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This paper studies the implication of the development of shear wall plastic hinges in high-rise dual systems. Multi-plastic hinge approach is intended to reduce the effects of higher modes of vibration in tall structural walls under earthquakes. This research investigated analytically the seismic response of three code conforming designed buildings with 16, 27 and 45 stories. These buildings which consist of a core wall/special moment frame dual system are modeled with four different approaches with single, dual, three and four plastic hinges, and some main structural responses including moment and shear distribution and values, drift ratio distribution and values, floor accelerations, contribution of frame in dual system and finally energy dissipation among plastic hinges are assessed. Findings of this research show that the application of multi-plastic hinge approach in wall design can properly affect seismic behavior of core walls and leads to improvement of system seismic capacity and economy of design. The investigation also shows that the application of multi-plastic hinge design concept can cause better use of frame nonlinear deformation capacity which would help better control of effects of higher modes. Based on analyses results, more frame contribution and improvement of wall behavior is observable in models with three and four plastic hinged walls in comparison with single plastic hinge model designed based on ACI 318-14 provisions. [ABSTRACT FROM AUTHOR]

Historical earthquakes in developing countries, particularly in South America, have caused devastating effects in essential buildings, such as hospitals. As a result, some structural retrofits and new designs of essential facilities in South American countries have concentrated on increasing the seismic design forces beyond what is normally required by building codes. This increased-strength approach can lead to quasi-elastic structural response during earthquakes with much larger induced floor accelerations than expected from code-designed structures. In critical structures, sub-par performance of critical non-structural elements, such as medical equipment in a hospital, due to high-induced floor accelerations can have consequences as devastating as structural failures. Passive seismic protection systems, such as seismic isolation, provide a practical means of controlling seismic demand and are now common in developed countries. However, the applications of protection systems have been far fewer in developing countries due to economic considerations and lack of technical expertise. This paper presents the experimental and numerical studies supporting the development of a novel low-cost sustainable protection system incorporating recycled automobile tires for isolating designated floors or rooms in essential buildings in developing countries. The main innovation of the proposed floor isolation system is the geometric arrangement of the rubber tires that allows isolation from both, horizontal and vertical floor accelerations. Horizontal and vertical cyclic testing conducted on tire specimens are first described followed by the development of a numerical model able to reproduce the experimental results. Finally, an existing case-study hospital in Ecuador is considered for evaluating numerically the seismic performance of the proposed floor isolation system. [ABSTRACT FROM AUTHOR]

According to most of current design standards, the need for high strength and ductility of reinforced concrete frame structures is accomplished utilizing a high amount of transverse reinforcement in beam-column joints. Reinforcement congestion can be overcome by means of Fiber Reinforced Concrete and High Performance Fiber Reinforced Concrete, which are known to improve the structural performance of single structural members or beam-column joints. Through an extended numerical simulation, this paper elaborates the overall benefits of using fiber reinforced concrete materials in critical regions to the seismic behaviour of regular reinforced concrete frame structures. An extensive number of non-linear static and dynamic analyses with distributed plasticity and fibre sections are performed to compare the behaviour of simple reinforced concrete and mixed reinforced concrete/fiber reinforced concrete frames in terms of total base shear and fragility curves and failure mechanisms. Even if execution and technological aspects are beyond the scope of the present work, the use of fiber reinforced concretes in critical regions of mixed frames seems to improve the structural performance of reinforced concrete frames at a global level. [ABSTRACT FROM AUTHOR]

Earthquakes trigger other earthquakes and build up clusters in space and time that in turn create a bias in seismic catalogues. Therefore, declustering is considered as a prerequisite in seismic studies, particularly for probabilistic seismic hazard analysis, not only to eliminate the bias but also to decouple mainshocks and triggered events. However, a declustering process is not a straightforward task due to the complex nature of earthquake phenomena. There exist several declustering methods that mostly employ subjective rules to distinguish between background seismicity and offsprings. Eventually, the final declustered catalogues usually deviate significantly according to the employed method. This issue is raising some concerns, such as how to select the most suitable declustering algorithm, or to assess how this selection affects seismic hazard assessment. In consequence, the main goal of this paper is to quantify the sensitivity of seismic hazard assessments to different declustering techniques. Accordingly, the recently compiled Turkish earthquake catalogue was declustered by making use of three declustering algorithms. A total of six declustered catalogues, two catalogues per method, one by implementing the default input parameters, and one by altering the free input parameters of the employed methods, were produced. The clusters of selected earthquakes were studied in terms of the spatial-temporal distribution of earthquake sequences. A sensitivity analysis was conducted through the major steps of seismic hazard assessment for Istanbul metropolitan city. The seismicity of Istanbul and surroundings was modeled on the basis of four areal source zones. Comparative studies showed that, while the selected declustering algorithm did not significantly affect the completeness periods of moderate to large size earthquakes, it considerably altered those of small magnitude events (e.g. Mw 4.3-5.2) and consequently the recurrence parameters of the source zones. Depending on the declustering algorithm and input parameters, the activity rate was observed to vary up to a factor of two. The differences in the declustered catalogues obtained from different declustering approaches resulted in considerable variations in seismic hazard estimations. The hazard maps at return periods of 475 and 2475 years indicated that peak ground acceleration values may vary up to 20% at some locations. Moreover, the differences in 5% damped elastic spectral accelerations at T = 0.2 for the return periods of 475 and 2475 years are about 18 and 12%, respectively, on the southern shores of Istanbul where the highest hazard levels are observed. [ABSTRACT FROM AUTHOR]

This paper describes how the earthquake parameters of historical earthquakes have been determined in Europe from macroseismic data by means of the so-called 'Boxer' method, in the frame of the European Commission 2009-2012 Project SHARE (Seismic Hazard Harmonization in Europe). The problems related to the assessment of magnitude are described with more detail; the methodological issues are developed with special reference to the 'stable continental region'. The paper first describes how the coefficients of the Boxer method are determined in five tectonic regions of the European area from the relevant calibration data sets, and discusses the problems dealt with while performing this task. Then it describes how the results have been checked against data different from those used in the previous phase. Finally, the application of the new coefficients to nearly a thousand of European earthquakes before 1900 is described. Stressing that, for the first time in Europe, homogeneous results have been obtained at such a large scale, the final part of the paper is devoted to analyse such results, with special reference to the general trends and to some case-histories. [ABSTRACT FROM AUTHOR]

