Search

The existing Reinforced Concrete (RC) buildings stock is often characterized by a significant seismic vulnerability, due to the absence of capacity design principles, even in regions with high seismic hazard, such as Italy. Approximately 67% of existing RC buildings in Italy have been designed without considering seismic actions (GLD), resulting in very low transverse reinforcement amount in beams and, particularly, in columns. Additionally, beam-column joints typically totally lack stirrups. Consequently, shear failures under seismic actions are very likely for this pre-code building typology, often limiting their seismic capacity. However, the assessment of shear failures in beams/columns or joints varies significantly from code to code worldwide. The main goal of this work is to quantify the impact of different code-based brittle capacity models on the seismic capacity assessment and retrofit, focusing on GLD Italian pre-1970 RC buildings. This comparative analysis is carried out by first considering three current codes, emphasizing their, even significant, differences: European (EN 1998-3-1. 2005), Italian (D.M. 2018), and American (ASCE SEI/41 2017) standards. Then, shear capacity models prescribed by the current drafts of the next generation of Eurocodes are implemented and compared to the current models. The assessment includes: (i) a parametric comparison among models; (ii) the evaluation of case-study buildings capacity in their as-built condition and after shear strengthening interventions. The latter is performed on 3D "bare" models, due to the lack of practical guidance in most codes on modelling masonry infills. [ABSTRACT FROM AUTHOR]

This study investigates the seismic response of archetype infilled reinforced concrete buildings representative of the existing Italian residential building stock by focusing on the modelling aspects of the existing infills, including their failure modes and interaction with the frame. The study compares the seismic response of the considered buildings, investigated through nonlinear static and dynamic analysis, with reference to two Performance Levels. The main variables considered are the construction period, the site hazard, the number of stories and the infill configuration. The observed return period capacity of the buildings mainly depends on the site hazard and on the construction period. [ABSTRACT FROM AUTHOR]

This study investigates the seismic response of reinforced concrete buildings designed according to Italian regulations and construction practices for three different post-WWII periods, up to the 1990s. Additional key investigated parameters are the number of stories and the site hazard. The main issues related to non-seismic and early seismic design practices are discussed. The study compares the seismic response of the buildings, investigated through nonlinear static and dynamic analyses, with reference to two performance levels, confirming and quantifying the increase in performance with the design codes evolution. The seismic behavior of infilled frames is investigated in the companion paper. [ABSTRACT FROM AUTHOR]

This work aims estimating seismic losses in residential-reinforced concrete buildings, highlighting the influence of infills and services. First, the mechanical-based "POST"-method is used to perform simplified (nonlinear static) structural analyses, in the "shear-type" building hypothesis. Then, drift-based fragility curves and repair cost analysis, specific for infills and services, are used to obtain expected damage and losses. Lastly, the whole proposed loss assessment methodology is applied to a wide building stock struck by L'Aquila (Italy) 2009-earthquake and damaged to infills. The numerical-versus-observed comparison of damage scenario and seismic losses allows a promising validation of the procedure. [ABSTRACT FROM AUTHOR]

The reliable estimation of seismic losses due to damage to buildings is paramount for the post-emergency management and the planning of recovery activities. For residential reinforced concrete (RC) infilled buildings, a significant role in the computation of seismic loss is played by non-structural components, above all infills, partitions and services, as shown in past earthquakes. In this work, a component-based methodology is proposed to assess seismic losses for residential RC buildings in Mediterranean region. The attention is focused on the repairing activities for masonry infills (typical enclosure or partitions elements in Italian and Mediterranean RC buildings), and for services (plumbing systems, electric equipment, floor/wall tiles...), commonly enclosed within the infill panels for the considered building typology. The described methodology can be used starting from the expected damage level to infills and partitions. It adopts given repair unit costs at different damage states of infills. The loss estimation methodology has been, first, validated by comparing predicted and actual repair costs for specific case-study buildings damaged by L'Aquila (Italy) 2009 earthquake. Then, the methodology has been applied to a wide dataset of RC buildings (about 2500 residential buildings) damaged by L'Aquila earthquake available from the literature, to show its possible application at a large-scale level. A good agreement between observed and predicted costs is obtained both for specific case-study buildings and for the wider building stock, especially when damage to structural components is very limited. [ABSTRACT FROM AUTHOR]

