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Direct displacement-based seismic design has been recently proposed for the seismic design of non-structural building elements. This paper deals with the development of damping models, relating equivalent viscous damping ratio to drift amplitude, for suspended piping trapeze restraint installations for direct displacement-based seismic design. The damping models are developed using reversed cyclic test data available in the literature. First, damping models are proposed using Jacobsen’s equal area approach. The damping models developed using Jacobsen’s approach are then assessed and calibrated using nonlinear time history analyses of single degree-of-freedom archetypes representing suspended piping trapeze restraint installations in buildings.

Non-structural elements (NSEs) are not designed to be part of the structural load-bearing system of a building but are subjected to the same dynamic environment as the supporting structure during an earthquake. Non-structural damage and ensuing losses have exceeded structural damage and losses in many buildings during recent earthquakes that have occurred in urban regions around the world. Damage to NSEs is strongly influenced by the amplitude, the frequency content and the duration of floor motions. Although the effects of amplitude and frequency content of floor motions are well captured by floor response spectra, little attention has been given on the characterisation of floor motion duration and how it can impact damage to NSEs, particularly for those responding in the inelastic range. To contribute to a better understanding of these issues, this paper develops a probabilistic strong floor motion duration model through multiple stripes non-linear time-history analyses of a population of 100 code-compliant reinforced concrete frame building models designed for a medium-to-high seismicity site in Italy. The resulting probabilistic model can be used when selecting historical or generating synthetic floor motions for the seismic response assessment of NSEs or when generating shake-table test records for the seismic qualification of NSEs.

Recent seismic events highlighted the importance of non-structural elements in seismic assessment and performance-based earthquake engineering. When referring to industrial facilities, storage tanks represent one of the most critical components for the continuous functionality of industrial and building plants after seismic events. At the same time, the dispersion of dangerous or inflammable materials, due to their collapse, could become a safety issue in terms of both human life and environmental impact. This study focuses on the seismic performance assessment of a liquid-storage tank installed in an industrial steel moment-resisting frame building. The performance is assessed in terms of fragility curves, that are provided for the meaningful limit states that affect the liquid-storage tank and considering several intensity measures. The results related to the structural performance are also discussed in detail in terms of fragility functions and floor response. The assessment is performed through nonlinear dynamic analyses using two different modelling approaches to evaluate the structural and non-structural performance. The first modelling approach explicitly accounts for the tank-structure interaction, while in the second one the tank is only modelled considering its seismic mass. The results show the importance of the modelling assumptions to accurately estimate the seismic demand on liquid-storage tanks and corresponding fragility, which is calculated in terms of different intensity measures (IM): average ground spectral acceleration, peak floor acceleration, and floor spectral accelerations. Peak floor acceleration, drift profiles, and absolute acceleration and relative displacement floor response spectra are instead scrutinised for what concerns demand. The comparison with the code formulations available in the literature for estimating the seismic demand to non-structural elements pointed out their inaccuracy for the analysed liquid-storage tank and the need for further efforts to develop more accurate procedures. Furthermore, the outcomes indicate that the IM adopted for secondary components, i.e. peak floor acceleration, may not always be the optimal one hence additional attention should also be paid to the definition of updated fragility curves for non-structural elements, identifying and adopting more suitable IMs.

The seismic performance of suspended piping systems can significantly compromise the functionality of critical facilities due to the incorporation of inadequate seismic design based on prescriptive empirical regulations and guidelines. The performance-based seismic design (PBSD) of non-structural elements requires the evaluation of performance parameters, based on experimental data or numerical studies, for comparison with engineering demand parameters. Few research studies available in the literature provide the performance parameters required to enable PBSD of piping systems and more specifically of suspended piping restraint installations. This paper discusses the numerical modelling of suspended piping trapeze restraint installations based on component testing. Reliable numerical models capable of predicting the force–displacement (backbone) curves of suspended piping restraint installations are developed based on monotonic and cyclic test data of the components that make up these installations. The prediction capabilities of the numerical models are assessed against the results of monotonic benchmark sub-assembly tests reported in a previous study. The numerical models developed in this study can be used to extract performance parameters from the predicted force–displacement curves to be used within a probabilistic PBSD framework without the need to conduct additional testing.

