Ground Motion Indices Research Articles

Evaluation of seismic damage to Iraqi educational reinforced concrete building using FEMA P-58 methodology

The building seismic performance assessment can be defined as a posterior phase of investigation in which a detailed analysis is executed in order to evaluation of seismic damages and quantify the sequences of the earthquake for a building, this approach could be probabilistic evaluation or deterministic one. The aim of this paper is to perform seismic damage evaluation for educational multi-storey reinforced Concrete Building in Al-Mustaqbal University College (MUC) in Al-Hilla City, Babylon governorate in the middle of Iraq by using FEMA P-58 methodology. A 3D mathematical modelling, pushover analysis by using SeismoStruct software. In addition, incremental dynamic analysis (IDA) and fragility curve according to FEMA P-58 are developed in order to obtain damage limits in term of performance levels of the case study building. Fragility curves are useful tools for showing the probability of structural damage due to earthquakes as a function of ground motion indices. IDA is performed for those simulated building using twelve ground motions with scaling peak ground acceleration increased every 0.1g until it achieved 1.5g to determine the drift capacity of the building in four performance levels, operational (OP), immediate occupancy (IO), life safety (LS) and near collapse (NC) as defined in FEMA P-58. Based on those capacities, fragility curves were developed in terms of peak ground acceleration (PGA) and elastic spectral displacement for drift levels with lognormal distribution assumption.

Seismic Fragility Curves for RC Flat Slab Buildings with and Without Infill

Rapid urbanization leads to more demand for construction of commercial buildings in Indian cities. The ease construction and more space demand of buildings are constrained in conventional buildings. To overcome constrained, the flat slab buildings evolved and practiced recent time in urban cities. It is becoming more popular for multistoried commercial buildings but experiences larger displacements under lateral load effect caused by earthquakes. These buildings need urgent to assess the vulnerability of buildings. In this fragility analysis is carried out, and it is useful for the evaluation of the probability of structural damage due to earthquakes as a function of ground motion indices. This paper is an attempt made to develop the fragility curves for seven-storey RC commercial buildings and a comparison made between the bare frame, flat slab, flat slab with drop, flat slab with drop and perimeter beam buildings without and with exterior infill walls. The building models are analyzed using ETABS software and designed as per IS 456. In this, infills are considered along the perimeter of the plan of the building and no infill in ground storey. The infill wall is modelled as equivalent diagonal strut model. The Auto hinges are assigned for both beam and column members. Pushover analysis has been performed on the building models using ETABS software. Yield and ultimate spectral displacement and spectral acceleration are obtained from capacity curves. For the development of fragility curves, HAZUS methodology has been used. Fragility curves are developed for all the eight building models and compared the probability of damage of structures for bare frames and open ground storey buildings. In this assumed, the expected intensity ground motion is considered as seismic zone PGA values. It is observed that in considered flat slab models, flat slab with drop and perimeter beam building is showing minimum probability of damage results in both with and without infill for given intensities.

Effect of R, µ and T on the Fragility Curves for Two Spans Reinforced Concrete Highway Bridges

Abstract Fragility curves are useful tools for evaluating the probability of structural damage due to earthquakes as a function of ground motion indices. The force reduction factor (R) is one of the seismic design parameters that determine the nonlinear performance of building structures during strong earthquakes. R factor itself is mostly a function of displacement ductility (µ), natural period of a structure, and soil conditions. A statistical method (Path Analysis) is proposed for the first time to determine the effect of R, µ and T on the column fragility curve parameters of typical box girder, two spans reinforced concrete highway bridge class. An analytical approach was adopted to develop the fragility curves based on numerical simulation. The R, µ and fundamental period T have been used to characterize different bridge configurations. The total, direct, and indirect effects of the variables as having significant effect on fragility curve parameters were identified.

Examination of the Efficiency of Retrofitting Methods through Fragility Analysis

Turkey has several devastating earthquakes throughout its history since it is being located in a highly seismically active region. Thus, seismic evaluation and retrofitting of the existing structures to decrease the potential damage of the future earthquakes is an essential part of the earthquake response plans. The aim of this study is to examine the efficiency of widely used two retrofitting methods of existing structures through fragility analysis. Fragility curves are useful tools to show the probability of structural damage due to earthquakes as a function of ground motion indices. Fragility curves of a hypothetical residential building which represents the existing building stock have been generated. Furthermore, fragility curves of two retrofitted building have also been obtained. The first one is a frame with jacketed columns and the second one has additional shear walls to the existing frame. Fragility curves have been obtained based on both local and global damage criteria limits in terms of interstory drift ratio. The obtained damage probabilities have shown that the damage criteria either local or global used for the generation of fragility curves are significantly effective on the results. Differences in damage probability indicate the importance of the damage criteria and corresponding limits used for the determination of damage probability.