Experimental works in literature have paid proper attention to the seismic response of hollow circular piers only quite recently, despite their widespread use in existing bridges. Herein, experimental cyclic tests on two scaled reinforced concrete piers with hollow circular cross-section, representative of typical existing Italian bridges, are carried out. Design criteria, adopted setup, experimental response, and damage evolution are discussed. A focus on shear–critical piers is performed, collecting an experimental database of tests from literature. The more specific existing shear strength models are compared with the collected data. Model by Ranzo and Priestley [2001] has finally shown promising results. [ABSTRACT FROM AUTHOR]

Autophagy agonists have been proposed to slow down neurodegeneration. Spermidine, a polyamine that acts as an autophagy agonist, is currently under clinical trial for the treatment of age‐related memory decline. How Spermidine and other autophagy agonists regulate memory and synaptic plasticity is under investigation. We set up a novel mouse model of mild cognitive impairment (MCI), in which middle‐aged (12‐month‐old) mice exhibit impaired memory capacity, lysosomes engulfed with amyloid fibrils (β‐amyloid and α‐synuclein) and impaired task‐induced GluA1 hippocampal post‐translation modifications. Subchronic treatment with Spermidine as well as the autophagy agonist TAT‐Beclin 1 rescued memory capacity and GluA1 post‐translational modifications by favouring the autophagy/lysosomal‐mediated degradation of amyloid fibrils. These findings provide new mechanistic evidence on the therapeutic relevance of autophagy enhancers which, by improving the degradation of misfolded proteins, slow down age‐related memory decline. [ABSTRACT FROM AUTHOR]

• An experimental program on square URM infills is presented. • The results of four combined IP/OOP tests are described. • Tests' results are compared with literature formulations' predictions. • Tests' results are compared with those obtained on rectangular infills. • The influence of aspect ratio on the IP/OOP interaction is analyzed. The analysis of the behaviour of masonry infills under out-of-plane (OOP) and in-plane (IP) loading is paramount to correctly assess the seismic performance of reinforced concrete (RC) frames. A very important issue about this topic is certainly the IP/OOP interaction, namely the analysis of how the IP damage, which affects infills during earthquakes, can influence their OOP behaviour (and vice-versa). Some studies about this topic were developed in the last years; nevertheless, only a dozen of tests currently exists in the literature to experimentally explore this key issue. This work first presents an experimental campaign carried out on square infill walls in RC frames to investigate about the OOP behaviour of the masonry infills, and about the IP/OOP interaction. On the whole, four specimens have been tested under OOP monotonic loading. Three of them have been first damaged under cyclic IP actions, with different extent; the remaining one, used as a reference, was tested under OOP loading only. The experimental campaign is described in detail in terms of specimens' characteristics, material properties, adopted setup and instrumentation layout. The experimental results are analysed in terms of IP and OOP force-displacement responses, vertical arch strength contribution evolutions, and damage state evolutions, and compared with prediction proposals from the literature. Then, the influence of the infill aspect ratio (width (w)-to-height (h) ratio) on the IP/OOP interaction is investigated by means of the comparison between data presented herein (collected on infills with w/h = 1) and a companion experimental campaign previously performed on nominally identical infills except that for the aspect ratio of the specimens (in that case, higher than the unit). It has been observed that under given IP drift levels, square infills presented lower IP damage levels with respect to rectangular infills (with w/h > 1), thus generally producing a less pronounced detrimental effect of the IP imposed drift on the OOP strength. Nevertheless, none of the predictions from literature takes into account the role of the aspect ratio on the IP/OOP interaction, generally resulting in conservative predictions, to be improved in future works. [ABSTRACT FROM AUTHOR]