The paper presents the application of the seismic assessment procedure developed in the PERPETUATE project on a single monument, the Neoclassical School in the Medieval City of Rhodes. The PERPETUATE methodology for the estimation of seismic risk of cultural heritage assets is based on the principles of performance-based assessment ( PBA), using nonlinear static procedures. The outcome of the PBA methodology is the maximum seismic intensity measure compatible to different performance levels. The focus of the paper is on the application of the methodology, considering the effects of both soil-foundation-structure interaction ( SFSI) and masonry foundation flexibility on the building response, before and after rehabilitation design measures. It is found that SFSI and foundation flexibility produce larger displacements and reduce the maximum ground acceleration that the building can sustain by over 50 %. However, despite the detrimental effects of SFSI on the acceleration capacity, SFSI and foundation flexibility may have a favorable effect on the structure safety, as they modify the collapse mechanism. The results of seismic analyses showed that the building, in its current state, does not sustain the demands for the Life Safety and Collapse Prevention performance levels. Stiffening the roof of the structure and providing sufficient anchorage to the structure, along with systematic grouting of the masonry walls, are the principal rehabilitation decisions considered herein. Mitigation measures were evaluated, considering SFSI and the analyses revealed the adequacy of the proposed retrofitting measure, which combines vertical (wall) and horizontal (roof) stiffening. [ABSTRACT FROM AUTHOR]

At present, the codified procedures for the seismic assessment of existing structures do not consider explicitly the use of sensitivity analysis that, on the contrary, is an essential tool due to the intrinsic and epistemic uncertainties involved. In particular, results of a sensitivity analysis allow, on one hand, to optimize the plan of investigations and tests, limiting it to what is really useful, and, on the other hand, to be aware of the propagation of uncertainties in the final outcome of the assessment. The paper proposes how to implement the sensitivity analysis in a systemic way, in order to define proper confidence factors, which are used within the semi-probabilistic approach of the performance-based assessment procedure. In relation to the procedures adopted by current standards, this method is aimed to overcome the following drawbacks: (1) the a priori definition of values for the confidence factor; (2) the a priori selection of parameters to which confidence factor has to be applied; (3) the weak connection between investigation and assessment. Despite the generality of most aspects of the proposed procedure, main attention is given in the paper to its application in the case of masonry existing buildings and, in particular, of those with a significant cultural value, where the minimization of invasiveness of investigations on the construction together with that of costs plays a crucial role for the aim of conservation. [ABSTRACT FROM AUTHOR]

The paper presents the vulnerability assessment of the Hassan Bey's Mansion, located in the Medieval City of Rhodes in Greece. To this aim, the procedure developed in PERPETUATE project for the seismic assessment at scale of a single monument is adopted: it follows the performance-based concept making use of nonlinear static analyses. The main outcome of the assessment is presented in the paper in terms of maximum seismic intensity measure (the one selected as the most representative for the examined asset) compatible to various performance levels: it is used to address also the rehabilitation decisions. Within this context, the attention of this paper is focused on the use of sensitivity analysis for the identification of the main parameters that affect the structural response. Uncertainties considered in this application are both aleatory and epistemic. The epistemic uncertainties concern the effectiveness of the infilled openings: in fact, this feature strongly characterizes this building that has been subjected to many transformations along its life. Moreover, seven random variables have been considered to account for the aleatory uncertainties: they involve the material properties, the material constitutive law as well as floor rigidity. A total of 60 nonlinear static analyses have been performed for the sensitivity analysis, which represents a powerful tool for setting-up a possible investigation plan and addresses the final assessment. The resulting safety factor, computed in terms of return period, varies from 0.20 to 0.27, highlighting that the structure is not able to satisfy the target performance levels. Possible rehabilitation measures are proposed afterwards, in particular by quantitatively assessing the effect associated to the stiffening of diaphragms (very flexible in the original state). [ABSTRACT FROM AUTHOR]

The seismic Performance-Based Assessment (PBA) of monumental buildings requires to consider safety and conservation objectives, including also the possible presence of artistic assets. In order to face these issues, the case study of the Great Mosque of Algiers is analysed in this paper: in fact, besides to be one of the remaining Almoradiv architecture and the oldest mosque of the city, it is also characterized by the presence of a mihrâb, a decorated arched niche that represents an interesting artistic asset to be included in the PBA. Within this context, particular attention has been paid to the choice of the most reliable modelling strategy for the application of the displacement approach in the PBA procedure, as a function of different possible seismic behaviours. In the case of Great Mosque both the current state of the building and a virtual strengthened condition are analysed. It is worth noting that, while in the current state the seismic behaviour of the asset is well described by a set of macroelements that may be analysed independently (through 2D models), in the second case the strengthening intervention leads to the adoption of a 3D global model (indeed, the roof bracing promotes a 'box-type' behaviour). In the paper, the integrate use of three different modelling strategies of different complexity is discussed: the finite element model, the equivalent frame approach and the macro-block model. The results of nonlinear analyses performed (static and kinematic) constitute the main tool to interpret the seismic response of the asset, perform the PBA and address the choice on the rehabilitation decisions. These latter in this case are mainly affected by the occurrence of too high deformations in local portions of the building, including that in which the artistic asset is located. [ABSTRACT FROM AUTHOR]

The structural performance of historical masonry elements can be understood provided the following factors are known: geometry; the characteristics of its masonry texture and morphology, state of damage and decay, physical, chemical and mechanical characteristics of the components (units, infill, mortar); the characteristics of built masonry as a composite material. In order to quantify the mechanical properties of the masonry both laboratory and in-situ tests are required. However, in the case of cultural heritage assets, the setting up of an effective knowledge procedure is strictly related to the minimization of invasiveness on the structure, with the aim of its conservation, rather than the cost-benefit optimization: thus it is essential to have available reference parameters to be adopted for different masonry types. Within this context, this State-of-the-Art paper on this topic is organized with integrated outcomes from the test campaigns carried out through the PERPETUATE project, that are also briefly presented. Reference parameters for effective seismic assessment are provided both for brick and stone masonry together with their upper and lower bound values for both mechanical parameters and damage limits for which proper limit states (LS) may be associated. Apart from the LS for structural elements (SE), the relevant LS's for artistic assets attached to the SE are also presented in this paper. [ABSTRACT FROM AUTHOR]

In arches and vaults, tie-rods play a decisive role in counterbalancing horizontal thrusts produced by both permanent and seismic loadings. In this paper, the effectiveness of flexible tie-rods to improve the seismic response of arch-pillars system is assessed by means of shaking table tests and simple analytical models, developed in the framework of displacement-based design. The reduced scale model, made of rigid blocks with dry joints, has been tested without tie-rod and considering different configurations of strengthening. Both experimental and theoretical results have proved the importance, in particular for this kind of flexible masonry structure, of improving displacement capacity rather then strength, because in this latter case other brittle mechanisms could be activated. The paper shows the possibility of describing the dynamic seismic response of rocking masonry structures, characterized by complex mechanisms made of many blocks and hinges, by an equivalent nonlinear SDOF system. [ABSTRACT FROM AUTHOR]