Recent studies evidenced that non-structural damage in buildings caused by earthquakes leads to high economic losses and can represent a threat for life safety. Particularly, piping network damage has been widely documented in post-earthquake inspections. In this study, a cascade analysis is conducted to evaluate the seismic demand on two types of piping networks installed in a reinforced concrete framed building. The cascade analysis is performed employing floor acceleration time-histories obtained through non-linear dynamic analyses of infilled and bare frames. The dynamic response of the piping networks is defined accounting for the non-linear behaviour of pipe joints and suspended piping restraint installations. The results show that the acceleration demand and the damage on the network significantly increase in infilled frames compared to bare frames. Additionally, a different seismic damage rate was observed comparing the two piping networks. The outcome of this study is used to provide design recommendations for suspended piping restraint installations, aimed at reducing the seismic vulnerability of the piping networks.

The seismic assessment of existing masonry infilled reinforced concrete (RC) building portfolios is a highly relevant issue in Italy and other Mediterranean countries, particularly in regions where a large part of the built environment was not designed according to modern seismic codes. In the past, masonry infills were generally considered as non-structural elements and were not accounted for in the design process. However, the results of experimental tests and past earthquake evidence demonstrated the influence of masonry infills on the global and local behaviour of RC buildings. Furthermore, the acknowledgment of different construction practices points out the significant variability affecting the masonry infills in terms of material properties, thickness, presence of openings and manufacturing techniques. This paper deals with the large-scale performance analysis of existing masonry infilled RC building portfolios accounting for the uncertainty related to the variability in the mechanical properties and the modelling of masonry infills. To accomplish this goal, a fully integrated building stock, representative of masonry infilled RC buildings designed according to the Italian codes in force between 1960 and 1980, was developed, using a simulated design approach. Statistical data and results of experimental tests were used to identify the main masonry infill typologies adopted in the Italian context. Detailed numerical models, whose prediction capability was appraised through the results of cyclic quasi-static tests, were developed to estimate the lateral response of the analysed RC buildings. Different response parameters, which can be easily implemented in seismic risk assessment frameworks, were considered and quantified, at the portfolio level, to understand the uncertainty propagation and impact of the masonry infills’ variability on the expected performance of existing RC buildings. The results demonstrated that the variability related to the definition and modelling of the masonry infills induces significant dispersion, with respect to the mean, on the lateral response of different classes of buildings within a given portfolio. Moreover, the provided parameters for multi-linear idealised capacity curves can be used in simplified seismic fragility and risk models for existing buildings, including a proper estimate of the associated uncertainty, leading to a more accurate quantification of economic losses.

Masonry existing structures are prone to significant structural damages when subjected to seismic actions. Over the last decades, innovative techniques emerged as attractive solutions for repair and retrofit of structures. In particular, composite materials with inorganic matrix (FRCMs-CRMs) have emerged as an alternative to fiber reinforced polymers for their better compatibility with masonry substrates. The effectiveness of the strengthening relies on the FRCM-substrate bond behavior, which needs to be characterized for the design of the reinforcement elements. Shear bond tests are able to determine the stress-slip law and the failure mode that rules the FRCM-substrate stress transfer capacity. In the last years, several experimental investigations on shear bond tests of strengthened masonry prisms were performed even if the knowledge about the influence of each variable parameter is not fully known. In this context, the numerical simulation may be a rapid and economic tool to study the incidence of the most relevant parameters in the bond mechanism. In this paper, a numerical study aimed at simulating the fiber-mortar bond behavior and at calibrating a shear stress (τ)-slip (s) constitutive bond law, is presented. Advanced 2D numerical models, able to simulate the most probable failure mode occurring in shear bond tests, have been developed. The results of the numerical simulations have been compared with the experimental results of a large database of tests on FRCM/CRM strengthened masonry prisms. An inverse analysis procedure has been used to fit the experimental bond stress versus slip curves and to predict the failure modes.

Post-earthquake damage reports have continuously highlighted the significant vulnerability of nonstructural elements to seismic events. Nonstructural damage has severe impact in the building recovery, increasing the socioeconomic losses even for low intensity events. In the last few years, research efforts have focused on the development of innovative nonstructural solutions, to be combined with damage-resistant structural skeletons in order to obtain an overall highperformance building. As part of a European Union (EU)-funded project, the effectiveness of such integrated skeleton&envelope low-damage system in reducing the earthquake related losses was investigated. Tridimensional shake table tests on a 1:2 scaled timber-concrete low-damage structural skeleton, “dressed” by different innovative nonstructural elements (glass/concrete facades, gypsum/ masonry partitions), were performed at the National Laboratory for Civil Engineering (LNEC) in Lisbon, Portugal. The shake table testswere carried out at increasing seismic intensities to investigate the structural and nonstructural performance up to a higher-than Collapse Prevention Limit State according to the Italian Code (975 years return period). This paper focuses on the dynamic behavior of nonstructural elements with detailed discussion on construction detailing, seismic demand and performance of the innovative solutions. The high performance of nonstructural elements proved the potential of the details introduced in the partitions/facades. Minimal or no damage was observed up to the end of the overall testing sequence, which reached moderate-to-high interstory drift ratios (more than 1.00%) - typically expected to cause severe damage to traditional nonstructural partitions/infills/facades.