Earthquakes that have occurred in the last twenty years in the Mediterranean area have had significant economic and social impacts. Most of the economic losses of reinforced concrete (RC) frames was due to nonstructural component damage, particularly masonry infills and partitions. Therefore, the seismic behaviour of masonry infills should be reliably characterized. The main goals of this study for a more reliable loss estimation for infilled RC frames are: (i) the analysis of the inter-story drift ratio (IDR) capacity at given damage states (DSs) with the aim to define drift-based fragility functions and (ii) analyse direct losses due to infill damage following seismic events. First, a database of experimental tests performed on 1-bay, 1-story scaled RC frames infilled with clay bricks or concrete blocks is collected. Drift-based fragility curves are obtained, which depend on the infill brick materials and properties. Then, the drift capacity threshold at each DS is correlated to the in-plane response of the infill panel to directly quantify the relationship that exists among them. The influence of openings on drift capacities is also evaluated. Then, seismic losses related to infills are computed, providing expected monetary losses depending on the infill typology. The required reparation activities and their costs are also listed. The bearing of each activity and cost at each DS is explicitly evaluated. Additionally, loss functions that directly depend on IDR demand are provided, thus fusing together the damage analysis and loss analysis. Finally, a simplified formulation for loss functions is proposed for a simple, practice-oriented loss calculation. [ABSTRACT FROM AUTHOR]

Abstract Memory capacity (MC) refers to the limited capacity of working memory and is defined as the number of elements that an individual can remember for a short retention interval. MC is impaired in many human pathologies, such as schizophrenia and ageing. Fronto-striatal dopamine regulates working memory, through its action on dopamine D1- and D2-like receptors. Human and rodent studies have suggested that MC is improved by D2 dopamine receptor agonists. Although D1 receptors have been crucially involved in the maintenance of working memory during delay, their role in regulating the capacity of WM remains poorly explored. In this study, we tested the effects of systemic injection of the D1-like and D2-like receptor antagonists, SCH 23390 and Haloperidol respectively, on MC in mice. For this, we used a modified version of the object recognition task, the Different/Identical Objects Task (DOT/IOT), which allows the evaluation of MC in rodents. The results showed a negative interaction between the dose of both drugs and the number of objects that could be remembered. The doses of SCH 23390 and Haloperidol that impaired novel object discrimination in the highest memory load condition were about 4 and 3 time lower, respectively, of those impairing performance in the lowest memory load condition. However, while SCH 23390 specifically impaired memory load capacity, the effects of Haloperidol were associated to impairment in exploratory behaviors. These findings may help to predict the cognitive side effects induced by Haloperidol in healthy subjects. [ABSTRACT FROM AUTHOR]

Most of the existing Reinforced Concrete (RC) bridges were designed before the recent advancements in earthquake engineering and seismic codes. The performance assessment of these bridges is, therefore, a crucial issue for seismic safety of bridge infrastructures and estimation of losses due to seismic events. Despite the seismic assessment of columns with solid cross-section in ordinary buildings may be considered as quite comprehensive, a similar conclusion cannot be drawn for shear-critical hollow core piers, widespread in existing bridge structures. The present work aims at contributing to the investigation about the response of RC piers with hollow rectangular cross-section under cyclic loading. The main goal of the study is the definition of a comprehensive and practice-oriented modelling approach for the assessment of seismic response of RC hollow rectangular piers, able to account for all the deformability contributions, and, particularly, able to reliably predict drift-capacity at shear failure and subsequent degrading stiffness. A three-component model, accounting for flexural flexibility, shear flexibility and slippage of rebars is adopted. The shear capacity assessment is dealt with more in details. A proper experimental database is collected, made up of cyclic tests on hollow rectangular piers failing in shear, with or without yielding of longitudinal reinforcing bars. A new empirical formulation for the assessment of the displacement capacity at shear failure, specifically for the investigated structural elements, is calibrated. The degrading stiffness also is empirically calibrated to completely define the degrading shear response. Finally, the proposed numerical model is validated through the comparison with the experimental results carried out by the Authors (also in terms of local deformability contributions) and with test results collected from literature, proving that it can be a simple and reliable tool for the seismic assessment of existing shear-critical bridge piers. [ABSTRACT FROM AUTHOR]