A series of earthquakes, the highest of magnitude $$\text{ M }_\mathrm{w}$$ 5.9, hit a portion of the Po Valley in Northern Italy, which was only recently classified as seismic. The paper reports the findings and the lessons learnt from a preliminary field survey which was conducted immediately after the second event. As a result of the economic attitude of the affected area, and possibly of the characteristics of the event, an unprecedented number of industrial precast buildings were affected, resulting into most of the casualties as well as in large economic losses. Whereas most of the damaged and collapsed buildings were designed for gravity loads only, evidence of poor behavior of some precast buildings designed according to seismic provisions were discovered. The paper provides a description of the performance of precast buildings, highlighting the deficiencies that led to their poor behavior as well as some preliminary recommendations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Paper describes the extensive work done in the SIGMA project, aimed at improving knowledge on data, methods and tools to better quantify uncertainties in seismic hazard assessment (SHA). The authors cooperated in the study of potential faults and geological structures, earthquake catalogues, selection of ground motion prediction equations, and methods for site effect evaluation suitable for SHA. All the contributions merged into a probabilistic seismic hazard study conducted for three representative sites of the Po Plain in Northern Italy. Po Plain is a low-to-moderate seismicity region, characterized by some critical features, such as blind faulting and deep alluvium sediments, and by scarcity of strong motion data; these sources of uncertainties in seismic hazard estimation are common to other low seismicity areas around the world. Within SIGMA, special care was devoted to: (a) the use of the single station sigma approach inside the probabilistic SHA, (b) the comparative use of generalized attenuation functions to evaluate the hazard contribution of composite fault systems, and (c) the study of the epistemic uncertainties at play when different modelling approaches to site effects are used. [ABSTRACT FROM AUTHOR]

The accurate evaluation and appropriate treatment of uncertainties is of primary importance in modern probabilistic seismic hazard assessment (PSHA). One of the objectives of the SIGMA project was to establish a framework to improve knowledge and data on two target regions characterized by low-to-moderate seismic activity. In this paper, for South-Eastern France, we present the final PSHA performed within the SIGMA project. A new earthquake catalogue for France covering instrumental and historical periods was used for the calculation of the magnitude-frequency distributions. The hazard model incorporates area sources, smoothed seismicity and a 3D faults model. A set of recently developed ground motion prediction equations (GMPEs) from global and regional data, evaluated as adequately representing the ground motion characteristics in the region, was used to calculate the hazard. The magnitude-frequency distributions, maximum magnitude, faults slip rate and style-of-faulting are considered as additional source of epistemic uncertainties. The hazard results for generic rock condition (Vs30 = 800 m/s) are displayed for 20 sites in terms of uniform hazard spectra at two return periods (475 years and 10,000 years). The contributions of the epistemic uncertainties in the ground motion characterizations and in the seismic source characterization to the total hazard uncertainties are analyzed. Finally, we compare the results with existing models developed at national scale in the framework of the first generation of models supporting the Eurocode 8 enforcement, (MEDD 2002 and AFPS06) and at the European scale (within the SHARE project), highlighting significant discrepancies at short return periods. [ABSTRACT FROM AUTHOR]

The estimation of the seismological parameters of historical earthquakes is a key step when performing seismic hazard assessment in moderate seismicity regions as France. We propose an original method to assess magnitude and depth of historical earthquakes using intensity data points. A flowchart based on an exploration tree (ET) approach allows to apply a consistent methodology to all the different configurations of the earthquake macroseismic field and to explore the inherent uncertainties. The method is applied to French test case historical earthquakes, using the SisFrance (BRGM, IRSN, EDF) macroseismic database and the intensity prediction equations (IPEs) calibrated in the companion paper (Baumont et al. Bull Earthq Eng, 2017). A weighted least square scheme allowing for the joint inversion of magnitude and depth is applied to earthquakes that exhibit a decay of intensity with distance. Two cases are distinguished: (1) a “Complete ET” is applied to earthquakes located within the metropolitan territory, while (2) a “Simplified ET” is applied to both, offshore and cross border events, lacking information at short distances but disposing of reliable data at large ones. Finally, a priori-depth-based magnitude computation is applied to ancient or poorly documented events, only described by single/sporadic intensity data or few macroseismic testimonies. Specific processing of “felt” testimonies allows exploiting this complementary information for poorly described earthquakes. Uncertainties associated to magnitude and depth estimates result from both, full propagation of uncertainties related to the original macroseismic information and the epistemic uncertainty related to the IPEs selection procedure. [ABSTRACT FROM AUTHOR]

The evaluation of realistic time histories for various locations around Marmara Region is aimed to provide reliable input for performance-based seismic design, hazard or risk management studies and developing new seismic standards. The applicability of empirical Green’s functions methodology and physics-based solution of earthquake rupture have been assessed in terms of modeling complex geologic structures. This paper has two main objectives. The first one is to simulate five medium-size magnitude earthquakes (Mw ≈ 5.0) recorded in the Marmara Region. A series of synthetic ground motion waveforms for three components are evaluated with a ‘physics-based’ solution of earthquake rupture. The simulation methodology is based on the studies of Hutchings and Wu (J Geophys Res 95:1187-1214, 1990), Hutchings (Seismol Soc Am 81:88-121, 1991; Seismol Soc Am 84:1028-1050, 1994), Hutchings et al. (Geophys J Int 168:569-680, 2007), and Scognamiglio and Hutchings (Tectonophysics 476:145-158, 2009). For each earthquake, we calculate synthetic seismograms by using 500 different rupture scenarios that are generated by Monte Carlo method for a selection of parameters within a range based on prior knowledge of where the earthquakes will occur. The second objective is to validate synthetic seismograms with real seismograms. To improve the credibility of synthetic seismograms from an engineering point of view, the methodology presented by Anderson (in 13th world conference on earthquake engineering, Vancouver, 2003) is followed. This methodology proposes a similarity score based on averages of the quality of fit measuring ground motion characteristics and uses a suite of measurements. In order to compute goodness of fit, ten different ground motion parameters were compared on a scale from 0 to 100, where 100 means perfect agreement. Because the methodology produces source- and site-specific synthetic ground motion time histories, and the goodness-of-fit scores of obtained synthetics are between ‘good’ and ‘excellent’ range (61.128-82.164) based on the Anderson’s score, we conclude that it can be used to produce reliable ground motion time histories for seismic risk regions to develop or improve seismic codes and standards. [ABSTRACT FROM AUTHOR]

In this paper economic seismic risk analysis of API 5L buried steel gas pipelines is carried out through incremental dynamic analysis using an ensemble of 20 ground motion records. Multiple performance limit states for buried steel pipelines are proposed. Fragility curves of 15 pipeline models of various diameter to thickness (D/t) ratios, burial depth to diameter (H/D) ratios, assumed soil conditions and steel grades are plotted for damage states corresponding to the defined limit states. Expected global economic loss of 1 km length of the pipelines for a given peak ground velocity is obtained using the fragility curves, a pipeline repair ratio as well as costs of leakage repairing and break-induced pipe replacement. The mean annual frequency of exceedance of loss for the investigated pipelines is calculated using a seismic hazard curve and the expected annual loss (EAL) is obtained. It is concluded that in case of the pipelines with the D/t ratio greater than 39.9, the probabilities of failure for a given return period increase with increasing D/t ratio. It is obtained that the probabilities of failure for a given return period increase with increasing H/D ratio and shear modulus of the soil (Gs). The results show that the probabilities of failure decrease with increasing steel grade of the pipes. It is found that for a given return period, the global economic loss increases for an increase in the D/t, H/D and Gs values. The results show that EAL of the pipelines decreases with increasing steel grade of the pipes and decreasing D/t ratio, H/D ratio as well as Gs value. It is obtained that frequency of exceedance of a given loss value increases with an increase in D/t, H/D and Gs values. It is noteworthy that the obtained results are valid only for Tehran, and the pipe and soil characteristics used in the study. [ABSTRACT FROM AUTHOR]

