the internal antiseismic stability analysis on the retaining wall. The reasonability of this method is verified by the results from other methods, for example, rule. The internal frictional angle of filling earth, the seismic intensity, and the frequency of the input earthquake wave have a predominant effect on the needed total tensile force of the lacing wires, which shows that (1) the needed total tensile force of the lacing wires goes up with the increase of the PGA and the internal frictional angle; (2) the needed total tensile force of the expandability lacing wires is bigger than that of the nonexpandability lacing wires; (3) the needed total tensile force of lacing wires is saddle distributed and the force achieves maximum value when the frequency of input wave equals the natural frequency of reinforced retaining wall. Besides, if the reinforced retaining wall is designed in compliance with the rules, the emergency capacity of reinforced retaining wall is reduced. At last, this paper not only takes into account the effect of three factors of the seismic wave (PGA, frequency, and duration) on the internal antiseismic stability analysis of reinforced retaining wall but also provides some valuable references for the time-frequency seismic design of other retaining structures.

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.

J1010302 地震観測データ分析に基づく免震構造物の振動性状に関する報告 : その1,建物の振動性状に基づく解析モデルによる観測波形の再現([J101-3]耐震・免震・制震 免震(1))

In this paper, the analytical model is developed based on seismic record, it is a purpose to demonstrate the reappearance of the response wave. Based on drawings, a three-dimensional analytical model is developed and calculated stiffness and mass layer from structural mechanics. A multi mass system analytical model is developed from these physical parameters. In order to the analytical model is verified validity, natural frequency and transfer function are found from observation wave pattern and response wave pattern of the analytical model. In comparison with seismic records, modified model that the primary natural frequency of the Seismic records identified is developed because natural frequency of the analytical model is low. The seismic records are set with the input earthquake wave, it is performed the earthquake response analysis. In comparison with seismic records, the layer low wave pattern are high reappearance of design model and modified model, but the layer high wave pattern are low reappearance. Thus, we will inspect it about the identification of other than primary natural frequency in future.

連続体置換および並列多質点系モデルを用いた単層円筒ラチス屋根構造物の地震応答評価に関する研究

In this paper, an alternative evaluation procedure of seismic responses using the continuum shell analogy and analogical lamped mass model has been proposed. Then, the linear time history response analyses for various input earthquake waves have been carried out. The adopted analytical parameters are of the open angle of cylindrical shell, the margin of safety ratio of roof members and the horizontal resistance of sub-structure. Also, the sectional area of roof members has been designed by dead load. As the result, it is proposed that the maximum response acceleration and displacement can be evaluated by using the present evaluation method even if the higher-mode vibrations are predominated. Based on these, it is suggested that the present simple evaluation method would be useful for seismic design for single layer cylindrical latticed shell roof structures.

Characteristic Analysis of 3.11 Seismic Waves

33 records of Japanese earthquake are extracted in this paper (referred to as 3.11 seismic waves in the article).Then, through studying the basic characteristics, spectrum characteristics and anisotropic of 3.11 seismic waves, as well as the similarities and differences of the response spectrum of 3.11 seismic waves contrasting with the response spectrum of the code. The results show that: a) 3.11 seismic waves have rich spectral components almost near the predominant frequency and its energy mainly concentrate in 0.1~10Hz.b) By analyzing the spectrum distribution of the seismic waves, its destruction strength on different structures can be evaluated. c) Damaging strength of horizontal seismic waves is much larger than the vertical seismic waves. Serious damage to the structure can be caused by the horizontal seismic waves’ excellence spectrum components focusing on the frequency of the structure in the engineering. Vertical seismic waves have greater damage to the structures’ periods between 0.02s to 1s, but much smaller to other structures. d) it can effectively assess the damaging strength on the structure,in time history analysis ,when make 3.11 seismic waves as the input earthquake waves.

Earthquake Response Analysis of Bridge Piers in Deep Water under Hydrodynamic Pressure Action

In order to ensure safety of long and huge bridges in deep water under earthquake action, it is significance to consider water and bridge pier dynamic interaction. Analysis method of water-bridge pier dynamic interaction under earthquake excitation is established using radiation wave theory, and earthquake induced hydrodynamic pressure apply program is complied. Considering different earthquake wave input, earthquake induced hydrodynamic pressure influence on dynamic responses of bridge pier in deep water is further studied. The results indicate that: Dynamic response of bridge pier in deep water is augmented because of hydrodynamic pressure action. Earthquake induced hydrodynamic pressure influence on seismic responses of bridge piers in deep water will change with different input earthquake wave.

Shaking Table Tests of a Free-Standing Cultural Relic Strengthened by Plastic Fasteners

Plastic fastener is a typical strengthening material for museum movable cultural relics in China.To find out strengthening effects of this material,by shaking table tests seismic responses of a ceramic relic in a 1:1 scale showcase model were studied.2 boundary conditions of the relic were considered:free-standing and strengthened by plastic fastener. By white noise excitation basic frequency of the showcase was obtained; by inputting El-centro earthquake waves of different intensities,seismic responses of both showcase and relic were studied,aseismic results of plastic fasteners were discussed. By simulation method finite element models for the showcase and strengthened relic were built,modal as well as time history analyses were carried out to validate the effectivity of shaking table tests.Results show that prominent frequency ingredients of the showcase are far greater than those of the input earthquake waves,thus the showcase is not damaged seriously; for the relic after it is strengthened by plastic fasteners,its peak displacement and acceleration response values decrease,which still embody obviously under strong earthquakes.Thus by plastic fasteners the relic can be effectively strengthened. Besides,simulation results are well in accordance with those of shaking table tests,which proves effectivity of the test method.

