Period Of Ground Motion Research Articles

Strong ground motion characteristics observed in the 13 June 2011 Mw6.0 Christchurch, New Zealand earthquake

This paper examines the salient characteristics of near-source strong ground motions recorded from the 13 June 2011 Mw6.0 Christchurch, New Zealand earthquake. 26 strong motions were recorded within Rrup=30km of the source, with maximum geometric mean horizontal shaking exceeding peak accelerations and velocities of PGA=1.5g and PGV=100cm/s, respectively. The polarity of strong motion recordings with Rrup<6km illustrate the complexity of the seismic source, supporting the two-fault model of Beavan et al. [4]. Directivity in the observed ground motions in eastern and central Christchurch is dominated by the secondary rupture of a right-lateral ENE-trending fault plane, which produces polarization in a predominantly NS direction. As seen in previous events in the Canterbury earthquake sequence, significant basin-generated surface waves led to strong long period ground motions with relatively long significant durations. The installation of strong motion instruments in the Port Hills following the 22 February 2011 Mw6.2 Christchurch earthquake resulted in five new observed ground motions on rock or shallow soil sites, relative to past events, with the PARS and GODS stations on top of the causative faults recording very large amplitudes, inferred as a result of site response and topographic effect coupling. Significant nonlinear site response is evident at several locations in eastern Christchurch, resulting in truncation of acceleration amplitudes, with liquefaction-induced cyclic mobility clearly evident at two locations. Pore pressure recordings at five locations in eastern Christchurch illustrate that significant excess pore water pressure (EPWP) generation in a Mw5.3 event, which occurred 80min prior to the Mw6.0 event, resulted in residual EPWP's that had a measurable influence on high frequency ground motion amplitudes at soft soil sites in the latter event. Finally, the observed ground motion amplitudes are compared with empirical models for response spectra and significant duration.

Collapse analysis of high-rise steel moment frames incorporating deterioration effects of column axial force – bending moment interaction

Existing high-rise steel moment resisting frames (SMRF) in Japan sustained severe damage under the background of Tohoku earthquake and face collapse risks if great ocean ridge earthquakes occur in the near future. This paper presents a numerical study on collapse analysis of existing high-rise SMRFs under long period ground motions over the design levels. A finite element model based on fiber discretized layers was employed to incorporate the deterioration effects in bending strength of beams and axial force-bending moment (N-M) interaction of columns. Parameters for the numerical model were validated by a series of component tests, and a shaking table test on a high-rise SMRF substructure. Simulation results shown reasonable accuracy for predicting the low-cycle fatigue of steel beams, post-local buckling of steel columns and side-sway collapse mode of high-rise SMRFs. Then, parametric analyses were conducted to evaluate the dominant factors controlling the collapse capacity of high-rise SMRFs with various story and degradation levels. It indicated that a beam-to-column strength deterioration factor (SDF) plays an important role on collapse behavior characterized by asymmetric sway deformation concentrated at lower stories. Finally, design recommendation in terms of critical buckling strength of columns is proposed to define the collapse capacity of critical columns in high-rise SMRFs.

Seismic response analyses and performance assessment of masonry-infilled reinforced concrete frame buildings in Bhutan without and with soft storey

Bhutan locates in a high seismicity region but has no seismic design code of its own. Recent devastating earthquake in Nepal, which is located in the same region as Bhutan and with similar construction types, raises the concern on the seismic safety of building structures in Bhutan. This study is aimed at assessing the performance of masonry-infilled and soft storey reinforced concrete frame buildings in Bhutan under the 475- and 2475-year return period ground motions predicted from the Probabilistic Seismic Hazard Analysis. A nonlinear strut model is used to model the infill wall, and the influence of openings and soil–structure interaction are considered in the analyses. The result suggests that the masonry-infilled reinforced concrete frame buildings in Bhutan could suffer repairable and irreparable damages under the 475-year return period ground motions and severe damages and even collapse under the 2475-year return period ground motion. The buildings with the soft storey are found to be more vulnerable than the normal masonry-infilled reinforced concrete buildings. The design recommendation of Indian Seismic Code improves the performance of soft storey buildings but cannot fully negate the soft storey effect. This study is the first such effort in assessing the performance of general building stocks in the high seismicity Bhutan. The results can guide the seismic strengthening options and can be used for further loss predictions for seismic preparedness of the country.

