Field observations from the Aquila, Italy earthquake of April 6, 2009

On April 6, 2009 an earthquake of magnitude 6.2 (M_w) struck the Abbruzzo region of Italy causing widespread damage to buildings in the city of L??Aquila and surrounding areas. This paper summarizes field observations made by the Earthquake Engineering Field Investigation Team (EEFIT) after the event. The paper presents an overview of seismological and geotechnical aspects of the earthquake as well as a summary of the observed damage to buildings and infrastructure. A brief overview of the earthquake casualties is also reported.     

农居地震安全技术网络服务系统的内容和原理.

针对目前农村房屋建造技术不科学,并且人们获取地震安全知识受时间和空间的限制等问题,本文介绍了基于网络环境面向用户的“农居地震安全技术网络服务系统”的建设内容.该系统包含了信息自动筛选、处理分析及信息整编等关键技术,可实现农居建造的抗震设防、场址选择、基础及结构选型的自动组合、合理筛选,为农民工匠、基层技术人员提供农居地震安全方面的初步技术信息.同时,本中还介绍了农居地震安全咨询软件的设计目标、主要内容和功能,重点讨论了系统的关键技术及其特点.     

Influence of infill distribution and design typology on seismic performance of low- and mid-rise RC buildings

A growing attention has been addressed to the influence of infills on the seismic behavior of Reinforced Concrete buildings, also supported by the observation of damage to infilled RC buildings after severe earthquakes (e.g. L’Aquila 2009, Lorca 2011). In this paper, a numerical investigation on the influence of infills on the seismic behavior of four different case study buildings is carried out: four- and eight-storey buildings, designed for seismic loads according to the current Italian technical code or for gravity loads only according to an obsolete technical code, are considered. Seismic capacity at two Limit States (Damage Limitation and Near Collapse) is assessed through static push-over analyses, within the N2 spectral assessment framework. Different infill configurations are considered (Bare, Uniformly Infilled, Pilotis), and a sensitivity analysis is carried out, thus evaluating the influence of main material and capacity parameters on seismic response, depending on the number of storeys and the design typology. Fragility curves are obtained, through the application of a Response Surface Method. Seismic performance is also expressed in terms of failure probability, given a reference time period.     

National Civil Protection Organization and technical activities in the 2012 Emilia earthquakes (Italy)

On May 2012, a severe seismic sequence occurred in the central part of the Po Plain (Northern Italy). It was characterized by two main shocks displaying local magnitudes 5.9 (on May 20th) and 5.8 (on May 29th), respectively; the maximum observed intensity was VII–VIII on the MCS scale. The emergency response was coordinated as usual by the Department of Civil Protection (DPC), within the general framework provided by the components and operational structures of the National Civil Protection Service. In addition to the search and rescue and to the population assistance activities, many technical activities were carried out to support the civil protection management of the recovery phase. Among these, mentioning is deserved by: the acquisition and dissemination of the accelerometric data from the National Accelerometric Network and the Seismic Observatory of the Structures, owned and operated by DPC; the evaluation of the liquefaction phenomena; the damage and building safety assessment; the regulations for the seismic safety assessment of industrial buildings, aimed at a rapid re-establishment of the productive activities; the actions undertaken following the evaluations by the Grandi Rischi Commission on the possible evolution of the seismic sequence. All these aspects will be examined under a civil protection perspective.     

Performance of non-structural elements in RC buildings during the L��Aquila, 2009 earthquake

In Italy infills and partitions (non-structural elements) are typically made up of hollow brick masonry, disposed in one or two parallel vertical walls. Many studies have analysed their role on the seismic behaviour of moment resisting framed RC buildings and many seismic codes, all over the world, have provided specific additional measures for them. During the Abruzzo seismic sequence, non-structural damage in RC buildings, both private and public, was extensive, varying from small cracks to collapse, along with minor or no damage to structural elements. This damage involved a number of buildings, both old and recently completed, determining heavy socio-economic consequences, including human casualties, loss of building functionality (particularly important in case of strategic constructions), and unusable buildings. In this paper a review of the most frequent damage patterns is performed, aimed at identifying the main causes of damage and linking them to commonly adopted construction rules. For this purpose, local and global structural configurations frequently exhibiting non-structural damage are described, aside from out-of-plane and in-plane failures. Furthermore, a review of code provisions on non structural elements has been performed in the paper making reference to the most prominent current seismic codes and, finally, some design and construction rules are suggested.     

