Seismic Damage Estimation Research Articles

Probabilistic methods for the estimation of potential seismic damage: Application to reinforced concrete buildings in Turkey

Three probabilistic methods, for the prediction of potential seismic damage to low and mid-rise reinforced concrete buildings in Turkey, are presented. As the first method, “best estimate” damage probability matrices for each seismic zone are developed by combining expert opinion and the damage statistics compiled from the recent earthquakes occurred in Turkey. Second method involves a reliability-based model, which treats the earthquake force and seismic resistance as random variables. This model expresses potential seismic damage in the form of a damage ratio distribution, which is a function of modified Mercalli intensity or peak ground acceleration. As the third methodology, discriminant analysis technique is utilized to carry out a statistical analysis on the damage data compiled during recent earthquakes that occurred in Turkey. Based on the classification procedure involved in this technique, the damage state probabilities corresponding to different modified Mercalli intensity levels are obtained. These three methods are applied on the building damage databases compiled in the aftermath of several recent earthquakes in Turkey: 1992 Erzincan, 1995 Dinar, and 1999 Duzce earthquakes. The probabilistic damage profile obtained according to these three methods is expressed in terms of damage ratios and the results are compared with each other.

Seismic Damage Estimation for Buried Pipelines: Challenges after Three Decades of Progress

This paper analyzes the evolution over the past three decades of seismic damage estimation for buried pipelines and identifies some challenges for future research studies on the subject. The first section of this paper presents a chronological description of the evolution since the mid-1970s of pipeline fragility relations—the most common tool for pipeline damage estimation—and follows with a careful analysis of the use of several ground motion parameters as pipeline damage indicators. In the second section of the paper, four gaps on the subject are identified and proposed as challenges for future research studies. The main conclusion of this work is that enhanced fragility relations must be developed for improving pipeline damage estimation, which must consider relevant parameters that could influence the seismic response of pipelines.

Development of a Damage Estimation Method for Electric Power Distribution Equipment

This paper describes a seismic damage estimation method for electric power distribution equipment to support its emergency restoration activity. The predominant factors associated with the seismic damage degree of electric power distribution equipment are classified based on the analysis of its seismic damage record of the 2007 Niigata-Ken Chuetsu-Oki earthquake. Based on the analysis, a seismic damage estimation model is proposed. The proposed model is applied to an actual damaged area and compared to existing damage estimation models used by local governments. Finally, the effectiveness of the proposed model and future subjects are discussed.

Seismic damage estimation through measurable dynamic characteristics

Ductility based design of reinforced concrete structures implicitly assumes certain damage under the action of a design basis earthquake. The damage undergone by a structure needs to be quantified, so as to assess the post-seismic reparability and functionality of the structure. The paper presents an analytical method of quantification and location of seismic damage, through system identification methods. It may be noted that soft ground storied buildings are the major casualties in any earthquake and hence the example structure is a soft or weak first storied one, whose seismic response and temporal variation of damage are computed using a non-linear dynamic analysis program (IDARC) and compared with a normal structure. Time period based damage identification model is used and suitably calibrated with classic damage models. Regenerated stiffness of the three degrees of freedom model (for the three storied frame) is used to locate the damage, both on-line as well as after the seismic event. Multi resolution analysis using wavelets is also used for localized damage identification for soft storey columns.

A comparison of two regional seismic damage estimation methodologies

This paper presents a comparison of the two main regional damage estimation methodologies currently in use, namely the modified Mercalli intensity (MMI) based approach and the spectral parameter based approach. In the first methodology, expected damage is related to ground shaking intensity in terms of MMI through damage probability matrices. In the second methodology, the ground motion intensity is described in terms of spectral acceleration (SA), and building response in terms of spectral displacement (SD). Both methodologies were applied to buildings in Vancouver of three different construction types: single-family wood-frame houses, low-rise unreinforced masonry buildings, and high-rise concrete frame structures with concrete shear walls. The two methodologies predict damage that lies in the same general damage categories of light and moderate, which are defined by fairly broad ranges in mean damage factors. The specific mean damage factors predicted by the two methods for a given location are significantly different, however. The significant differences in mean damage factors imply significant differences in damage costs and hence in seismic risk.Key words: earthquake, damage, seismic risk, vulnerability, modified Mercalli intensity (MMI), spectral response, displacement, acceleration.