Shaking Table Test of Quarter Scale 20 Story RC Moment Frame Building Subjected to Long Period Ground Motions

Shaking table test of a quarter-scale 20-story reinforced concrete building model was carried out. Employed input waves were kinds of long period and long duration ground motion. Test results showed that structural slabs were fully effective for building strength, which could be expressed in detailed analysis using nonlinear FEM. However, the observed hysteretic damping after yielding was fairly smaller than the expected by the current design custom, which caused smaller and unsafe estimated response than that observed in the test.

浄水場における傾斜板沈降装置のスロッシング被害対策に関する研究

High rate plate settler modules are solid and liquid separation devices to improve precipitation efficiency of purification in settling tanks in purification plants. In the 2011 off the Tohoku Pacific coast Earthquake, the high rate plate settler module fell off and it was damaged. As a result, supply of the water stopped for a long time. It is considered that liquid sloshing by long period ground motion caused these damages. There are examples of damage as liquid sloshing in the past, fire of an oil tank, and damage of device in a tank, overflow of fluid in storage pool for spent nuclear fuel in a nuclear power plant. From these backgrounds, there are a lot of researches of sloshing for those oil tanks and those nuclear power plants. On the other hand, there are few researches for settling tank in purification plant. Settling tank in purification plant is an important lifeline essential to economy and activity. Therefore, it is necessary to take measures so such kind of damage will not occur again. The purpose of this study is to propose high rate plate settler module with mechanism, which can suppress damage by liquid sloshing and has good repairability. In this paper, we examined that the sloshing occurred by purification plant inclined plates were moved in a long period ground motion. When the inclined plates damaged and falling off, its have became a problem. Therefore, we proposed vibration control devices. Authors performed the sloshing experiment by the miniatures, and investigated the effect of the vibration control devices. Authors carried out the identification of the result based on Housner theory, construction of the analysis model by mass system. Examination of sloshing damage carried out by using the analysis model.

Estimation Algorithm for Low Frequency Seismic Motions Based on Extended Semblance Function

Abstract Monitoring low frequency and long period ground motions is very important for earthquake detection and alarm systems, and signal processing techniques help to investigate the mechanism of deep ground motions and earthquake occurrence by detecting effective seismic information from the seismograms. In this paper a frequency domain algorithm is presented to estimate the travel time difference of seismic waves with multi-path interferences caused by the refraction effect. The spectra of the seismograms are calculated through the fast algorithm, and the multi-path parameters as well as the difference of travel time between a reference position and the seismographic stations are given by an optimization algorithm in the frequency domain. The new approach can work under conditions of refraction interference, and improve the estimation performance by using an extended semblance function. Its effectiveness is demonstrated through some numerical examples, and it is shown that the proposed algorithm is applicable to the analysis of low frequency seismograms.

Evaluation of CPT-based Liquefaction Procedures at Regional Scale

The liquefaction database describing the response of the Christchurch area in the 2010–2011 Canterbury Earthquake Sequence (CES) provides a unique basis for evaluating the regional application of various liquefaction analysis procedures, from liquefaction triggering analyses through to liquefaction vulnerability parameters. This database was used to compare the Robertson and Wride [17], Moss et al. [15] and Idriss and Boulanger [7] liquefaction triggering procedures as well as evaluate the impact of the 2014 versus 2008 Cone Penetration Test (CPT)-based liquefaction triggering procedure by Idriss and Boulanger on four liquefaction vulnerability parameters (SV1D, LPI, LPIISH and LSN), the correlation of those parameters with observed liquefaction-induced damage patterns in the CES, and the mapping of expected damage levels for 25, 100 and 500 year return period ground motions in Christchurch. The effects on SV1D, LPI, LPIISH and LSN were small relative to other sources of variability for the majority of the affected areas, particularly where liquefaction was clearly severe or clearly not. Nonetheless, considering the separation of the land damage populations as well as consistency between the events, the the IB-2008 liquefaction triggering procedures appears to give a slightly better fit to the mapped liquefaction-induced land damage for the regional prediction of liquefaction vulnerability for the Christchurch soils. The Boulanger and Idriss [1] triggering procedure produces improved agreement between the liquefaction vulnerability parameters and observations of damage for: areas south of the Central Business District (CBD) where there tends to be higher soil Fines Content (FC), and localized areas that experienced liquefaction during the smaller Magnitude (M) earthquake events. Implementation of the 2014 liquefaction triggering procedure for mapping of expected liquefaction-induced damage at 25, 100 and 500 year return period ground motions is shown to require use of representative Peak Ground Acceleration (PGA)-M values consistent with the de-aggregation of the seismic hazard. Use of equivalent magnitude-scaled PGA-M7.5 pairs, where the equivalency relates to previously published MSF relationships, with the 2014 liquefaction triggering procedure is shown to be unconservative for certain situations.

