Experience Of Past Earthquakes Research Articles

Simulation‐based methodology to identify damage indicators and safety thresholds for post‐earthquake evaluation of structures

AbstractAfter a strong earthquake, criteria are needed to determine whether buildings are safe to reoccupy based on observable damage. This paper presents a simulation‐based methodology to identify relevant damage indicators and safety thresholds for building structures. Prior knowledge of the most relevant damage indicators and their thresholds can increase the accuracy and confidence of post‐earthquake evaluations. Current practice to translate observable damage into a tagging decision relies on qualitative guidelines based on past earthquake experience and judgment, which may be susceptible to speculation and interpretation. In addition, past experience may not be relevant to newer structural systems and to large or complex (e.g., high‐rise) buildings. To augment past observations and data from structural component tests, nonlinear dynamic analyses can be used to estimate the collapse safety of structures with simulated damage. Technologies to execute these simulations have matured over the years, although to date they have not been systematically applied to evaluate the destabilizing effects of simulated damage on collapse safety. In this paper, a methodology is presented to use numerical simulations of damage to identify and evaluate relevant damage indicators that can be quantitatively related to safety thresholds. Damage indicators are selected based on their reliability in estimating the structural safety and their sensitivity to modeling uncertainty, that is, where the preferred indicators are insensitive to variability in the structural materials and model parameters. The safety threshold for each damage indicator is selected to maximize accuracy in post‐earthquake building assessments. The methodology is demonstrated through an application study of ductile reinforced concrete frame buildings. Results show that aggregated indices of structural component damage (e.g., aggregated over the floor of a building) outperform other damage indicators based on peak or residual drifts or simpler percentages of damaged components. Subject to agreement of a number underlying assumptions, this methodology can be applied to a wider variety of structures to improve post‐earthquake evaluation guidelines.

Experimental investigation of grooving method in seismic retrofit of beam-column external joints without seismic details using CFRP sheets

The experience of past earthquakes has shown that the beam to column joints in moment frames is one of the key members in the path of lateral load transfer and their weak performance causes the destruction of the whole structure. The use of FRP composites in strengthening and repairing these members as an effective solution has a special place in the construction industry. However, the separation of FRP composites from the concrete surface has become the biggest challenge facing researchers. In the present study, the grooving method has been used to install CFRP composites and the ability of this method to delay or eliminate the separation of FRP composites in shear strengthening of reinforced concrete beam-column joints has been investigated. In this paper, four external concrete beam-column joints with a scale of 1/2 have been made in the laboratory. There are two specimens as controls, one of which has special seismic details in accordance with ACI regulations and the other specimen does not have seismic details. The two retrofitted specimens also lack seismic details, and CFRP composites are employed for the retrofit. In one of the retrofitted specimens, CFRP composites are installed on the concrete surface in the usual way, and in another specimen, CFRP composites are installed on the concrete surface by the grooving method. The specimens are subjected to cyclic loading with incremental amplitude. The results were evaluated by comparing hysteresis curves, envelope curves, energy dissipation, stiffness reduction and cracking pattern. The results show that the applied method eliminates the separation phenomenon and a significant increase in bearing capacity, ductility and energy dissipation was observed.

Modeling of Seismic Impacts on the Main Pipeline

In this article, a seismic calculation of a section of an underground pipeline is performed using the Ansys software package. The linear-spectral analysis of this calculation was based on the response spectrum obtained from a variety of real records of seismic ground vibrations at the Petropavlovsk seismic station. This method makes it possible to take into account the experience of past earthquakes, reducing the likelihood of exceeding the expected loads on the structure during a new earthquake. The results of the seismic calculation of the pipeline made it possible to form a complete picture of the distribution of stresses in the pipeline for various forms of the trench and the material of its backfill. A comparison is made of the maximum stresses in the pipeline for various methods of its seismic protection.

