Search

The structural identification from environmental vibration testing of a hospital building in Avezzano (Abruzzo - Italy) was presented. The comparison of the results enables to verify and calibrate numerical pre-dictions on the base of data obtained from modal testing. The response of the structure in the time domain was recorded by highly sensitive sensor network, integrated by a data acquisition system. The identification was performed using techniques of modal extraction in the frequency domain (frequency domain de-composition). During the calibration process of the numerical model the values initially adopted were successively corrected in order to identify a reliable structural model to be used to have an accurate seismic vulnerability assessment of the hospital building.

This paper evaluate the potential for progressive collapse of steel moment-resisting frame buildings designed according to the Italian Seismic Code. Three analysis procedures (linear static, nonlinear static and nonlinear dynamic) are applied to the problem of disproportionate collapse of steel moment frames due to a sudden column loss. In particular, a technique termed pushdown analysis that is inspired by the pushover method commonly used in earthquake engineering is applied to investigate the robustness of building for various missing column scenarios. The results are compared with dynamic analyses, and the dependence from location of column removal and number of building stories is finally investigated.

Despite significant progress in research and development of aluminum shear panels in recent decades, their implementation for seismic retrofit of existing reinforced concrete (RC) buildings can still be significantly extended. Their application is limited by the general lack of relatively simple and effective design criteria and proper guidelines. This paper develops a design method for the seismic retrofit of reinforced concrete buildings using aluminum multi-stiffened shear panels as dampers. Both the nonlinearity in the structure and the dampers-structure interaction are considered to give an optimal distribution of the shear panels over the height of the building. The analytical laws refer to dissipative aluminum shear panels recently tested and analyzed by the authors. The proposed procedure has been described in detail. Its applicability has been demonstrated by analyzing two typical RC buildings having drift capacity-to-demand ratios ranging from 0.505 to 0.624. The design value of the panel-to-frame stiffness ratio has been found to range from 0.594 to 1.432 as a function of the lateral stiffness of the existing building. The verification of the proposed procedure has been carried out by checking the validity of the design assumptions. The first one (i.e., the mode shapes remain the same before and after retrofit) has been checked using the modal assurance criterion that gives values ranging from 0.992 to 0.998. The second one (i.e., uniform yield drift distribution over the building height) has been checked by comparing the yield drifts with their average value giving a standard deviation ranging from about 11 to 15%. The effectiveness of the design method has been finally validated through nonlinear time-history analysis for different seismic accelerograms and hysteresis models. The results show that the seismic retrofit design procedure is effective in significantly reducing inter-story drift (maximum inter-story drift ratio demands ranging from 1.04 to 2.07%) thus satisfying the acceptance criteria of the building, and avoiding drift concentration and consequential weak story collapse.

The retrofit of a RC hospital building using low impact strengthening techniques based on steel bracing and cabling is illustrated in the paper. A preliminary investigation of the seismic performance capability of the building has been made, in such a way to address the possibility to improve the earthquake protection together with structural robustness. Out of the possible low impact structural solutions, the ones relying on steel concentric braces and catenary cables have been considered and analyzed in detail. The proposed solutions are critically examined as to parameters like ease of implementation, global impact on the construction, and intervention reversibility. Both seismic and progressive collapse resisting capacity of the retrofitted building are assessed and discussed based on nonlinear static and dynamic analyses.

The progressive collapse of the building structures due to abnormal loads has attracted global attention in recent years. Many studies in the literature have been dedicated to the analysis and design procedures for progressive collapse resistance, and several technological solutions have been developed for progressive collapse retrofit. However, many studies are based on simple models and their validity and possibility to generalize the research results to current practice are rather limited. Moreover, there are still not many case studies developed based on full-scale real buildings. The present paper contributes to filling this gap by investigating the robustness of a quite complex real case study, namely a steel braced frame building erected in the early ‘60 s in Naples-Italy to house the Civil Engineering Authority. To this aim, different column removal scenarios have been considered and both nonlinear static and dynamic analyses have been carried out. The results have highlighted that the simple braced frames are susceptible to progressive collapse due to the weak brace connections. However, joint strengthening is not a viable solution, because it would prevent the full functionality of this strategic building during the implementation of the progressive collapse retrofit. As an alternative, an outrigger-belt truss system has been developed that applies the concept of Vierendeel truss system to redistribute the loads due to the column removal. The effectiveness of the proposed retrofit strategy to improve the progressive collapse resistance of the building has been verified through nonlinear dynamic analyses, proving its feasibility for practical applications.