Strong ground motion simulation for the 2013 Lushan MW6.6 earthquake, Sichuan, China, based on the inverted and synthetic slip models

It is well known that quantitative estimation of slip distributions on fault plane is one of the most important issues for earthquake source inversion related to the fault rupture process. The characteristics of slip distribution on the main fault play a fundamental role to control strong ground motion pattern. A large amount of works have also suggested that variable slip models inverted from longer period ground motion recordings are relevant for the prediction of higher frequency ground motions. Zhang et al. (Chin J Geophys 56:1412–1417, 2013) and Wang et al. (Chin J Geophys 56:1408–1411, 2013) published their source inversions for the fault rupturing process soon after the April 20, 2013 Lushan earthquake in Sichuan, China. In this study, first, we synthesize two forward source slip models: the value of maximum slip, fault dimension, size, and dimension of major asperities, and corner wave number obtained from Wang’s model is adopted to constrain the generation of k−2 model and crack model. Next, both inverted and synthetic slip models are employed to simulate the ground motions for the Lushan earthquake based on the stochastic finite-fault method. In addition, for a comparison purpose, a stochastic slip model and another k−2 model (k−2 model II) with 2 times value of corner wave number of the original k−2 model (k−2 model I) are also employed for simulation for Lushan event. The simulated results characterized by Modified Mercalli Intensity (MMI) show that the source slip models based on the inverted and synthetic slip distributions could capture many basic features associated with the ground motion patterns. Moreover, the simulated MMI distributions reflect the rupture directivity effect and the influence of the shallow velocity structure well. On the other hand, the simulated MMI by stochastic slip model and k−2 model II is apparently higher than observed intensity. By contrast, our simulation results show that the higher frequency ground motion is sensitive to the degree of slip roughness; therefore, we suggest that, for realistic ground‐motion simulations due to future earthquake, it is imperative to properly estimate the slip roughness distribution.

Development of framework for seismic response analysis of storage tank based on fault-structure system

In this study, the framework for the seismic response analysis of oil-storage tank along fault-structure system concept has been presented; where the long period ground motion simulation and sloshing simulation based on 3D finite element method (FEM) is integrated. Three dimensional finite element model is constructed using multi-resolution structured and unstructured mesh for the ground motion prediction. For the sloshing analysis Lagrangian Finite Element Method is used. Also the effect of surface topography on the sloshing response is checked and the effect is found to be significant.

J1010601 長周期構造物に設置する粘性-摩擦ハイブリッドダンパに関する研究([J101-6]制振(2))

Every year, many earthquakes occur in Japan. Many high rise structures which are in a long distance from the hypocenter of the earthquake resonate with the long period ground motion. Recently, many structures require countermeasure for long period ground motion. Various viscous dampers have been developed and applied to actual structures to suppress vibration response. However, the vibration control performance decreases with the long duration time of earthquake because of a temperature rise of the viscous material. Therefore, there is concern that these viscous dampers can not suppress vibration response in case of long period ground motion. In order to solve this problem, a viscous-friction damper in series is proposed in this study. Then, in this hybrid damper, the friction damper can absorb vibration energy as well in case of the long period ground motion. In this paper, seismic response analysis is conducted to confirm performance of hybrid damper.

