Ground Motion Acceleration Research Articles

DAMAGE INVESTIGATION AND RE-ANALYSIS OF DAMAGED BUILDING AFFECTED BY THE GROUND MOTION OF THE 2009 PADANG EARTHQUAKE

The purpose of this paper is to introduce a complete assessment to damaged buildings due to earthquake event in earthquake-prone areas. Padang city is located on the western part of the island of Sumatra, Indonesia, an earthquake-prone area. One of the largest earthquake events (Mw 7.6) occurred on 30 September 2009, striking the west coast of Sumatra. A total of 106,658 houses and 4,000 other buildings suffered damage classified from slight to severe, and a reported 1,117 people were killed. Some large-scale reinforced concrete buildings in Padang, as the capital of West Sumatra province, were also damaged. In order to determine the antiseismic deficiencies of these buildings, the authors assessed three buildings (BPKP, UNP and PU building) on soft soil (the predominant period is greater 2s and Vs30 400m/s) to the BPKP building (Vs30<150m/s), the peak ground motion acceleration at BPKP was found to have amplified 1.47 times. This result enables us to conclude that the soil characteristics (rock to soft) influence ground motion amplification and affect the degree to which buildings suffer damage.

A Study on the Sloshing Problem of Vertical Storage Tanks under the Action of Near‐Fault Earthquakes

In this study, through a vibration table test, finite element simulation, and research on the rationality of the wave‐height fortification of national storage tank specifications, the sloshing response of vertical storage tanks under the action of near‐fault ground motion was analyzed. The test results showed that the sloshing wave height of a vertical storage tank was larger under near‐fault or long‐period ground motions, and the relationship between the sloshing wave height and the peak acceleration of input ground motions was approximately linear. The numerical simulations of the model tank showed that the simulation wave height and the test wave‐height data were well fitted. Therefore, it was feasible to simulate the sloshing of large vertical storage tanks using ADINA software. In addition, a large number of sloshing simulations of near‐fault ground motions on 10,000 m3 vertical storage tanks were performed. The simulated wave height had a high correlation with the predominant period or pulse period of near‐fault ground motions. Under the calculation with similar parameters, the wave height of the tank standard in several countries had a lower fortification of the near‐fault excitation wave height. Through the root mean‐square method using a small sample size, a wave‐height correction under a near‐fault effect was applied to the wave‐height formula for the Chinese tank seismic specification. Finally, the problem of a double‐damping correction was addressed by adjusting China’s GB50341 wave‐height formula. This work provides a reference value for practical engineering applications.

Alteration of Ground Motion Acceleration at Ground Level Due to Tunnel Excavation

Underground tunneling is one of the alternative solutions to diminish traffic congestion in large cities. One of the most important effects of tunneling is the displacement of the ground surface, the settlement around the tunnel, and the variation in earthquake acceleration. The performance and behavior of underground structures have been studied by several researchers, but the impact of tunnel excavation on earthquake records and its effects on structures above the ground level have received less attention. This research emphasizes changes of earthquake acceleration at the ground level, structural response and Fourier spectrum by excavating a horseshoe tunnel. Results show that digging a horseshoe tunnel will change the characteristics of the earthquake record at ground level.

Numerical analysis of influence of different track structures on vibration response of subway

Taking Beijing metro line 5 as the research vehicle model, the influence of different track structure on subway vibration is analyzed. According to the coupling dynamic equations of vehicle rail, the coupling dynamic equations of vehicle body models under integrated rail bed, plate rail bed and floating plate rail structure are established, respectively, and the vibration response of vehicle body models under three kinds of rail structure is calculated. The evaluation indexes of dynamic characteristics of rail coupling are analyzed. The analysis results show that with the increase of subway speed, the vertical displacement and acceleration between the vehicle and the middle point of the track gradually increase, and the vibration response of the fourth wheel to the maximum wheel-rail force also gradually increases. With the increase of the buried depth of subway tunnel, the maximum vertical displacement and ground motion acceleration of the three tracks gradually decrease, which indicates that this method can accurately analyze the vibration response of subway under different track structures.

