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In seismic design of extended multi-span bridges the question always arises whether using either natural or artificially generated earthquake records that are identical at all bridge supports is valid or not. It is likely that earthquake ground motion remarkably differs at the various support/pier locations in terms of amplitude, frequency content and arrival time, inducing under certain circumstances significant forces and deformations that would not develop if the assumption of synchronous excitation was adopted. This paper hence illustrates the impact of ground motion spatial variability on the seismic performance and vulnerability of extended continuous box girder bridges in both bridge orthogonal directions (longitudinal and transverse). For illustration purposes, a nine-span bridge with a total length of 430 m is adopted. Non-linear time history analyses are carried out using opensees software. The effects of the spatial variability in the ground motions at the different bridge supports are investigated using a set of 20 artificially simulated seismic ground motions generated using sim software developed in the mid-nineties, considering different degrees of loss in coherency and various soil types (i.e., frequency contents). Results of the non-linear time history analyses performed in an incremental dynamic analysis context are hence manipulated through a probabilistic analysis framework to generate fragility curves associated with various performance levels for the case study bridge. Fragility curves giving the conditional probability of exceeding various performance levels are then integrated with generated hazard curves defining the expected seismic hazard in Egypt. The outcome of this integration process results in values of mean annual frequency of exceeding pre-defined performance levels. [ABSTRACT FROM AUTHOR]

This paper presents the record of damages which were observed in Pakistan due to a strong earthquake on 16 April 2013 in Iran. Mashkel was the nearest town in Pakistan close to the epicentre of earthquake. The damages were documented by a survey team during the visit of Mashkel. The intensity of earthquake in most of the visited areas was found to be VIII on the Modified Mercalli Intensity scale. The infrastructure facilities were undamaged and were operating satisfactorily. On the other hand, heavy damage to adobe buildings was caused by the earthquake. Most of the building failure was resulted by the out-of-plane wall collapse; nearly 40 % adobe buildings were collapsed due to ground shaking in some of the affected areas. Reinforced concrete and cement concrete block masonry buildings performed better than adobe buildings. Using the data of building damage and earthquake intensity fragility curves for adobe buildings in Mashkel were developed. [ABSTRACT FROM AUTHOR]

The response of historic masonry buildings to tectonic ground displacements is studied through analysis of a simple yet representative soil-foundation-masonry wall system. A nonlinear 3D finite element method is developed and employed to reproduce the strong nonlinear response of the rupturing soil, as well as the masonry structure. Following a sensitivity analysis of the effect of the exact location of the structure with respect to the emerging fault, the paper discusses several characteristic mechanisms of soil-structure interaction and evaluates the associated structural distress. The observed failure pattern and the consequent structural damage are shown to depend strongly, varying from minimal to dramatic, on the exact position of the structure relative to the fault. Alleviation of tectonic risk through foundation enhancement/improvement is investigated by considering alternative foundation systems. Results highlight the advantageous performance of rigid embedded and continuous foundations as opposed to more flexible and isolated supports indicating that foundation strengthening may provide important shielding against settlement and structural drift. [ABSTRACT FROM AUTHOR]

Remnants of Greek Temples are found all over the Mediterranean, surviving in most cases in the form of free-standing columns. The drums are resting on top of each other without any connection, being considered susceptible to strong seismic shaking. Their seismic response is complex, comprising a variety of mechanisms, such as rocking of sliding of the drums relative to each other. This paper studies experimentally the seismic performance of such structures, aiming to derive insights on the key factors affecting the response. Physical models of such multi-drum columns were constructed at reduced scale and tested at the shaking table of the NTUA Laboratory of Soil Mechanics. The marble specimens were excited by idealized Ricker wavelets and real seismic records. The tested multi-drum columns were proven to be very earthquake-resistant. Even when subjected to the strongest motions ever recorded in Greece, their permanent deformation was minimal. [ABSTRACT FROM AUTHOR]

The seismic assessment of rocking masonry structures is a complex task, due to the high sensitivity of the behavior to the characteristics of the input motion. The paper compares the results offered by different models and the reliability of widely used intensity measures. A displacement-based approach based on an incremental limit analysis of rigid blocks is proposed for the performance-based assessment of rocking masonry structures, such as: rocky structures (archeological remains, obelisks, columns, trilithons), arch-piers systems (e.g. triumphal arches, belfries), out-of-plane mechanisms of walls (standing out walls, façades in buildings or churches etc.) or artistic assets prone to overturn (pinnacles, statues etc.). The method is compatible with the format of the PERPETUATE performance-based assessment method for cultural heritage assets [ABSTRACT FROM AUTHOR]

In this paper we propose reduction factors accounting for the decrease of stiffness of monumental masonry foundations due to aging, weathering, or other deteriorating effects. The proposed reduced stiffness values can be readily used in finite element structural analysis software in the framework of performance-based assessment, representing linear elastic springs at the foundation level. These springs account for foundation-soil system flexibility and soil-foundation interaction (SFI) at low-frequency vibrations. Accordingly, we propose a procedure to reduce monumental masonry foundation-wall stiffness from the rigid-footing assumption, with respect to the relative stiffness between the foundation and the soil. The proposed procedure is applied to the historical structure Arsenal De Milly in the Medieval City of Rhodes, where period elongation and ductility increase are highlighted, because of SFI and foundation flexibility. [ABSTRACT FROM AUTHOR]