想定東海地震の長周期震動予測に及ぼす破壊開始点の不確定性の影響

東海地震を例題とし、震源モデルにより算定される長周期震動に及ぼす断層内の破壊開始点の不確定性の影響を検討した。断層面内に破壊開始点が一様に分布するものとしたサンプルサイズ30,000のモンテカルロシミュレーションを行い、破壊開始点の変動に伴う長周期震動の統計量を求めた。数値実験の結果から、速度応答スペクトルの長周期領域における最大値の統計分布は、極値Ⅲ型分布により良く表されること、さらにその統計分布には上限が存在し得ることを極値統計理論を用いて示した。

Lateral and Base Shear Forces Acting on 20 Stories Building in Bujumbura City during the Seismic Activity

For designing a high-rise building in Bujumbura city, it is very important to know that the city is located in the seismic zone and therefore take adequate conceptual measures. This study was inspired by a tendency to high-rise building in Bujumbura city while the designers of these buildings do not have sufficient data on the impact of seismic activity in the area lying in the extension of the Rift Valley. By referring to the International Building code (Berkeley 2003) and the ASCE7 data, it is easy to draw a response spectrum curve for Bujumbura city based on the short period ground motion range (To), the characteristic period of ground motion (Ts) and the spectral response acceleration Ss and S 1 . By using the Extended Three Dimensional Analysis of Building Systems (ETABS) software for the 20 stories building, the seismic base shear forces (V) can reach -2000KN and the seismic stories lateral forces (Fx) can reach 230 KN.

Bound Direct Displacement-Based Seismic Design of Buildings

Limitations of probabilistic model appear when information is insufficient. Convex set model, which much less information is needed, is employed to model uncertainties of target displacement, peak acceleration and predominant period of ground motion. A new bound direct displacement-based seismic design method is proposed. The interval of seismic design results is obtained by considering the uncertainties of design variables and the relative risk of any design scheme within the interval is also simultaneously provided. The results of a four-storey RC building show that the base shear and beam sectional area by Xue's design scheme are close to the lower bound of the bound design method, and the column sectional area and the weight of steel bar are just over the middle value to the upper bound. The sensitivity analysis indicates that the base shear is more sensitive to target displacement.

Finite Element Analysis of Reinforced Concrete Beam-Column Joint under Low Cyclic Loading with Different Load Systems

Seismic performance of RC beam-column joints under low cyclic loading with different cycle numbers was analyzed by FEA software, to study duration effect of long period ground motion. The loading with different cycle numbers was used to simulate the duration of the ground motion. Hysteretic curves and skeleton curves of the joints were obtained. The results indicate that as the cycle number increases, the capacity and ductility of the joint declines, and the stiffness of the joint attenuates faster.

A New Zealand-Specific Pseudospectral Acceleration Ground-Motion Prediction Equation for Active Shallow Crustal Earthquakes Based on Foreign Models

Abstract The applicability of foreign ground‐motion prediction equations (GMPEs) for predicting geometric‐mean pseudospectral acceleration amplitudes from active shallow crustal earthquakes in New Zealand (NZ) is examined. Four different foreign GMPEs were considered, as well as the NZ‐based McVerry et al. (2006) (McV06) model. It was found that the McV06 model exhibited the lowest applicability with a database of 2437 recorded ground motions, and that the Chiou et al. (2010) (C10) modification of the Chiou and Youngs (2008b) (CY08) model was the most applicable. Discrepancies between the C10 model and the NZ database, which were empirically identified and theoretically justified, were used to modify the C10 model for: (1) small magnitude scaling; (2) scaling of short period ground motion from normal faulting events in volcanic crust; (3) scaling of ground motions on very hard rock sites; (4) anelastic attenuation in the NZ crust; and (5) consideration of the increased anelastic attenuation in the Taupo Volcanic Zone. The developed NZ‐specific model therefore contains features as evident from recorded ground motions in NZ and consistent scaling for parameters not well constrained by NZ data. Comparisons with ground motions from the 4 September 2010 Darfield and 22 February 2011 Christchurch earthquakes, which occurred following completion of the NZ‐specific model, illustrate that it provides an empirical prediction with sufficient accuracy and precision.

An approach to improve Rayleigh-wave ellipticity estimates from seismic noise: application to the Los Angeles Basin

S U M M A R Y We present an approach for seismic noise which improves Rayleigh-wave ellipticity estimates by reducing the influences from body waves and Love waves. The method requires three-component seismographs and uses the phase-shift information between the vertical and horizontal components. We select data that show the phase-shift of about 90◦ in order to separate Rayleigh waves from body waves and Love waves. In comparison to the usual H/V approach, the estimates for Rayleigh-wave ellipticity are systematically different by about 20 per cent because the existence of S waves and Love waves systematically increases horizontal amplitudes. The differences in the inverted S-wave velocity structure reach up to about 20 per cent in the upper 20 km. The method is limited to a relatively low-frequency range, below 0.3 Hz, as the 90◦ phase-shift peaks become difficult to identify above 0.3 Hz. Despite this limitation in the frequency range, this approach can improve the S-wave velocity structure in the upper 5–10 km, which should lead to a better prediction of long-period ground motions for periods of about 5–10 s. An improved prediction of such long-period ground motion is important for hazard mitigation in the world’s metropolitan areas with high-rise buildings. This approach is applied to the structure in the broader Los Angeles basin in Southern California and improvement of the reference velocity structure in the upper 5–10 km is demonstrated.