Analysis of a building under composite structural system: A review

A composite structural system or dual structural system is a structural system in which a whole frame provides strength for gravity load and moment-resisting frame or bracings provide support for lateral loadings. The objective of the study is to review the distinctive lateral load resisting system that is being used for lateral strength but still not entirely satisfied with the enactment of the structure under the dynamic response of a building. For the contemplation of dynamic nature, the important parameters like Base shear, Base moment, Storey shear, story displacement, and relative displacement are taken into consideration and for time period analysis parameters like the total height of the building, story height, stiffness, mass and number of storeys is taken into consideration and are reviewed from the literature and their effect in both linear and non-linear dynamic states are studied. The paper contemplated the response of building against lateral load and a comparative response is studied between the bare frame and frame with the shear wall, bracings, and other probable measures embracing distinctive structural configurations is carried out and the results are conferred taking different steel sections, and bracings pattern. The paper also focused on the effect of ground motion acceleration of different magnitude incorporating with distinctive non-linear dynamic parameters specifically the effect of variation in Peak Ground Acceleration on roof displacement, roof acceleration and base shear in different directions and studied that it’s not necessary peak PGA results in peak response of roof drift, displacement, base shear and acceleration.

Physical mechanism for severe seismic hazard in the 2010 Yushu, China, earthquake (Mw= 6.9): insights from FEM simulations

The moderate-size 2010 Yushu earthquake (Mw 6.9) caused severe seismic damage around the source region which is situated on the sparsely populated hinterland of the Tibetan Plateau. But until now the mechanisms have not been well understood. To this end, we constructed the model to simulate the fault spontaneous rupture propagation, in which the realistic fault with a curved bend is imbedded. Our modeling results show that the special fault geometry controlled the rupture behavior, which encouraged rupture propagation speed transition from subshear to supershear with the speed of 5.17 km/s larger than the local shear wave velocity. Moreover, calculation results demonstrated that strong ground motion acceleration was greatly intensified by supershear ruptures, leading to widespread destruction. This may be the main reason why serious earthquake damage happened in the Yushu earthquake. In particular, we can see from numerous numerical experiments that rupture styles will be different if geometries of fault are varied. It is confirmed that it is the special geometry of the seismogenic fault of the Yushu mainshock produced grave seismic hazard. Thus, deeply investigating fault geometry will be helpful to better understand seismic source process and seismic hazard assessment. Key Points Curved bend in the seismogenic fault for the 2010 Yushu earthquake encouraged the supershear rupture transition. Strong ground motion acceleration was greatly intensified by supershear ruptures. Special geometry of the fault of the Yushu mainshock lead to seriouos seismic damage.

Hydrological response to the Sea of Galilee 2018 seismic swarm

Co-seismic and post-seismic groundwater response to the Sea of Galilee 2018 seismic swarm, along with other teleseismic earthquakes are analyzed in nine water pressure monitoring wells, with high sampling rates (40 sps). The largest event of the swarm (Mw 4.6) caused significant water level oscillations of 0.216 bar (2.16 m) and sustained water level drop of 0.121 bar (1.21 m). The response of groundwater to this event and two other distant large events include co-seismic oscillations, co-seismic undrained sustained change, and post seismic drained change. In addition, the proximity of the earthquake swarm to high resolution monitoring wells provides an opportunity to analyze the changes in the oscillations’ amplitudes of most events. The ratio of the water level to ground motion acceleration amplitudes increased after the Mw 4.6 event, suggesting that the aquifer poro-elastic properties have changed. These co-seismic amplitude changes are more sensitive measure than the water level response to earth tides that showed no significant change in the phase and amplitude associated with any of the events. The maximum amplitude of the oscillations is correlated to the amount of drained response, suggested to be caused by activation of a nearby fault and drainage of water between aquifers. The undrained behavior is related to poro-elastic properties changes within the aquifer and depends on the duration of the oscillations. Details of the groundwater high sampling rate can shed light on deformation processes that were described previously as step like changes.

Development of surface ground motion and spectral acceleration based on modified shear wave propagation analysis

The shear wave propagation analysis (SPA) is a method for developing surface ground motion and spectral acceleration by conducting seismic wave propagation from bedrock to surface elevation. The bedrock elevation and soil profile from bedrock through surface elevation are important information needed for SPA. The shear wave velocity, damping ratio, soil density and shear modulus are the four parameters that are needed for developing SPA. This paper describes a modified SPA for developing surface ground motion and spectral acceleration by conducting two different soil deposit model, actual and modified bedrock elevation models. The difference in the two models depends on the bedrock elevation used for SPA. The actual bedrock elevation model is conducted based on the real bedrock elevation observed using microtremor test. However, the second model is performed based on the final depth of soil boring investigation. The study was conducted at the Engineering Faculty of Diponegoro University. Based on the microtremor observation, the bedrock elevation was predicted at 50 metres below the surface level. However, two soil boring investigations conducted in this study area were stopped at 30 metres below the surface level. The surface ground motion and spectral acceleration developed from both models are almost equal.