Reinforced Concrete (RC) buildings with clay masonry infills are a very common structural typology worldwide for civil, strategic or productive use. Damage to infills may cause danger for human lives and strongly affects economic losses, as shown during past earthquakes. Despite their role is crucial in terms of global and local response of RC buildings in the event of an earthquake, in current practice, infills are considered as partition elements without any structural function. The behaviour of infills under seismic actions has to be reliably characterized, starting from the analysis of their displacement capacity at different performance levels due to in-plane actions, and a proper complete numerical modelling, able to reproduce their influence on the global behaviour of RC frames under seismic actions. Some models have been already proposed in literature, but their reliability should be yet proved on the basis of an as wide as possible experimental database. Therefore, in this paper, a homogenous extensive database of experimental tests on RC frames infilled with hollow clay-masonry infills – typical of Italian and Mediterranean RC building stock – is collected and presented. The experimental responses of the infills under lateral loads are obtained and the main related numerical models existing in literature are investigated and compared with the experimental results. A new modelling proposal is carried out to obtain a simple practice-oriented force-displacement envelope to significantly reduce the errors in the prediction of the infill in-plane behaviour under lateral loads. The experimental evolutions of damage under increasing displacement demand are also analysed, and the displacement capacity at given performance levels are identified and correlated to the in-plane behaviour of the infill panels. The analysis of the damage evolution to the infills during the experimental tests finally allows the definition of drift-based fragility functions for these components, representing a key point for a more reliable estimation of losses due to earthquakes. [ABSTRACT FROM AUTHOR]

Experimental tests on four full-scale exterior unreinforced reinforced concrete (RC) beam-column joints, representative of the existing non-conforming RC frame buildings, are carried out. The specimens have different longitudinal reinforcements (plain or deformed) and they are designed in order to be representative of two typical design practices (for gravity loads only or according to an obsolete seismic code). Different failure modes are observed, namely joint failure with or without beam yielding. The local response of the joint panel is analyzed. The different joint deformation mechanisms and their contribution to the deformability and to the energy dissipation capacity of the sub-assemblages are evaluated. [ABSTRACT FROM AUTHOR]

The seismic performance of existing Reinforced Concrete (RC) frames is significantly influenced by the behaviour of beam-column intersections, especially in non-conforming buildings with poor structural details and completely unreinforced joints. In literature, a very limited number of studies deals with specimens reinforced with plain hook-ended longitudinal bars, widespread in Italian and Mediterranean building stock, or with the analysis of local aspects, such as the experimental evaluation of joint shear strains. The almost totality of the models proposed in literature for simulating the cyclic behaviour of RC joints was developed and calibrated by means of tests performed on elements with deformed bars, and, thus, these models may be not adequate for elements with hook-ended plain bars, especially due to the peculiarities in terms of failure mode and interaction mechanisms between concrete and steel. This study analyses the experimental cyclic behaviour of four full-scale exterior unreinforced RC beam-column joints with plain reinforcing bars in beams and columns, which differ for joint aspect ratio and beam longitudinal reinforcement ratio. First, experimental global and local responses of such tests – including energy dissipation capacity and observed damage evolution – are analysed. The main deformation mechanisms ascribable to the joint – namely rotation at the interface between beam/columns and joint, and shear deformation of the joint panel – are experimentally evaluated to provide a realistic support for the numerical modelling of this typology of beam-column joints. Then main joint shear strength models existing in codes and literature are compared with the experimental results. Finally, the numerical modelling of the specimens is carried out under monotonic loading to reproduce the envelope of the experimental responses. The joint panel constitutive parameters are defined to reproduce the experimental joint shear stress-strain relationships. Additionally, modelling of bond-slip is particularly taken into account due to the poor quality of steel-concrete interaction in the specific case of plain reinforcing bars. [ABSTRACT FROM AUTHOR]

