Search

High strength steel (HSS) wire ropes are widely used in civil engineering to act as hangers or bridge cables. These kinds of structural members are particularly prone to both corrosion and fatigue damage owing to typical exposition and load conditions. Within this framework, in the present paper a comprehensive state of the art review dealing with literature and normative models for fatigue checks of corroded wire ropes is presented. Most peculiar aspects related to correct fatigue demand and strength evaluation in wire ropes are discussed on the basis of over 40 research works.

The use of high strength (HS) steel in seismic applications is very attractive due to economical and mechanical benefits. The combined use of HSS for non-dissipative members and MCS for dissipative zones is generally termed “dual-steel” concept and it could likely represent a valuable aid to satisfy capacity design criteria and to control the global frame behaviour, even contemporarily reducing the constructional cost. The current paper investigates the benefits of applying dual-steel concept to the seismic design of eccentrically braced frames equipped with short links in the framework of EN 1998-1:2005. With this purpose, a comprehensive numerical parametric study has been carried out: both static and dynamic nonlinear analyses have been performed to investigate the advantages of using HSS to enhance strength and ductility of a set of mid and high-rise simple and dual eccentrically braced frames.

The steel exoskeleton systems are widespread structures applied on the external perimeter of an existing building designed to absorb the horizontal actions providing at the same time useful support for energy efficiency upgrading and architectural restyling. The growing interest in the use of exoskeletons is due to the possibility of creating an integrated retrofit (structural, energetic, formal and functional), combining “structural safety” with the concepts of “deep renovation”. Among many solutions present in the literature, in the present work, the steel exoskeletons placed orthogonally to the facade of the existing building have been analysed; this structural typology has the advantage to allow rapid retrofit execution without interfering with the activities carried out within the existing structure. In this framework, the aim of the present work is the introduction of a detailed step-by-step design procedure for steel exoskeletons systems adopted for seismic retrofit of existing buildings looking also at the accessibility and operability aspects. Each step of the procedure was individually explained and it was applied for the design of a strengthening intervention on a real single-storey steel industrial building. The existing building is located in Nusco (Av, Italy) which is classified as in medium–high seismic intensity area which corresponds a peak ground acceleration (ag) equal to 0.238 g. Non-linear analyses were conducted to assess the existing structure’s performance as well as to verify the effectiveness of the strengthening solutions designed. The use of the exoskeleton systems allows to strongly increase both the elastic stiffness and the resistance of the investigated industrial building without interrupting its product activity.

Strategies for the protection of the Cultural Heritage priceless value are highly demanded, being both earthquake and support movement (and a combination of the two of them) severe threats for their safety and integrity. To this scope, computer-based numerical formulations have been representing a powerful tool for the simulation of expected loss in terms of pieces of art damages, with the scope to save them as much as possible. In this framework, the conference paper is devoted to the vulnerability assessment of monumental artworks using dynamic analysis in a rigid block modelling environment. The numerical formulation adopts a discrete rigid block-based model, where the mortar joints contribution is accounted for by frictional, no-tension interfaces between the masonry units. The procedure adopted to solve the formulation is based on a dual variational problem where equilibrium, kinematic and failure conditions equations are involved at the same time, and which is solved via mathematical programming. An application to a system of two blocks vertically stacked, one representing the support and one representing the artefact, subjected to free rocking motion will be proposed in the paper. The main scope is to investigate the seismic response of such a system, which is typical for most of museum's collections (e.g., statues). The computational efficiency and accuracy of the proposed numerical strategy will be discussed.

The orthogonal exoskeletons can be used in seismic application to retrofit an existing building without interfere with the structure operativity. These types of structures are usually placed on the external perimeter of the existing structures and contribute to absorb the horizontal action in case of seismic events. The exoskeletons should be designed in function of the design target and depending on the lateral stiffness of the existing structures. Therefore, the exoskeletons lateral stiffness represents one of the key parameters in the design procedure; however, their structural stiffness is influenced by the joint features. In this work, the influence of the geometrical and mechanical characteristics of the joint on the global exoskeleton's performance is investigated. Non-linear numerical analyses were performed in order to investigate the performance of the exoskeletons accounting for the presence of the joints by the introduction of a no-dimensional local spring. The results show that the local response of the exoskeletons is affected by the joints features, and that in the design phase it is important to take into account the real exoskeletons lateral stiffness.

Arundo Donax L. is a natural material used for traditional vernacular architectures. Main issues and applications are briefly presented. Actually, there are not guidelines or standards for the use of Arundo Donax as a construction material. In this perspective, the paper deals with the investigation on the mechanical characteristics of the Arundo Donax through experimental tests. In particular tests in compression on single culms are shown. Therefore the architectural project of a gridshell in common canes, tied with hemp ropes and covered by lime mixed with Arundo Donax inerts is illustrated. The Arundo Donax shows good performance capabilities in compression comparable with traditional building materials, in addition it is renewable non-polluting, recyclable and suitable for sustainable architecture.