Seismic Assessment, Repair and Strengthening of a Medieval Masonry Tower in Southern Italy

Many historical masonry towers belong to architectural heritage. Their preservation is still a critical issue in several countries. In fact, the experience of past earthquakes has shown that even earthquakes of moderate intensity can cause the collapse of these historical structures due to their slenderness together with irregularities, openings, leaning phenomena and adjacent lower buildings. The damage and changes suffered over the centuries, and the complex behaviour of the materials makes the performance of this type of structures more uncertain, and the seismic analysis and the remedial measures to achieve their protection a very complex task. This paper presents a complete study (from the on-site diagnostic investigations to the seismic assessment and non-invasive strengthening) of an ancient masonry tower in Torre Orsaia (Southern Italy). The paper, through the discussion of the case study, shows effective procedures to assess the seismic safety of masonry towers and plan interventions without too time- and cost-consuming processes. The results have established that the deep and wide cracks on the belfry are due to the loss of tension of the ancient tie-rods. The seismic safety of the tower has been carried out using three levels of analysis: LV1 (evaluation with simplified models), LV2 (analysis of local collapse mechanisms) and LV3 (global analysis). The analyses have shown that the critical mechanism is the simple overturning of the masonry piers of the belfry due to the ineffective tie-rods. The corresponding safety index in terms of peak ground acceleration is 0.305. To avoid this undesired mechanism and, at the same time, fully close the cracks, a strengthening intervention based on stainless steel reinforcing rings has been developed. This chaining system avoids the local mechanisms of the piers of the belfry and allows developing global mechanisms. After retrofit intervention, the seismic analysis has shown that the safety index increases to 0.716 for the LV2 analysis and 0.793 for the LV3 analysis.

Seismic performance of steel plate reinforced concrete shear wall and its application in China Mainland

Reinforced concrete (RC) shear wall is one of the predominant structural components used extensively in high-rise buildings to resist lateral loads induced by earthquakes around the world. However, the past earthquake experience and previous research indicated that RC shear walls at the bottom of high-rise buildings may display the undesirable performance when subjected to severe earthquakes. For this reason, the steel plate reinforced concrete (SPRC) composite shear walls have been developed, and especially popularly used in super-tall buildings in China Mainland in recent years. At first, the application of SPRC shear walls in China Mainland is briefly introduced. Then the modelling techniques with the aid of software OpenSees to simulate the hysteretic behavior of SPRC shear walls are presented and validated by typical experimental results. The verified numerical model is further used in the parametric study focusing on a number of important parameters, including the steel plate ratio, the axial compressive load ratio, the concrete strength, and the web reinforcement ratio. The results of this parametric study provide useful information for the engineering application of SPRC shear walls.

Using ambient vibration measurements to generate experimental floor response spectra and inter-story drift curves of Reinforced Concrete (RC) buildings

Achieving the global good seismic performance of a building as required in modern building codes is contingent upon maintaining the integrity and functionality of its structural system as well as its Non-Structural Components (NSCs). Experience of past earthquakes has shown that many buildings have suffered from the failure of NSCs, which caused life safety hazards, costly property damages, and significantly impacted the building functionality. Avoiding these undesired consequences is of great importance particularly in post-disaster buildings that have to remain operational during and after earthquakes. In spite of advances in seismic analysis of NSCs, there is still a need for a simple, practical and yet reasonably accurate approach for seismic design of NSCs. To gain acceptance in practice, this approach must be capable of circumventing the shortcomings of existing analytical approaches as well as of current building code provisions. This study proposes an original experimental approach to generate the Floor Response Spectra (FRS) and Inter-Story Drift (ISD) curves based on Ambient Vibration Measurements (AVM) in buildings. These outputs provide robust tools for the seismic evaluation of NSCs. This paper presents the application of the proposed method to a RC building. It addresses the dependence of the output results on NSC response parameters such as NSC location in the building, NSC dynamic properties (internal damping and natural periods), and natural periods of the building. The comparison of the results with the NBCC 2015 (National Building Code of Canada) provisions for NSCs shows that these empirical recommendations typically underestimate the seismic demands on NSCs.

Implementation of the Square‐Root‐Impedance Method to Estimate Site Amplification in Iran Using Random Profile Generation

Abstract The experience of past earthquakes has shown repeatedly that the characteristics of ground motions and resulting damages are highly dependent on the local condition of the site. It is clearly known that the underlying layers may amplify the earthquake excitation to some extent. This phenomenon is called the site effects. The site amplification depends on several factors such as stiffness, thickness, and density of the subsurface layer. In the present article, the 1D yet acceptable square‐root‐impedance method is used to estimate the frequency‐dependent amplification function for various site classes in Iran. To achieve this goal, a stochastic method is applied to generate several thousand velocity profiles down to 8000 m. These profiles are randomly generated and constrained based on the features of 458 available shallow velocity profiles and crustal structure models across Iran. Then, the resulted amplification functions are multiplied by near‐surface attenuation function to obtain the site response in the frequency domain. The comparison of the mean spectra of different site classes demonstrates that although the softer classes (the ones with lower V S 30 ) have higher amplifications at lower frequencies, the trend is completely reversed at higher ones. Finally, the generated profiles are employed to derive models for Z 1.0 (the depth at which the shear‐wave velocity is equal to 1 km/s). This depth is very important, because it is included in the new generation of ground‐motion prediction equations.

