Seismic vulnerability assessment and characterisation of the buildings on Faial Island, Azores     

Filipe Neves  Aníbal Costa  Romeu Vicente  C. Sousa Oliveira  Humberto Varum 《Bulletin of Earthquake Engineering》2012,10(1):27-44

The earthquake of the 9th of July 1998 that hit in the central group of the Azores archipelago greatly affected the islands of Faial, Pico and S?o Jorge, reaching a magnitude of Mw 6.2 with the epicentre located about 15km northeast of the Faial Island. This earthquake allowed the collection of an unprecedented quantity of data concerning the characterisation of the building stock and the damage suffered by construction. This is the main purpose of this research, consisting essentially of three main aspects: (i) A detailed characterisation of the building stock, assigning a five category classification, from old traditional rubble stone masonry to reinforced concrete moment framed buildings; (ii) A detailed damage grade classification based on the different damage mechanisms observed; and, (iii) A seismic vulnerability assessment of the building stock. The results of the vulnerability assessment together with the building stock database and damage classification were integrated into a GIS tool, allowing the spatial visualation of damage scenarios, which is potentially useful for the planning of emergency response strategies and retrofitting priorities to mitigate and manage seismic risk.  相似文献   

Out-of-plane behaviour of existing stone masonry buildings: experimental evaluation     

Alexandre A. Costa  António Arêde  Aníbal Costa  Carlos Sousa Oliveira 《Bulletin of Earthquake Engineering》2012,10(1):93-111

Masonry structures can be considered as the simplest type of structures concerning its assemblage but, at the same time, it is one of the most complex construction materials in terms of mechanical properties and correct behaviour assessment. In this context, the work herein presented aims at describing an experimental testing campaign recently carried out in order to characterize the out-of-plane behaviour of traditional masonry constructions. Taking advantage of the existence of a traditional two-storey masonry building abandoned after the 1998 Azores earthquake, several in-situ tests were defined and performed with the application of quasi-static cyclic loads at the building top level in the out-of-plane direction. In addition, the efficiency of retrofitting and/or strengthening techniques applied during the 1998 Azores reconstruction process was also experimentally evaluated. Finally, an overall discussion of these techniques is presented, resorting also to previous tests’ results carried out by the same authors, aiming at inferring and suggesting quantifications of strengthening techniques’ contributions for future interventions on existing buildings. For this purpose, simple analytical mechanical approaches were adopted in order to provide numerical estimates of strength that were found in good agreement with the experimental results.  相似文献   

Treatment of Domestic Sewage in an Anaerobic–Aerobic Fixed‐bed Reactor with Recirculation of the Liquid Phase     

Antonio Pedro de Oliveira Netto  Marcelo Zaiat 《洁净——土壤、空气、水》2012,40(9):965-971

This study reports the performance of a combined anaerobic–aerobic packed‐bed reactor that can be used to treat domestic sewage. Initially, a bench‐scale reactor was operated in three experimental phases. In the first phase, the anaerobic reactor was operated with an average organic matter removal efficiency of 77% for a hydraulic retention time (HRT) of 10 h. In the second phase, the reactor was operated with an anaerobic stage followed by an aerobic zone, resulting in a mean value of 91% efficiency. In the third and final phase, the anaerobic–aerobic reactor was operated with recirculation of the effluent of the reactor through the anaerobic zone. The system yielded mean total nitrogen removal percentages of 65 and 75% for recycle ratios (r) of 0.5 and 1.5, respectively, and the chemical oxygen demand (COD) removal efficiencies were higher than 90%. When the pilot‐scale reactor was operated with an HRT of 12 h and r values of 1.5 and 3.0, its performance was similar to that observed in the bench‐scale unit (92% COD removal for r = 3.0). However, the nitrogen removal was lower (55% N removal for r = 3.0) due to problems with the hydrodynamics in the aerobic zone. The anaerobic–aerobic fixed‐bed reactor with recirculation of the liquid phase allows for concomitant carbon and nitrogen removal without adding an exogenous source of electron donors and without requiring any additional alkalinity supplementation.  相似文献   

Minaret behavior under earthquake loading: The case of historical Istanbul     

C. S. Oliveira  E. Çaktı  D. Stengel  M. Branco 《地震工程与结构动力学》2012,41(1):19-39

Minarets are very slender structures with an old existence. The historical ones are made of cut‐stone‐block masonry assembled in peripheral cylindrical wall with an interior helicoidal stair supported on a central core and on the wall. They are spread throughout the Islamic world and constitute an important heritage not only of religious value, but also of great cultural interest. Throughout the times, these structures as part of a mosque, have suffered significant damage during the earthquakes. Istanbul presents interesting characteristics to evaluate their dynamic behavior, as they are in great number, in an area where a large event in the next 30 years has been predicted. In this paper, we performed a series of in situ ambient vibration tests to old minarets of various sizes and compared results of frequencies with numerical modeling of the same structures. For the low‐amplitude motion, the frequency values of the first modes can be obtained from an empirical formulae function of the inertia of the cross‐section and of the height of the main ‘body.’ Damping ratios for these amplitudes are of the order of 0.5–1.0%. Dynamic linear analyses of these structures indicate that for most cases very high stresses develop for PGA above 0.5 g, an input with a reasonable chance of occurring in the next 30 years. These high stresses are expected to cause the toppling of the minarets in the form that has been observed in the recent past events. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