Research on infilled reinforced concrete frames is fundamental for the vulnerability assessment of existing buildings. The analysis of the interaction between infill and frame is an open issue in performance-based earthquake engineering due to its importance in predicting the dynamic behavior and failure modes of buildings. This study provides an open access database of laboratory tests on masonry infilled reinforced concrete frames, collected from the literature and harmonized in a consistent framework. The database is named Masonry Infill Database 1.1 (MID 1.1). The data were grouped in categories to calibrate a piecewise linear curve representing the lateral response of the infill depending on the masonry wall and the frame details. The gathered data were used to assess analytical models and numerical studies from the literature with the aim of revising the formulations currently used in the equivalent strut approach. An empirical model for the equivalent strut was developed through a power-law multiple regression of the database. The open access database in its spreadsheet form is intended to provide a useful tool for the analysis of infilled reinforced concrete frames.

This paper investigates the seismic demand on acceleration-sensitive nonstructural components in buildings equipped with fluid viscous dampers. Nonlinear dynamic response analyses were conducted on three steel moment-resisting archetype frames of different heights, and incorporating linear and nonlinear viscously damped braces. The FEMA P695 far-field ground motion records set scaled to various intensities were used as seismic input. The main variables investigated in the parametric study included three different target supplemental damping levels, two different distributions of damper properties along the frames' height, and six different nonlinear damper velocity exponents. The numerical results indicate that the inclusion of fluid viscous dampers generally improves the seismic response of the archetype frames. However, the seismic demand on acceleration-sensitive nonstructural components varies significantly depending on the properties of the dampers. For some combinations of dampers' properties, the peak floor horizontal accelerations and floor spectral absolute accelerations in certain nonstructural period ranges can exceed that of the control frames without fluid viscous dampers. These results highlight the limitations of the peak floor acceleration as an engineering demand parameter for acceleration-sensitive nonstructural components.

The importance of non-structural elements in performance-based seismic design of buildings is presently widely recognized. These elements may significantly affect the functionality of buildings even for low seismic intensities, in particular for the case of critical facilities, such as hospital buildings. One of the most important issues to deal with in the seismic performance assessment of non-structural elements is the definition of the seismic demand. This paper investigates the seismic demand to which the non-structural elements of a case-study hospital building located in a medium&ndash, high seismicity region in Italy, are prone. The seismic demand is evaluated for two seismic intensities that correspond to the definition of serviceability limit states, according to Italian and European design and assessment guidelines. Peak floor accelerations, interstorey drifts, absolute acceleration, and relative displacement floor response spectra are estimated through nonlinear time&ndash, history analyses. The absolute acceleration floor response spectra are then compared with those obtained from simplified code formulations, highlighting the main shortcomings surrounding the practical application of performance-based seismic design of non-structural elements. The absolute acceleration floor response spectra are then compared with those obtained from simplified code formulations. The results, both in terms of absolute acceleration and relative displacement floor response spectra, highlighted the influence of the higher modes of the structure and the inaccuracy of the code provisions, pointing out the need for more accurate simplified methodologies for the practical application of performance-based seismic design of non-structural elements.

The influence of the masonry infills on the seismic performances of Reinforced Concrete (RC) frames is generally evaluated in analytical and numerical studies by adopting the equivalent strut model; it is based on experimental observations showing that at the onset of damage, stresses migrate to the diagonal of the panel and are transferred to the surrounding frame through the contact zones at the corners. Above the different equivalent strut models available in literature, single-strut models are generally used to evaluate the global behaviour, while multi-strut approaches are preferred to investigate on local interaction phenomena between panel and frame. In case of existing buildings, with poor transversal reinforcement of the columns, the presence of the infills can lead to pre-emptive brittle failure. The present study is aimed at evaluating the influence of the modelling approach on the evaluation of the seismic performance both in terms of global and local behaviour. Nonlinear dynamic analyses have been performed on an 8-storey infilled RC frame, following the Incremental Dynamic Analysis procedure, in order to evaluate structural performances depending on the model adopted to simulate the infills.

Performance-based earthquake engineering requires the harmonization of performances between structural and nonstructural elements. This paper discusses the performance-based seismic design of nonst...

