Earthquake-prone Countries Research Articles

Strengthened infilled RC frames: Continuum and macro modeling in nonlinear finite element analysis

Abstract Strengthening and retrofitting masonry infill Reinforced Concrete (RC) frames is crucial due to the large use of this structural typology in earthquake-prone countries. Masonry infills can provide a positive and negative effect on the seismic response. A positive effect is due to the fact that the infills dissipate energy and therefore increase the overall damping. A negative effect may take place if their disposition is irregular or if they fail irregularly, thus the structure behavior becomes irregular. Furthermore, the infills generally stiffen the structure and thus increase the base shear force. It has been shown that by using an adequate infill strengthening technique, performance and safety of the structures and of the infills can be improved. Several models for Un-Reinforced Masonry (URM) infills have been developed in the past, but there is a lack of models available to describe the behavior of strengthened infilled frames. A simplified analytical strut and tie model is proposed based on the results obtained by Finite Element (FE) analyses. The mechanical characteristics of the tension tie and of the compression strut depend on the stiffness and strength of the reinforcement in addition to the geometrical and mechanical parameters of the infilled frame. The proposed model is validated with experimental results of a Carbon Fiber Reinforced Polymer (CFRP) strengthened infilled RC frame. The experimental data are reproduced by means of continuum FE models in order to assess the influence of various parameters on the seismic response and to calibrate the simplified model's parameters. Lateral stiffness and strength obtained with this simplified model show a good agreement with the experimental results and the continuum FE models.

Strength, functionality and beauty of university buildings in earthquake-prone countries.

Strength, functionality and beauty are the three qualities identifying well-designed architecture. For buildings in earthquake-prone countries such as Japan, emphasis on seismic safety frequently leads to the sacrifice of functionality and beauty. Therefore, it is important to develop new structural technologies that can ensure the seismic performance of a building without hampering the pursuit of functionality and beauty. The moment-resisting frame structures widely used for buildings in Japan are likely to experience weak-story collapse. Pin-supported walls, which can effectively enhance the structural story-by-story integrity of a building, were introduced to prevent such an unfavorable failure pattern in the seismic retrofit of an eleven-story building on a university campus in Tokyo, while also greatly aesthetically enhancing the façade of the building. The slight damage observed and monitoring records of the retrofitted building during the 2011 Tohoku earthquake in Japan demonstrate that the pin-supported walls worked as intended, protecting the building and guaranteeing the safety of its occupants during the earthquake.

Communicating Earthquake Preparedness: The Influence of Induced Mood, Perceived Risk, and Gain or Loss Frames on Homeowners' Attitudes Toward General Precautionary Measures for Earthquakes.

Despite global efforts to reduce seismic risk, actual preparedness levels remain universally low. Although earthquake-resistant building design is the most efficient way to decrease potential losses, its application is not a legal requirement across all earthquake-prone countries and even if, often not strictly enforced. Risk communication encouraging homeowners to take precautionary measures is therefore an important means to enhance a country's earthquake resilience. Our study illustrates that specific interactions of mood, perceived risk, and frame type significantly affect homeowners' attitudes toward general precautionary measures for earthquakes. The interdependencies of the variables mood, risk information, and frame type were tested in an experimental 2 × 2 × 2 design (N = 156). Only in combination and not on their own, these variables effectively influence attitudes toward general precautionary measures for earthquakes. The control variables gender, "trait anxiety" index, and alteration of perceived risk adjust the effect. Overall, the group with the strongest attitudes toward general precautionary actions for earthquakes are homeowners with induced negative mood who process high-risk information and gain-framed messages. However, the conditions comprising induced negative mood, low-risk information and loss-frame and induced positive mood, low-risk information and gain-framed messages both also significantly influence homeowners' attitudes toward general precautionary measures for earthquakes. These results mostly confirm previous findings in the field of health communication. For practitioners, our study emphasizes that carefully compiled communication measures are a powerful means to encourage precautionary attitudes among homeowners, especially for those with an elevated perceived risk.