Investigation into the Nonlinear Time-History Analysis of CNT-Reinforced Concrete Column by a Multiscale Approach

Many concrete structures have been damaged during recent earthquakes due to the low ductility of their columns. Hence, several recent research contributions have been dedicated to producing high-performance concrete materials. Among these contributions, carbon nanotubes (CNTs) are of superior mechanical properties and can be used as additive in concrete. In this research, a sequential multiscale method, including nano-, micro-, meso- and macro-scales, is used to investigate the cyclic and seismic responses of concrete columns through numerical simulations. The aim of this research is to investigate the load-carrying capacity and energy absorption of CNT-reinforced concrete columns under cyclic loading. The results of the current research indicate that both of these properties improve significantly in the presence of CNTs. Furthermore, the results of fragility analysis reveal that for similar damage states, a CNT-reinforced column reaches the specified damage state at higher peak ground motion acceleration than an ordinary concrete column. Hence, the use CNTs in concrete structures may prove beneficial for high-seismic risk areas.

Seismic Performance Levels of a Large Underground Subway Station in Different Soil Foundations

ABSTRACT With the soil constitutive model developed for the dynamic large deformation of soft soil, a finite element model was constructed to simulate the soil–underground structure static and dynamic coupling interaction system, in which the dynamic contact between soil and underground structure and the dynamic damage of reinforced concrete were considered. The seismic performance and damage mechanism of the large underground subway station in different soil foundations were investigated and evaluated in detail. It was proven that the interaction mechanism between the soil and underground structure would change with the type of soil foundation and the peak acceleration of input ground motion, which can be evaluated by the interaction coefficient between the soils and underground structure. At the same time, some regulations on the seismic performance of underground structure in China code are already unsuitable for evaluating the seismic performance of a large underground subway station in the soft soil foundation or subjected to a strong earthquake, which should be investigate by the specialized time–history analysis method instead. In this study, five seismic performance levels were firstly defined by the inter-storey drift angle of underground structure and corresponding earthquake damage states.

Stochastic analysis of linear structural systems under spectrum and site intensity compatible fully non-stationary artificial accelerograms

In seismic areas one of the most important problems for engineers is to characterize in the most correct way the future ground motion accelerations. Building codes allow the practitioners to use artificial time-history compatible with a target pseudo-acceleration spectrum. The spectrum compatible seismic accelerations are usually represented by samples of stationary processes, even if it is well know that the ground motion accelerations should be modelled as samples of fully non-stationary processes. Moreover, the spectrum compatible accelerograms are not able to catch the site intensity of seismic events. In this paper methods able to catch the main features of recorded earthquakes, generating both spectrum compatible fully non-stationary accelerograms and artificial fully non-stationary accelerograms compatible with the site intensity of recorded accelerograms, are presented.In order to quantify the influence of the input model on the structural response, several numerical applications will be carried out and the results will be compared with the Monte Carlo simulation method.

Attenuation Relationship for Peak Horizontal Acceleration of Strong Ground Motion of Uttarakhand Region of Central Himalayas

ABSTRACT An attenuation relationship has been developed for Uttarakhand, a state of Republic of India (part of central Himalayas) by using the records of earthquakes occurred in the region in the past by strong ground motion networks of U.P. array, project “National strong motion Instrumentation network” and network of project “Earthquake early warning system for Northern India”. Uttarakhand region lies in the central seismic gap where scientists have estimated that a large-sized earthquake is overdue. Largest peak ground acceleration of two horizontal components of total 116 records of 9 earthquakes (5.0≤ Mw≤6.8) are used in the development of the new relationship. Two-step stratified regression model is chosen. The proposed attenuation relationship is: where A is peak horizontal acceleration in g of strong ground motion, M is magnitude and X is hypocentral distance from the source. The standard error () of the proposed relationship is 0.281. The developed attenuation relationship will be useful for site specific studies, seismic hazard estimation and other engineering applications. The attenuation relationship can be further upgraded with the availability of earthquake records in future.