The seismic performance of non-structural elements is nowadays recognized to be a key issue in performance-based earthquake engineering. The knowledge of construction details within a building is of paramount importance in order to reduce uncertainties and improve the quality of the analysis and design, particularly in regards to non-structural elements. The use of Building Information Modelling (BIM) could represent a new frontier in the seismic design of non-structural elements by increasing the reliability of the seismic design and/or assessment. This study discusses the effectiveness of using Building Information Models in seismic design of non-structural building elements. A simple tool has been developed to perform automatically the seismic design of sway braces for pressurized fire suppressant sprinkler piping systems based on information extracted from a Building Information Models. The effectiveness of the proposed procedure was validated via a case study.

Background The measurement of bone mineral density (BMD) with dual-energy X-ray absorptiometry (DXA) is the current “gold standard” for diagnosing and monitoring osteoporosis, any errors in demographic information, improper patient positioning, incorrect scan analysis or interpretation can lead to erroneous results and decisions [1]. Moreover, a common condition represented by osteoarthritis, by modifying the joint soft tissues composition, can alter the values of BMD [2]. In patients affected by discarthrosis, in fact, osteoporotic T-score values at femoral neck (FN) can be associated with normal or osteopenic T-score values of the lumbar spine (LS), the latter influenced by the presence of osteophytes and/or subchondral bone sclerosis. Objectives: To evaluate the predictive value of an innoative densitometric technique, the Radiofrequency Echographic Multi Spectrometry (REMS) [3], in detecting bone fragility in patients affected by osteoarthitis. Methods: The T-score values of 35 postmenopausal women with clinical and/or radiological signs of osteoarthritis (mean age 71 years, average BMI 24,2) obtained by DXA at lumbar spine and femoral neck were compared with those obtained by REMS technique performed in the same anatomical sites. Results: In all the subjects, LS T-score resulted significantly higher than the FN one according to DXA measurement. However, REMS outcomes in both the sites were significantly lower than the corresponding DXA measurement (significant difference between DXA and REMS T-score for both LS (p = 0.006) and FN (p = 0.010), and spinal REMS T-scores resulted more similar to femural REMS (average REMS T-score LS: -2.6 ± 1,6 vs T-score FN: -2.4 ± 0, 6) and to femural DXA values. Conclusion: These preliminary data suggest that REMS technique, which has been shown to have high sensitivity, specificity and accuracy when compared with DXA in diagnosing and monitoring osteoporosis [3], is not affected by the presence of alterated soft tissues composition. it would therefore be particularly useful for the evaluation of bone fragility in subjects at risk of osteoarthritis. References [1] Watts NB. Ost Intern2004;15(11):847–854; [2] Blake GM, Fogelman I. J Bone Min Res 2008; doi: 10.1359/JBMR.0711; [3] Di Paola M, et al. Ost Int2018; doi:10.1007/s00198-018-4686-3. Disclosure of Interests: None declared

Diffusion-weighted magnetic resonance imaging can be used to non-invasively probe the brain microstructure. In addition, recent advances have enabled the identification of complex fiber configurations present in most of the white matter. This has improved the investigation of structural connectivity with tractography methods. Whole-brain structural connectivity networks, or connectomes, are reconstructed by parcellating the gray matter and performing tractography to determine connectivity between these regions. These complex networks can be analyzed with graph theoretical methods, which measure their global and local properties. However, as these tools have only recently been applied to structural brain networks, there is little information about the reproducibility and intercorrelation of network properties, connectivity weights and fiber tractography reconstruction parameters in the brain. We studied the reproducibility and correlation in structural brain connectivity networks reconstructed with constrained spherical deconvolution based probabilistic streamlines tractography. Diffusion-weighted data from 19 subjects were acquired with b=2800 s/mm2 and 75 gradient orientations. Intrasubject variability was computed with residual bootstrapping. Our findings indicate that the reproducibility of graph theoretical metrics is generally excellent with the exception of betweenness centrality. A reconstruction density of approximately one million streamlines is necessary for excellent reproducibility, but the reproducibility increases further with higher densities. The reproducibility decreases, but only slightly, when switching to a higher order in constrained spherical deconvolution. Moreover, in binary networks, using sufficiently high threshold values improves the reproducibility. We show that multiple network properties and connectivity weights are highly intercorrelated. The experiments were replicated by using a test-retest dataset of 44 healthy subjects provided by the Human Connectome Project. In conclusion, our results provide guidelines for reproducible investigation of structural brain networks.