Predicting the seismic performance of typical R/C healthcare facilities: emphasis on hospitals

Reinforced concrete (RC) type of buildings constitutes an important part of the current building stock in earthquake prone countries such as Albania. Seismic response of structures during a severe earthquake plays a vital role in the extent of structural damage and resulting injuries and losses. In this context, this study evaluates the expected performance of a five-story RC healthcare facility, representative of common practice in Albania, designed according to older codes. The design was based on the code requirements used in this region during the mid-1980s. Non-linear static and dynamic time history analyses were conducted on the structural model using the Zeus NL computer program. The dynamic time history analysis was conducted with a set of ground motions from real earthquakes. The building responses were estimated in global levels. FEMA 356 criteria were used to predict the seismic performance of the building. The structural response measures such as capacity curve and inter-story drift under the set of ground motions and pushover analyses results were compared and detailed seismic performance assessment was done. The main aim of this study is considering the application and methodology for the earthquake performance assessment of existing buildings. The seismic performance of the structural model varied significantly under different ground motions. Results indicate that case study building exhibit inadequate seismic performance under different seismic excitations. In addition, reasons for the poor performance of the building is discussed.

Risk assessment of people trapped in earthquake based on km grid: a case study of the 2014 Ludian earthquake, China

ABSTRACTChina is one of the most earthquake-prone countries in the world. The highest-priority mission after an earthquake is to rapidly save lives, and to minimize the loss of life. Rapid judgment of the trapped personnel location is the important basis to identify the emergency supply demands and carry out the search and rescue work after the earthquake. Through analyzing the main influencing factors, we constructed an assessment model of people trapped in collapsed buildings caused by the earthquakes. The accuracy of the estimation results from the model was then tested against the actual investigation data in 2014 Ludian earthquake-hit area. Results showed that, the trapped personnel distribution assessed by this model is generally concordant with that obtained by the actual survey in Ludian earthquake. The grid-based assessment of people trapped in earthquakes can meet the requirements of key search and rescue zone identification and rescue forces allocation in the early stage of earthquake emergency. Although there were some limitations in the study, it offers a simple and rapid approach for assessing the trapped people losses based on basic empirical data. The approach can be further improved to provide more information and suggestions for earthquake emergency search and rescue.

Incentives and Motivators for Improving Building Resilience to Earthquake Disaster

AbstractEncouraging property owners to adopt measures to improve the resilience of their buildings to seismic hazard has been a major challenge in many earthquake-prone countries. Owners of buildin...

Developing hybrid parameters for measuring damage potential of earthquake records: case for RC building stock

This study investigates the feasibility of using combination of present ground motion parameters to have a hybrid parameter that is more correlated with damage. Since RC buildings constitute the prevailing type of construction in many earthquake prone countries, low and mid-rise RC buildings are targeted in an example study. Displacement demand is assumed to represent the seismic damage. Its mean value is determined for 1056 capacity curves for each of 466 acceleration records. Then an optimization study is performed to select and weight the commonly used ground motion parameters to have a high correlation with displacement demands. Hence, equations for hybrid parameters are defined. It is observed that by combining the ground motion parameters, better results up to 6–28% may be achieved depending on the relevant factors and cases. This approach may be applied to other types of structures, as well. Using this type of case specific hybrid ground motion parameter relations, significant improvements may be obtained for the evaluation and assessment of seismic damage.

Coseismic landslide susceptibility assessment using geographic information system