In the paper, possibilities of correlation of structural damage and damage of attached artistic assets on multi-leaf stone masonry walls by means of destructive and non-destructive testing (NDT) methods are investigated. Results from two testing campaigns carried out at the University of Genoa and University of Ljubljana are briefly presented. In particular, diagonal tests with different levels of pre-compression and shear tests under different boundary conditions were carried out in Genoa and Ljubljana, respectively. During the tests, different damage limit states (DL) of both masonry walls (SE) and attached plasters (AA) were investigated by means of NDT's. Two different types of rubble stone masonry were considered (uncoursed random rubble vs. coursed squared rubble). For AA the results are presented in relative form in dependence from the DL of SE. Obtained results are influenced both by the type of test and tested masonry. Results of NDT revealed strong potential and a need for data fusing of both investigated methods for the evaluation of the state of the degradation behind the plaster. [ABSTRACT FROM AUTHOR]

Ancient monumental masonry buildings are complex structures that were not based on an engineered design, underwent many transformations during their life and often present lack of connections among the structural elements. Earthquakes are the main cause of damage for ancient masonry structures and, in order to reduce their vulnerability with compatible and light interventions, it is necessary to have accurate models for the seismic analysis, able to simulate the nonlinear behavior of masonry, and a well defined performance-based assessment procedure, aimed to guarantee the acceptable level of risk for the occupants and for the conservation of the monument itself. The paper outlines the guidelines that were developed within the PERPETUATE European research project. The wide variety of architectural assets is classified and the related proper modeling strategies are identified; moreover, immovable artistic assets are considered in the assessment. A displacement-based approach is adopted, because these structures crack even for low intensity earthquakes and can survive severe ones only if they have a sufficient displacement capacity. Safety and conservation requirements are proposed by considering distinct sets of performance levels, related to use and safety of people, conservation of the building and of the artistic assets that might be present. Some indications on the seismic hazard assessment are provided, considering the distinctive features of some types of ancient structures. Within the fundamental knowledge phase, sensitivity analysis is proposed in order to address and optimize the in-situ investigation and to define proper confidence factors, aimed to consider epistemic and statistical uncertainties. Different modeling approaches and methods of analysis are considered, depending on the characteristics of the structure; both static pushover and incremental dynamic nonlinear analyses are considered. Related verification procedures are defined to evaluate the seismic intensity measure, and the corresponding return period, which is compatible with each performance level that must be fulfilled. [ABSTRACT FROM AUTHOR]

One of the objectives of the PERPETUATE EU-FP7 project was to determine a sound approach to the quantification of the seismic vulnerability of historic centres at territorial scale. The procedure presented herein provides a ten steps guideline from how to select building samples in the area of study, to how to compute the buildings' seismic performance and finally how to evaluate rehabilitation decisions to reduce the seismic fragility of the studied typologies over an entire district or city. The procedure is illustrated in this paper by way of application to The Casbah of Algiers, a world heritage site composed of building clusters from the Ottoman to the French period. Pre-existing seismic damage, decay due to lack of maintenance and environmental factor and a urban irregular and complex lay-out make this application particularly challenging. A total number of around 150 houses, characterised by the most representative features of the Algerian historic construction, have been selected in collaboration with the Directorate of the Office for Management of Cultural Property of the Ministry of Culture,. The seismic Vulnerability Assessment Method (VAM) underpinning the 10-step procedure is is FaMIVE (Failure Mechanism Identification and Vulnerability Evaluation), a mechanical approach based on limit state analysis and kinematics, which allows computing collapse load factor, deriving capacity curves and determining fragility functions. As the approach identifies also the collapse mechanisms, it provides a base for choosing and evaluating the effects of strengthening interventions, which are rolled out at territorial level to improve the seismic performance of the whole sample. The effectiveness of the present procedure for the identification of the seismic vulnerability at territorial scale is discussed in the conclusions. [ABSTRACT FROM AUTHOR]

The ground acceleration is usually modeled as a filtered Gaussian process. The most common model is a Tajimi-Kanai (TK) filter that is a viscoelastic Kelvin-Voigt unit (a spring in parallel with a dashpot) carrying a mass excited by a white noise (acceleration at the bedrock). Based upon the observation that every real material exhibits a power law trend in the creep test, in this paper it is proposed the substitution of the purely viscous element in the Kelvin Voigt element with the so called springpot that is an element having an intermediate behavior between purely elastic (spring) and purely viscous (dashpot) behavior ruled by fractional operator. With this choice two main goals are reached: (i) The viscoelastic behavior of the ground may be simply characterized by performing the creep (or the relaxation) test on a specimen of the ground at the given site; (ii) The number of zero crossing of the absolute acceleration at the free field that for the classical TK model is $$\infty $$ for a true white noise acceleration, remains finite for the proposed model. [ABSTRACT FROM AUTHOR]