地震入力レベルを考慮した連結機構摩擦ダンパーの免震戸建て住宅への適用性

For the extremely large or the long period ground motions, it is feared that the base isolation layer collides with the side wall due to the extremely large displacement. In case dampers with large capacity are incorporated with the base isolation layer, the effect of the base isolation decreases due to the large reaction force of dampers in small seismic events. To realize the control of the displacement and the acceleration which is the important factor of the base isolation effect, the friction damper with coupling mechanism is proposed. Analytical studies are conducted using the base isolated detached houses with slide bearings and the proposed dampers. To decide a series of damper parameters, the optimum design method is used. Results indicate that the friction damper with coupling mechanism can control the maximum displacement and the maximum acceleration within the design criteria which is decided individually for the input ground motion level.

Effect of Short Period Ground Motion on Seismic Design of Bridges and Viaducts

Recently earthquake ground motions with high frequency components have been observed on a regular basis. It is well known that the "effective input motion" is reduced in the high frequency range due to the effect of Kinematic interaction of the soil-pile system. Dynamic soil-pile interaction analyses, therefore, were conducted by varying the conditions of both the ground and piles, and the influence of input loss from the pile foundation was investigated. The result revealed that the input loss was negligibly small in case of ground motion whose amplitude was predominantly in the 1-2 Hz range, such as the Hyogoken Nanbu earthquake. On the other hand, the input loss was quite large in the case of high frequency seismic motion such as that observed in the Tohoku earthquake. A simplified expression of input loss, which could be used in practice for seismic design and is based on the Winkler-type spring model, was proposed.

Estimation of Long Period Ground Motion Earthquake Effects to High-rise Buildings at Hanoi and HoChiMinh Cities, Vietnam

Estimation of dynamic characteristics of subsurface such as predominant period, amplification factor, shear wave velocity play an important role in researchs of the effects of long-period ground motion earthquakes on high-rise buildings in big cities. However, in Vietnam, due to the lack of observation devices, there is a shortage of dynamic ground information. Consequently, in this paper, at first, the results of applying the Nakamura Method to data processing of microtremor observations in Hanoi and HoChiMinh City of Vietnam are presented. By using this method, the predominant period of the ground at the sites could be estimated from the horizontal to vertical (H/V) spectral ratios of microtremors. The obtained results show that the grounds of the mentioned two cities have considerable possibility of resonating with long-period ground motions. Then, the spectral accelerations in bedrock of Hanoi and HoChiMinh city were estimated by attenuation relationship of Uchiyama and Midorikawa 2006 with the far-source rupture faults that were Sumatra earthquake 2004 and Tha-Khaek fault line in Thailand. Next, the accelerations on ground surface of the above two Vietnamese cities were calculated by using spectral ratio of microtremor and inverse Fourier transform. Finally, those obtained accelerations were used to do the time history analysis applied for 8 high-rise buildings in Hanoi and HoChiMinh city. The results of this final step show that far-source rupture faults have considerable possibility to generate long-period ground motions that cause certain affects to the behaviors of high-rise buildings in Vietnamese cities.

Correlation of Site Characteristic Period with Predominant Period of Ground Acceleration by a Simplified Model

Site characteristic period is an important index in seismic zonantion and seismic resistance design. The characteristics of the ground motions are conceptually related with site characteristics. A simplified single-layer model is used for simulating horizontal strata under seismic loading to calibrate the correlation of site characteristic period with the predominant period of ground motion. The analytical results show that the inputted motions were amplified considerably by the site typically for the period components which were close to the site characteristic periods; with the shear wave velocity of the soil layer decreases with respect to the initial shear wave velocity, the predominant period of ground motion increases; the site characteristic periods are consistent with the predominant periods of the ground motion.