The 2016 August 24th, Mw6.0 Amatrice (Central Italy) normal faulting earthquake produced a remarkable number of Earthquake-Rotated Objects (EROs) that affected chimneys, as well as pillars and capitals on gates and walls. In this paper we present the EROs dataset, and perform some qualitative analyses to evaluate if specific geological and seismological features such as intensity, epicentral distance, potential amplification of the seismic shaking at the site, heterogeneities of the rupture on the fault and directivity effects, and peak ground accelerations, favoured the distribution of EROs observed after the earthquake. A first important outcome is that the distribution of the EROs of Amatrice 2016 mimics the general pattern of damage, and that EROs occurrence should be regarded as a diagnostic element of intensity degrees lower than those presently established by formalized scales. We also find that site factors, namely the surface geology and the local amplification, are the most significant contributors to the EROs occurrence. In addition, we find that the position respect to the fault can enhance the occurrence of local rotations. The distinctive features characterizing the 2016 EROs dataset resemble and substantiate the most important findings produced by previous studies carried out following the 2009 L’Aquila and 2012 Emilia seismic sequences, and allow to calibrate the empirical relations on the EROs distribution presented in the world Catalog of Earthquake-Rotated Objects. [ABSTRACT FROM AUTHOR]

The M = 7.8 Muisne event of April 16, 2016 occurred on Saturday at 18:58:37 local time off-shore of the west coast of northern Ecuador. Several cities in the province of Manabí were directly affected and a state of emergency was declared in six provinces encompassing a total area of 70,000 km. The building stock was severely damaged. 80% of the buildings were destroyed in the city of Pedernales, while several multi-storey reinforced concrete structures totally collapsed in the cities of Manta and Portoviejo. Field observations on the seismic performance of reinforced concrete buildings inspected by the authors are presented in this paper. Also, numerical results from three-dimensional pushover analysis of a representative case study building are discussed. The effect of corrosion and masonry infills, which played a key role in the observed damage, was directly taken into account in the analytical model. [ABSTRACT FROM AUTHOR]

The paper introduces a number of new analytic techniques and practical technologies that lead to the development of an efficient earthquake resistant system. The proposed structural system consists of a grade beam supported moment frame connected to a rigid rocking core through story level rigid links. The new system tends to bend and tilt as an upright simply supported beam with minimal uniform drift and prevents the formation of soft story failure within the moment frame. It is capable of preventing severe damage to its columns and footings and can be equipped to prevent catastrophic collapse due to strong ground motion and re-center itself afterwards. The analytic development is based on global, design led analysis and results in closed form, exact solutions that are highly suitable for preliminary, manual, as well as spread sheet computations. Several examples have been provided to verify and demonstrate the applications of the proposed formulations. All numerical results have been verified by independent computer analysis. [ABSTRACT FROM AUTHOR]

The assessment of earthquake risk in portfolio, urban or regional scale constitutes an important element in the mitigation of economic and social losses due to earthquakes, planning of immediate post-earthquake actions as well as for the development of earthquake insurance schemes. Earthquake risk assessment methodologies consider and combine three main factors: earthquake hazard, fragility/vulnerability and inventory of assets exposed to hazard. These factors exhibit aleatory and epistemic uncertainties embedded in their various components. Challenges exist in the characterization of the earthquake hazard as well as in the determination of the fragilities/vulnerabilities of the physical and social elements exposed to the hazard. The simulation of the spatially correlated fields of ground motion using empirical models of correlation between intensity measures is an important tool for hazard characterization. Vulnerability relationships for physical elements, derived from empirical, analytical or expert opinion based methods, provide the probability of loss ratio, conditional on a level of intensity measure. The uncertainties involved in these relationships and especially the correlation in these uncertainties are important to obtain the bounds of the expected losses. Rather simplified procedures exist for the rapid post-earthquake assessment of physical, social and economic losses. The reduction of the uncertainties inherent in the basic ingredients of such rapid earthquake loss assessment is an important issue that needs to be tackled in the future for their viability and reliability. The uncertainties inherent in the determination of exposed assets and their fragilities/vulnerabilities needs to be tackled in the future for the viability and reliability of such rapid loss assessments. The commonly used risk metrics in earthquake insurance are the Average Annual Loss and Loss Exceedance Probability curves. A rigorous treatment of uncertainty and correlation are needed for the proper estimation of these metrics and earthquake insurance related decisions. This paper looks at the current practices in regional and urban earthquake risk assessment, discusses current issues and provides illustrative applications. [ABSTRACT FROM AUTHOR]

In this paper, we separate the residuals of ground motion prediction equations into different components, calculating the repeatable site-specific ( $$\delta S2S_{s}$$ ), location-specific ( $$\delta L2L_{r}$$ ) and path-specific ( $$\delta P2P_{er}$$ ) correction for the median model. In this way, we can reduce the total standard deviation (sigma) of the ground-motion model by Lanzano et al. (Bull Seismol Soc Am 106(1):73-92, 2016), removing these components and overcome the ergodic assumption. These repeatable terms are empirically estimated using a dataset composed by acceleration waveforms of Italian events mainly occurred in the Po plain and Eastern Alps (Northern Italy), in the time interval 1976-2015. The analysis is carried out on 2241 recordings, from 88 shallow earthquakes recorded by 168 sites. A local model, specifically tailored for Northern Italy, is used as the reference GMPE, which predicts the geometric mean of the horizontal peak ground accelerations and response spectral ordinates in the period range 0.04-4 s. Because most of the propagation paths sampled only once, the path-specific components and the resulting aleatory variability are also calculated from the spatial correlation of residuals, following the approach of Lin et al. (Bull Seismol Soc Am 101(5):2281-2295, 2011). We find a significant reduction of the overall ground motion variability to an extent comparable to what observed from previous studies on empirical and simulated datasets. The estimated median corrections and variance components can be used in probabilistic seismic hazard assessment for a single site and a single path in Northern Italy. As an example, we compute the hazard curves at some sites by means of three different approaches (ergodic, partially non-ergodic and full non-ergodic), in order to quantify the impact of relaxing the ergodic assumption. [ABSTRACT FROM AUTHOR]