On Wednesday 11th May 2011 at 6:47 pm (local time) a magnitude 5.1 Mw earthquake occurred 6 km northeast of Lorca with a depth of around 5 km. As a consequence of the shallow depth and the small epicentral distance, important damage was produced in several masonry constructions and even led to the collapse of one of them. Pieces of the facades of several buildings fell down onto the sidewalk, being one of the reasons for the killing of a total of 9 people. The objective of this paper is to describe and analyze the failure patterns observed in reinforced concrete frame buildings with masonry infill walls ranging from 3 to 8 floors in height. Structural as well as non-structural masonry walls suffered important damage that led to redistributions of forces causing in some cases the failure of columns. The importance of the interaction between the structural frames and the infill panels is analyzed by means of non-linear Finite Element Models. The resulting load levels are compared with the member capacities and the changes of the mechanical properties during the seismic event are described and discussed. In the light of the results obtained the observed failure patterns are explained. Some comments are stated concerning the adequacy of the numerical models that are usually used during the design phase for the seismic analysis. [ABSTRACT FROM AUTHOR]

This paper outlines the response of the healthcare system in the area mainly affected by the 2012 Emilia earthquake by drawing on specific surveys and information from local health authorities. Some hospitals were evacuated after the M $$_\mathrm{l}$$ = 5.8 May 20 seismic event due to damage to non structural components and minor structural damage. A short description of the damage suffered and characteristics of the healthcare system as a whole is offered initially, followed by a detailed description of the effects which took place at the Santa Maria Bianca hospital of Mirandola. The focus has been on damage to non structural elements and content, whose integrity is of primary importance for healthcare structures performance during and after a seismic event. Some instruments for the acquisition of accelerometric data were installed after the May 20 event both outside and inside a building which is part of the hospital complex. The seismic behavior of this building has also been analysed by means of a purposely made finite element model and on the basis of the recorded data. The contribution of undamaged and damaged masonry infills to the global seismic response has also been estimated thus providing some hints on the observed building performance. [ABSTRACT FROM AUTHOR]

The Lorca earthquake (southeast Spain) on May 11, 2011; Mw 5.1, and its aftershocks, have provided an important set of accelerograms recorded by the strong motion network of the Instituto Geográfico Nacional of Spain. It is particularly noticeable that the record obtained in Lorca town, very near of the fault rupture, presents a PGA value close to 0.37 g in the N30W component. This paper provides an overview of the strong motion data recorded during the Lorca seismic series, with particular attention to the accelerograms from the mainshock and foreshock and its characteristics. Due to the special circumstances of these two records, a more detailed processing has been required, in which various alternatives to adjust the baseline have been considered and analyzed. Based on this special processing, small residual displacements were obtained and reported in some of these cases. However, given the sensitivity of the process and the small obtained values, these findings should be taken with caution. Besides, response spectra have been analyzed and compared with design spectra proposed by the Spanish Seismic Code (NCSE-02) for the towns of Lorca, Alhama de Murcia and Mula. Large amplitude differences were observed in these spectra if compared to those recorded in Lorca. Also noteworthy is that the design spectra proposed for this town were exceeded by some horizontal directions of the response spectra. [ABSTRACT FROM AUTHOR]

A complex seismic sequence characterised by two thrust earthquakes of magnitudes M $$_\mathrm{L}$$ 5.9 and M $$_\mathrm{L}$$ 5.8 occurred on May 20 and 29, 2012, respectively, and activated the central portion of the Ferrara Arc structure beneath the Po Plain in northern Italy. The sequence, referred to as Emilia 2012, was recorded by the Italian Strong Motion Network, the Irpinia Network, the Friuli Venezia Giulia Network and 15 temporary stations installed by the Civil Protection Department. In this study, we compile and analyse a large dataset that contains 3,273 waveforms from 37 $$M_\mathrm{L} \ge 4.0$$ seismic events. The main aim of this paper is to characterise the ground motion induced by the Emilia 2012 seismic sequence and compare it with other data in the Italian strong motion database and to the recent Ground Motion Prediction Equations (GMPEs) developed for northern Italy, all of Italy and Europe. This is achieved by (1) the computation and analysis of the strong motion parameters of the entire Emilia Strong Motion Dataset (ESMD) and (2) a comprehensive investigation of the May 29 event recordings in terms of time-frequency analysis, the ground motion parameters and the response spectra. This detailed analysis was made possible by the temporary Civil Protection Department stations that were installed soon after the May 20 event at several municipalities in the epicentral area. Most of the recordings are characterised by low-frequency content and long durations, which is a result of the thick sedimentary cover that is typical of the Po Plain. The distributions of the observed horizontal peak ground accelerations and velocities (PGAs and PGVs) with distance are generally consistent with the GMPEs. This is particularly true for the data from M $$_\mathrm{L} \ge $$ 5.0 (M $$_\mathrm{W}\ge $$ 5.0) events, though the data are scattered at distances beyond approximately 60-70 km and show faster attenuation than the European GMPEs. The horizontal components for the May 29 event at two near-fault stations (Mirandola and San Felice sul Panaro) are overestimated by all of the analysed GMPEs. In contrast, the vertical components, which played an important role in the shaking near the source, are underestimated. The May 29 event produced intense velocity pulses on the horizontal components and the highest peak ground acceleration ever recorded in Italy on the vertical component of the Mirandola near-fault station. The ground motion recordings contained in the ESMD significantly enrich the Italian strong motion database. They contribute new information about (1) the possibility of exceeding the largest recorded PGA in Italy, (2) the development of a spectral design that takes into account the role of the vertical component and the extreme variability of the near-fault ground shaking, and (3) the characterisation of the ground motions in deep sedimentary basins. [ABSTRACT FROM AUTHOR]