Indonesia is one of the most earthquake prone countries in the world. More than 14,000 earthquakes of magnitude greater than 5 occurred in Indonesia between 1897 and 2009. Earthquakes are a major cause of slope instability eventually triggering coseismic landslides, which cost 1.5 million US$/ year in Java: one of the most densely islands in Indonesia. This paper aims to assess coseismic landslide susceptibility using Geographic Information System (GIS) on the western flank of Baturagung Escarpment, 8 km southeast of the Yogyakarta City, a data sparse area. Therefore, we have used a probabilistic seismic hazard analysis to calculate the peak ground accelerations, while the coseismic landslide susceptibility analysis was done by the scoring method in the GIS adopted from Mora and Vahrson model (Costa Rica), which is well adopted for data sparse areas. The west flank of Baturagung Escarpment is dominated by moderate level of coseismic landslide with an average Coseismic Landslide Susceptibility Level (CLSL) of 33–162. The upper slope of Baturagung Escarpment, which consists of Semilir Formation has the CLSL of 163–512, corresponding to medium level CLSL (Mora and Vahrson model). The low level CLSL is mainly located on the foot slopes of Baturagung Escarpment, while the alluvial and colluvial plains located along the Opak River have very low CLSL (0–6). Based on the mapped landslide occurrence, the landslides tend to occur in the zone of moderate CLSL and they are distributed along the border between moderate and low coseismic landslide zone, meaning that the change on local condition could be playing an important role in triggering coseismic landslide.

Dynamic and cyclic response of a full-scale 2-storey cold-formed steel structure with and without infill materials

Cold-Formed Steel (CFS) has become more and more popular in recent years as an alternative construction material. Short construction time and very high strength to weight ratio under lateral forces made cold-formed steel an attractive option in earthquake prone countries such as Japan, New Zealand and the US. These structures are formed of CFS frames with either boards and sheatings attached to the frames or infill materials sprayed to the frames on-site. This paper presents the results of dynamic and cyclic experiments conducted on two different 3-D and 2-storey models. The first model was CFS frame system without infill material and the second one was with infill material. In order to identify the actual dynamic characteristics of models such as modal frequencies and damping ratios, large-scale tests are conducted instead of 2-D panel tests. Ambient vibration tests were carried out to determine modal frequencies of the models at different damage states and forced vibration tests were carried out to determine modal damping ratios at high vibration levels. In addition to ambient and forced vibration tests, cyclic tests were performed to obtain the hysteretic behavior of the model. It was observed that with the application of infill material, lateral load resisting capacity increased by 3.5 times, ductility of the model increased from 2.58 to 3.96 and damping ratio increased from 6.7 to 9.0%. In addition to identification of dynamic characteristics, the main motivation of this study is to investigate the possible use of ambient vibration surveys in the determination of damage level. Results showed that ambient vibration surveys can be used as a damage detection tool after an earthquake or any other hazard.

Building typologies and failure modes observed in the 2015 Gorkha (Nepal) earthquake

Nepal is one of the most earthquake-prone countries in the world, and at the same time is one of the most economically deprived. On 25 April 2015 mid-western Nepal was hit by the devastating Gorkha earthquake measuring Mw 7.8 with the epicentre located 76 km north-west of Kathmandu. The earthquake was followed by a series of aftershocks, with the most significant occurring on 12 May 2015 with Mw 7.3 and an epicentre located north-east of Kathmandu. The earthquake and the associated aftershocks resulted in the destruction of half a million buildings, leaving millions of people homeless and causing a loss of more than $3.5 billion (USD) to the housing sector alone. Approximately 9,000 people were killed and over 23,000 people were injured - mostly due to damaged or collapsed buildings.
 A number of documents have been published pertaining to general observations following the 2015 Gorkha earthquake and aftershocks. Here the common building typologies and related failure modes observed during inspection surveys by the authors who were part of the various reconnaissance teams following the earthquakes are summarised. A brief background on the 2015 Gorkha earthquake is provided with an outline of the tectonic environment and seismological background of Nepal and a brief summary of previous earthquake activities in the region is presented. Common construction practices identified during the reconnaissance are illustrated and briefly explained to provide context to the observed earthquake damage, with an emphasis placed on unreinforced masonry (URM) building typologies and construction practices. Comparisons between URM building damage and published macro-element failure modes are provided using various photographic and schematic examples. Commonly observed failure modes and potential causes of failure are also highlighted for buildings constructed of reinforced concrete (RC) frames with masonry infill. A brief review of adopted temporary shoring techniques is also included.