The progressive collapse retrofit of a RC hospital building making use of steel braces is described in the paper. The vulnerability of the construction when subjected to specific threat scenarios is preliminary analysed by removing critical column and applying the alternate load path method to evaluate the capability of the damaged structure to bridge across the removed column. A detailed three-dimensional model of the building has been created to carry out both nonlinear static and nonlinear dynamic analyses. Both geometrical and material nonlinearities have been considered in the analysis in order to account for the inelastic behaviour following the sudden column removal and the possible subsequent catenary effects. In order to retrofit the building against progressive collapse the use of steel braces in some bays has been proposed, designed on the basis on simple equilibrium conditions under vertical loads. The retrofitting bracing system proved to be effective in improving the global building behaviour under several accidental scenarios.

In recent years, a new generation of seismic lateral force resisting systems has been proposed that sustains little or no damage under severe earthquakes thus reducing the repair time and cost. This has stimulated the development of many types of self-centering (SC) earthquake-resistant systems even based on innovative materials. Among them, shape memory alloy (SMA) dampers have been proposed that use superelastic nitinol wires to dissipate energy and self-center the structure. Many studies have been dedicated to SMA-brace devices applied to steel moment frames. Only a few studies have employed these devices for the seismic retrofit of existing reinforced concrete buildings. Moreover, their applicability has been experimentally and numerically tested only on small scale brace-components, while applications to real RC buildings are still lacking. Finally, there is a general lack of reliable design procedures. This paper presents a study that investigates the seismic performance of a reinforced concrete building retrofitted with self-centering (SC) shape memory alloy (SMA) braces. A design procedure is applied that satisfies displacement-based performance criteria and allocates the damped braces over the height according to an optimal damper distribution rule. Finally, nonlinear response-history analyses are carried out to evaluate the effectiveness of both the self-centering retrofit solution and the design procedure. The results show the excellent recentering behavior of the SC-SMA braces together with their not negligible energy dissipation capacity.

Background: The seismic retrofitting of frame structures using hysteretic dampers is a very effective strategy to mitigate earthquake-induced risks. However, its application in current practice is rather limited since simple and efficient design methods are still lacking, and the more accurate time-history analysis is time-consuming and computationally demanding. Aims: This paper develops and applies a seismic retrofit design method to a complex real case study: An eight-story reinforced concrete residential building equipped with buckling-restrained braces. Methods: The design method permits the peak seismic response to be predicted, as well as the dampers to be added in the structure to obtain a uniform distribution of the ductility demand. For that purpose, a pushover analysis with the first mode load pattern is carried out. The corresponding story pushover curves are first idealized using a degrading trilinear model and then used to define the SDOF (Single Degree-of-Freedom) system equivalent to the RC frame. The SDOF system, equivalent to the damped braces, is designed to meet performance criteria based on a target drift angle. An optimal damper distribution rule is used to distribute the damped braces along the elevation to maximize the use of all dampers and obtain a uniform distribution of the ductility demand. Results: The effectiveness of the seismic retrofit is finally demonstrated by non-linear time-history analysis using a set of earthquake ground motions with various hazard levels. Conclusion: The results proved the design procedure is feasible and effective since it achieves the performance objectives of damage control in structural members and uniform ductility demand in dampers.

Introduction: The conservation and preservation of existing buildings, in particular public infrastructures, is currently a significant issue in Italy and Europe, considering their strategic role and the risk represented by human losses, management issues and also economic disruption in case of collapse. In this context, the interest in conservation is not restricted to monumental or artistical buildings but also includes the several buildings composing the Italian infrastructural heritage, which in many cases are made of reinforced concrete and show signs of ageing after half a century and more from their construction. Methods: On the basis of these premises, in the present paper, a preliminary investigation on an infrastructural case study located in Naples port is presented. Such a study is part of a research activity aimed at defining critical structural issues of the central administrative building of the Central Tyrrhenian Sea Port System Authority. Results: A system of high-sensitivity and low-cost MEMS acceleration sensors were installed on the structure, with the aim of investigating its dynamic behaviour. A Finite Element model of the building was created, including information about material properties and cross-section details from prior experimental activities. A model updating procedure was carried out, based on the dynamic data collected by the monitoring system and post-processed to estimate the fundamental frequencies. Conclusion: This has allowed highlighting the main features of the dynamic response of the building, and the critical role played by deformability of infill panels and floors on the modal properties of the structure.