In the last years an increasing interest has been addressed to the assessment of the expected mean annual losses of single buildings as well as of building portfolio(s). Field observation of damage/failure in the aftermath of past earthquakes demonstrates that the losses related to the non-structural elements could significantly exceed the structural losses. At the same time, it is worth noting that the damage related to the non-structural elements could affect the functionality of the buildings and critical facilities. Based on these considerations, a detailed assessment of the expected annual losses requires data both on the structural and non-structural elements. In comparison to structural elements and systems, however, there is much less information and experimental data to undertake the assessment and design of non-structural elements for multiple-performance levels. Shake table testing could thus be very useful to assess the seismic performance of non-structural elements and to achieve the required information for loss estimation studies. In this paper, the results of shake table testing of acceleration-sensitive non-structural elements are presented. Equivalent single degree of freedom numerical models of the analyzed acceleration-sensitive non-structural element was developed using the results of the tests and a performance evaluation was carried out.

The implementation of linear and nonlinear viscous dampers improves the seismic performance of a structure. The velocity coefficient which governs the hysteretic behavior of nonlinear viscous dampers modifies the seismic response and consequently the seismic performance of the structure. A six-story steel moment-resisting frame building was selected as an archetype structure to investigate the effect of nonlinear viscous dampers on its seismic performance. This building, incorporating brittle beam-column connections common in the pre-Northridge earthquake designs, was retrofitted with different configurations of viscous dampers to improve its seismic performance. Linear and nonlinear viscous dampers were designed by following two different design approach: 1) a uniform distribution design approach in which similar dampers are introduced at every level of the structure and 2) an equivalent lateral stiffness distribution design approach for which proportional damping is preserved. An incremental dynamic analysis was carried out with the FEMA P695 far-field ground motion set. The seismic performance of the archetype building was evaluated in terms of collapse capacity, median peak inter-story drifts, and median peak damper forces. The results showed a considerable improvement of the seismic performance with the implementation of fluid viscous dampers. However, the design approach and the velocity coefficient modified the seismic response, affecting the seismic demand on the structure.

Reinforced concrete (RC) frame buildings with masonry infills represent one of the most common structural typologies worldwide. Although, in the past, masonry infills were frequently considered as non-structural elements and their interaction with the structure was neglected, earthquakes occurring over the last decades have demonstrated the important role of these elements in the seismic response of all RC-infilled building typologies. In this regard, the selection of the most suitable numerical modelling approaches to reproduce the hysteretic response of the masonry infills&mdash, and their interaction with the RC frames&mdash, is still an open issue. To deal with this issue, in this study, a macro-classification based on different available databases of experimental tests on infilled RC frames, is firstly proposed to understand the variability in the infill properties and the corresponding numerical modelling uncertainties. Five masonry infill types are selected as representative for the typical existing configurations in Italy and other Mediterranean countries. Three of those masonry infill types are then selected to carry out a more detailed analysis, namely their numerical modelling validation using experimental testing results, considering and comparing the main formulations available in the literature for the definition of the hysteretic behaviour of infills. From such a comparison, the model that minimizes the prediction error, according to specific features of the selected masonry infill, is identified for each masonry infill type.

The damages observed during the earthquakes occurred in the last decades have clearly shown as the influence of infill panels on the seismic behaviour of Reinforced Concrete (RC) buildings should be taken into account; the global stiffness and the strength of the RC frames are significantly modified by the infills. In the present study the influence of infills in terms of shear forces has been analyzed by means of linear static analysis; a parametric study has been carried out to evaluate the behavior of infilled frames varying both modelling approach and the mechanical properties of the masonry infills. In terms of modelling approach the single and multi-strut models have been adopted; the Young modulus of masonry infills have been varied in the common range proposed in literature. The results show that multi-strut approach is able to predict both global and local behavior. In addition, the importance of the mechanical properties of masonry infills in the evaluation of the elastic period and shear force in the columns is underlined.

The seismic performance of non-structural elements is now recognized to be a key issue in the seismic assessment and earthquake related loss estimation of buildings, both at the individual and regional scale. The evaluation of the seismic demand on non-structural elements in many modern building codes is often based on inaccurate distributions of floor accelerations. For this reason, some design oriented simplified methodologies have been developed recently to predict floor response spectra in reinforced concrete buildings. Although the influence of masonry infills on the seismic performance of reinforced concrete buildings has been widely demonstrated, infills are generally neglected both in the design and in the evaluation of floor response spectra, which could lead to un-conservative design of non-structural elements. In this paper, the effect of masonry infills on absolute acceleration and relative displacement floor response spectra for reinforced concrete buildings subjected to frequent (serviceability level) earthquakes is investigated through a probabilistic framework. A database of one hundred masonry infilled reinforced concrete frames, representative of the European context, was generated and each building analyzed through nonlinear time history analyses. From the results of these analyses, the acceleration and displacement response spectra at different floor levels of both bare and infilled frame archetypes were then computed. The effectiveness of the most common assumptions made in regional risk models to estimate the non-structural losses is investigated and a first attempt at a more refined approach taking into account the effect of masonry infills is proposed.