Seismic Risk Assessment: With an Application to the South African Insurance Industry

This study provides a seismic risk assessment for various sites in South Africa and discusses the possible impact of seismic activity on the South African insurance industry in the light of this analysis. The work begins with an introduction and an historical perspective on the estimation of seismic damage to buildings. The methodology for the estimation of expected damage from a probabilistic point of view is presented. The work continues with an application of the described methodology to several sites around the country. The result of the investigation is that the seismic risk faced by South Africa is non-negligible. Keywords: Seismic risk, seismic hazard, expected damage, South Africa, short-term insurance South African Actuarial Journal: 2003 3: 1-28

二次元有効応力解析法の解析精度向上に関する検討

The influences of many factors on the accuracy of the damage prediction have been evaluated for a two-dimensional effective stress analysis program code: FLIP. Although many improved numerical models for more precise prediction have been proposed, the influences of those improved models varied with the difference of structural type and situation. This study was carried out to verify th accuracy ofthe seismic damage estimation for various types of quay wall on the liquefiable ground by the FLIP code with all these improved models simultaneously.Through the seismic damage analyses of sheet pilequaywall, gravity quaywall and piled pier constructed on the liquefiable ground, it was observed that the improved models work well not only for the structure in which the conventional model had worked well, but also for the structure in which the conventional model cannot work.

실측 지진응답을 이용한 지진손상도 평가 및 소성모형 추정

본 논문에서는 다자유도계 구조물의 진동대 실험결과 분석에서 효율적인 지진손상도 평가 및 소성모형 추정을 목적으로, 계측결과를 각 부재별 소성이력으로 환산하고 이 소성이력에 대해 비선형 계수 추정법을 적용하는 다단계 방안을 연구하였다. 이때, 추정된 부재별 소성이력은 부재별 지진 손상도를 평가하는 지표로 활용될 수 있으며, 추정된 비선형 모형 계수를 이용하여 구축된 비선형 다자유도계 구조는 다양한 구조재해석의 모형으로 활용될 수 있다. 제시된 방법의 검증을 위해, 해석적 방법과 실험적 방법의 예제해석이 수행되었다. 예제해석 결과는 해석적 방법과 실험적 방법 모두에서 본 논문의 방법이 매우 효과적임을 보여 주고 있다. In this paper, the nonlinear parameter estimation method using the estimated hysteresis of each structural members was studied for the purpose of efficient seismic damage prediction and estimation of MDOF nonlinear structural model in the shaking table test. The hysteresis of each structural members can be obtained by the conversion of measured response histories into relative motions of each structural members and member forces. These hysteresis can be used to evaluate various kinds of damage indices of each structural members. The MDOF nonlinear structural model for further analysis(re-analysis) can be easily reconstructed using estimated nonlinear structural parameters of each structural members. To demonstrate the proposed techniques, several numerical and experimental example analyses are carried out. The results indicate that the proposed method can be very useful to assess local seismic damages of structures.

Neural network based methodology for estimating bridge damage after major earthquakes

A neural network based seismic bridge damage estimation system is proposed to estimate damage to the bridges in Taiwan after major earthquakes. The damage estimation system is composed of two parts: a peak ground acceleration (PGA) estimator and a bridge damage estimator. The PGA neural network estimator was first trained by the ground motion data recorded from the eight largest earthquakes in Taiwan over the past ten years. The magnitude, depth, and epicenter coordinates of the earthquake were used as the inputs in this neural network. The damage estimator was trained to learn the relationship among bridge coordinates, structure types, PGAs and damage levels to bridges based on the data collected from the 1999 Chi‐Chi earthquake. Sixty‐four sets of bridge data were used to train a 7–8–8–2 neural network. These two neural networks were then integrated into one system and were tested, using another twenty sets of bridge damage data. The result has demonstrated that the proposed method is able to successfully assess the damage of bridges due to major earthquakes in Taiwan.

Seismic Hazard and Risk Assessment for Tulbagh, South Africa: Part II - Assessment of Seismic Risk

This is the second part of our study on the assessment of seismic hazard and seismic risk for Tulbagh, the settlement, located about 90 km N-E from Cape Town, where the strongest and most damaging earthquake known in the existing earthquake history of South Africa took place. This part of our study, which can be read independently from Part I, concentrates on the probabilistic seismic risk analysis (PSRA) for Tulbagh. The work begins with an introduction and a historical perspective on the estimation of seismic damage to buildings. The methodology for the estimation of expected damage from a probabilistic point of view is then presented. The work closes with an application of the described methodology to a site in the vicinity of Tulbagh.

