564 research outputs found
A DESIGN PROPOSAL FOR DISSIPATIVE SEISMIC-RESISTANT AUTOMATED RACK SUPPORTED WAREHOUSES
No full textIn logistic field, Automated Rack Supported Warehouses (ARSWs) are buildings for the storage of goods which adopts the steel racks as both stoking areas and primary structural system. Re-cent collapses and damages after seismic events highlighted the criticalities of the current de-sign, which is based on the regulations for traditional racks (i.e. EN16681) or for ordinary buildings (as Euro-codes) that are not fully appropriate, given the peculiarities of ARSWs. In this paper, possible so-lutions to design dissipative and seismic-resistant ARSWs are investigated. Starting from the tech-nical solutions currently adopted and from regulations for dissipative buildings, global optimization is performed with the aim of selecting the most appropriate structural type allowing to fulfill all the requirements (i.e. the hierarchy rules). Then, local optimization is carried out for the dissipative elements, with the aim of obtaining an over-resistant connection with respect to the element. Indeed, the fulfillment of this request is challenging for the profiles adopted in ARSWs, which are thin walled, implying a limited bearing capacity of the connection. As a solution to this issue, the cross section of the profiles is locally reduced to limit tensile resistance, but this also weaken the element, affecting the behaviour in compression and due to cyclic loading. Numerical optimization is per-formed for the optimization of the layout of the reduced parts, aiming to find the right balance among tensile resistance, ductility demand and good performance in compression
EXPERIMENTAL BEHAVIOR OF DISSIPATIVE THIN-WALLED BRACINGS
No full textThis paper presents the dissipative capacities of thin-walled reduced-section elements evaluated through an experimental campaign. The reduction of the cross section is introduced to fulfill of hierarchy rules for dissipative structures when these elements are used as diagonals in Automated Rack Supported Warehouses. Indeed, cold-formed thin-walled elements are adopted in these struc-tures, and for these elements the limited bearing capacity of their connections to the other elements does not allow the dissipation of seismic energy through yielding and plastic deformation of diag-onals. The reduction of the cross section is so necessary, allowing to obtain a resistance of the diagonal lower than the bearing capacity. Anyway, it introduces issues related to the local stability of the reduced part. The behavior of this type of elements is firstly numerically predicted, selecting four possible different layouts for the reduced parts. Then, the actual behavior is validated through the execution of an extensive experimental campaign where tensile and compression monotonic tests are per-formed, as well as cyclic ones. The results of the experimental campaign are used for the calibration of the numerical models and the final evaluation of the performance of whole case-study structures where these dissipative elements may be implemented
TVTδ Concept for Long-Span Glass–Steel Footbridges
No full textTransparency and structural lightness are inspiring ideas in the design of footbridges. Glass is the most performing transparent
material to be used for structural purposes because of its high compressive strength, chemical stability, and absence of fatigue and viscosity
phenomena at room temperature. However, its fragility constitutes a challenging limit in structural applications. This research provides and
discusses a specific concept named TVTδ (Travi Vitree Tensegrity) for lightweight long-span beam-like footbridges made of structural glass.
Hence, two design approaches of fail-safe design (FSD) and damage avoidance design (DAD) are applied to guarantee adequate safety levels
and postcracking serviceability, respectively, with low damages on the main components. FSD provides the adoption of structural collaboration
between glass and steel. Following DAD, glass is segmented into triangular panels, and reciprocal diffuse prestress is performed by
steel tendons. This strategy assures low rehabilitation costs because only collapsed elements should be replaced once failed. At ultimate limit
state (ULS), the TVTδ footbridge attains a global ductile behavior in which the yielding of steel tendons occurs before any fragile failure.