A WebGis tool for seismic hazard scenarios and risk analysis

The WebGis development represents a natural answer to the growing requests for dissemination and use of geographical information data. WebGis originates from a combination of web technology and the Geographical Information System, which is a recognised technology that is mainly composed of data handling tools for storage, recovery, management and analysis of spatial data. Here, we illustrate two examples of seismic hazard and risk analysis through the WebGis system in terms of architecture and content. The first presents ground shaking scenarios associated with the repetition of the earthquake that struck the Lake of Garda area (northern Italy) in 2004. The second shows data and results of a more extensive analysis of seismic risk in the western part of the Liguria region (north-western Italy) for residential buildings, strategic structures and historic architecture. The adoption of a freeware application (ALOV Map) assures easy exportability of the WebGis structures for projects dealing with natural hazard evaluation.     

Field Study of Soil Vapor Extraction for Reducing Off-Site Vapor Intrusion

Soil vapor extraction (SVE) is effective for removing volatile organic compound (VOC) mass from the vadose zone and reducing the potential for vapor intrusion (VI) into overlying and surrounding buildings. However, the relationship between residual mass in the subsurface and VI is complex. Through a series of alternating extraction (SVE on) and rebound (SVE off) periods, this field study explored the relationship and aspects of SVE applicable to VI mitigation in a commercial/light-industrial setting. The primary objective was to determine if SVE could provide VI mitigation over a wide area encompassing multiple buildings, city streets, and subsurface utilities and eliminate the need for individual subslab depressurization systems. We determined that SVE effectively mitigates offsite VI by intercepting or diluting contaminant vapors that would otherwise enter buildings through foundation slabs. Data indicate a measurable (5 Pa) influence of SVE on subslab/indoor pressure differential may occur but is not essential for effective VI mitigation. Indoor air quality improvements were evident in buildings 100 to 200 feet away from SVE including those without a measurable reversal of differential pressure across the slab or substantial reductions in subslab VOC concentration. These cases also demonstrated mitigation effects across a four-lane avenue with subsurface utilities. These findings suggest that SVE affects distant VI entry points with little observable impact on differential pressures and without relying on subslab VOC concentration reductions.     

Performance of masonry buildings during the Emilia 2012 earthquake

The earthquake sequence started on May \(20\) th 2012 in Emilia (Italy) affected a region where masonry constructions represent a large part of the existing building stock and the construction of new modern masonry buildings is a common practice. The paper is focused on the performance of common architectural configurations, typical for residential or business use. The large majority of old masonry buildings is made of fired clay bricks. The seismic performance of these buildings is particularly interesting since major past earthquakes in Italy affected areas with mainly stone masonry structures. Apart from examples showing systematic or peculiar structural deficiencies governing the vulnerability of several buildings, the overall seismic performance of these structures to repeated shaking, with PGA as large as 0.25–0.3 g was rather good, despite the major part of them were only conceived for carrying vertical loads. In fact, seismic design is mandatory in the area only since 2003. Modern low-rise masonry buildings erected after this date and incorporating seismic design and proper detailing resulted in most cases practically undamaged. The examples reported in the paper allow an evaluation of the superior performance of seismically designed modern masonry buildings in comparison to older ones.     