This paper addresses the structural damage to the main buildings of the cities of Reggiolo and Carpi after the primary earthquake shocks on May 20th and 29th, 2012, in Emilia Romagna. The damage survey, performed via form-based methods, highlights the different seismic behaviour of several types of buildings, especially those having historical features, and the consequences of the damage in terms of costs. Moreover, an analysis of some failure mechanisms activated in Reggiolo enables the evaluation of the local peak ground acceleration, due to the soil amplification. [ABSTRACT FROM AUTHOR]

Vernacular buildings are a relevant part of the building stock affected by the Emilia, 2012, earthquakes and they contribute to shape the rural landscape of the Po valley. Unfortunately, due to overall layout, constructive details and poor maintenance, they have shown a very poor seismic performance. Because most of these buildings are lightly used or abandoned, the risk that they will be demolished is rather high; this could be the most long-lasting outcome of the seismic sequence, deeply affecting the traditional landscape of this portion of the Po valley. In this paper a brief description of the architectural features of these buildings is given and their typical seismic performances are analysed. Because damage is usually related to local-collapse mechanisms, rocking spectra are computed for the near field accelerograms and they are compared with observed behaviours. Finally, suggestions are given to improve the earthquake response of these structures, with the aim of preserving important testimonies of the civilisation of the area. [ABSTRACT FROM AUTHOR]

Urban systems are characterized by very complex interactions. After an earthquake, a wide variety of services, networks and urban facilities may be unavailable to the public during the system failure and recovery processes, thereby causing disruptions in the basic social needs of the affected area. After a disaster, communities face several challenges. For example, the lack of education may impose population migrations, or malfunctions in the electricity distribution system can produce electrical power outages of varying duration with respect to time and space, which generates consequences in the water distribution system, transportation, communications, etc. A methodology called the Disruption index (DI), based on graph theory, includes these multiple interdependencies. It has been developed to estimate the dysfunction of some fundamental dimensions of urban systems on a broad level, starting with the physical damages directly suffered by the exposed assets, proceeding to the impacts that each node has on the functional performance of the nodes depending on them, until reaching the top node. This paper presents the fundamental theory to support the DI concept. The DI provides the likely impacts and consequences of an earthquake in an urban area to fulfill hazard mitigation and provide civil protection agencies and local and state governments with a new decision-making instrument to reduce or prevent severe and recurrent impacts. The DI concept can also be extended to other natural and man-made disasters and may be used as a tool for optimizing the resources of the system components. [ABSTRACT FROM AUTHOR]

Due to the increased need of storage, larger and higher structures are being built all over the world, thus requiring a more careful evaluation of the mechanical performance of their foundation deposits both in terms of bearing capacity and compressibility behaviour. The design of such structures and their serviceability and stability is largely governed by the effects of the dynamic loading conditions principally because of their significantly elevated risk in seismic prone zones. In this paper, numerical analyses using an advanced constitutive model, able to account for the initial soil structure and its progressive degradation, have been performed to investigate the seismic response of a silo foundation built on structured clays. The proposed analyses involve the use of a fully-coupled finite element approach. For the dynamic simulations, three different input motions have been selected form earthquake databases according to the seismic hazard study of the specific site. The results of the silo dynamic response are illustrated in terms of signal amplification, permanent excess pore water pressures, accumulated displacements and structure induced degradation during and after the seismic loading. The dynamic behaviour of the footing indicates that extreme earthquake events can induce large destructuration in natural clays, leading to ground settlements up to twice the observed ones under static loads, which need to be properly accounted for in the design. This suggests that there are significant advantages in using advanced models which recognise the existence of initial soil structure and its subsequent damage due to the applied dynamic loads. [ABSTRACT FROM AUTHOR]

Nepal is located in a highly active tectonic region of the Himalayan belt, one of the most severe earthquake prone areas of the world. Nepal is lying between the Indian and the Eurasian plate, which are moving continuously, resulting in frequent devastating earthquakes. Moreover, different authors state that the accumulated slip deficit (central seismic gap) is likely to produce large earthquakes in the future. Cultural heritage buildings and monuments are, therefore, at risk, and the eventual cultural loss in the consequence of an earthquake is incalculable. Post-seismic surveys of past earthquakes have shown the potential damage that unreinforced masonry structures, particularly Pagoda temples, may suffer in future earthquakes. Most of the Nepalese Pagoda temples, erected during XIV century, are considered non-engineered constructions that follow very simple rules and construction detailing in respect to seismic resistance requirements and, in some cases, without any concern for seismic action. Presently, conservation and restoration of Nepalese temples is one of the major concerns, since they are considered world heritage with universal value. The present paper is devoted to outline particular building characteristics of the UNESCO classified Nepalese Pagoda temples and the common structural fragilities, which may affect their seismic performance. Moreover, based on a parametric sensitivity analysis, structural weaknesses and fragilities of Pagoda temples were identified associated to the local and traditional construction techniques, detailing and common damages. [ABSTRACT FROM AUTHOR]