The cone penetration test is often used in geological and geotechnical surveys for characterising soil layers and to solve a wide set of geotechnical problems, especially for large scale studies that need to cover as wide an area as possible with more cost and time savings. For more than 30 years, there has been considerable interest in using CPT also to evaluate the liquefaction resistance of soils. The CPT-based simplified methods used for liquefaction resistance evaluation require in situ measurements from electrical cone penetrometers even if they are frequently applied using measurements from mechanical CPTs that are still preferred by current engineering practice in many countries. In the present paper, a dataset of more than 3900 pairs of measurements of cone tip resistance and sleeve friction pertaining the same soil levels and measured with the two different types of cone penetration equipment (mechanical and electrical) were obtained from 44 sites located in Northern and Central Italy. Statistical analyses and regression processes allowed for the definition of some correction equations to be included in some of the most used CPT-based methods for liquefaction resistance estimation from CPT mechanical data. A probabilistic approach based on Taylor's method was proposed for determining the uncertainties. Finally, the reliability of the suggested correction procedure was tested on the dataset available for this study. [ABSTRACT FROM AUTHOR]

This paper proposes a modification of the empirical method for seismic vulnerability assessment of reinforced concrete buildings in urban areas. In the RISK-UE LM1 framework, the values of the behaviour modifiers related to: (i) the level of seismic code design; (ii) the number of storeys above ground; and (iii) the structural joint between adjoining buildings, have been modified according to an analysis of the actual seismic performance of buildings and a review of the currently available models, providing continuity to the progress of the previous works published to date. The new model has been applied to the city of Lorca, Spain following the damage data from the earthquake of May 11, 2011. Less dispersion between actual observed and estimated damage in buildings is presented in comparison with the previous studies, with a statistical significance level of 5%, thus achieving a more accurate evaluation of seismic risk based on the typological, structural and urban parameters of the buildings. Nevertheless, future work to further improve these modifiers is necessary in order to achieve a better adjustment between the estimated and observed damage. By using GIS techniques, the proposal can also be used to develop the planning and management of post-earthquake emergency situations, allowing for a better definition of several damage scenarios. [ABSTRACT FROM AUTHOR]

The 23 October 2011 Van (Mw 7.1) earthquake that occurred in Eastern Turkey resulted in heavy damage particularly in the city of Van and town of Ercis. This paper presents ground motion simulations of Van earthquake by using stochastic finite fault method (EXSIM, Motazedian and Atkinson in Bull Seismol Soc Am 95:995-1010, ; Boore in Bull Seismol Soc Am 99:3202-3216, ) that provides a simple and effective tool to generate high frequency strong motion. The input parameters related to source, path, and site effects are calibrated on the basis of minimizing the error functions between simulations and observations both in time and frequency domain. Validated model parameters are used to produce synthetics in regional extent with the aim of understanding the level and distribution of the ground shaking particularly in the near fault region where no recordings are available within the 40 km of the epicenter. This paper evaluates the effect of two different slip models on ground motion intensity measures over the area of interest and addresses the variability in the near fault region associated with the source effect. The synthetics are compared with the corresponding estimations of ground motion prediction equations by Boore and Atkinson (Earthq Spectra 24:99-138, ), Akkar and Bommer (Seismol Res Lett 81:195-206, ) and Akkar and Cagnan (Bull Seismol Soc Am 100:2978-2995, ). Our results indicate that despite the limitation of the method for incorporating the directivity effect and inadequate representation of the soil conditions at the individual stations, a satisfactory match between synthetics and observations are obtained both in time and frequency domain. Spatial distributions of the synthetics in regional level also show reasonable correlation with ground motion prediction equations and damage observations. [ABSTRACT FROM AUTHOR]

The collapse of stone masonry is one of the greatest causes of death in major earthquake events around the world. This paper investigates a recently developed retrofitting technology specifically aimed at preventing or prolonging the collapse of stone masonry buildings under strong earthquakes. This technology uses common polypropylene packaging straps to form a mesh, which is then used to prevent or prolong collapse. This paper examines the findings from static and dynamic testing of the proposed retrofit. It is shown that the proposed technique effectively prevents brittle masonry collapse and the loss of debris. [ABSTRACT FROM AUTHOR]

The present paper investigates the coupled effect of the supporting soil flexibility and pounding between neighbouring, insufficiently separated equal height buildings under earthquake excitation. Two adjacent three-storey structures, modelled as inelastic lumped mass systems with different structural characteristics, have been considered in the study. The models have been excited using a suit of ground motions with different peak ground accelerations and recorded at different soil types. A nonlinear viscoelastic pounding force model has been employed in order to effectively capture impact forces during collisions. Spring-dashpot elements have been incorporated to simulate the horizontal and rotational movements of the supporting soil. The results of the numerical simulations, in the form of the structural nonlinear responses as well as the time-histories of energy dissipated during pounding-involved vibrations, are presented in the paper. In addition, the variation in storeys peak responses and peak dissipated energies for different gap sizes are also shown and comparisons are made with the results obtained for colliding buildings with fixed-base supports. Observations regarding the incorporation of the soil-structure interaction and its effect on the responses obtained are discussed. The results of the study indicate that the soil-structure interaction significantly influences the pounding-involved responses of equal height buildings during earthquakes, especially the response of the lighter and more flexible structure. It has been found that the soil flexibility decreases storey peak displacements, peak impact forces and peak energies dissipated during vibrations, whereas it usually leads to the increases in the peak accelerations at each storey level. [ABSTRACT FROM AUTHOR]

The architectural heritage was severely damaged by the seismic sequence that occurred in Emilia (Northern Italy) in May 2012. This paper investigates the seismic behavior of three masonry churches that were damaged by the 2012 Emilia earthquake. The analyzed churches are located in the South-East area of the province of Mantua: they are representative of some churches, denoted as 'Matildic churches', belonging to the territorial area between Lombardia, Emilia Romagna and Toscana and built during the Matilde di Canossa domain, between the X and the XI centuries. The study was based on detailed field surveys, in situ tests, visual inspections and existing archives in order to obtain an accurate knowledge of the churches and a proper evaluation of the damage caused by the earthquake. Then, detailed finite element models of the churches were developed and non-linear dynamic analyses with different peak ground accelerations were performed. The numerical simulations provided a deep insight into the seismic behavior of the analyzed churches, identifying the damage patterns and the main collapse mechanisms for different seismic intensity levels. The obtained results appear to be in a good agreement with the damage experienced by the churches during the earthquake. This study can be considered as a first step to assess the seismic vulnerability of the 'Matildic churches', extremely important for their historical and architectural value. [ABSTRACT FROM AUTHOR]