Site dependent and spatially varying response spectra

The goal of this study is to provide a stochastic method to investigate the effects of the randomness of soil properties due to their natural spatial variability on the response spectra spatial variation at sites with varying conditions. For this purpose, Monte Carlo Simulations are used to include the variability of both incident ground motion and soil parameters in the response spectra by mean of an appropriate coherency loss function and a site-dependent transfer function, respectively. The approach is built on the assumption of vertical propagation of SH type waves in soil strata with uncertain parameters. The response spectra are obtained by numerical integration of the governing equation of a single-degree-of-freedom (SDOF) system under non-stationary site-dependent and spatially varying ground motion accelerations simulated with non-uniform spectral densities and coherency loss functions. Numerical examples showed that randomness of soil properties significantly affects the amplitudes of the response spectra, indicating that as the heterogeneity induced by the randomness of the parameters of the medium increases, the spectral ordinates attenuate.

Influence of spatial variability of ground on seismic response analysis: a case study of Bangkok subsoils

The objective of this study was to observe the spatial variation in the geological subsoil condition on the seismic ground response of Bangkok subsoils during the remote 6.8 Mw Tarlay earthquake in 2011 in Northern Thailand. A simulation of random locations was initially performed to define the studied locations. The dynamic parameters, such as the soil index properties, shear modulus, and shear wave velocity, were determined from the subsurface modeling of Bangkok subsoils. Next-generation attenuation analysis was performed to define the input ground motion at each investigated site. Non-linear one-dimensional site response analysis was performed to investigate the surface ground motion, amplification factor, and spectral acceleration during short (0.2 s) and long (1 s) time periods. In general, it is important to consider the ground spatial variation in any seismic ground response analysis. The results show that Bangkok subsoils could magnify the seismic wave during an earthquake. For example, in the 2011 Tarlay earthquake, the magnification varied from two- to four-fold. The results from this study can be used to define the microzonation of the ground motion characteristic of Bangkok subsoils, such as the peak ground acceleration and the spectral acceleration, at short and long periods.

Ground motion acceleration and response spectra of Al-Mashair area, Makkah Al-Mukarramah, Saudi Arabia

The residential buildings of Makkah Al-Mukarramah constructed mostly on a soft Quaternary deposits with various thicknesses reaching to more than 30 m in most districts. The spatial variation of ground motion in Al-Mashair area has been assessed by synthetic ground motion acceleration using a point source model coupled by a site response analysis. The bedrock level acceleration time histories have been generated at 27 sites within Al-Mashair area generated by earthquake of 5.0 moment magnitude, using a synthetic ground motion model. While, the ground surface response spectral curves with 5% of the critical damping were assessed using shear-wave velocity profiles of multichannel analysis of surface waves besides the earthquake time histories. Surface ground response spectra were mapped using the ArcGIS platform for 1.5 Hz, 3.0 Hz, 5.0 Hz, 8 Hz, and 10 Hz where this frequency range includes the range of natural frequencies of tall to single story buildings. The surface ground motion maps display that the hazard level ranges from low to moderate, where peak spectral acceleration varies between 13 cm/s2 and 124 cm/s2. The maximum surface ground motion values are calculated with 5% damped horizontal spectral acceleration at 10 Hz, which is equal to the natural frequency of low-rise buildings. These results should be taken into consideration from decision-makers, urban planners, and civil engineers during the design of earthquake-resistant structures in Makkah Al-Mukarramah city in general and Al-Mashair zone in particular.

Influence of Seismic Precautionary Intensity on Some Kind of Super High-rise Building’ Structure Plan

The paper can give reference to select structural scheme of the same kind of super high-rise building (150m and 180m). Different seismic precautionary intensity (SPI) and frame-corewall structure plans are compared. SPI is from 6 to 8 degree (design basic acceleration of ground motion (DBAGM) is assumed as 0.2g, g=9.8m/s2). When floor height is low and inclined beams can’t appear in rooms, it is essential to set inner circle columns between outer circle columns and corewall. The computations shows when SPI is low, inner circle columns between core wall and outer circle columns get few. Outer walls of core wall get thin and inner walls get few. The steel and reinforced concrete (SRC) columns below the 10~15th floor can be set to get small columns. When the length width ratio of the structural plan is small, the mass of unit area of every floor and the building cost is few.