In this paper, we focused our attention on a cross-section of the Aterno River Valley where a good quality geological and geophysical dataset allowed to reconstruct accurately the geometry and the Vs profiles along all the plane of the section. Its trace is deliberately aligned close to the strong motion stations that recorded the Mw 6.3 (April 6th 2009) L'Aquila earthquake. We analysed strong and weak motion data available at these latter stations as well as at one of the temporary stations installed during the Microzonation activities and located on outcropping bedrock, in proximity of the cross-section. We used the H/V technique to select a reliable reference site and once we found it, we applied the SSR technique to compute amplification functions in correspondence of two strong motion stations. In turn, for both sites we performed a site response numerical modelling with two different 2D codes and we compared simulated versus experimental transfer functions. We found that the cross-section is well constrained based on the very reasonable agreement between results of numerical modelling and earthquake data analysis. We pointed out also a strong amplification of the deposit at the centre of the valley due to the constructive interference of S and surface waves, not predictable by means of 1D numerical modelling. We also compared the H/V as well as the SSR obtained from strong motion data with the ones computed from weak motion finding evidences of non-linearity in soil behaviour. [ABSTRACT FROM AUTHOR]

The seismic events occurred in recent years highlighted the extreme vulnerability of large part of the existing constructed facilities and the need to adopt innovative solutions to improve their seismic performance. With this purpose, the possible exploitation of a seismic early warning system (SEWS) in the framework of semi-active structural control using magnetorheological (MR) dampers is herein investigated. The main idea consists in the use of these time-varying properties devices to control an hosting structure by changing their behaviour according to an anticipate estimate, provided by the SEWS, of the peak ground acceleration (PGA) of the incoming earthquake. In this way, the dampers are able to adapt their mechanical characteristics to the specific earthquake obtaining the optimal seismic response. The present paper describes the application of this protection technique to a case-study problem, a highway bridge located in Southern California. The seismic response of the benchmark bridge is investigated by nonlinear time-history analyses by adopting 16 real earthquake ground excitations. These accelerograms cover a wide variety of magnitudes, distances to fault and soil types. Possible errors on estimation of PGA provided by SEWS and their effects on the proposed control system are also considered. The results obtained confirm that unavoidable errors in the PGA estimates provided by the SEWS do not propagate to the seismic response. Conversely, the proposed strategy turns out to damp these errors, resulting in a robust seismic behaviour of the protected structure. [ABSTRACT FROM AUTHOR]

A buried pipe extends over long distances and passes through soils with different properties. In the event of an earthquake, the same pipe experiences a variable ground motion along its length. At bends, geometrically a more complicated problem exists where seismic waves propagating in a certain direction affect pipe before and after bend differently. Studying these different effects is the subject of this paper. Two variants for modeling of pipe, a beam model and a beam-shell hybrid model are examined. The surrounding soil is modeled with the conventional springs in both models. A suitable boundary condition is introduced at the ends of the system to simulate the far field. Effects of angle of incidence in the horizontal and vertical planes, angle of pipe bend, soil type, diameter to thickness ratio, and burial depth ratio on pipe strains at bend are examined thoroughly. It is concluded that extensional strains are highest at bends and these strains increase with the angle of incidence with the vertical axis. The pipe strains attain their peaks when pipe bend is around $$135^{\circ }$$ and exceed the elastic limit in certain cases especially in stiffer soils, but remain below the rupture limit. Then equations for predicting the seismic response of the buried pipe at bend are developed using the analytical data calculated above and regression analysis. It is shown that these semi-analytical equations predict the response with very good accuracy saving much time and effort. [ABSTRACT FROM AUTHOR]

The work of John Milne, the centenary of whose death is marked in 2013, has had a large impact in the development in global seismology. On his return from Japan to England in 1895, he established for the first time a global earthquake recording network, centred on his observatory at Shide, Isle of Wight. His composite bulletins, the 'Shide Circulars' developed, in the twentieth century, into the world earthquake bulletins of the International Seismological Summary and eventually the International Seismological Centre, which continues to publish the definitive earthquake parameters of world earthquakes on a monthly basis. In fact, seismology has a long tradition in Britain, stretching back to early investigations by members of the Royal Society after 1660. Investigations in Scotland in the early 1840s led to a number of firsts, including the first network of instruments, the first seismic bulletin, and indeed, the first use of the word 'seismometer', from which words like 'seismology' are a back-formation. This paper will present a chronological survey of the development of seismology in the British Isles, from the first written observations of local earthquakes in the seventh century, and the first theoretical writing on earthquakes in the twelfth century, up to the monitoring of earthquakes in Britain in the present day. [ABSTRACT FROM AUTHOR]

Recent earthquakes such as the Haiti earthquake of 12 January 2010 and the Qinghai earthquake on 14 April 2010 have highlighted the importance of rapid estimation of casualties after the event for humanitarian response. Both of these events resulted in surprisingly high death tolls, casualties and survivors made homeless. In the Mw = 7.0 Haiti earthquake, over 200,000 people perished with more than 300,000 reported injuries and 2 million made homeless. The Mw = 6.9 earthquake in Qinghai resulted in over 2,000 deaths with a further 11,000 people with serious or moderate injuries and 100,000 people have been left homeless in this mountainous region of China. In such events relief efforts can be significantly benefitted by the availability of rapid estimation and mapping of expected casualties. This paper contributes to ongoing global efforts to estimate probable earthquake casualties very rapidly after an earthquake has taken place. The analysis uses the assembled empirical damage and casualty data in the Cambridge Earthquake Impacts Database (CEQID) and explores data by event and across events to test the relationships of building and fatality distributions to the main explanatory variables of building type, building damage level and earthquake intensity. The prototype global casualty estimation model described here uses a semi-empirical approach that estimates damage rates for different classes of buildings present in the local building stock, and then relates fatality rates to the damage rates of each class of buildings. This approach accounts for the effect of the very different types of buildings (by climatic zone, urban or rural location, culture, income level etc), on casualties. The resulting casualty parameters were tested against the overall casualty data from several historical earthquakes in CEQID; a reasonable fit was found. [ABSTRACT FROM AUTHOR]