Reinforced concrete buildings designed according to obsolete seismic codes or for gravity loads only are widespread in Italian and Mediterranean building stock. Past earthquakes showed that, for these buildings, shear failure in beam–column joints can lead to structural collapse mainly due to the inadequate joint confinement. The construction details used in these structural elements are commonly recognized as the likely cause of non-ductile structural failure modes under seismic actions, due to the lack of capacity design principles. A significant amount of research on seismic performance of unreinforced beam–column joints has been carried out in last years, but a very few portion of them handled with specimens unreinforced in the joint region and with plain hook-ended longitudinal bars. A higher number of tests is needed to deeper understand joint seismic response in order to validate the (few) existing models or calibrate new ones. This study aims at improving the understanding of seismic performance of exterior non-conforming joints in existing RC buildings. Two experimental tests on joints without transverse reinforcement are designed and carried out. The specimens are different for beam longitudinal reinforcement ratio and they are both reinforced with plain longitudinal bars. Two different kinds of joint failure are expected, with or without yielding of the adjacent beam. Design criteria, adopted setup and main experimental results are described. Strain gauges located on beam bars and displacement transducers on the joint panel allow the complete definition of both the deformability contributions of fixed-end-rotation and shear strain of joint panel. Finally, a comparison between joint shear strength models existing in literature or codes and experimental results (considering a wider experimental database) is carried out. [ABSTRACT FROM AUTHOR]

In the performance assessment of typical existing buildings, seismic collapse safety might be significantly affected by non-linear behavior of joints that are involved in the failure mechanism, especially if they are characterized by poor structural detailing such as the lack of an adequate transverse reinforcement in the joint panel. Unfortunately, commonly accepted tools to assess existing joints capacity are not available. Few reliable approaches for modeling all sources of nonlinearity are proposed in literature for poorly designed beam–column joints because of relatively poor information from experimental tests. The present study aims at improving the understanding of seismic performance of exterior joints without transverse reinforcement in existing RC buildings through experimental tests. Two full-scale exterior unreinforced beam–column joint sub-assemblages are tested under cyclic loading. The specimens are reinforced with deformed bars but they are different for beam longitudinal reinforcement ratio. Two different kinds of joint failure are expected, with or without the yielding of the adjacent beam. Strain gauges located on beam bars and displacement transducers on the joint panel allow the complete definition of both the main deformability contributions, namely fixed-end-rotation and shear strain of joint panel, highlighting the differences between failure modes. Design criteria, adopted setup and experimental results are described and discussed. Finally, experimental results are compared with proposals from literature in terms of shear strength. [ABSTRACT FROM AUTHOR]

• Experimental tests on TRM-strengthened infilled frames under OOP loading. • Analysis of dynamic properties of the TRM-strengthened infills. • Comparison of response with and without IP damage and with and without strengthening. • Database of experimental tests on TRM-strengthened infilled frames under OOP loading. • Analysis of predictive equations for OOP strength of TRM-strengthened infills. In existing Reinforced Concrete (RC) buildings, the out-of-plane (OOP) collapse of masonry infills can be a significant issue for resulting damage and life safety in case of earthquake. Quite recently, research works from the literature have studied possible strengthening strategies to reduce the vulnerability of the infill panels due to OOP loading. Among these techniques, the use of Textile Reinforced Mortars (TRM) as an innovative reinforcing plater has rapidly become very popular, due to its good compromise between costs of intervention and effectiveness, along with its durability properties. Nevertheless, still quite few studies exist on this topic to experimentally prove the TRM effectiveness on masonry infills, above all in case of pre-existing in-plane (IP) damage. Even fewer studies in the literature are currently devoted to the prediction of the OOP strength of TRM-strengthened infills, despite the necessity to quantify the beneficial effect of the strengthening solution in a force-based safety check. This work shows the experimental outcomes of four full-scale infilled frames under OOP loading, with or without a TRM-based strengthening technique and with or without previous IP damage. First, a look insight the effect on dynamic properties of the TRM strengthening strategy is reported and commented. Then, the (cyclic) IP and (half-cyclic) OOP pseudo-static testing results are shown and compared to each other to analyze the effect of the IP damage on the OOP response with and without strengthening. Lastly, the very few predictive proposals for OOP strength of TRM-strengthened specimens have been analyzed, based on a dedicated collected database, to lastly provide some suggestions for future design tools for TRM applications on infills. [ABSTRACT FROM AUTHOR]