The fragility of buried electrical cables is often neglected in earthquakes but significant damage to cables was observed during the 2010-2011 Canterbury earthquake sequence in New Zealand. This study estimates Poisson repair rates, similar to those in existence for pipelines, using damage data retrieved from part of the electric power distribution network in the city of Christchurch. The functions have been developed separately for four seismic hazard zones: no liquefaction, all liquefaction effects, liquefaction-induced settlement only, and liquefaction-induced lateral spread. In each zone six different intensity measures (IMs) are tested, including peak ground velocity as a measure of ground shaking and five metrics of permanent ground deformation: vertical differential, horizontal, maximum, vector mean and geometric mean. The analysis confirms that the vulnerability of buried cables is influenced more by liquefaction than by ground shaking, and that lateral spread causes more damage than settlement alone. In areas where lateral spreading is observed, the geometric mean permanent ground deformation is identified as the best performing IM across all zones when considering both variance explained and uncertainty. In areas where only settlement is observed, there is only a moderate correlation between repair rate and vertical differential permanent ground deformation but the estimated model error is relatively small and so the model may be acceptable. In general, repair rates in the zone where no liquefaction occurred are very low and it is possible that repairs present in this area result from misclassification of hazard observations, either in the raw data or due to the approximations of the geospatial analysis. Along with hazard intensity, insulation material is identified as a critical factor influencing cable fragility, with paper-insulated lead covered armoured cables experiencing considerably higher repair rates than cross-linked polyethylene cables. The analysis shows no trend between cable age and repair rates and the differences in repair rates between conducting materials is shown not to be significant. In addition to repair rate functions, an example of a fragility curve suite for cables is presented, which may be more useful for analysis of network connectivity where cable functionality is of more interest than the number of repairs. These functions are one of the first to be produced for the prediction of damage to buried cables. [ABSTRACT FROM AUTHOR]

In this paper, we address the issue of evaluating the seismic site response for sites located on large alluvial plains, for which no reference sites can be identified, but some earthquakes can be simultaneously recorded at both surface and depth. In the proposed method, surface and borehole records are firstly used to assess the local 1D velocity model, then a model representing a virtual reference rock site is defined, and finally the site spectral amplification is calculated through numerical modeling. The effectiveness of the method is demonstrated at the site of Mirandola (Italy). This site is located in an area which suffered heavy damage during the seismic sequence that started in Northern Italy with the Mw = 5.8 event on May 20th, 2012. That time, the site hosted an accelerometer of the National Accelerometric Network, which recorded the whole sequence. A new station, named MIRB (MIRandola Borehole), was installed during 2014; it is equipped with three accelerometric sensors deployed at surface, 31 and 126 m depth, respectively. The results of this study evidence that Mirandola is characterized by an amplification level consistent with that of a class-C soil for up to a period of about 0.45 s, while for higher periods, the amplification lays between class-B and C soils. [ABSTRACT FROM AUTHOR]

Investigating relationships between macroseismic intensity and strong-motion data requires the existence of these two records for the same seismic event and site. In Italy, this comparison is feasible through the cross-matching of the Italian Macroseismic Database (DBMI) and the Italian Strong-Motion Database (ITACA) which are the most comprehensive sources of both data. However, the two databases lack a direct link which would allow performing joint analysis of macroseismic data points and strong-motion recordings, making the comparison a time consuming job for the researcher. This paper demonstrates the usefulness of cross-database identifiers, and presents their use in a web-tool called Rosetta, an initial proof-of-concept that helped testing linking procedures among DBMI and ITACA, and user friendly visual solutions. The development allowed the working group to exchange expertise on their respective database structures and workflows, laying the groundwork for a consistent, low-maintenance, and durable solution that will be easily updatable each time a new version of DBMI or ITACA will be released. [ABSTRACT FROM AUTHOR]

The Chilean subduction zone is one of the most active in the world. Six events of magnitude greater than $$M_w = 7.5$$ have occurred in the last 10 years, including the 2010 $$M_w = 8.8$$ Maule, the 2014 $$M_w = 8.2$$ Iquique, and the 2015 $$M_w = 8.3$$ Illapel earthquakes. These events have produced a considerable dataset to study interface thrust and intraslab intermediate depth earthquakes. In this paper, we present a database of strong motion records for Chilean subduction zone earthquakes and develop a ground motion prediction equation (GMPE) for peak ground acceleration and response spectral accelerations with 5% damping ratio for periods between 0.01 and 10 s. The dynamic soil amplification effects are considered in a new empirical model based on two parameters, the predominant period of the soil ( $$T^*$$ ) and the average shear wave velocity down to 30 m depth ( $$V_{S30}$$ ). The spectral accelerations prediction equations at short periods are generated using 114 records of intraslab earthquakes ( $$M_w$$ = 5.5-7.8) and 369 records of interface earthquakes ( $$M_w$$ = 5.5-8.8); a reduced number of these records are used for longer periods. The proposed GMPE can predict the ground motion of large Chilean subduction earthquakes ( $$M_w > 8$$ ) with no need of extrapolation from small-magnitude earthquake data. Intraslab earthquakes show a steeper attenuation slope than that of interface ones, which is consistent with other GMPE results derived from worldwide subduction zones data. Moreover, the Chilean interface earthquakes show a flatter attenuation slope relative to the Japanese ones. [ABSTRACT FROM AUTHOR]

For important facilities, such as hospitals or schools, advanced seismic risk assessment methodologies have been developed and are now available for use by owners and facility managers. These include seismic hazard analysis coupled with structural and non-structural response and damage analyses leading to a final consequence analysis that provides indications of performance measures, which are often referred to as decision variables. Typical decision variables are repair costs, probability of collapse of the entire building and downtime. These decision variables do not provide specific information regarding the likelihood of individual rooms to remain functional after an earthquake. For the case of a hospital, for example, information regarding the functionality of specific critical rooms (e.g. operating or emergency rooms) could influence major design/retrofit decisions by the owner or facility manager. The main objective of this paper is to present, through a case study hospital building in Italy, a methodology for assessing the loss of functionality of individual rooms in critical facilities following an earthquake event. The methodology includes all the aspects that are usually considered individually in seismic risk assessment, such as ground motion selection for probabilistic seismic hazard analysis, structural performance of the building, and the performance of non-structural elements that can affect the functionality of selected rooms. [ABSTRACT FROM AUTHOR]

A comprehensive comparison among the three strongest earthquakes occurred in Italy in the past 30 years is presented. These three earthquakes struck the regions of Umbria and Marche in 1997, Abruzzo in 2009, and Emilia-Romagna, Lombardia and Veneto in 2012, respectively. They were assigned exactly the same local magnitude, Ml5.9, and comparable focal depths. In spite of having occurred in the same country, these earthquakes displayed considerable differences from both the scientific and the civil protection points of view. Differences can be ascribed to the released energy, the seismotectonic and geomorphological features, as well as the diverse population density, building features and socio-economic conditions that characterize the three epicentral areas. Nevertheless, the overall economic losses come out to be almost the same, although deriving from quite diverse distributions among the different categories of costs. Differences and similarities among the three events are carefully analysed and discussed in the paper. [ABSTRACT FROM AUTHOR]

After the seismic events of the 20th and 29th of May 2012 in Emilia (Italy), most of the monumental and historic buildings of the area were severely damaged. In a few structures, partial collapse mechanisms were observed (e.g. façade tilting, out-of-plane overturning of panels...). This paper presents the case-study of the bell tower of the Santa Maria Maggiore cathedral, located in Mirandola (Italy). The dynamic response of the structure was evaluated through operational modal analysis using ambient vibrations, a consolidated non-destructive procedure that estimates the dynamic parameters of the bell-tower. The dynamic tests were carried out in pre-intervention and post-intervention conditions in order to understand the sensitivity of dynamic measurements to safety interventions. Furthermore, a comparative study is made with similar cases of undamaged masonry towers up to the 6th mode. Finally, an investigation on the state of connections and of the building itself is carried out via FE model updating. [ABSTRACT FROM AUTHOR]