A numerical model for simulation of RC beam-column connections

Beam to column connections in reinforced concrete (RC) frames are among the elements having essential effects in determining the performance and behavior of structure under different loads. Role of these connections against the lateral loads especially strong earthquakes is such important that experience of past earthquakes confirm their effect in defining value and extent of structural damages. Therefore, to appropriately address the seismic performance of new or existing RC frames, engineers need models able to predict the connection behavior with an acceptable accuracy and enough simplicity. In this research, a numerical model for simulating the elastic and inelastic behavior of RC beam-column connections is presented. This model consists of a rigid offset element and beam and column elements with concentrated plasticity. The rigid offset element is calibrated to give a good estimation of the initial stiffness based on the shear demand ratio of the connection. Each of the beam and column elements with concentrated plasticity includes two rotational springs in series. One spring represents the nonlinear behavior of beam and column and the other contains the nonlinear behavior of the connection. Each one of the rotational springs possesses its own moment-rotation response curve. Comparison of the simulated response with that of the existing experimental results confirms that the suggested model follows the seismic response of beam-column connections with a very good accuracy.

Earthquake experience and preparedness in Turkey

Purpose – The purpose of this paper is to measure and compare the level of earthquake preparedness of individuals living in Eastern Anatolia region of Turkey, evaluate whether prior earthquake experience has an impact on earthquake preparedness and discuss the cultural factors that may play a role in determining the level of preparedness. Design/methodology/approach – Three locations were identified for the study. Aşkale and Erçiş district had experienced a major earthquake where Erzurum City Center had no major earthquake experience. A total of 174 participants were included in the study. Earthquake preparation was assessed using the Turkish version of the Wellington Earthquake Preparedness Scale by Spittal et al. (2006). Findings – The results showed a significant relationship between the place of living, earthquake experience and preparation. Those who had prior earthquake experience had higher preparation than those who had no prior earthquake experience. Home owners had taken more steps to prepare for an earthquake than non-home owners Individuals who were married had higher preparation scores than those who were single or widowed. A comparison of general perception of preparedness levels reported by participants having a major earthquake experience and no earthquake experience showed that Erçiş and Aşkale residents were significantly more prepared for an earthquake than Erzurum residents. Home ownership and past earthquake experience were found to be predictors of preparation. Originality/value – Although the Eastern Anatolia region of Turkey encounters many earthquakes resulting in mass destruction, the issue of whether individuals living in this region are ready and prepared for a possible earthquake has not been researched sufficiently.

The Study on Information Extraction Technology of Seismic Damage

In order to improve the information extraction technology of seismic damage assessment and information publishing of earthquake damage. Based on past earthquake experience it was constructed technical flow of earthquake damage assessment rapidly, this study, take Yushu earthquake as example, studies the framework and establishment of the information service system by means of Arc IMS and distributed database technology. It analysis some key technologies, build web publishing architecture of massive remote sensing images. The system implements joint application of remote sensing image processing technology, database technology and Web GIS technology, the result could provide the important basis for earthquake damage assessment, emergency management and rescue mission.

The Seismic Damage Assessment and Information Service System

In order to improve the information extraction technology of seismic damage assessment and information publishing of earthquake damage. Based on past earthquake experience it was constructed technical flow of earthquake damage assessment rapidly, This paper ,take Yushu earthquake as example, studies the framework and establishment of the information service system by means of ArcIMS and distributed database technology. It analysis some key technologies , build web publishing architecture of massive remote sensing images. The system implements joint application of remote sensing image processing technology, database technology and WebGIS technology, The result could provide the important basis for earthquake damage assessment ,emergency management and rescue mission.