We propose a method to remove motion blur in a single light field captured with a moving plenoptic camera. Since motion is unknown, we resort to a blind deconvolution formulation, where one aims to identify both the blur point spread function and the latent sharp image. Even in the absence of motion, light field images captured by a plenoptic camera are affected by a non-trivial combination of both aliasing and defocus, which depends on the 3D geometry of the scene. Therefore, motion deblurring algorithms designed for standard cameras are not directly applicable. Moreover, many state of the art blind deconvolution algorithms are based on iterative schemes, where blurry images are synthesized through the imaging model. However, current imaging models for plenoptic images are impractical due to their high dimensionality. We observe that plenoptic cameras introduce periodic patterns that can be exploited to obtain highly parallelizable numerical schemes to synthesize images. These schemes allow extremely efficient GPU implementations that enable the use of iterative methods. We can then cast blind deconvolution of a blurry light field image as a regularized energy minimization to recover a sharp high-resolution scene texture and the camera motion. Furthermore, the proposed formulation can handle non-uniform motion blur due to camera shake as demonstrated on both synthetic and real light field data.

A wide number of experimental studies conducted in latest years pointed out the high influence of the mechanical properties of masonry units and mortar bed joints on lateral strength and stiffness of masonry panels. This feature significantly modifies the global response of infilled frames under seismic actions as well as the local interaction phenomena. Despite a wide investigation on the influence of the infills on global behaviour of reinforced concrete (RC) frames has already been provided, different features characterizing the seismic performances of buildings suggest the need of accurately evaluating local interaction phenomena as well as the influence of the panel on specific and relevant aspects, as the accelerations transferred to non-structural components. This study provides a parametrical analysis of the influence of shear strength and elastic modulus of masonry infills on the seismic behaviour of RC frames originally designed for gravity loads. Regular buildings with different height were analysed using the Incremental Dynamic Analysis in order to provide fragility curves, investigate on the collapse mechanisms and define the floor spectra depending on the properties of the infills. Results obtained pointed out the high influence of the considered parameters on the fragility of existing RC frames, often characterized by inadequate transversal reinforcement of columns, which may lead to brittle failure due to the interaction with the infills. Floor response spectra are also significantly affected by the influence of masonry infills both in terms of shape and maximum spectral accelerations. Lastly, on the basis of the observed failure mechanisms, a parameter defining the ductility of the frames depending on the properties of the infills was also provided (Capacity Design Factor). The correlation between the mechanical properties of the infills and this parameter suggests its reliability in the simplified vulnerability analysis of existing buildings as well as for the design of new buildings.

Hospitals must be fully operational in the event of an emergency after an earthquake to protect the lives of patients and health workers as well as to provide emergency care and medical treatment to the subsequently increased number of patients who will be driven to healthcare facilities. Surveys performed in the aftermath of recent earthquakes have shown that the performance of hospitals and their functionality after an earthquake are related not only to structural damage but also to damage that occurs to nonstructural elements and medical equipment. For a large-scale mapping of the seismic risk to hospitals, it is impossible to proceed with advanced methodologies; simplified methodologies are thus required. These methodologies must consider the performance of nonstructural elements and equipment. In this work, a rapid visual screening method is proposed to determine a Safety Index for hospital buildings. The newly developed procedure provides a risk index by evaluating the main parameters that affect the vulnerability of buildings during a systematic sidewalk survey. The procedure has been applied to two Italian hospitals located in different seismic areas, and the results are compared with a similar index obtained from a push-over analysis. Finally, the proposed RVS method has also been applied to two hospitals damaged by the 2009 L'Aquila Earthquake and the 2012 Emilia Earthquake.

Unreinforced masonry infilled R.C. frames are a widespread structural system worldwide; even if the damages observed during past earthquakes highlight the influence of masonry infills on the seismic performance of structures, the common practice considers the infill as nonstructural elements. The infills are made with a large variety of materials and with different construction typologies; nevertheless, a large number of studies have been carried out in the last years to investigate the interaction between the infill panels and the surrounding R.C. frames, few researches have been focused on the influence of mechanical properties of masonry infills on the structural performance. In this study the seismic performance of R.C. frames designed for gravity loads according to the code prescription in force in Italy between 1950s and 1970s has been evaluated. A parametric analysis has been performed to investigate the influence of the mechanical and geometrical properties of masonry infills on the whole structural response; the seismic behaviour has been analyzed in terms of capacity, ductility and collapse mechanisms. The results showed as the mechanical properties of masonry infills should be adequately evaluated before to proceed to the seismic vulnerability assessment of existing structures because they significantly affect the global behaviour of R.C. frames.