This paper presents analytical developments devoted to the evaluation of the effective behaviour of grain in flat-bottom silos during an earthquake. This research work starts from all the same basic assumptions of Eurocode 8 except for the one regarding the horizontal shear forces among consecutive grains. Only this difference leads to a new physically-based evaluation of the effective mass of the grain which horizontally pushes on the silo walls. The analyses are developed by simulating the earthquake ground motion with time constant vertical and horizontal accelerations and are carried out by means of simple dynamic equilibrium equations that take into consideration the specific mutual actions developing in the ensiled grain. The findings indicate that, in case of squat silos (characterized by low, but usual, height/diameter slenderness ratios), the portion of the grain mass that interacts with the silo walls turns out to be noticeably smaller than the total mass of the grain in the silo and the effective mass adopted by Eurocode 8. [ABSTRACT FROM AUTHOR]

The paper contains a discussion of the inelastic dynamic magnification of seismic shear forces in cantilever walls with rectangular cross-sections. An extensive parametric study was performed in order to determine the reliability of the procedure in Eurocode 8 (EC8). A large number of single cantilever walls which are characteristic for the design practice in Europe and designed to satisfy all the EC8 requirements were analysed. The results obtained with the (modified) code procedures were compared with the results of inelastic response history analyses. If properly applied, the EC8 procedure for DCH walls usually yields good results for the base shears. However, as presently formulated and understood in the EC8, it can yield significantly incorrect results (overestimations of up to 40%). For this reason three modifications were introduced: (1) Keintzel's formula, which is adopted in EC8, should be used in combination with the seismic shears obtained by considering the first mode of the excitation only; (2) the upper limit of the shear magnification factor should be related to the total shear force; and (3) a variable shear magnification factor along the height of the wall should be applied. The present procedure in EC8 for DCM structures (using a constant shear magnification factor of 1.5 for all walls) is non-conservative. For DCM walls it is strongly recommended that the same procedure as required for DCH walls be used. [ABSTRACT FROM AUTHOR]

This paper presents empirical correlations between amplification factors and simple site parameters derived from a large subset of the KiK-net data. The amplification factor is estimated from the ratios between the surface and down-hole horizontal response spectra, corrected for the varying depths and impedance of the down-hole sites (Cadet et al. in Site effect assessment using KiK-net data-part 1-a simple correction procedure for surface/downhole spectral ratios, ). Several site parameters are selected on the basis of their simplicity and availability at relatively low cost. They are the shallow time-average velocities V, with z equal to 5, 10, 20 and 30 m, and the fundamental frequency f. The amplification factors are then correlated with each of the individual site parameters; four other 'twin-parameter'-couples (f, V)-are also considered and the correlation with amplification factors is performed through a normalization of the frequencies by each site fundamental frequency. The quality of the correlations is given by a misfit compared with the original data variance. The largest variance reduction is obtained with twin-parameter characterizations, out of which the couple (f, V) proves to provide the lower misfit. The performance of single parameter correlations is relatively lower; however, the best single parameter proves to be the fundamental frequency, which provides smaller misfit than the Vsz parameters. A comparison is also performed with the amplification factors recommended in European regulations, showing that it is possible right now to significantly improve both the site characterization criteria and the associated amplification factors, for use in building codes and microzonation studies. [ABSTRACT FROM AUTHOR]

Up to now, the search for increased reliability in probabilistic seismic hazard analysis (PSHA) has concentrated on ways of assessing expert opinion and subjective judgement. Although in some areas of PSHA subjective opinion is unavoidable, there is a danger that assessment procedures and review methods contribute further subjective judgements on top of those already elicited. It is helpful to find techniques for objectively assessing seismic source models that show what the interpretations physically mean in terms of seismicity. Experience shows that well-meaning but flawed design decisions can lead to source models that are incompatible with the seismic history that was used as input. In this paper a method is demonstrated in which large numbers of synthetic earthquake catalogues, that match the completeness thresholds of the historical catalogue, are generated. The study area can be divided into a grid of uniform cells, and the number of earthquakes in each cell in both the historical catalogue and each simulated catalogue are then counted. Comparison of the historical pattern and a set of 1,000 simulated patterns, using a X test, shows if the historical pattern is credibly a member of the set of outcomes obtainable from the seismic source model. A second method is to chart the distribution of a large sample of simulated catalogues in terms of magnitude frequency, and observe whether the historical catalogue is comfortably within this distribution, or an outlier. If it proves impossible to replicate the historical catalogue using the model, it casts doubt on whether the model is a valid depiction of the seismicity rates that will govern the future hazard. At the very least, the disparity needs careful investigation to ensure the model is error-free. A worked example is presented here for the UK, using a source model that was used in Global Seismic Hazard Map (GSHAP), compared to one that was artificially constructed to be credible but flawed. Two tests find the GSHAP model to be an acceptable representation of the pattern of seismicity in the UK, while the artificial model is conclusively rejected. [ABSTRACT FROM AUTHOR]