The strike slip Yammouneh fault is the longest fault in Lebanon, crossing the territory from South to North. It was responsible for major historical earthquakes like the 1202 A.D. earthquake, estimated to M7.6. This paper presents a site-specific estimation of the ground motion caused by a potential M7.5 earthquake on the Yammouneh fault, similar to the 1202 event, for various sites within the Beirut area. The empirical Green's function technique EGF is used to estimate the median and the standard deviations of the seismic ground motion at the reference station BHL, taking into account epistemic and aleatory uncertainties related to source parameters. These uncertainties were quantified through a sensitivity analysis of the position of the rupture nucleation X, the slip roughness parameter K, the corner frequency f and the magnitude M of the EGF. The rock ground motion is then transferred to various other sites within the Beirut area, using instrumental Fourier transfer functions. Site amplification factors are next deduced by computing the ratio between response spectra at sediment sites and at a reference rock station. Considering the limits of the EGF method in the near field of extended sources, the EGF approach is considered only up to a magnitude M of 6.5. Selected Ground Motion Predictive Equations are then used to simulate a M7.5 event at a reference station. By applying the amplification factors, the response spectra at the different sites of Beirut are also calculated and compared with the actual response spectra used in the Lebanese regulations. [ABSTRACT FROM AUTHOR]

Depletion of gas fields, even in a tectonically inactive area can induce earthquakes. This is the case for the Groningen gas field, located in the north of the Netherlands. Increased seismic activity raised public concern which led to the government trying to understand the cause of the earthquakes and optimize production such as to minimize the risk of induced seismicity. The main question is how production is correlated with induced seismicity. In this paper we deal with the statistics of seismic events using Bayesian model comparison and a Bayesian change point model. We have developed a method to assess seismic event rate, its changes and tendencies. These statistical analyses are in agreement with each other and find a constant event rate up to 2003, an increasing event rate from 2003 to 2014 and a preference for a decreasing event rate from early 2014 to now. Seasonality in the production and the number of events is present. The seasonality indicates a delay ranging between 2 and 8 months between seismicity and production changes. The question of interest is whether the production reduction since January 2014 has had an effect on the seismicity occurring in the Groningen field. The number of events in the Groningen field in the area affected by the production change has been reduced significantly. We present evidence that changes in seismicity are closely related to changes in production. [ABSTRACT FROM AUTHOR]

The reports after major earthquakes indicate that the earthquake-induced pounding between insufficiently separated buildings may lead to significant damage or even total collapse of structures. An intensive study has recently been carried out on mitigation of pounding hazards so as to minimize the structural damages or prevent collisions at all. The aim of this paper is to investigate the effectiveness of the method when two adjacent three-storey buildings with different (substantially different) dynamic properties are connected at each storey level by link elements (springs, dashpots or viscoelastic elements). The results of the study indicate that connecting the structures by additional link elements can be very beneficial for the lighter and more flexible building. The largest decrease in the response of the structure has been obtained for links with large stiffness or damping values, which stands for the case when two buildings are fully connected and vibrate in-phase. Moreover, by comparing the effectiveness of different types of link elements, it has been confirmed that the use of viscoelastic elements reduces the peak displacement of the structure at lower stiffness and damping values comparing to the case when spring and dashpot elements are applied alone. On the other hand, the results of the study demonstrate that applying the additional link elements does not really change the response of the heavier and stiffer building. The final conclusion of the study indicates that linking two buildings allows us to reduce the in-between gap size substantially while structural pounding can be still prevented. [ABSTRACT FROM AUTHOR]

This paper presents a reassessment of the seismic intensity estimated for the 2011 Lorca (southeastern Spain) earthquake based on detailed vulnerability data and its comparison with the observed damage. Building and urban data are gathered in selected areas during a field campaign and are completed with office work. The significance of vulnerability modifiers in the final vulnerability distribution is analyzed, and their relation with observed damage trends is explored. A direct application of the vulnerability modifiers is not capable of reproducing the observed damage patterns. A significant increase of vulnerability related to the performance of buildings presenting soft story is required to reach a damage distribution consistent with intensity estimates in the study areas. Accordingly, an intensity increase in certain study zones (as compared to other areas of the city of Lorca) is suggested. Although the approach followed in this study is applied in a city of Spain, it can be extrapolated to other areas where detailed vulnerability assessment is feasible and damage data are available. [ABSTRACT FROM AUTHOR]

A vulnerability analysis of some historical and monumental buildings in the city of Málaga is presented in this paper. More than twenty of these monuments were severely damaged or completely destroyed due to the large earthquake ( I = VIII-IX) occurred in the Málaga region in October 1680. The vulnerability index methodology has been used in this paper. This technique is based on statistical data from seismic damage caused to Italian monuments for the past 30 years. For each building, vulnerability curves have been obtained and damage grades have been estimated. A comparison has been carried out between the expected damage grades and the damage observed from past earthquakes, in order to check the feasibility of applying this methodology to Spanish monuments. This comparison has been possible due to the fact that detailed seismic damage information exists for monuments in the city of Málaga that still exist today, which is a very uncommon case in Spain. Results show a good consistency between expected and observed damage, especially for the churches type. Two seismic scenarios have been proposed for the city centre, one deterministic and one probabilistic, where 54 historical and modern buildings have been analyzed. Both scenarios show worrying results, especially for the types of churches, chapels and towers, where expected high probabilities of suffering very heavy damage or even collapse have been obtained. It is highly recommended to take the necessary measures, in the hope of trying to avoid the possible damage that can be expected from future earthquakes. [ABSTRACT FROM AUTHOR]

This paper studied the reasons behind the four trends in torsional effects in asymmetric-plan buildings observed in the current literature. It was found that the modal eccentricities and the non-proportionality between the modal translations and the modal rotation are key to understanding these trends in torsional effects in asymmetric-plan buildings. These key points were obtained from the three-degree-of-freedom modal systems, which represent the single vibration mode of a two-way asymmetric-plan building. This paper showed that the modal eccentricities, rather than the overall structural eccentricities, are the critical parameters for deciding the trend of the unequal displacement demand on the floor diaphragm. In addition, the non-proportionality between the modal translations and the modal rotation leads to the trend that the torsional effects generally decrease when plastic deformations increase. [ABSTRACT FROM AUTHOR]