Earthquake safety in India: achievements, challenges and opportunities

The Indian subcontinent has suffered some of the greatest earthquakes in the world. The earthquakes of the late nineteenth and early twentieth centuries triggered a number of early advances in science and engineering related to earthquakes that are discussed here. These include the development of early codes and earthquake-resistant housing after the 1935 Quetta earthquake in Baluchistan, and strengthening techniques implemented after the 1941 Andaman Islands earthquake, discovered by the author in remote islands of India. Activities in the late 1950s to institutionalize earthquake engineering in the country are also discussed. Despite these early developments towards seismic safety, moderate earthquakes in India continue to cause thousands of deaths, indicating the poor seismic resilience of the built environment. The Bhuj earthquake of 2001 highlighted a striking disregard for structural design principles and quality of construction. This earthquake was the first instance of an earthquake causing collapses of modern multi-storey buildings in India, and it triggered unprecedented awareness amongst professionals, academics and the general public. The earthquake led to the further development of the National Information Centre of Earthquake Engineering and the establishment of a comprehensive 4-year National Programme on Earthquake Engineering Education that was carried out by the seven Indian Institutes of Technology and the Indian Institute of Science. Earthquake engineering is a highly context-specific discipline and there are many engineering problems where appropriate solutions need to be found locally. Confined masonry construction is one such building typology that the author has been championing for the subcontinent. Development of the student hostels and staff and faculty housing on the new 400-acre campus of the Indian Institute of Technology Gandhinagar has provided an opportunity to adopt this construction typology on a large scale, and is addressed in the monograph. The vulnerability of the building stock in India is also evident from the occasional news reports of collapses of buildings under construction or during rains (without any earthquake shaking). Given India’s aspirations to be counted as one of the world’s prosperous countries, there is a great urgency to address the safety of our built environment. There is a need: to create a more professional environment for safe construction, including a system for code enforcement and building inspection; for competence-based licensing of civil and structural engineers; for training and education of all stakeholders in the construction chain; to build a research and development culture for seismic safety; to encourage champions of seismic safety; to effectively use windows of opportunity provided by damaging earthquakes; to focus on new construction as opposed to retrofitting existing buildings; and to frame the problem in the broader context of overall building safety rather than the specific context of earthquakes. Sustained long-term efforts are required to address this multi-faceted complex problem of great importance to the future development of India. While the context of this paper is India, many of the observations may be valid and useful for other earthquake-prone countries.

火力発電所を対象とした制振構造の適用に関する研究

Japan is one of the most earthquake-prone countries in the world. In the great east Japan earthquake, power plants were severely damaged by strong ground motion and tsunami, and power generation at some power plants had been stopped for a long time. These suspensions of power generation impacted public institutions and industry. Therefore, improving the earthquake resistance of power plants is very important at present. In particular, thermal power plants are important power plants assuming the current Japanese power supply. In current thermal power plants, simple anti-vibration devices made of steel are installed between boiler and its support structure. However these devices do not have enough damping against after shocks following a main shock, because devices made of steel are damaged by repeated deformation. Therefore we propose applying dampers to thermal power plants in order to improve their earthquake resistance. In this paper, boiler structure is modeled to two mass points model at first. Next, earthquake response analysis is carried out in order to compare vibration control performance of dampers (steel damper, friction damper, oil damper, viscous damper, viscoelastic damper). As a result, it was confirmed that the friction damper and the viscous damper have good vibration control performance. The friction damper and the viscous damper suppressed relative displacement between a boiler and its support structure. Additionally convergence of the response after the earthquake was quick.

Earthquake-induced slope failure susceptibility in eastern Nepal

Nepal is considered as one of the earthquake-prone countries in the region. Earthquake is a major concern of Nepal because of rapid population growth, poor land use planning, precarious settlement patterns, and poorly implemented building code. Earthquakes in Nepal have been reported since 1255 while major earthquakes were recorded in 1408, 1681, 1810, 1833, and 1866, 1934, 1980, 1988, 2011, and 2015. An earthquake in September 18, 2011 measuring 6.9 in Richter scale, killed 6 people and injured 30 people in Nepal. There were many roadside slope damages near the epicenter area. To assess the roadside slope damages after this earthquake, a field visit was conducted and a landslide inventory map along the roadside slope was prepared for most damaged area. This paper provides a comprehensive information about earthquake-induced slope failures occurred in the Mechi Highway of eastern Nepal and also discusses an approach of earthquake-induced slope failures hazard mapping in Nepal.