Extensive damage to school buildings has been observed during past earthquakes in Italy, with the 2002 Molise event resulting in the complete collapse of a school building leading to numerous casualties. As part of a wider project in Italy to assess the seismic risk in school structures, six school buildings of various construction typologies were surveyed and instrumented to validate detailed numerical models of typical school structures located throughout Italy.

The common practice in civil engineering considers the infill as nonstructural elements, thus they are often neglected in the evaluation of the structural seismic behavior. However, the damages observed in past earthquakes around the world, have shown as the presence of infills significantly influence the seismic performance of Reinforced Concrete (RC) resisting frames. Several studies conducted in the last years emphasize the importance of infills on the evaluation of the elastic period of infilled frames; however the influence of mechanical properties of infills walls is often neglected. In this study the effect of infills in the seismic behavior of R.C. frames has been analyzed in terms of modal properties, namely evaluating the elastic period by means an eigenvalue analysis on 2D models. A parametric analysis has been performed taking into account the height of frames, the presence of flat/deep beams, the influence of infills Young modulus and the percentage of openings in the infills. Also the presence of setbacks in the frames has been considered. The numerical results provided useful information about the influence of masonry infill properties and allowed to define a new relationship to evaluate the elastic period of vibration.

Experimental campaigns are a key tool for the evaluation of the behaviour of Masonry Infilled Reinforced Concrete (RC) frames. The case of masonry infills in RC frames is also a regional feature making the homogenous classification for a database a real challenge. This first attempt of a Masonry Infill Database (MID) includes a preliminary selection of experimental tests carried out on models of masonry-infilled RC frames under quasi-static or pseudo-dynamic loading. Each test is characterized in order to include, in a homogenous framework, all the relevant aspects of different experimental campaigns for easy access to the data for future applications. A Damage Classification is introduced, valid for both solid infill panels and for infill with openings. Finally, all monotonic backbones are fitted with a force-displacement piecewise linear approximation for future applications in Performance Based Earthquake Engineering.

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a noninvasive imaging method, which can be used to investigate neural tracts in the white matter (WM) of the brain. However, the voxel sizes used in DW-MRI are relatively large, making DW-MRI prone to significant partial volume effects (PVE). These PVEs can be caused both by complex (e.g. crossing) WM fiber configurations and non-WM tissue, such as gray matter (GM) and cerebrospinal fluid. High angular resolution diffusion imaging methods have been developed to correctly characterize complex WM fiber configurations, but significant non-WM PVEs are also present in a large proportion of WM voxels. In constrained spherical deconvolution (CSD), the full fiber orientation distribution function (fODF) is deconvolved from clinically feasible DW data using a response function (RF) representing the signal of a single coherently oriented population of fibers. Non-WM PVEs cause a loss of precision in the detected fiber orientations and an emergence of false peaks in CSD, more prominently in voxels with GM PVEs. We propose a method, informed CSD (iCSD), to improve the estimation of fODFs under non-WM PVEs by modifying the RF to account for non-WM PVEs locally. In practice, the RF is modified based on tissue fractions estimated from high-resolution anatomical data. Results from simulation and in-vivo bootstrapping experiments demonstrate a significant improvement in the precision of the identified fiber orientations and in the number of false peaks detected under GM PVEs. Probabilistic whole brain tractography shows fiber density is increased in the major WM tracts and decreased in subcortical GM regions. The iCSD method significantly improves the fiber orientation estimation at the WM-GM interface, which is especially important in connectomics, where the connectivity between GM regions is analyzed.

Blind deconvolution is the problem of recovering a sharp image and a blur kernel from a noisy blurry image. Recently, there has been a significant effort on understanding the basic mechanisms to solve blind deconvolution. While this effort resulted in the deployment of effective algorithms, the theoretical findings generated contrasting views on why these approaches worked. On the one hand, one could observe experimentally that alternating energy minimization algorithms converge to the desired solution. On the other hand, it has been shown that such alternating minimization algorithms should fail to converge and one should instead use a so-called Variational Bayes approach. To clarify this conundrum, recent work showed that a good image and blur prior is instead what makes a blind deconvolution algorithm work. Unfortunately, this analysis did not apply to algorithms based on total variation regularization. In this manuscript, we provide both analysis and experiments to get a clearer picture of blind deconvolution. Our analysis reveals the very reason why an algorithm based on total variation works. We also introduce an implementation of this algorithm and show that, in spite of its extreme simplicity, it is very robust and achieves a performance comparable to the top performing algorithms.