Seismic Hazard Visualization from Big Simulation Data: Cluster Analysis of Long-Period Ground-Motion Simulation Data

This paper describes a method of extracting the relation between the ground-motion characteristics of each area and a seismic source model, based on ground-motion simulation data output in planar form for many earthquake scenarios, and the construction of a parallel distributed processing system where this method is implemented. The extraction is realized using two-stage clustering. In the first stage, the ground-motion indices and scenario parameters are used as input data to cluster the earthquake scenarios within each evaluation mesh. In the second stage, the meshes are clustered based on the similarity of earthquake-scenario clustering. Because the mesh clusters can be correlated to the geographical space, it is possible to extract the relation between the ground-motion characteristics of each area and the scenario parameters by examining the relation between the mesh clusters and scenario clusters obtained by the two-stage clustering. The results are displayed visually; they are saved as GeoTIFF image files. The system was applied to the long-period ground-motion simulation data for hypothetical megathrust earthquakes in the Nankai Trough. This confirmed that the relation between the extracted ground-motion characteristics of each area and scenario parameters is in agreement with the results of ground-motion simulations.

Empirical Fragility Curves of Buildings in Northern Miyagi Prefecture During the 2011 off the Pacific Coast of Tohoku Earthquake

In this study, empirical fragility curves expressed in terms of relationship between damage ratio indices of buildings and ground motion indices were developed in northern Miyagi prefecture located in near-field areas during the 2011 off the Pacific coast of Tohoku Earthquake. The ground motion indices were evaluated from observed ground motions at strong-motion stations and estimated at sites at which no strong-motion accelerometers were deployed during the mainshock. The ground motions at the non-instrumental sites were estimated using the empirical Green’s function method based on bedrock motions inverted from observed records on surfaces from small events that occurred inside the source fault, transfer functions due to underground velocity structures identified from microtremor H/V spectral ratios, and a short-period source model of the mainshock. The findings indicated that the empirical fragility curves as functions of Japan Meteorological Agency (JMA) instrumental seismic intensity during the 2011 Tohoku Earthquake almost corresponded to those during the 1995 Kobe Earthquake and the seven disastrous earthquakes that occurred between 2003 and 2008. However, the empirical fragility curves as functions of peak ground velocity were the lowest. A possible reason for this is that the response spectra of the ground motions in the period ranging from 1.0 s to 1.5 s were small during the 2011 Tohoku Earthquake. Another reason could be the seismic resistant capacities of buildings in the studied districts involved during the 2011 Tohoku Earthquake exceeded those in the cities affected during the 1995 Kobe Earthquake.

Seismic Hazard Visualization from Big Simulation Data: Construction of a Parallel Distributed Processing System for Ground Motion Simulation Data

We have developed a data mining system of parallel distributed processing system which is applicable to the large-scale and high-resolution numerical simulation of ground motion by transforming into ground motion indices and their statistical values, and then visualize their values for the seismic hazard information. In this system, seismic waveforms at many locations calculated for many possible earthquake scenarios can be used as input data. The system utilizes Hadoop and it calculates the ground motion indices, such as PGV, and statistical values, such as maximum, minimum, average, and standard deviation of PGV, by parallel distributed processing with MapReduce. The computation results are being an output as GIS (Geographic Information System) data file for visualization. And this GIS data is made available via the Web Map Service (WMS). In this study, we perform two benchmark tests by applying three-component synthetic waveforms at about 80,000 locations for 10 possible scenarios of a great earthquake in Nankai Trough to our system. One is the test for PGV calculation processing. Another one is the test for PGV data mining processing. A maximum of 10 parallel processing are tested for both cases. We find that our system can hold the performance even when the total tasks is larger than 10. This system can enable us to effectively study and widely distribute to the communities for disaster mitigation since it is built with data mining and visualization for hazard information by handling a large number of data from a large-scale numerical simulation.