A survey for low-mass spectroscopic binary stars in the young clusters around σ Orionis and λ Orionis     

P. F. L. Maxted  R. D. Jeffries  J. M. Oliveira  T. Naylor  R. J. Jackson 《Monthly notices of the Royal Astronomical Society》2008,385(4):2210-2224

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Early Warning Systems: Feasibility and End-Users' Point of View     

C. S. Oliveira  F. Mota de Sá  M. Lopes  M. A. Ferreira  I. Pais 《Pure and Applied Geophysics》2015,172(9):2353-2370

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The role of the urban system dysfunction in the assessment of seismic risk in the Mt. Etna area (Italy)     

F. Meroni  G. Zonno  R. Azzaro  S. D’Amico  T. Tuvè  C. S. Oliveira  M. A. Ferreira  F. Mota de Sá  C. Brambilla  R. Rotondi  E. Varini 《Bulletin of Earthquake Engineering》2016,14(7):1979-2008

A procedure for seismic risk assessment is applied to the Mt. Etna area (eastern Sicily, Italy) through assessment of urban system dysfunction following the occurrence of an earthquake. The tool used is based on the Disruption Index as a concept implemented in Simulator QuakeIST, which defines urban disruption following a natural disaster. The first element of the procedure is the definition of the seismic input, which is based on information about historical seismicity and seismogenic faults. The second element is computation of seismic impact on the building stock and infrastructure in the area considered. Information on urban-scale vulnerability was collected and a geographic information system was used to organise the data relating to buildings and network systems (e.g., building stock, schools, strategic structures, lifelines). The central idea underlying the definition of the Disruption Index is identification and evaluation of the impact on a target community through the physical elements that most contribute to severe disruption. The procedure applied in this study (i.e., software and data) constitutes a very useful operational tool to drive the development of strategies to minimise risks from earthquakes.  相似文献   

A methodology for the probabilistic assessment of behaviour factors     

Aníbal Costa  Xavier Romão  Carlos Sousa Oliveira 《Bulletin of Earthquake Engineering》2010,8(1):47-64

Given the importance that traditional force-based seismic design still currently exhibits, studies addressing issues related to the definition of the behaviour factor values are considered to be of most interest. A probabilistic methodology is proposed for the calibration of the q-factor relating its value with two fundamental parameters, the displacement ductility capacity measured at a relevant location of the structure and the failure probability P _f . The general foundation of this procedure is based on the probabilistic quantification of the seismic action and, by applying a transformation procedure, of the structural seismic demand in terms of displacement ductility. By recalling well established structural reliability procedures and by making use of nonlinear analysis methods, both static and dynamic, a general probabilistic framework, which is able to relate the ductility capacity, the failure probability P _f and the behaviour factor, is defined. In order to illustrate some of the potentialities of the methodology, an application example is presented, addressing the q-factor assessment for a set of regular and irregular reinforced concrete frame structures, enforcing a given P _f and two different ductility levels.  相似文献   

Assessing Seismic Damage Through Stochastic Simulation of Ground Shaking: The Case of the 1998 Faial Earthquake (Azores Islands)   总被引：2，自引：0，他引：2  

G. Zonno  C. S. Oliveira  M. A. Ferreira  G. Musacchio  F. Meroni  F. Mota-de-Sá  F. Neves 《Surveys in Geophysics》2010,31(3):361-381

In July 1998, an M _w = 6.2 earthquake struck the islands of Faial, Pico and San Jorge (in the Azores Archipelago), registering VIII on the Modified Mercalli Intensity scale and causing major destruction in the northeastern part of Faial. The main shock was located offshore, 8 km North East of the island, and it triggered a seismic sequence that lasted for several weeks. The existing data for this earthquake include both the general tectonic environment of the region and the teleseismic information. This is accompanied by one strong-motion record obtained 15 km from the epicentre, the epicentre location of aftershocks, and a large collection of the damage inflicted to the building stock (as poor rubble masonry, of 2–3 storeys). The present study was carried out in two steps: first, with a finite-fault stochastic simulation method of ground motion at sites throughout the affected islands, for two possible locations of the rupturing fault and for a large number of combinations of rupture mechanisms (as a parametric analysis); secondly, the damage to buildings was modelled using a well-known macroseismic method that considers the building typologies and their associated vulnerabilities. The main intent was to integrate different data (geological, seismological and building features) to produce a scenario model to reproduce and justify the level of damage generated during the Faial earthquake. Finally, through validation of the results provided by these different approaches, we obtained a complete procedure for the parameters of a first model for the production of seismic damage scenarios for the Azores Islands region.  相似文献   

Trace metal retention in mangrove ecosystems in Guanabara Bay,SE Brazil   总被引：1，自引：0，他引：1  

Machado W  Silva-Filho EV  Oliveira RR  Lacerda LD 《Marine pollution bulletin》2002,44(11):1277-1280

Along contrasting environmental conditions (e.g., degree of trace metal contamination and mangrove forest structural development), sediments of Laguncularia racemosa-dominated mangrove stands in Guanabara Bay (SE Brazil) presented a trend of trace metal accumulation in forms with low potential of remobilization and biotic uptake. Concurrently, a relatively low transfer of sediment-bound metals to L. racemosa leaves was observed, which may moderate the metal export from the forests via leaf litter transport and the metal availability to enter in food chains based on leaf consumption.  相似文献