Inelastic response of RC frame buildings with seismic isolation

A comprehensive parametric study on the inelastic seismic response of seismically isolated RC frame buildings, designed for gravity loads only, is presented. Four building prototypes, with 23 m × 10 m floor plan dimensions and number of storeys ranging from 2 to 8, are considered. All the buildings present internal resistant frames in one direction only, identified as the strong direction of the building. In the orthogonal weak direction, the buildings present outer resistant frames only, with infilled masonry panels. This structural configuration is typical of many existing RC buildings, realized in Italy and other European countries in the 60s and 70s. The parametric study is based on the results of extensive nonlinear response‐time history analyses of 2‐DOF systems, using a set of seven artificial and natural seismic ground motions. In the parametric study, buildings with strength ratio (F_y/W) ranging from 0.03 to 0.15 and post‐yield stiffness ratio ranging from 0% to 6% are examined. Three different types of isolation systems are considered, that is, high damping rubber bearings, lead rubber bearings and friction pendulum bearings. The isolation systems have been designed accepting the occurrence of plastic hinges in the superstructure during the design earthquake. The nonlinear response‐time history analyses results show that structures with seismic isolation experience fewer inelastic cycles compared with fixed‐base structures. As a consequence, although limited plastic deformations can be accepted, the collapse limit state of seismically isolated structures should be based on the lateral capacity of the superstructure without significant reliance on its inherent hysteretic damping or ductility capacity. Copyright © 2012 John Wiley & Sons, Ltd.     

Analysis of the impact of large scale seismic retrofitting strategies through the application of a vulnerability-based approach on traditional masonry buildings

The buildings’ capacity to maintain minimum structural safety levels during natural disasters, such as earthquakes, is recognisably one of the aspects that most influence urban resilience. Moreover, the public investment in risk mitigation strategies is fundamental, not only to promote social and urban and resilience, but also to limit consequent material, human and environmental losses. Despite the growing awareness of this issue, there is still a vast number of traditional masonry buildings spread throughout many European old city centres that lacks of adequate seismic resistance, requiring therefore urgent retrofitting interventions in order to both reduce their seismic vulnerability and to cope with the increased seismic requirements of recent code standards. Thus, this paper aims at contributing to mitigate the social and economic impacts of earthquake damage scenarios through the development of vulnerability-based comparative analysis of some of the most popular retrofitting techniques applied after the 1998 Azores earthquake. The influence of each technique individually and globally studied resorting to a seismic vulnerability index methodology integrated into a GIS tool and damage and loss scenarios are constructed and critically discussed. Finally, the economic balance resulting from the implementation of that techniques are also examined.     

Evaluation of seismic vulnerability of a complex RC existing building by linear and nonlinear modeling approaches

Recent earthquakes, that stroked Italian regions in past decades (Umbria— Marche 1997; Molise 2002; L’Aquila 2009), pointed out the high vulnerability of reinforced concrete existing buildings causing severe damages in the structures and consequently life losses. This is mainly due to the fact that such structures were often built without reference to seismic actions or on the basis of old standard provisions. Nowadays in Italy, Public Authorities are requested to evaluate the seismic vulnerability of their building stock assessing the actual capacity of such structures, as a consequence of new hazard levels and seismic microzonation introduced by new standards. According to Eurocode 8 or Italian standard NTC 2008, the seismic analysis of existing reinforced concrete buildings can be performed by one of the established procedure (i.e. Linear Static Analysis LSA, Linear Dynamic Analysis LDA, Nonlinear Static Analysis NSA, Nonlinear Dynamic Analysis NDA), depending on the achieved knowledge level about the structural system and materials. In order to compare efficiency and differences of previously described approaches, a deep investigation was executed on a reinforced concrete existing building whose dynamic behaviour was evaluated by an experimental dynamic analysis. In such a way, updated models were obtained and adopted for seismic analysis performed by using linear and nonlinear approaches, taking into account the stiffness and strength contribution of masonry infill walls. It was so possible to get useful indications on the reliability and discrepancies of different modelling approaches as well as on the influence of masonry infills on the seismic response of existing r.c. buildings.     