Such result is achieved through a hierarchic calibration of the chain of failures. In glass panels, which are mostly precompressed, the buckling
failure, representing the main risk, is delayed by the mutual stabilization of the panels’ compressed edges with steel clamping. However,
because an accidental event may cause a localized or diffuse brittle failure of glass components, the system is designed to maintain a residual
load bearing capacity in this scenario. At the serviceability limit state (SLS), the TVTδ footbridge is highly stiffened by the presence of glass
panes, partially encased in metallic frames. Crack initiation is delayed by precompression
Formation of a long-lived radical pair in a Sn(iv) porphyrin-di(l-tyrosinato) conjugate driven by proton-coupled electron-transfer
Full text linkThe novel conjugate 1, featuring two l-tyrosinato residues axially coordinated to the tin centre of a Sn(iv)-
tetraphenylporphyrin, is reported as the first example of a supramolecular dyad for photochemical PCET. It is noteworthy that
the excitation of 1 in the presence of a suitable base is followed by photoinduced PCET leading to a radical pair state with a
surprisingly long lifetime
Steelwar Research Project - Publications
No full textSTEELWAR – Advanced structural solution for automated STEELrack supported WARehouses is a European Research Project funded by the Research Fund for Coal and Steel (RFCS) that aims at the definition of specific design rules for Automated Rack Supported Warehouses (ARSWs). These constructions are huge steel buildings where palletized goods are stored before distribution, and steel racks, where pallets are placed, also constitute the main structure of the warehouse. This makes ARSWs peculiar buildings with very distinctive and particular structural characteristics and needs, which make standards and limitations for steel structures hardly applicable. STEELWAR research project started on the 1st of July 2017 and was concluded on the 31st of March 2022. The research team is composed of Academic Partners, Industrial Partners (IP), and a company expert on the logistic field. The Academic Partners are: University of Pisa (which is also the coordinator of the project), FINCON consulting Italia S.r.l, National Technical University of Aachen, Rheinisch-Westfaelische Technische Hochschule Aachen, Hasselt University, University of Florence. The Industrial Partners are: Noega Systems S.L., Modulblok S.p.A., Sacma S.p.A., Nedcon B.V., Mecalux S.p.A. These IPs are companies that design, produce, and sell traditional racks and ARSWs at least all over Europe. The company expert in logistics is System Logistics S.p.A. Finally, SCL Ingegneria Strutturale is a subcontractor of Fincon expert in racks structures. One of the strongest points of the STEELWAR project is the participation of Industrial Partners. This gave continuous occasion of discussion and drove all the design proposals to the right direction in terms of industrial feasibility. For this reason, all the outcomes of STEELWAR project are surely applicable for practical purposes and provide a wide and reference pre-normative framework dedicated specifically to ARSWs, which till now is absent.Publications and any other aspects concerning the dissemination of results are here collected
Investigation of reinforced concrete bridges by using a dual-polarized high-frequency GPR
No full textGround penetrating radar is a non-invasive technique that, amongst the various available state-of-the-art methods, is capable of accurately locating both metallic and nonmetallic buried objects. The main object of this paper is to describe the application of a GPR strategy to the non-destructive testing of concrete structures, particularly bridges, where there is a need to identify, quantify and categorize structural reinforcements. The new C-Thrue radar, developed by IDS GeoRadar, was used to investigate two bridges near Pisa (Italy). The acquisition of dense and regular grids was used to provide a full reconstruction of the geometry of the investigated area. Moreover, through the use of sensors in different polarizations, and dedicated data processing techniques, the C-Thrue radar enables the creation of spatially correlated data sets that represent scanned 3-D volumes of the ground, allowing demonstrable benefits in overall assessment of the required structural parameters
An Artificial Neural Network for the prediction of the structural and foundational attention class of bridges according to the Italian Guidelines
No full textThe state of conservation, maintenance and monitoring of bridges has gained attention in the last decade over the world especially in Italy, where a large number of structures are present and, multiple cases of collapses of bridges have recently occurred. To address this problem and to provide a prioritization on bridges where detailed safety assessments are necessary, in 2020 the Italian Ministry of Transport and Infrastructure issues Guidelines, based on a multi-level and multi-risk approach. Six levels of assessment are foreseen: the first three must be applied to all bridges (Levels 0-2), while the last three (Levels 3-5) only for the bridges which are characterized by high risk deriving from the analyses of the previous levels. Focusing on the first three levels, Level 0 consists of a census of all the existing bridges, collecting registry data mainly deriving from the existing documentation. Level 1 consists of visual inspections, which are used to point out the conservation status of the bridge and the surrounding area. Level 2 provides for a risk-based classification starting from the data previously collected. Levels 0-2 must be applied indiscriminately to all bridges. Thus, to prioritize inspections, it could be helpful to have a tool capable to predict the state of conservation of bridge and to assess the associated risks, starting from data gathered with census. For this reason, this paper proposed an Artificial Neural Network (ANN) capable to assess the level of degradation and structural and foundational risk level of existing bridges, using a reduced set of information derived from Level 0 activities. This tool can be used to: I) rationally schedule the inspections, starting from structures that could have a higher probability to be heavily degraded, II) support managing and planning activities at territorial level, promptly furnishing information about the structural and foundational risk of the bridges
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