A large part of the existing building stock was not designed according to the current codes in seismic prone regions. The poor performance of some reinforced concrete structures was related to the presence of the masonry infill walls. Although the infill walls can increase the lateral resistance of frames in many cases, it is widely recognized that there is a high vulnerability of the masonry infill walls subjected to loadings along and perpendicular to their plane. Several collapses were observed after past earthquakes in infilled frame buildings. For this reason, different retrofitting design approaches have been proposed and used during the last years; however, many of them do not fit with the building's owners' economic demands or technical knowledge of the workmanship. Over the years, significant research has been conducted for masonry wall elements retrofitted with textile-reinforced mortar (TRM). However, much less has been carried for masonry-infilled frame RC frames. Thus, this manuscript aims to provide a literature review about research on assessing the effectiveness of using TRM technique to reduce masonry-infilled RC frames' seismic vulnerability. Experimental findings will be deeply analysed to provide full insight concerning the TRM's efficiency under in-plane and/or out-of-plane demands of infilled frames and some variables such as anchorage of the TRM to the structure. Numerical modelling approaches to simulate the complex behaviour of infilled frames with TRM are also presented to stress their benefits or limits. Covering completely all aspects of this manuscript is essential to briefly describe the studies conducted so far to examine either numerically or experimentally the effectiveness of using TRM for retrofitting masonry wall elements. [ABSTRACT FROM AUTHOR]

• Three experimental tests on the IP/OOP interaction on square infill walls are presented. • A wider experimental database is collected including these test results. • The effectiveness of existing proposals to predict the IP/OOP interaction is assessed. • The influence of infill geometric properties and IP damage level is analyzed. • New empirical formulations are proposed for the OOP strength and stiffness reduction. The out-of-plane (OOP) response of unreinforced masonry (URM) infill walls under seismic loading has been widely studied in very recent times with both experimental and numerical investigations. It is recognized that the damage of infills due to in-plane (IP) seismic actions has a significant influence on their OOP response, by reducing the OOP strength and stiffness: this phenomenon is named IP/OOP interaction. Current code provisions propose the use of formulations derived from the literature to predict the OOP strength reduction due to IP damage. In this study, experimental tests are performed to assess the IP damage effects on the OOP response of square URM infills with relatively low slenderness ratio in reinforced concrete frames. Tests' results are used to enrich the currently available experimental database, to assess the effectiveness of current provisions regarding the prediction of the IP/OOP interaction effects and to propose empirical formulations for the prediction of the IP/OOP interaction effects in terms of OOP strength and stiffness reduction as a function of geometric properties of the infill (namely, the slenderness ratio and the aspect ratio) and of the IP displacement demand. [ABSTRACT FROM AUTHOR]