Earthquake Damage Scenarios of the Building Stock of Potenza (Southern Italy) Including Site Effects

Damage scenarios relevant to the building stock of the town of Potenza, Southern Italy, are presented. A procedure for the preparation of scenarios has been purposely set up. In the first step, the inventory of the building stock has been made. Location and characteristics of buildings have been obtained from a survey carried out after the 1990 Potenza earthquake and further updated in 1999. In the second step, the absolute vulnerability of the buildings has been evaluated. A hybrid technique has been used, where typological analyses and expert judgement are combined together. Beyond the classes of vulnerability A, B and C of the MSK scale, the class D of EMS98 scale, for the less vulnerable buildings, has been considered. The third step has been the selection of the reference earthquakes by including also local amplification effects. Two events with 50 and 475 years return periods have been chosen as representative, respectively, of a damaging and of a destructive seismic event expected in Potenza. The sites that may exhibit important amplification effects have been identified using the first level method of the TC4 Manual. Damage scenarios of dwelling buildings have been prepared in the fourth step and reported in a GIS. They are relevant to the selected reference earthquakes, taking into account or not site effects. The generally low vulnerability of buildings results in a limited number of damaged buildings for the lower intensity earthquake, and of collapsed buildings, for the higher intensity earthquake. The influence of site effects on the damage distribution is significant. This revised version was published online in July 2006 with corrections to the Cover Date.     

Probabilistic neural networks for seismic damage mechanisms prediction

The procedure commonly employed to assess the seismic vulnerability of buildings uses simplified qualitative and quantitative observations obtained from the measured data entered into report forms. In Italy, the data sheets adopted by the National Defence Group against Earthquakes (Gruppo Nazionale per la Difesa dai Terremoti—GNDT) play a unifying and reference role. This paper proposes a method for the processing of the data contained in such report forms which is based on probabilistic neural networks producing a Bayesian classification. The final goal is to exploit the fundamental learning and generalization capabilities of neural networks to obtain an estimate of the vulnerability of structural systems. In particular, the aim is to be able to predict the damage mechanisms which may be triggered in the macro-elements of public worship buildings. Copyright © 1999 John Wiley & Sons Ltd.     

SOFIE project – 3D shaking table test on a seven‐storey full‐scale cross‐laminated timber building

Multi‐storey buildings made of cross‐laminated timber panels (X‐lam) are becoming a stronger and economically valid alternative in Europe compared with traditional masonry or concrete buildings. During the design process of these multi‐storey buildings, also their earthquake behaviour has to be addressed, especially in seismic‐prone areas such as Italy. However, limited knowledge on the seismic performance is available for this innovative massive timber product. On the basis of extensive testing series comprising monotonic and reversed cyclic tests on X‐lam panels, a pseudodynamic test on a one‐storey X‐lam specimen and 1D shaking table tests on a full‐scale three‐storey specimen, a full‐scale seven‐storey building was designed according to the European seismic standard Eurocode 8 and subjected to earthquake loading on a 3D shaking table. The building was designed with a preliminary action reduction factor of three that had been derived from the experimental results on the three‐storey building. The outcomes of this comprehensive research project called ‘SOFIE – Sistema Costruttivo Fiemme’ proved the suitability of multi‐storey X‐lam structures for earthquake‐prone regions. The buildings demonstrated self‐centring capabilities and high stiffness combined with sufficient ductility to avoid brittle failures. The tests provided useful information for the seismic design with force‐based methods as defined in Eurocode 8, that is, a preliminary experimentally based action reduction factor of three was confirmed. Valid, ductile joint assemblies were developed, and their importance for the energy dissipation in buildings with rigid X‐lam panels became evident. The seven‐storey building showed relatively high accelerations in the upper storeys, which could lead to secondary damage and which have to be addressed in future research. Copyright © 2013 John Wiley & Sons, Ltd.     

通信高塔对临近建筑物防雷安全的影响

本文为客观地评述高塔对临近区域的建筑物在防雷方面的现实影响,以某移动基站的通讯塔对其临近的养鸽场造成的雷电影响分析为例,从引雷效应、落雷几率两方面的分析论述了高塔的存在对雷击环境的改变;从空间电磁辐射、静电感应、电磁感应和瞬间电位的抬高四个方面分析了高塔对二次雷击干扰的影响;并就如何消解通信高塔对临近建筑物带来的雷电威胁,提出了在雷电防护手段上应加强的几个关键方面,得出通信高塔影响临近建筑物的防雷安全,但可以采取措施消解这种安全影响的结论。     

Road Network and Damaged Buildings in Urban Areas: Short and Long-term Interaction