Fragility analysis of R/C frame buildings based on different types of hysteretic model

Estimation of damage probability of buildings under a future earthquake is an essential issue to ensure the seismic reliability. Fragility curves are useful tools for showing the probability of structural damage due to earthquakes as a function of ground motion indices. The purpose of this study is to compare the damage probability of R/C buildings with low and high level of strength and ductility through fragility analysis. Two different types of sample buildings have been considered which represent the building types mentioned above. The first one was designed according to TEC-2007 and the latter was designed according to TEC-1975. The pushover curves of sample buildings were obtained via pushover analyses. Using 60 ground motion records, nonlinear time-history analyses of equivalent single degree of freedom systems were performed using bilinear hysteretic model and peak-oriented hysteretic model with stiffness - strength deterioration for each scaled elastic spectral displacement. The damage measure is maximum inter-story drift ratio and each performance level considered in this study has an assumed limit value of damage measure. Discrete damage probabilities were calculated using statistical methods for each considered performance level and elastic spectral displacement. Consequently, continuous fragility curves have been constructed based on the lognormal distribution assumption. Furthermore, the effect of hysteresis model parameters on the damage probability is investigated.

Analytical fragility curves for typical Algerian reinforced concrete bridge piers

This paper illustrates the results of a seismic vulnerability study aimed to derive the fragility curves for typical Algerian reinforced concrete bridge piers using an analytical approach. Fragility curves express the probability of exceeding a certain damage state for a given ground motion intensity (e.g., PGA). In this respect, a set of 41 worldwide accelerometer records from which, 21 Algerian strong motion records are included, have been used in a non-linear dynamic response analyses to assess the damage indices expressed in terms of the bridge displacement ductility, the ultimate ductility, the cyclic loading factor and the cumulative energy ductility. Combining the damage indices defined for 5 damage rank with the ground motion indices, the fragility curves for the bridge piers were derived assuming a lognormal distribution.

Reevaluation Method of Fragility Curves of Wooden House Based on Collected Damage Information

The distribution of earthquake damage plays an important role in the rescue operation and the restoration work in the aftermath of a seismic event. Immediately after an earthquake, the building damage ratios are estimated using ground motion indices and fragility curves constructed from the prior earthquake damage information. However, it should be noted that the fragility curves may sometimes provide less accurate estimations for recent earthquakes. On the other hand, some researchers are focusing efforts on collecting the actual damage information efficiently soon after an earthquake has occurred. The increased attention to collecting the actual damage information is expected to improve the efficiency in the near future and become increasingly helpful for a rapid disaster assessment. In this study, a method for data synthesis to restructure fragility curves is proposed, with respect to the actual gathered damage information. Either the mean or the standard deviation of the prior fragility curve is updated based on collected building damage datasets after recent earthquakes. As a result, the restructured fragility curves with the updated mean values show better estimations than the original ones.

地震動記録に基づく青森県内の強震観測点のサイト増幅度

地震動記録に基づく青森県内の強震観測点のサイト増幅度

Fragility analysis of mid-rise R/C frame buildings

Fragility curves are useful tools for showing the probability of structural damage due to earthquakes as a function of ground motion indices. The aim of this study is to develop the fragility curves for mid-rise R/C frame buildings in Istanbul, which have been designed according to the 1975 version of the Turkish seismic design code, based on numerical simulation with respect to the number of stories of the buildings. Sample 3, 5 and 7 story buildings were designed according to the Turkish seismic design code. Incremental dynamic analyses were performed for those sample buildings using twelve artificial ground motions to determine the yielding and collapse capacity of each sample building. Based on those capacities, fragility curves were developed in terms of elastic pseudo spectral acceleration, peak ground acceleration (PGA) and elastic spectral displacement for yielding and collapse damage levels with lognormal distribution assumption. To investigate the effect due to the number of stories of the building on fragility parameters, regression analysis has been carried out between fragility parameters and the number of stories of the building. It was observed that fragility parameters change significantly due to the number of stories of the building. Finally, using constructed fragility curves and statistical methods, the maximum allowable inter-story drift ratio and spectral displacement values that satisfy the “immediate occupancy” and “collapse prevention” performance level requirements were estimated.

Correlation of JMA instrumental seismic intensity with strong motion parameters

AbstractThe Japan Meteorological Agency (JMA) seismic intensity (IJMA) has been used as a measure of strong shaking for many years in Japan, and it necessitates to know the correlation between the JMA seismic intensity and other strong motion indices, e.g. Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and Spectrum Intensity (SI). In this study, two strong motion data sets were selected; in which, the first set consists of 879 three‐components non‐liquefied records selected from 13 major earthquake events that occurred in Japan, the United States, and Taiwan, and the second set consists of 17 liquefied records selected from 7 major earthquake events that occurred in Japan and the United States. The JMA seismic intensity and other ground motion indices were calculated using the selected data sets. The relationships between the JMA seismic intensity and PGA, PGV, and SI were then derived performing a two‐stage linear regression analysis. Results from the analysis show that the JMA instrumental seismic intensity shows higher correlation with SI than PGA or PGV, and it shows the highest correlation with the parameters such as the combination of PGA and SI or the product of PGA and SI. The obtained relationships are also compared with the ones obtained by other studies, which may be useful for the disaster management agencies in Japan and deployment of new SI‐sensors that monitor both PGA and SI. Copyright © 2002 John Wiley & Sons, Ltd.