Perception of Earthquake Risk in Taiwan: Effects of Gender and Past Earthquake Experience

This study explored how individuals in Taiwan perceive the risk of earthquake and the relationship of past earthquake experience and gender to risk perception. Participants (n= 1,405), including earthquake survivors and those in the general population without prior direct earthquake exposure, were selected and interviewed through a computer-assisted telephone interviewing procedure using a random sampling and stratification method covering all 24 regions of Taiwan. A factor analysis of the interview data yielded a two-factor structure of risk perception in regard to earthquake. The first factor, "personal impact," encompassed perception of threat and fear related to earthquakes. The second factor, "controllability," encompassed a sense of efficacy of self-protection in regard to earthquakes. The findings indicated prior earthquake survivors and females reported higher scores on the personal impact factor than males and those with no prior direct earthquake experience, although there were no group differences on the controllability factor. The findings support that risk perception has multiple components, and suggest that past experience (survivor status) and gender (female) affect the perception of risk. Exploration of potential contributions of other demographic factors such as age, education, and marital status to personal impact, especially for females and survivors, is discussed. Future research on and intervention program with regard to risk perception are suggested accordingly.

The impact of disaster education on public preparation and mitigation for earthquakes: a cross-country comparison between Fukui, Japan and the San Francisco Bay Area, California, USA

Whether individuals do, or do not prepare and mitigate for future earthquake occurrences is significantly affected by the degree to which they engage in public education activities about the earthquake hazard. This study is guided by the following questions in Fukui, Japan, and the San Francisco Bay Area, California, USA: what types of education are the most suitable for people to undertake proper activities to get ready for future earthquakes? How does disaster education enhance people's readiness? Is disaster education possible to motivate people to undertake specific activities? And, do cultural differences indicate that different ways of disaster education are necessary to be undertaken for the public? This study defines a new index of overall readiness to estimate the degree to which an individual's readiness for earthquakes is sufficient and appropriate. The index enables a cross-country comparison of data from questionnaire surveys conducted in both seismic areas. American respondents show relatively good readiness in terms of goods, whereas, in Fukui, the readiness of residences, social activities and educational sources is slightly higher. In both areas, respondents with disaster education are more ready than respondents without disaster education, but the enhancement is not so significant. Various educational sources for Fukui respondents and printed materials for American respondents are effective approaches. Awareness of disaster, knowledge about neighborhood, and past earthquake experience also function as educational information which contributes especially to the improvement in readiness regarding social activities and educational sources. Various types of disaster education should be readily available at accessible places to the public.

Seismic qualification of motor operated valves—alternate approach

This paper presents a potential alternate method for determining operating capacity of motor-operated valves subjected to seismic and other applicable loadings. As a result of programs at nuclear facilities to ensure the operational capability of MOVs (under NRC GL89-10), extensive analytical focus to develop the structural capability of valves has ensued. In the past, seismic qualification of valves typically addressed the strength of the topwork structure to resist inertial loading from excitation of the large valve actuator mass. These evaluations paid little or no consideration to the loading resulting from valve closing forces. The focus of the recent efforts is to develop the maximum operational capability of the valve, in terms of thrust, with consideration of seismic and other services loading as applicable. The alternate method outlined in this paper presents a series of thrust capacity curves, with reduction factors for seismic loading which can be applied and developed to determine safe thrust loadings without performing extensive analytical effort. A similar approach was put forward by the SQUG GIP approach to MOVs to ensure the safe operation of valves based on past earthquake experience. However, the GIP approach cannot be used to determine safe operational loads and thus has limited use in the necessary analysis required for GL89-10 programs at nuclear facilities.

Piping seismic adequacy criteria recommendations based on performance during earthquakes

Design and analysis of piping in a typical nuclear power plant has been estimated to cost as much as $80 million, at least 60% of which is associated with the implementation of current seismic design criteria. These current design criteria require seismic qualification of nuclear plant piping based on rigorous and expensive mathematical analysis and testing. Past earthquake experience has shown that piping within power facilities which have undergone little or no seismic qualification have performed very well with only a limited number of resulting cases in which the pressure boundary has been breached. The purpose of this paper is to document the performance of piping in past earthquakes and to explore the possibilities of using the results of this earthquake experience data to guide the development of a more reasonable criteria for assessing the seismic adequacy of power piping. Experience data has shown that the three critical areas to be considered for a seismic adequacy assessment of a welded steel piping system are: (1) seismic anchor movement, (2) corrosion, and (3) system interaction. The data presented within this study implies that excessive emphasis in both time and money are currently being expended to demonstrate the adequacy of piping for inertia effects.

Survey, repair and strengthening of buildings for earthquake damage

Introduction In a previous paper, I discussed the techniques for ensuring the earthquake resistance of new buildings. Experience of past earthquakes demonstrates that incorporating the methods and advances of the last 30 years in the planning, design and construction of new buildings is the best way of minimising loss of life and investment during major earthquakes.