Despite extensive research studies, the seismic response of infilled reinforced concrete buildings remains an open problem due to both the complexity of the interaction between the infill and the frame and the large number of parameters involved. Thus, guidelines for both modelling and analysis are still lacking and the infill walls are normally treated as nonstructural components in seismic codes. However, it may be not conservative to neglect the influence of infills. In fact, the infill masonry walls may significantly affect the stiffness, strength, and energy dissipation capacity of RC buildings, even when they are regularly distributed. Recognizing this influence and its importance on the vulnerability of infilled frames, Eurocode 8 requires amplifying seismic action effects due to infills. In this paper, the effectiveness of the Eurocode 8 design provisions for infill irregularity in plan and/or elevation was investigated. To this aim, different in-plan layouts of infill walls were selected as marginal cases for which Eurocode 8 does not require amplification of the action effects due to the presence of infills, or the additional measures to counteract these effects are not mandatory. The seismic vulnerability of the infilled RC buildings was evaluated using nonlinear static and nonlinear dynamic analyses. Both cracking and crushing of masonry and stiffness and strength degradation were considered in the analysis. The effect of the layout of the masonry infills on the seismic response in terms of resistance and displacement was evaluated. Results show that in one of the case studies here examined, it is not conservative to neglect the influence of infill panels. In fact, structural failure due to torsion and soft-storey effects may occur even in cases where Eurocode 8 does not require the amplification of the action effects. Finally, the total shear demand on columns may be underestimated, even in cases where the code provisions for infills irregularity are not mandatory, and the additional shear demand in the columns induced by the masonry infill is very low.

The occurrence of a pituitary adenoma located entirely outside the sella turcica, so-called ectopic adenoma, is extremely rare. We report a case of a non secreting-pituitary adenoma located above the diaphragma sellae, with no invasion into the sella turcica, confirmed at surgery. The tumor was initially treated unsuccessfully by operations via the transphenoidal route. After initial negative exploration by the transphenoidal route, the patient was successfully treated by an endoscopic endonasal transphenoidal approach extended to the tuberculum sellae and the posterior planum sphenoidale to access the suprasellar supraglandular region. A brief review of ectopic adenomas and a discussion of the preoperative diagnosis are presented.

Lo studio sulle attività alieutiche nei secoli dell'età moderna consente di ricostruire una specifica storia del Mediterraneo che trova nel Cinquecento un'epoca di transizione tra antiche e nuove maniere di pescare. La ricerca sulle fonti archivistiche ha restituito un quadro assai efficace dell'evoluzione della pesca dal XVI al XIX secolo che permette di seguire il passaggio dalla pratiche piscatorie svolte prevalentemente in prossimità della costa, a tecniche di pesca a strascico in alto mare esercitate con l'ausilio di tipi navali e attrezzature fino a quel momento mai sperimentati. L'aumento della produzione sollecita anche una migliore organizzazione dello smercio del pesce con l'utilizzo di ghiaccio per bloccare il facile deperimento del prodotto (conserve, neviere) e favorirne il trasporto sulle lunghe distanze. Nonostante le non poche problematiche sociali e organizzative del settore si avvia la trasformazione del commercio ittico che porta fra Sette e Novecento, in virtù del significativo allargamento della rete distributiva del prodotto fresco, anche un radicale cambiamento nelle abitudini alimentari.

GnRH agonist therapy is known to reduce uterine leiomyoma volume, although the molecular mechanisms responsible for this effect remain poorly understood. In this study, we have investigated the molecular mechanisms involved in the anti-proliferative effect of a GnRH agonist, leuprolide acetate (LA), in uterine leiomyomas obtained from six patients treated with LA for 3 months before surgery (group B), compared with tumours from six untreated patients (group A). To this end, we have evaluated the expression and the activity of molecules involved in the regulation of cell survival and proliferation. In group B, the total activity of PI3K was reduced by 60% compared with control samples. Furthermore, LA caused a reduction of PKB activation of approximately 50%, measured as serine 473 phosphorylation. In parallel with PKB reduction in LA samples, we observed a 60% reduction in the phosphorylation of its substrate BAD. While Bcl-xL/BAD association was not significantly modified in LA-treated leiomyomas, BAD/14.3.3 interaction was reduced, due to a 50% decreased 14.3.3 expression. In addition, LA was able to reduce the expression of the antiapoptotic proteins FLIP and PED/PEA15 by 70 and 50% respectively, compared with control samples. We next evaluated the activation of MAP kinases in leiomyomas. Activation of p42 and p44 MAP kinase isoforms was increased by 30% in group B. However, the phosphorylation of the transcription factor Elk1 was not increased in a similar fashion in LA-treated leiomyomas compared with group A. Thus, these data suggest that LA reduction of leiomyoma volume is mediated at least in part by a decreased activation of the PI3K/PKB survival pathway and by the suppression of antiapoptotic factors.