A new method of deriving the acceleration and displacement design spectra of pulse-like ground motions based on the wavelet multi-resolution analysis

Pulse-like ground motions usually have higher spectral displacements and spectral accelerations than other motions in long periods and can cause severe damage on structures. However, there is still no a generally accepted method to incorporate the features of this type motion in the code-based design spectrum. The pulse period is one of the key parameters to characterize the features of pulse-like ground motions. The relations between the pulse period and the earthquake magnitude have been well studied, and many prediction equations have been proposed. However, these results cannot be considered in the process of deriving the design spectrum of pulse-like ground motions. This paper proposes a new method to derive the acceleration and displacement design spectra of pulse-like ground motions based on the wavelet multi-resolution analysis. To consider the influence of the frequency content of ground motions, the frequency band of ground motions is divided into several continuous sub-bands. One or more ground motion components obtained by the wavelet multi-resolution analysis are used to represent the frequency content in each sub-band. Differing from previous methods, the design spectral shape of the proposed method can be changed according to the frequency content of ground motions, and the prediction equations between the pulse period and the earthquake magnitude can be used to improve the current code-based design spectrum.

Ground motion prediction equations for higher order parameters

Amplitude, duration and frequency content are the three key characteristics of a ground motion time history. Few ground motion parameters quantifies two and rarely three of these features. There are even fewer ground motion prediction equations (GMPEs) available for these ground motion parameters. In this study, new GMPEs are derived for a total of 21 parameters representing peak amplitude, energy, intensity, frequency, duration and evolutionary characteristics of a ground motion acceleration time history. An extensive dataset of Japan, comprising 96880 ground motions with magnitudes ranging from Mw 5.0 to Mw 9.0 is used to calibrate the model. The model includes the effects of magnitude saturation, tectonic source mechanism, focal mechanism, geometric and anelastic attenuation, volcanic arc and site effects. Median results of estimates are compared against recorded data of the twin Kumamoto earthquakes of Mw 7.3 and 6.5. These results are also compared against previously developed GMPEs of the region. Further, towards the verification of the functional form, behavior of inter and intra event residuals is verified against magnitude (Mw), distance and shear wave velocity (Vs30) respectively.

Analisis PGA (Peak Ground Acceleration) Berdasarkan Data Gempa untuk Wilayah Jakarta Timur Menggunakan Software PSHA

The purpose of this research was to produce a contour map of ground motion acceleration (hazard map) for exceeded probability of 10% as an effort to mitigate earthquake tectonics in East Jakarta. This study uses the applied theoretical research method approach using PSHA software. The data used comes from data released from BMKG and the Geological Agency. Based on the map of the acceleration of soil movement (hazard map) in East Jakarta resulting from the PSHA process, for a return period of 500 years (10% PE 50 years) the PGA value generated is 0,03 g - 0, 15 g. East Jakarta is a fairly stable region with a low level of earthquake hazard. Increasingly to the south and southwest, the PGA value is increasing due to close to subduction and volcanic activity. The PGA value in this study is almost the same as the revision of the Indonesian SNI earthquake map 03-1726-02 in 2010.

A directionally-dependent evolutionary lagged coherency model of nonstationary horizontal spatially variable seismic ground motions for engineering purposes

A novel directionally-dependent evolutionary lagged coherency model for nonstationary horizontal spatially variable seismic ground motions is developed for engineering purposes. Evolution of the model is achieved by varying the values of the parameters in time. First, based on the generalized harmonic wavelets, the approach for estimating the evolutionary lagged coherency of realistic seismic ground motions is presented. Then, the evolutionary lagged coherency model of spatially variable seismic ground motions is formulated. This proposed model is based on the analytic form of the cross correlation function for a plane wave in a homogeneous random medium. The parameters of the model are treated as piecewise constant variables for describing the evolutionary characteristics of the estimated coherency. Finally, the evolutionary lagged coherency of the spatially variable ground motion accelerations recorded at the SMART-1 array, Taiwan, during Event 45, is investigated and modeled. The ground motions are divided into three sections: a build-up portion, a high-intensity portion and a decaying portion. The model parameters are identified in these three sections respectively. The comparisons between the actual estimated coherency and the model indicate that the proposed evolutionary lagged coherency model can well reflects the time-dependent correlation of the realistic spatially variable seismic ground motions.