• Experimental assessment of strengthening solutions to prevent the out-of-plane collapse of masonry infills in RC buildings. • Four nominally identical full-scale one-bay-one-story RC infilled frames were tested. • Three specimens were strengthened by means of Textile Reinforced Mortar techniques. • Experimental parameters were mortar plaster typology and TRM-to-RC frame connection's effectiveness. • Support towards the choice of the best strategies for future further investigations and applications. Seismic events worldwide clearly showed that a crucial issue for life-safety and reduction of losses due to earthquakes for reinforced concrete (RC) buildings is related to the out-of-plane (OOP) collapse of infill masonry walls. In the literature, few studies addressed this paramount topic. This paper presents an experimental work about the assessment of possible strengthening solutions to prevent the out-of-plane collapse of masonry infills in RC buildings. Four nominally identical full-scale one-bay-one-story RC frames were built and infilled with a thin masonry wall made up of horizontal hollow clay bricks. The first specimen was representative of the as-built condition. The other specimens were strengthened against the out-of-plane collapse by means of Textile Reinforced Mortar (TRM) strengthening techniques based on the application of high-ductility or common mortar plaster and fiberglass reinforcing bidirectional nets, varying the TRM-to-RC frame connection's effectiveness. Tests consisted of a semi-cyclic history of imposed displacements in the OOP direction through small uniformly distributed pneumatic jacks. Experimental results are shown and compared to assess the effectiveness of the selected strengthening techniques and to provide a support towards the choice of the best strategies for future further investigations and applications. [ABSTRACT FROM AUTHOR]

Research efforts are still required for modelling the seismic behaviour of infilled frames, especially for existing buildings, generally characterised by shear failures. This work discusses the experimental seismic behaviour and the related modelling of four conforming (compliant with modern seismic codes) and non-conforming (gravity-loads-designed) Reinforced Concrete (RC) frames with and without infills (with hollow-clay bricks). The experimental results are analysed, showing that non-conforming frames exhibited shear failures involving the infill panel and the RC columns/joints. A proposed modelling approach able to reproduce these shear failures is carried out, providing support towards more reliable numerical simulations of RC buildings. [ABSTRACT FROM AUTHOR]

• Exterior RC joints strengthened with prestressed steel strips were tested. • Non-strengthened joints with or without stirrups were tested for comparison. • The non-strengthened joint without stirrups showed a BJ-failure. • The adopted strengthening was effective in increasing joint shear strength. • Local measurement data supported the observation of strengthening effectiveness. The response of unreinforced beam-column joints represents a key issue in seismic vulnerability and fragility assessment of existing Reinforced Concrete (RC) buildings. A great attention has been focused on the investigation of the experimental response of unreinforced joints and their possible strengthening strategies. In this study, an experimental investigation of the response of exterior RC beam-column joints strengthened with prestressed steel strips is presented. Four full-scale specimens were tested, two non-strengthened and two strengthened. The non-strengthened specimens were built with (specimen S) or without (NS) stirrups in the joint panel and were tested for reference and comparison purposes, in order to reproduce a seismic code-compliant and a non-conforming RC joint, respectively. The strengthened specimens had two different layouts characterized by a higher (CAM1) or lower (CAM2) complexity of installation and level of building disruption. The response of specimen NS was controlled by joint panel failure following beam yielding, whereas the specimen S showed a ductile response, controlled by beam flexural failure. The response of specimens CAM1 and CAM2 demonstrated the effectiveness of the adopted technology. For CAM1, a ductile response was observed, similar to specimen S. For CAM2, a joint panel failure following beam yielding was observed, as for specimen NS, but with a significantly higher global ductility. The presence of prestressed steel strips led to a delay in the onset of diagonal cracking, with a slight increase in strength at this condition, i.e. by 8%, but a significantly higher deformation capacity, with the drift increasing, on average, by 122%. The strengthening led to a relatively slight increase in the resistance of the subassemblage, which was very similar in specimens S, CAM1 and CAM2, and, on average, 11% higher than in specimen NS. Instead, a much more significant difference was observed in terms of deformation capacity, with the drift at conventional ultimate condition in specimens CAM1 and CAM2 77% and 61% higher than specimen NS, respectively. The experimental results are reported, and the effectiveness of the tested strengthening solutions is discussed, in terms of global response of the subassemblage, observed damage evolution, energy dissipation capacity, and local response, such as joint shear distortion and measured strain of strengthening steel strips. [ABSTRACT FROM AUTHOR]