In this paper, a model able to analyse the seismic behaviour of road network in urban areas, considering interaction between buildings and roads is presented. Damage to buildings and short-term countermeasures, such as propping, can affect roads and even block them, reducing capacity of the road network. Two successive phases are considered. In the first, immediately after the seismic event, emergency services have to reach the relevant buildings. Here, the network topology is of interest. In the second, in the long term, network capacity is not yet completely restored and network demand has to account for displaced people due to unusable buildings. In this case, road serviceability is of interest. In order to consider uncertainties on building behaviour, a probabilistic approach is developed and the network is analysed by means of Monte Carlo simulation. The methodology is applied to the municipality of Potenza (southern Italy) evaluating in the short term, the probability of strategic buildings are not connected and, in the long term, road serviceability.     

The 1708 Manosque earthquake (France): A reading of its archaeological traces as a contribution to estimate the effects on buildings

Archaeological techniques and methodology are used to identify seismic traces and disorders in ancient buildings. Clear evidence could be identified as direct seismic consequences or as communities’ technical answers for repair or reinforcement of buildings in order to reduce their vulnerability. This methodology is called “archaeological reading of buildings.” It is based on the identification of different construction phases, modifications and past events (human actions or natural phenomena) suffered by buildings during their life. The data read from the buildings are successively observed, identified, described, and recorded, following the principal of archaeological stratigraphy, in order to explain the buildings history. The seismic pathologies are identified according to detailed engineering knowledge of the behaviour of buildings during seismic motion. In this case study, our approach is applied to the historical city of Manosque, located in a seismic area along the “Moyenne–Durance” active fault. As a result of historical researches (Quenet G, Baumont D, Scotti O, Levret A, Ann Geophys, 47(2/3):583–595, 2004), many historical documents gave evidence about this earthquake’s effects. Among these documents, was an exceptional one: the record of a survey made in Manosque by bricklayers a few days after the 14th August 1708 shock. This gave us specific information concerning the seismic damage caused in the town of Manosque and was the starting point to validate the method. In the present paper, the archaeological reading of buildings method is illustrated by two specific cases: the Charité building in Manosque and the Sainte-Agathe chapel in Saint-Maime village. The buildings suffered various modifications during many centuries. This complicates the application of the method, however the observations made from the buildings correlate well with the indications deduced from written sources, validating our approach. The study highlights the necessity to cross correlate different field data in the frame of a multidisciplinary approach in order to obtain valuable results concerning details of seismic damage, its approximate dating by architectural chronology and the communities’ reaction in terms of repairs and reinforcement techniques.     

基坑排桩对建筑抗震性的影响分析

以往对建筑抗震性影响因素的研究仅限于施工材料、技术手段等外部条件,忽略了基坑土体安全系数、基坑状态对建筑抗震性的影响,一定程度上削弱了建筑的抗震性能。本文从基坑排桩角度对建筑抗震性的影响展开分析,通过有限元强度折减法获取土体的安全系数与基坑状态的判断标准,在该标准下基于土体安全系数采用有限元强度折减法计算公式,获取各个土层计算参数。基于该参数使用ABAQUS有限元软件构建基坑排桩有限元分析模型(土体和桩体分别采用莫尔-库仑弹塑性模型和二维弹性模型)。实验采用所提分析方法,从基坑排桩排距、刚度两方面对建筑抗震性能进行分析。实验结果表明,当基坑排桩排距进行适当取值时,建筑抗震性越好;双排桩的刚度越大,建筑抗震性越好,且随着刚度的增加建筑抗震性能趋于平稳。     

Shaking table tests on 24 simple masonry buildings

The paper presents the results of a large experimental programme carried out on models, scaled 1:2, of two-storey masonry buildings. After suffering damage, the models were repaired and strengthened and tested again. A total of 24 buildings were subjected to 119 shaking-table tests, by ISMES (Italy) and LEE (Greece) facilities. The results allow to assess the efficiency of the various strengthening techniques employed and to describe the change of dynamic properties of the systems at the increase of damage. © 1998 John Wiley & Sons, Ltd.