When data is available, the estimation of site effects is usually performed using the 'standard spectral ratio' (SSR) technique with respect to an outcropping, reference rock site. This study uses the Japanese KiK-net network, which has more than 600 pairs of surface-downhole stations allowing the computation of empirical borehole transfer functions, consisting of mean spectral ratios of surface over downhole recordings. The borehole transfer function deviates from the SSR in two respects: the reference is located at depth, and the downhole velocity varies from one site to another. These differences bias the estimation of the transfer function with reference to a standard outcrop rock site. The goal of this paper is to develop a simple and robust methodology to correct for such bias. The proposed correction procedure consists of two steps: a depth correction designed to account, in a simplified and physically acceptable way, for the existence at depth of destructive interferences and the absence of free-surface effects in the high-frequency range; and an impedance correction designed to normalize the shear wave velocity at depth. The depth correction involves a simple, frequency-dependent curve to be adapted for each site as a function of the first destructive interference frequency at depth. The impedance normalization combines the use of 'generic' rock velocity profiles and a quarter-wavelength approach, resulting in a smooth frequency-dependent amplitude correction. The proposed methodology is applied on a large subset of KiK-net data in view of analysing the correlation between site amplification factors and site parameters in a companion paper. [ABSTRACT FROM AUTHOR]

In this paper, the seismic resistance of unreinforced masonry (URM) cylindrical columns is investigated with an equivalent static analysis procedure. To this end, an existing numerical model developed for the stability analysis of masonry elements with rectangular cross-section is utilized and modified for the cylindrical columns. In the numerical model which takes into account the cracking of the sections and the second-order effects, the columns are divided ideally into sufficiently high number of elements, each having uniform curvature. The columns are modeled as prismatic cantilevers undergoing their own weights, eccentric vertical loads and distributed and concentrated static horizontal loads equivalent to the inertia actions. By considering two examples of columns, firstly a reference column and secondly a column from a real building, lateral seismic coefficient versus top drift level curves are obtained. On the basis of these curves, lateral load behavior of the columns is interpreted and maximum seismic load values which can be resisted by each column are determined. Implementing parametric analyses on the reference column, sensitivity of the seismic resistance to parameters such as column slenderness, magnitude and eccentricity of vertical top load, and the flexibility parameter is determined. The influence of some structural imperfections such as the deviation from vertical on the seismic resistance is also discussed in the paper. [ABSTRACT FROM AUTHOR]

Traditional non-reinforced masonry walls are particularly prone to failure when subjected to out-of-plane loads and displacements caused by earthquakes. Moreover, singularities such as openings in façades may trigger local collapse, for either in-plane or out-of plane motion. Bearing in mind all the former limitations, STAP, with the scientific support of ICIST and LNEC, has been developing a reduced intrusiveness seismic strengthening methodology for traditional masonry structures. The technique consists in externally applying Glass Fibre Reinforced Polymer (GFRP) composite strips to one or both faces of walls. Connection between GFRP composite strips and masonry substrate is enhanced through specifically detailed anchorages or confinement connectors. This technique has been developed and studied through an extensive series of experimental tests, which are briefly reviewed. This paper focuses more deeply on the latest experimental program, aimed at the characterization of the masonry-GFRP composite interface behaviour. This testing program comprised 29 masonry specimens, strengthened with externally bonded GFRP composite strips with anchorages. The testing variables were the number and spacing of anchorages as well as the loading history type: monotonic or repeated. Results clearly show that the use of anchorages dramatically enhances bond behaviour and that its number and spacing have a significant effect on deformation capacity and a less pronounced effect on strength. Based on experimental evidence, this paper also provides a calculation model and ULS safety assessment procedure for out-of-plane strength of reinforced masonry walls. This calculation model leads to interaction curves on strengthened masonry walls subjected to compression and out-of-plane flexure. [ABSTRACT FROM AUTHOR]

L'Aquila earthquake, which occurred on April 6, 2009, proved the high vulnerability of cultural heritage, with particular reference to churches. Damage assessment in the emergency was carried out on more than 700 churches with a methodology aimed at recognizing the collapse mechanisms in the different architectonic elements of the church. The method was developed after the earthquake in Umbria and the Marches (1997) and has been widely used in the last decade; this approach is also very useful for seismic prevention, as it allows one to single out the most vulnerable structures. Some examples are presented in this paper, representative of recurrent damage in the main elements of the church: the façade, the roof, the apse and the belfry. It emerges that, for a correct interpretation of damage and vulnerability, it is necessary a deep knowledge of local construction techniques and of the historic transformation sequence. Moreover, the bad behaviour of churches strengthened by modern techniques, such as the substitution of original timber roofs with stiff and heavy r.c. slabs, was observed. Starting from the observation of some case studies, the paper achieves some worth results, which may be useful for correctly driving future strengthening interventions. [ABSTRACT FROM AUTHOR]

The earthquake that struck Faial, Pico and São Jorge in 1998 has allowed the collection of an unprecedented quantity of good-quality data on damage to construction, costs of repair and other variables. A general overview of the impact of the earthquake is presented, and its effects on the population, housing, monumental structures and economy 10 years after its occurrence are analysed and briefly reported in this paper. We present the overall results obtained from multiple sources of information, primarily from an integrated database containing all the data gathered. The results that describe the inflicted damage, costs of repair and other variables are presented both statistically and geographically. This information was valuable for the construction of an overall earthquake impact based on the systemic analysis of the urban area through the identification of criteria and definition of descriptors leading to a disruption index. The paper is developed as follows. First, we introduce the descriptions of the earthquake effects on the broader set of existing urban systems. In the second part we present the main methodological aspects leading to the disruption index, as well as analysing and discussing the data to provide a clearer picture of how the analysed systems and their disruption affect an urban area. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Soon after the earthquake that damaged L'Aquila municipality and its Province in the Abruzzi Region, Italy, on the 6th of April 2009, a widespread damage and usability assessment of buildings was launched. In 3 months, about 70,000 buildings were inspected, with the AeDES form, by public servants and professionals coordinated by the Italian Civil Protection Department. The paper, after describing the procedures and the form that were used for the assessment, discusses the time evolution of the inspections and analyses the data on building type and seismic damage. The empirical damage distribution conditional upon seismic intensity and building type is provided and the role of several vulnerability factors, such as the quality of masonry, the construction year, the number of stories, and the pre-existing damage, is highlighted. Lastly the damage consequences, such as the immediate occupancy conditional upon building damage and building type, are reported. [ABSTRACT FROM AUTHOR]

The paper presents the results of a broad experimental investigation conducted through diagonal compression tests on masonry specimens strengthened with a mortar coating applied on both surfaces of the wall and reinforced with a glass fiber reinforced polymer (GFRP) mesh. Four types of masonry, three different types of masonry mortar and five diverse GFRP meshes for the reinforcement were considered. In particular, solid brick masonry 250 and 380 mm thick, two-leaf brick masonry with rubble conglomerate infill and rubble stone masonry were tested. The diagonal compression tests, performed on 60 square masonry specimens with loading-unloading cycles up to the collapse, evidenced a good effectiveness of the strengthening technique in terms of both resistance and ductility. Results also showed the resistance increment in reinforced samples is generally greater for weaker masonry types and, referring to a single masonry type, for specimens built with a weaker mortar. Furthermore, the different GFRP meshes influenced very little the resistance of specimens, but higher reinforcement contents induced a lower decrease of the diagonal load after the cracking. [ABSTRACT FROM AUTHOR]