The presence of α-synuclein aggregates in the retina of Parkinson's disease patients has been associated with vision impairment. In this study we sought to determine the effects of α-synuclein overexpression on the survival and function of dopaminergic amacrine cells (DACs) in the retina. Adult mice were intravitreally injected with an adeno-associated viral (AAV) vector to overexpress human wild-type α-synuclein in the inner retina. Before and after systemic injections of levodopa (L-DOPA), retinal responses and visual acuity-driven behavior were measured by electroretinography (ERG) and a water maze task, respectively. Amacrine cells and ganglion cells were counted at different time points after the injection. α-synuclein overexpression led to an early loss of DACs associated with a decrease of light-adapted ERG responses and visual acuity that could be rescued by systemic injections of L-DOPA. The data show that α-synuclein overexpression affects dopamine neurons in the retina. The approach provides a novel accessible method to model the underlying mechanisms implicated in the pathogenesis of synucleinopathies and for testing novel treatments. [ABSTRACT FROM AUTHOR]

This study investigates the seismic response of reinforced concrete buildings designed according to the current Italian building code. Number of stories, site hazard, presence and distribution of masonry infill panels, and type of lateral resisting system are the key investigated parameters. The main issues related to design and modeling are discussed. Two Limit States are considered, namely Global Collapse and Usability-Preventing Damage. The main aim of the study is a comparison between the seismic response of the buildings, investigated through nonlinear static and dynamic analyses. Irregularity in the distribution of infill panels and site hazard emerge as the most influential parameters. [ABSTRACT FROM AUTHOR]

Nigro-striatal dopamine transmission is central to a wide range of neuronal functions, including skill learning, which is disrupted in several pathologies such as Parkinson's disease. The synaptic plasticity mechanisms, by which initial motor learning is stored for long time periods in striatal neurons, to then be gradually optimized upon subsequent training, remain unexplored. Addressing this issue is crucial to identify the synaptic and molecular mechanisms involved in striatal-dependent learning impairment in Parkinson's disease. In this study, we took advantage of interindividual differences between outbred rodents in reaching plateau performance in the rotarod incremental motor learning protocol, to study striatal synaptic plasticity ex vivo. We then assessed how this process is modulated by dopamine receptors and the dopamine active transporter, and whether it is impaired by overexpression of human α-synuclein in the mesencephalon; the latter is a progressive animal model of Parkinson's disease. We found that the initial acquisition of motor learning induced a dopamine active transporter and D1 receptors mediated long-term potentiation, under a protocol of long-term depression in striatal medium spiny neurons. This effect disappeared in animals reaching performance plateau. Overexpression of human α-synuclein reduced striatal dopamine active transporter levels, impaired motor learning, and prevented the learning-induced long-term potentiation, before the appearance of dopamine neuronal loss. Our findings provide evidence of a reorganization of cellular plasticity within the dorsolateral striatum that is mediated by dopamine receptors and dopamine active transporter during the acquisition of a skill. This newly identified mechanism of cellular memory is a form of metaplasticity that is disrupted in the early stage of synucleinopathies, such as Parkinson's disease, and that might be relevant for other striatal pathologies, such as drug abuse. [ABSTRACT FROM AUTHOR]

The main features of the Reinforced Concrete (RC) building stock that was struck by the Emilia 2012 earthquake and damage observed after the event are analyzed. Building stock characteristics and historical seismic classification are employed for the definition of two benchmark structures, representative of the whole building stock. Seismic capacity of the two structures, at different damage states, is assessed through static push-over analyses, within the N2 spectral assessment framework. Infill panels׳ contribution in terms of strength and stiffness is explicitly taken into account in the analytical model. Damage States are defined according to a mechanical interpretation of EMS-98 scale. Fragility functions at each Damage State are obtained through the application of a Response Surface Method. Finally large-scale damage scenarios are obtained crossing the geo-referenced census data regarding the characteristics of the Emilia RC building stock and starting from the seismic input provided by the shake map of the event. The scenarios seem to be in reasonable agreement with the observed damage. [ABSTRACT FROM AUTHOR]