Shaking Table Tests of a Free-Standing Cultural Relic Strengthened by Plastic Fasteners

Plastic fastener is a typical strengthening material for museum movable cultural relics in China.To find out strengthening effects of this material,by shaking table tests seismic responses of a ceramic relic in a 1:1 scale showcase model were studied.2 boundary conditions of the relic were considered:free-standing and strengthened by plastic fastener. By white noise excitation basic frequency of the showcase was obtained; by inputting El-centro earthquake waves of different intensities,seismic responses of both showcase and relic were studied,aseismic results of plastic fasteners were discussed. By simulation method finite element models for the showcase and strengthened relic were built,modal as well as time history analyses were carried out to validate the effectivity of shaking table tests.Results show that prominent frequency ingredients of the showcase are far greater than those of the input earthquake waves,thus the showcase is not damaged seriously; for the relic after it is strengthened by plastic fasteners,its peak displacement and acceleration response values decrease,which still embody obviously under strong earthquakes.Thus by plastic fasteners the relic can be effectively strengthened. Besides,simulation results are well in accordance with those of shaking table tests,which proves effectivity of the test method.

The Dynamic Responses of Anti-Slide Piles Reinforced in the Rubble Soil Landslide

Acoording to the servic eability limit state, use the numerical analysis the method, using the fiinte element analysis software to the elastoplastic and the big distortion on the power solidifies in the finite element model, by using above coupled non-linear numerical approach, the dynamic response of piles and the earthquake resistance reinforcement. A computation method of raft foundation is brought foward in which many factors are considered. The method corresponds to real foundation working conditions. The results indicated as follows: Under the earthquake load function, the slope and anti-slide piles displacement response was amplified as the seismic motion propagated upwards through the slope. The greater the earthquake acceleration, the larger the deformation of the anti-slide pile. And the displacements of the pile were decreased from top to bottom. The different elevational point of the dynamic moment in the change tendency is the same. the dynamic moment to increase along with the input earthquake wave acceleration increases. There were larger differences occurring in the maximum value of resistances on the partial pile lain in stable rockmass and resistance distribution forms with different accelerations in different times. The calculation indicates that the new method may better reflect the actual locating state and sliding process of debris landslide and anti-slide piles under earthquake.

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.

Seismic Response of Bridge Pier in Deep Water Considering close Fluid-Structure Interaction Effects

Based on the Navier-Stokes equations which are set up with the arbitrary Lagrange-Euler description, a finite element model considering close fluid-structure interaction (FST) is established to analyze the seismic response of bridge piers in the deep water. The influence of close FSI on the bridge pier is analyzed including the relative displacement, shear force and bending moment. In addition, the close FSI and its effects are discussed with respect to different water levels. The results of the case study indicate that the displacement and internal force will become larger obviously when the FSI is considered. Effects of the close FSI on seismic response of the pier are related to the frequency characteristics of the input earthquake wave. The larger the peak displacement of input earthquake wave, the larger the FSI effects on the displacement response of the pier are and the smaller the FSI effects on the internal force response of the pier. Additionally, the effect of the water level on internal force response of the pier is more remarkable than that on the displacement response of the pier.

Shaking table test of utility tunnel under non-uniform earthquake wave excitation

A series of shaking table tests were conducted on scaled utility tunnel models with and without construction joints under non-uniform input earthquake wave excitation. Details of experimental setup are first presented with particular focuses on: design and fabrication of double-axis laminar shear box with a rectangular hole opened on its side walls; design of two devices for measuring the slippage between the interface of test soil and the structure, and the relative deformation and rotation between joints of the structure model; and procedure for construction of input earthquake wave. The experiments were conducted in three phases. Phase 1 is free-field test. A 2-norm index is suggested to quantify the boundary effect and it is found that the designed laminar box does not impose significant boundary effect. Phases 2 and 3 are model tests in longitudinal and transversal directions, respectively. Test results are discussed in items of shear force–slip relationship at the soil–model structure interaction surface, movement and rotation of the construction joint, and effect of non-uniform earthquake input. The comparison shows that structural response under non-uniform earthquake excitation is larger than that under uniform excitation. The effect of spatial distribution of earthquake excitation should be considered in the seismic design of utility tunnel.

A STUDY OF EVALUATION OF EARTHQUAKE INPUT ENERGY BASED ON RESPONSE SPECTRUM CHARACTERISTIC

In this paper, the influences of the phase characteristic and the response spectrum characteristic of the earthquake wave on the earthquake input energy are examined based on the earthquake response analysis using the simulated seismic wave which is adjusted the normalized response spectrum. As a result, the characteristic of ƒ value proposed by Akiyama and Kitamura is clarified, and proposes the response spectrum effect value SM and ƒ* value considering SM value. The earthquake input energy of any earthquake wave without the case that earthquake response analysis is able to estimate using ƒ* value. Moreover in this paper, ƒ* value corresponding to the earthquake load which Japanese Building Standard Act provide is presumed by conducting seismic response analysis of real buildings. Therefore, on the comparing with ƒ* values of the existing seismic waves, the quantitative evaluation about that earthquake damage can be performed. The evaluation of the earthquake input energy based on ƒ* value as well as acceleration at the maximum is necessary for the evaluation of the earthquake wave. The ƒ* values are useful on the evaluation of the input earthquake wave.