In linea con le tendenze degli ultimi anni, che prevedono l’utilizzo di costruzioni altamente performanti ed a basso impatto, è appena terminato un progetto di ricerca dal nome “ECCElSA”, svolto in collaborazione tra l’Università di Napoli “Federico II” e l’azienda calabrese Lamieredil S.p.A. Il progetto ha avuto come principale obiettivo lo sviluppo di soluzioni innovative per le costruzioni leggere in acciaio, finalizzate all’ottenimento di elevate prestazioni strutturali, termiche e ambientali. A tal fine è stato concepito un nuovo sistema parete sismo-resistente, che consiste principalmente in una parete costituita da profili in acciaio formato a freddo controventata da barre di acciaio ultra-alto resistenziale pre-tese, poste in configurazione a “V”. Oltre allo sviluppo del sistema sismo-resistente, nell’ambito del progetto sono state studiate anche diverse soluzioni per l’involucro edilizio, che riducono i ponti termici e migliorano le prestazioni energetiche dell’intero edificio. Lo sviluppo del sistema parete sismo-resistente è stato condotto attraverso un approccio basato principalmente sulla sperimentazione fisica, che ha previsto un’ampia campagna sperimentale con prove di trazione sui materiali strutturali, prove di rilassamento sull’acciaio ultra-alto resistenziale, prove di trazione sull’assemblaggio barra-dado e prove su pareti in scala reale. Le prove sperimentali sono state condotte presso il Laboratorio del Dipartimento di Strutture per l’Ingegneria e l’Architettura dell’Università degli Studi di Napoli “Federico II”. I risultati sperimentali ottenuti hanno evidenziato una risposta soddisfacente della parete in termini di rigidezza, resistenza e capacità di deformazione, confermando le previsioni teoriche. Come step conclusivo del progetto, al fine di validare le soluzioni sviluppate nonché analizzare i processi produttivi e la fase esecutiva, è stato costruito un edificio prototipo di due piani, progettato interamente in ambiente BIM e realizzato con l’ausilio di tecnologie di produzione CAD/CAM. termico ed acustico, lo studio delle combinazioni di accoppiamento tipiche dei sistemi a multistrato e a sandwich.

The non-linear monotonic and hysteretic behaviour of as-built and retrofitted beam-to-column joints of an existing non-code conforming steel multi-storey building was investigated by means of finite element simulations. The building case study was originally designed to resist only gravity and wind loads without any capacity design principle. The as-built joints have continuous beam and interrupted columns that are bolted with end-plate splice to the tapered flange of the beams in the nodal zone. These joints were analysed to assess their non-linear response. The finite element analyses showed adequate resistance against gravity loads, but poor performance under seismic and column loss scenarios. Two retrofit strategies were designed in order to enhance the local and global performance in order to guarantee the weak beam-strong column condition, namely: (i) strengthening the column and its connection; (ii) weakening of the beam. Different types of interventions were designed per examined strategy and numerically analysed to assess the global and local response of both external and internal joints. A TOPSIS multicriteria analysis was also performed to identify the most suitable type of intervention.

Among various architectural non-structural components in a building, Lightweight Steel (LWS) drywall partitions are one of the most widely used partition systems. A set of simplified numerical models are proposed here for LWS drywall partitions to simulate their in-plane response, that can be easily integrated with the building models and possess the ability to better estimate damages in them, when linked to their fragility information. Models are calibrated experimentally using the quasi-static cyclic test results, available from the recent research carried out at University of Naples "Federico II". The models are developed in OpenSees software by using a single discretized spring to simulate the lumped behaviour of the walls for the twelve individual different configurations of the tested partitions. The accuracy of model is demonstrated by comparing the experimental and the numerical results in terms of the hysteretic response curves and the cumulative energy dissipated.

Two storey X bracings are currently very popular in European practice, as respect to chevron and simple X bracings, owing to the advantages of reducing the bending demand in the brace intercepted beams in V and inverted V configurations and optimizing the design of gusset plate connections. However, rules for two storey X braced frames are not clearly specified within current version of EN1998 1, thus leading to different interpretations of the code by designers. The research presented in this paper is addressed at investigating the seismic behaviour of two storey X concentrically braced frames in order to revise the design rules within EN1998 1. Therefore, five different design criteria are discussed, and their effectiveness is investigated. With this aim, a comprehensive numerical parametric study is carried out considering a set of planar frames extracted from a set of structural archetypes that are representative of regular low, medium and high rise buildings. The obtained results show that the proposed design criteria ensure satisfactory seismic performance.

Hybrid structures are efficient and economical systems that can be successfully adopted for modular buildings. Novel hybrid industrialized and modular buildings with truss girder made of lightweight steel profiles and connected to tubular columns by means of innovative plug-and-play joints has been recently proposed within the RFCS INNO3DJOINTS with the aim to develop solution ensuring fast-track construction and increasing the quality of the finished product. In this paper, a preliminary study on the seismic behaviour of these innovative hybrid frames equipped with plug-and-play joints is summarized. Nonlinear static and dynamic analyses were performed on 2D models of a reference structural archetype. The obtained results showed that this type of structure may also be used in low seismicity zones.