TABANI İZOLE MÜZE BİNALARINDA GÖRÜNTÜLENEN ESKİ HEYKELLERİN DİKEY SİSMİK İZOLASYONU

In order to protect the precious art and historical objects on display, recently the museum buildings in earthquake prone countries are designed and constructed with seismic base isolation devices, at the foundation level. However, when adopting conventional base isolation devices (e.g. LRB, friction pendulum), the horizontal accelerations in the building can be significantly reduced, while the vertical accelerations are directly transmitted to the building’s contents. If these vertical accelerations reach significant values, the stability of the objects decreases against overturning, and this causes the object to lose its full contact with the ground and to start rocking. Therefore, to protect the contents of a base isolated museum building against three dimensional earthquake excitations, a vertical seismic isolation solution must also be introduced at the base level of the object. This study aims to assess the performance of vertical isolation devices for the seismic protection of the ancient statues displayed in base isolated museums.

Developing seismic vulnerability curves for typical Iranian buildings

Iran is one of the most earthquake-prone countries in the world. In recent earthquakes, the low quality of constructions has caused huge losses, both in human and economic terms. The high level of seismic hazard in combination with a high physical vulnerability of structures leads to a high earthquake risk of Iran, which has to be managed in some ways. Earthquake happening in populated areas causing economic and human losses has shown the vital role of assessing buildings’ vulnerabilities as well as loss estimations. Vulnerability curve is one of the essential instruments to evaluate structural losses before the events. Regarding the lack of categorized vulnerability curves for Iranian buildings, this study focuses on filling this critical gap. For this reason, empirical approach involving statistical processing on existing data from the previous studies is used to develop vulnerability curves for Iranian buildings by critiquing the existing fragility/vulnerability curves in Iran and other countries. The logic-tree method is used to combine these curves by weighting in accordance with the condition of construction provisions, seismic code and engineering judgment. Finally, vulnerability curves are developed for the 42 Iranian building types. Results are presented by median ( Sa) and lognormal standard deviation [Formula: see text] values for all types of selected buildings and related uncertainties are considered as well.

The Earthquake Impact on Telecommunications Infrastructure in Nepal: A Preliminary Spatial Assessment

This paper examines the spatial clustering and correlation of epicenters of the 2015 Gorkha earthquake and its spatial relationship to the telecommunications infrastructure of Nepal. Ripley’s K function analysis suggests that epicenters of the main earthquake shock and aftershocks and base stations of Worldwide Interoperability for Microwave Access are generally clustered. However, the cluster patterns decline over distance. Moran’s I statistics further suggested that the epicenters and base stations at the district level are spatially significant and positively correlated. As Nepal is one of the most earthquake-prone countries in the world, this paper recommends that the Government of Nepal, operators, and other concerned parties should identify the importance of telecommunications infrastructure and develop a critical infrastructure plan including location and redundancy options to mitigate and minimize the detrimental impacts of earthquakes and other disasters on telecommunications services in the country.

A comparative study on housing renovation policies in earthquake-prone countries

Givensubstantial contribution of housing inhuman life and geographical position of Iran in Alpine-Himalayancollision belt, it seems urgent to deal with that in case of absence ofreasonable and correct management approaches for post-earthquake housingrenovation, wide varieties of socioeconomic issues and catastrophes will emerged. hence, in respect tosome drawbacks while houses renovatingin earthquake-stricken areas of Iran, the present research aims at comparative analysis of housingrenovation policies of some earthquake-prone countries in order to promoterenovation policies in Iran. To satisfy this end, a comparative study was conductedon housing renovation policies among Iran, china, Japan, India and Indonesiausing descriptive-analytical approach. The results showed Iran's weakness in someareas such as zoning hazard-prone area while renovation, compliance to seismicstrength criteria, and superiority in programs such as materials availabilityand government investment on affairs in which people are not involved. Eventuallyto compensate such shortcomings, some guidelines for promote renovation plan inIran are suggested.