Ground-motion prediction equations (GMPEs) for spectral accelerations have traditionally focused on the range of response periods most closely associated with the dynamic characteristics of buildings. Providing predictions only in this period range (from 0.1 to 2 or 3 s) has also accommodated the assumed limitations on the usable period range resulting from the processing of accelerograms. There are, however, engineering applications for which estimates of spectral ordinates are required at shorter response periods. Recent work has demonstrated that high-frequency spectral ordinates are relatively insensitive to record processing, contrary to previous assumptions. In the light of this finding, additional regressions are performed to extend a recent pan-European GMPE to higher response frequencies. This model and others that also include coefficients for spectral ordinates at several high response frequencies are used to explore options for interpolating coefficients for equations that do not provide good coverage in this range. The challenges and uncertainties associated with such interpolations are discussed. The paper concludes that a set of standard response frequencies could be usefully established for future GMPEs. [ABSTRACT FROM AUTHOR]

In this paper earthquake damage scenarios for residential buildings (about 4200 units) in Potenza (Southern Italy) have been estimated adopting a novel probabilistic approach that involves complex source models, site effects, building vulnerability assessment and damage estimation through Damage Probability Matrices. Several causative faults of single seismic events, with magnitude up to 7, are known to be close to the town. A seismic hazard approach based on finite faults ground motion simulation techniques has been used to identify the sources producing the maximum expected ground motion at Potenza and to generate a set of ground motion time histories to be adopted for building damage scenarios. Additionally, site effects, evaluated in a previous work through amplification factors of Housner intensity, have been combined with the bedrock values provided by hazard assessment. Furthermore, a new relationship between Housner and EMS-98 macroseismic intensity has been developed. This relationship has been used to convert the probability mass functions of Housner intensity obtained from synthetic seismograms amplified by the site effects coefficients into probability mass function of EMS-98 intensity. Finally, the Damage Probability Matrices have been applied to estimate the damage levels of the residential buildings located in the urban area of Potenza. The proposed methodology returns the full probabilistic distribution of expected damage, thus avoiding average damage index or uncertainties expressed in term of dispersion indexes. [ABSTRACT FROM AUTHOR]

The paper presents the results of a research study concerning the seismic response and design of r/c frames with overstrength discontinuities in elevation. The discontinuities are obtained assigning overstrengths either to the beams or to the columns of a 'regular frame' (assumed as reference). Two 'regular frames' are designed: one according to the Eurocode 8 (EC8) medium ductility class (DCM) rules and the other one according to the EC8 high ductility class (DCH) rules. For all frames the criteria of vertical strength irregularity of many international seismic codes are applied. Non linear static and dynamic analyses are performed; mechanical non linearity is concentrated at the element ends. These analyses are carried out according to EC8 provisions: for non linear static analysis the N2 method is applied; in the case of non linear time-history analyses, seven real earthquakes, selected in order to fit on average the elastic design spectrum, are used as input. The seismic response of frames characterised by the assigned overstrength is not very different with respect to the 'regular frame' one; furthermore all the frames satisfy the Ultimate Limit State, verified by the application of non linear static and dynamic analyses. This demonstrates that the sensitivity of frames, designed according to EC8 medium and high ductility classes, to overstrength vertical variations is low. Consequently, international code provisions on vertical strength regularity should be reviewed. [ABSTRACT FROM AUTHOR]

The paper proposes an alternative method for the earthquake-resistant design of HDC external beam-column joints which is based on the assumption that the load transferred from the beam and column elements to the joint is predominantly resisted by a diagonal strut mechanism. The validity of the proposed method is verified experimentally through a comparative study of the behaviour of seven full-size beam-column joint sub-assemblages-three of them designed in compliance with the current European Codes and four in accordance with the proposed method-under cyclic loading. The results obtained indicate that, in contrast with the specimens designed in compliance with current code provisions, those designed so as to comply with the proposed specifications fully satisfy the code performance requirements. [ABSTRACT FROM AUTHOR]

This paper is an explanation of how earthquakes have been interpreted by our predecessors since written records began. Before that we can only surmise that different societies had deities associated with mythological creatures able to cause earthquakes on one pretext or another. Here I have used the Japanese catfish-or 'namazu'-creature to a large extent, partly because it is well-documented, but also because it is still used as a metaphor for earthquakes in official Japanese disaster prevention activities. Both the Bible and the Koran explain that earthquakes are God's punishment for committed sin, and this idea was used until the seventeenth century, particularly by the Christian Church, in explaining their occurrence. The earliest rational approach appears to have come from the founding of Scientific Societies in Europe, beginning in Naples in 1560 and followed quickly by others in many European capital cities including London, where the Royal Society, founded in 1660, had the almost unique benefit of knowledge about earthquakes brought to London by its trade with many parts of the known world. Its Fellows had an opportunity to develop a more balanced approach, producing ideas which often centred on subterranean fire in the earth. Even so, the notion that God was the immediate cause had not disappeared. The 1755 the Great Lisbon earthquake was a seismic event in the religious and philosophical explanation of its cause. European philosophers, led by Leibnitz and Voltaire held contrary views about God and the world, with the latter concluding that earthquakes were caused by natural events with an unknown cause, about which the sins of the people had no influence. Rousseau was another philosopher of influence, initiating the concept of risk, arguing that it was the actions of people which turned an event into a disaster. These philosophers had the benefit of scientific knowledge about the world, originating with Copernicus and subsequently developed by those Scientific Societies referred to above which were created as early as the sixteenth century. [ABSTRACT FROM AUTHOR]