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a non-invasive imaging method, which can be used to investigate neural tracts in the white matter (WM) of the brain. Significant partial volume effects (PVEs) are present in the DVV signal due to relatively large voxel sizes. These PVEs can be caused by both non-WM tissue, such as gray matter (GM) and cerebrospinal fluid (CSF), and by multiple non-parallel WM fiber populations. High angular resolution diffusion imaging (HARDI) methods have been developed to correctly characterize complex WM fiber configurations, but to date, many of the HARDI methods do not account for non-WM PVEs. In this work, we investigated the isotropic PVEs caused by non-WM tissue in WM voxels on fiber orientations extracted with constrained spherical deconvolution (CSD). Experiments were performed on simulated and real DW-MRI data. In particular, simulations were performed to demonstrate the effects of varying the diffusion weightings, signal-to-noise ratios (SNRs), fiber configurations, and tissue fractions. Our results show that the presence of non-WM tissue signal causes a decrease in the precision of the detected fiber orientations and an increase in the detection of false peaks in CSD. We estimated 35-50% of WM voxels to be affected by non-WM PVEs. For HARDI sequences, which typically have a relatively high degree of diffusion weighting, these adverse effects are most pronounced in voxels with GM PVEs. The non-WM PVEs become severe with 50% GM volume for maximum spherical harmonics orders of 8 and below, and already with 25% GM volume for higher orders. In addition, a low diffusion weighting or SNR increases the effects. The non-WM PVEs may cause problems in connectomics, where reliable fiber tracking at the WM G M interface is especially important. We suggest acquiring data with high diffusion-weighting 2500-3000 s/mm(2), reasonable SNR (similar to 30) and using lower SH orders in GM contaminated regions to minimize the non-WM PVEs in CSD.

In this paper we study the problem of blind deconvolution. Our analysis is based on the algorithm of Chan and Wong [2] which popularized the use of sparse gradient priors via total variation. We use this algorithm because many methods in the literature are essentially adaptations of this framework. Such algorithm is an iterative alternating energy minimization where at each step either the sharp image or the blur function are reconstructed. Recent work of Levin et al. [14] showed that any algorithm that tries to minimize that same energy would fail, as the desired solution has a higher energy than the no-blur solution, where the sharp image is the blurry input and the blur is a Dirac delta. However, experimentally one can observe that Chan and Wong's algorithm converges to the desired solution even when initialized with the no-blur one. We provide both analysis and experiments to resolve this paradoxical conundrum. We find that both claims are right. The key to understanding how this is possible lies in the details of Chan and Wong's implementation and in how seemingly harmless choices result in dramatic effects. Our analysis reveals that the delayed scaling (normalization) in the iterative step of the blur kernel is fundamental to the convergence of the algorithm. This then results in a procedure that eludes the no-blur solution, despite it being a global minimum of the original energy. We introduce an adaptation of this algorithm and show that, in spite of its extreme simplicity, it is very robust and achieves a performance comparable to the state of the art.

The performance of single image deblurring algorithms is typically evaluated via a certain discrepancy measure between the reconstructed image and the ideal sharp image. The choice of metric, however, has been a source of debate and has also led to alternative metrics based on human visual perception. While fixed metrics may fail to capture some small but visible artifacts, perception-based metrics may favor reconstructions with artifacts that are visually pleasant. To overcome these limitations, we propose to assess the quality of reconstructed images via a task-driven metric. In this paper we consider object classification as the task and therefore use the rate of classification as the metric to measure deblurring performance. In our evaluation we use data with different types of blur in two cases: Optical Character Recognition (OCR), where the goal is to recognise characters in a black and white image, and object classification with no restrictions on pose, illumination and orientation. Finally, we show how off-the-shelf classification algorithms benefit from working with deblurred images.

We consider the problem of non-blind deconvolution of images corrupted by a blur that is not accurately known. We propose a method that exploits dictionary-based image priors and non Gaussian noise models to improve deblurring accuracy in the presence of an inexact blur. The proposed image priors express each image patch as a linear combination of atoms from a dictionary learned from patches extracted from the same image or from an image database. When applied to blurred images, this model imposes that patches that are similar in the blurred image retain the same similarity when deblurred. We perform image deblurring by imposing this prior model in an energy minimization scheme that also deals with outliers. Experimental results on publicly available databases show that our approach is able to remove artifacts such as oscillations, which are often introduced during the deblurring process when the correct blur is not known.