Earthquake risk assessment in urban fabrics based on physical, socioeconomic and response capacity parameters (a case study: Tehran city)

Determination of the priorities for improvement of vulnerable urban fabrics based on a comprehensive assessment is among the main desires of local governments in earthquake-prone countries like Iran. However, in most countries, the comprehensive and absolute estimation of seismic risk is not possible due to shortages of the required data. In this paper, a new method is proposed for estimation of the risk through combination of hazard, vulnerability and response capacity indicators. Also, new evaluation methods based on relative scheme are presented for simple quantification of indicators in urban areas suffering from limited or insufficient database. For this purpose, important vulnerability parameters at urban areas are classified into physical, human life and socioeconomic groups. New hazard factors are also defined to evaluate the risk through combination of each vulnerability indicator and its directly related hazard factor. In addition, the capacity of response activities is accounted for in the model using planning, resource, accessibility and evacuation capacity indicators. The post-earthquake reduction of response capacity is also measured by means of reduction factors. Then, total relative seismic risk index is defined and calculated at each urban division (or zone) by weighted combination of the mentioned risk and response capacity indicators. This index represents the state of the risk in each zone in comparison with the others. The proposed method is applied to assess the earthquake risk at 22 municipal districts of Tehran. The results show that physical, human life and overall risk indices in district 15 of the city are considerably greater than the others. Meanwhile, in socioeconomic aspects, district 6 has the highest risk. Also, the analysis of the results demonstrates the major contribution of the response capacity term to determine the mitigation priorities. Finally, the results are compared with JICA (2000), using the same data, to show the efficiency of the proposed model. It is shown that the introduced method can significantly improve the results of the risk estimation and mitigation priorities.

Fracture behavior of RC members subjected to bending shear and torsion using acoustic emission method

Japan is one of the most earthquake-prone countries in the world and therefore urgent seismic countermeasures are needed. The Great Hanshin Earthquake occurred in Hyogo Prefecture in January 1995, and several reinforced concrete (RC) piers on the Hanshin Expressway collapsed.As the course of the collapsed RC piers, the effect of torsion was estimated at the main cause about 11% among the damaged RC piers. Since construction of asymmetrical RC structures has increasing in urban areas, those asymmetrical piers could receive torsion forces. From previous research, it is known that RC members loaded by pure torsion generated spiral cracks on the entire surface. In addition, when RC members are loaded by bending shear and torsion, major cracks are found on one side while minor cracks are found on the opposite side. As a result, RC members would rapidly be broken; in the present paper, in order to clarify the fracture behaviors and fracture energy in RC members under torsion, acoustic emission (AE) measurement applied. Concerning fractures in RC members loaded by pure torsion, the fractures progress only in the outer circumference of the cross section until the web reinforcement yields. Here, the pure torsion fracture and the bending shear destruction are the primary factors in controlling the shear flow of RC members loaded by bending shear and torsion, before they reached one-third of the maximum strength.

Design of RC frames for pre-selected collapse mechanism and target displacement using energy–balance

In earthquake-prone countries, structures may be exposed to several seismic loads in any stage of building’s life. It is expected that the structures designed by engineers will show ductile behaviour under the effect of vertical and lateral loads and remain stable without making a sudden collapse. In consequence of nonlinear behaviour, plastic hinges are expected to form in structural members which are under the effect of external loads. Earthquake input energy is dissipated in plastic hinges, so, structures behave ductile. In this study, total energy of RC frames is calculated and the energy-based base shear force is determined by equating the total internal energy to the work done by external lateral design forces for pre-selected target displacement and collapse mechanism. Sections of RC frames are controlled if they can resist the calculated design lateral loads or not. If the capacity of the sections cannot withstand the external design loads, the design is rearranged and new sections are chosen. Beam and column sections that can resist the design loads securely are accepted as final sections of the energy-based design methodology. Pre-selected target displacement for desired performance level is checked using the results of nonlinear analyses. The results of the presented design methodology in this study are compatible with the results of nonlinear analyses.