Effect of earthquake ground motions on fragility curves of highway bridge piers based on numerical simulation

AbstractFragility curves express the probability of structural damage due to earthquakes as a function of ground motion indices, e.g., PGA, PGV. Based on the actual damage data of highway bridges from the 1995 Hyogoken‐Nanbu (Kobe) earthquake, a set of empirical fragility curves was constructed. However, the type of structure, structural performance (static and dynamic) and variation of input ground motion were not considered to construct the empirical fragility curves. In this study, an analytical approach was adopted to construct fragility curves for highway bridge piers of specific bridges. A typical bridge structure was considered and its piers were designed according to the seismic design codes in Japan. Using the strong motion records from Japan and the United States, non‐linear dynamic response analyses were performed, and the damage indices for the bridge piers were obtained. Using the damage indices and ground motion indices, fragility curves for the bridge piers were constructed assuming a lognormal distribution. The analytical fragility curves were compared with the empirical ones. The proposed approach may be used in constructing the fragility curves for highway bridge structures. Copyright © 2001 John Wiley & Sons, Ltd.

Comparison of Analytical Fragility Curves for RC Bridge Piers Designed by Using Japanese Old and Recent Seismic Design Codes

To estimate damage levels (slight, moderate, extensive and complete) of highway bridge piers due to earthquakes, we need a set of fragility curves, which predict the damage level for a given level of ground motion indices (e.g., PGA, PGV and SI). Based on the actual damage data of highway bridges from the 1995 Hyogoken-Nanbu (Kobe) earthquake, a set of empirical fragility curvst) were developed. However, these fragility curves do not consider structural parameters and sffuctural responses. Considering structural parameters and variation of input ground motion, an analytical approach') wus adopted to construct such kind of fragility cufves. In this study, a hypothetical bridge is considered. Then its pier is modeled using the old (1964) and recent (1998) seismic design codes') for highway bridges in Japan' From a static analysis the yield force and yield displacement of the pier is obtained for the both cases. Then the damage analysis of the RC bridge pier is performed using the sffong ground motion records that were chosen from the Hyogoken-Nanbu earthquake. The damage indices are obtained from a nonlinear dynamic response analysis and finally using these damage indices and ground motion indices, the analytical fragility curves are constructed for the both cases. Then the fragility curves are compared to see the damage behavior of the piers due to seismic actlon.

Statistical analysis of peaks and directivity of earthquake ground motion

AbstractConversion factors are useful for attenuation and damage estimation relationships. These factors among different definitions of peaks (i.e. larger, average and resultant) for peak ground motion indices and acceleration response spectrum were investigated. A large number of horizontal acceleration records recorded at 76 free‐field sites of the Japan Meteorological Agency were used in this study. Two orthogonal horizontal components were combined in the time domain to get the maximum resultant peak ground motion indices and acceleration response spectrum in the horizontal plane. From the analysis, the means of the larger/resultant ratio were found to be 0·934 for acceleration, 0·926 for velocity, and 0·913 for displacement. A similar decreasing trend was observed for the means of the average/resultant ratio of the ground motion indices and acceleration response spectrum. The directivity of peak ground motion indices was also examined. It was found that the peak ground motion is more likely to occur in the transverse direction than in other directions. This trend is more prominent in the long‐period contents of ground motion.

Neural networks for quick earthquake damage estimation

AbstractThis paper proposes the use of neural networks to predict damage due to earthquakes from the indices of recorded ground motion. Since the relationship between ground motion indices and resulting damage is difficult to express in mathematical form, neural networks are conveniently applied for this problem. Simulated earthquake ground motions are used to have a well‐distributed data set and the ductility factor from non‐linear analysis of two single‐degree‐of‐freedom structural models is used to represent the damage. A sensitivity analysis procedure is described to identify qualitatively the input parameters that have a greater influence on the damage. The result of the trained neural network is then verified by using several recorded earthquake ground motions. It is found that some instability in the prediction can occur. Instability occurs when input values exceed the range of the training data. The neural network model using PGA and SI as input give the best performance in the recall tests using actual earthquake ground motion, demonstrating the usefulness of neural network models for the quick estimation of damage through earthquake intensity monitoring.