Novel self-lubricating materials are currently being proposed to be used in sliding isolation systems such as the curved surface sliding isolator system, or pendulum bearing system, for the protection of buildings and structures. The current codes for anti-seismic devices are focused on the evaluation of the performance of the whole isolation system; as a consequence, a reliable procedure for the pre-assessment of the material combinations of sliding interfaces is currently missing. Therefore in this paper, an experimental methodology is proposed for the characterization of self-lubricating materials through tests on small-scale specimens performed using customized equipment able to reproduce the operational conditions of real isolation systems as per contact pressure, sliding velocity, temperature and slide path. The testing sequence has been designed in order to evaluate the sliding properties of the material in terms of static and dynamic coefficient of friction and wear resistance. Examples are reported for the assessment of two self-lubricating materials with different sliding characteristics. In order to validate the method and to confirm the reliability of extrapolating the results to real working conditions, prototypes of pendulum isolation systems incorporating the assessed materials have been tested according to the AASHTO (Guide specifications for seismic isolation design, 2nd edn. American Association of State Highway and Transportation Officials, Washington, DC, ) specifications and the relevant dynamic properties assessed from the Horizontal Load-Displacement loops. The experimental outcomes confirmed that the frictional characteristics provided by the proposed procedure can be reliably used in the design of seismically isolated structures. [ABSTRACT FROM AUTHOR]

The extended N2 method has been developed, which takes into account higher mode effects both in plan and in elevation. The extension is based on the assumption that the structure remains in the elastic range when vibrating in higher modes. The seismic demand in terms of displacements and storey drift can be obtained by combining the results of basic pushover analysis and those of standard elastic modal analysis. In the paper, the proposed procedure was summarized and applied to a test example which represents an actual 8-storey reinforced concrete building. The results obtained by the extended N2 method were compared with the results of nonlinear response history analysis and basic N2 analysis without the consideration of higher modes. The extended N2 method was able to provide fair, conservative estimates of response in the case of the test example. In comparison to the basic N2 method, the prediction of seismic demand was greatly improved in the upper part of the building and at the flexible edges. [ABSTRACT FROM AUTHOR]

This paper reports on the study of the seismic response of an urban building block located in Faial, a town of the Horta Island of the Azores, Portugal. The work fits within the framework of studying strengthening schemes suitable for the reconstruction process of a town damaged by an earthquake action and includes numerical modelling of all the building blocks with calibration of material and structural parameters based on ambient vibration tests. The study aims at understanding a number of issues that are likely to influence the global behaviour of the block and the local response of individual buildings, namely the group effect of adjacent constructions, the in-plane stiffness of floors and/or roofs and the presence of possible localized strengthening interventions in selected parts of the block. [ABSTRACT FROM AUTHOR]

The paper describes the earthquake performance assessment of two historical buildings located in Istanbul exposed to a M = 7+ earthquake expected to hit the city and proposes solutions for their structural rehabilitation and/or strengthening. Both buildings are unreinforced clay brick masonry (URM) structures built in 1869 and 1885, respectively. The first building is a rectangular-shaped structure rising on four floors. The second one is L-shaped with one basement and three normal floors above ground. They survived the 1894, M = 7.0 Istanbul Earthquake, during which widespread damage to URM buildings took place in the city. Earthquake ground motion to be used in performance assessment and retrofit design is determined through probabilistic and deterministic seismic hazard assessment. Strength characteristics of the brick walls are assessed on the basis of Schmidt hammer test results and information reported in the literature. Dynamic properties of the buildings (fundamental vibration periods) are measured via ambient vibration tests. The buildings are modelled and analyzed as three-dimensional assembly of finite elements. Following the preliminary assessment based on the equivalent earthquake loads method, the dynamic analysis procedure of FEMA 356 (Pre-standard and commentary for the seismic rehabilitation of buildings, American Society of Civil Engineers, Reston, ) and ASCE/SEI 41-06 (Seismic rehabilitation of existing buildings, American Society of Civil Engineers, Reston, ) is followed to obtain dynamic structural response of the buildings and to evaluate their earthquake performance. In order to improve earthquake resistance of the buildings, reinforced cement jacketing of the main load carrying walls and application of fiber reinforced polymer bands to the secondary walls are proposed. [ABSTRACT FROM AUTHOR]

This paper is focused on the illustration of on site works developed on some historical centres struck by L'Aquila earthquake of April 6, 2009 starting from the first emergency phase. The large number of minor historical centres damaged and the highly differentiated level of damage occurred implied the need of different procedures to study them. The common goal of all these studies is to illustrate the variability of the seismic response of historical masonry buildings trying to identify both the causes that have increased the damage (vulnerabilities) and the factors that have limited or prevented it (strengths). The preliminary results allow to formulate a first evaluation in view of drawing up reconstruction plans. [ABSTRACT FROM AUTHOR]

An introduction to papers on Lorca's earthquake in Spain is presented which includes geologic and seismologic aspects, accelerograms and response spectra, and structural response of buildings.