Earthquake Damage Assessment Based on Fuzzy Logic and Neural Networks

Potential damage assessment is fundamental for defining mitigation procedures and risk management strategies. Damage assessment involves the difficulties of defining, assessing, and modeling the variables involved, as well as handling uncertainty. Seismic damage estimation of structures does not only depend on the behavior of the structural system, but it involves other factors, which differ in nature. The paper presents a methodology for damage assessment of structures that combines systems theory, fuzzy logic, and neural networks. A feed-forward neural network supported on the systemic organization of information is used to assess the expected structural damage for a given earthquake. The methodology provides a very useful environment to consider the context of the building structure. The network has been trained using the damage observed in the recent earthquake that occurred in central Colombia. Several sets of structures were evaluated and the results compared to the damage observed. The model showed to be highly reliable and a good representation of experts' opinions. Computer software ERS-99 was developed and is currently being used for teaching and consulting purposes.

Theoretical models and recorded response in the estimation of cumulative seismic damage on non-linear structures

A damage-function model is proposed for the inelastic response of structures in terms of initial damage and of displacement amplitudes and secant stiffnesses of response cycles. The model is used to obtain an analytical closed-form solution for the probability distribution of cumulative damage after an earthquake ground motion given the distribution prior to such excitation and information on the inelastic structural response. The formulation is applied to a reinforced concrete frame and the results show the capabilities of the method to yield updated distributions of damage. Copyright © 2000 John Wiley & Sons, Ltd.

名古屋市域の地盤・強震動・微動データのコンパイルと地盤震動性状区分

In this paper, various soil data, observed seismic ground motions and microtremor data have been collected and compiled in Tokai area and Nagoya city. Now we have over 500 seismic observation sites in Aichi, Gifu and Mie prefectures, and over 300 points in and around Nagoya city have been examined by microtremor observations. Database are totally organaized and is opend to public by use of WWW. Such data are important for the newly developed performance based seismic design and the seismic damage estimation for urban disaster prevention.

「強震記録のウェーブレット解析による履歴復元力特性を有する建築物の累積損傷の推定」に対する討論(曽根彰, 山本鎮男, 増田新, 中岡明, 芦野隆一著 日本建築学会構造系論文報告集, 第476号, 1995年10月掲載)

Basic questions are presented on the applicability of the proposed method of seismic damage estimation of building structures by means of wavelet analyses. Major points are as follows: 1)The applicability of the method was examined only for the by-linear type hysteresis curves having a sharp change from the elastic region to the inelastic region, but since an actual structure has a smooth transition from linearity to non-linearity, the proposed method seems to be useless in spite of the authors's desire; 2)The damage estimation was based on the Miner's fatigue law, but since the cracks generated in several cycles of plastic strains are not fatigue cracks but ductile ones, the conventional linear estimation of cumulative damage may not be applied for earthquake damage.

Estimation of seismic motion and damage to structures for new bullet trains

It is necessary to investigate the earthquake-resistance of existing railway structures against a supposed earthquake in order to implement earthquake-resistant reinforcement. This paper describes the method, of predicting the degree of damage that may be caused by a supposed earthquake based on estimation of the surface earthquake motion. The paper will be of help for selection of the structures that require reinforcement and for determination of the extent of such reinforcement works.

Seismic damage estimation for low‐ and mid‐rise buildings in japan

AbstractWhile much effort has been spent on analysis of individual structures, building class seismic damage estimators, of value in disaster planning, code‐writing, city planning, national hazards policy formulation, etc., have been little investigated. Based largely on data from Sendai City, Japan in the 12 June, 1978 Miyagiken‐oki earthquake (ML = 7.4), estimators of seismic damage for low‐ and mid‐rise buildings in urban Japan have been determined. For low‐rise buildings, based on damage to over 60,000 buildings, damage ratios for onset of damage and collapse and for cost of damage are found to correlate best with response spectra at 0.75 s. Using published test data and average building properties, a seismic damage model explains the low‐rise building behaviour and permits examination of the effect of structural changes on the estimated damage. For mid‐rise buildings, damage states (0: none, 4: total) are determined as a function of maximum storey displacement, based on published natural period determinations (pre‐ and post‐earthquake) for 189 mid‐rise buildings in Sendai. The effects of structural changes on expected damage can also be estimated. With these two building class damage estimators, a large part of future seismic damage to urban Japan can be estimated, as well as the effects of various mitigation measures.