Experimental static and dynamic tests on a large-scale free-form Voronoi grid shell mock-up in comparison with finite-element method results

Abstract Grid shells supporting transparent or opaque panels are largely used to cover long-spanned spaces because of their lightness, the easy setup, and economy. This paper presents the results of experimental static and dynamic investigations carried out on a large-scale free-form grid shell mock-up, whose geometry descended from an innovative Voronoi polygonal pattern. Accompanying finite-element method (FEM) simulations followed. To these purposes, a four-step procedure was adopted: (1) a perfect FEM model was analyzed; (2) using the modal shapes scaled by measuring the mock-up, a deformed unloaded geometry was built, which took into account the defects caused by the assembly phase; (3) experimental static tests were executed by affixing weights to the mock-up, and a simplified representative FEM model was calibrated, choosing the nodes stiffness and the material properties as parameters; and (4) modal identification was performed through operational modal analysis and impulsive tests, and then, a simplified FEM dynamical model was calibrated. Due to the high deformability of the mock-up, only a symmetric load case configuration was adopted

Form-finding and Buckling Optimization of Grid Shells using genetic Algorithms

We present a strategy for the design of gridshells where form-found structures are optimised for buckling resistance. A genetic algorithm is employed for the initialisation of pre-stress forces required in form-finding using dynamic relaxation. Dynamic relaxation takes this initial pre-stress, a flat grid, as well as self-weight and nodal loads to calculate a static equilibrium. The structure is then analysed for the estimation of the critical buckling load. Different boundary conditions, structural parameters and typology of connections are compared, including a gridshells with triangular and quadrangular patterns. Optimised structures are measured against the trivial solution, which is a structure where dynamic relaxation is initialised with uniform pre-stress. Our results show the proposed strategy can successfully form find gridshells with improved buckling performance

Modellazione reologica della prova di aderenza a compressione-taglio per compositi laminati vetro-vetro e vetro-metallo

La meccanica della prova di aderenza su campioni laminati vetro -vetro e vetro-metallo mediante prova di compressione-taglio viene modellata analiticamente e numericamente nella ipotesi di legame forza-scorrimento non lineare. I risultati teorici vengono confrontati con quelli sperimentali

Conception And Parametric Design Workflow For A Timber Large-Spanned Reversible Grid Shell To Shelter The Archaeological Site Of The Roman Shipwrecks In Pisa

Reciprocal structures or nexorade are composed by the assembling of groups of three or more beams mutually connected by mono-lateral T joints in a way that any relative movement is suppressed. This kind of structures can be easily built in relatively unprepared sites, dismantled, transported and re-used even by not specialized handcraft. For these reasons, reciprocal structures have been widely used in the past for military purposes, and nowadays they seem to satisfy very well the different requirements of a quick and temporary shelter of a large archaeological area when they are shaped as grid shells. This paper proposes the design of a reversible, reciprocal framed grid shell to shelter the archaeological site of the Roman Shipwrecks in Pisa. The structure must protect excavations and archaeologists from the weather and provide an easy access to visitors. Additionally, it must allow for easy disassembling and moving to another site. The design choices aim at optimizing both structural efficiency and esthetical qualities. A parametric workflow for both the form finding and the digital fabrication processes has been developed, and a prototype of accommodative steel T-joint for timber reciprocal beams has been realized. Finally, a model using CNC-cutting tested the structural feasibility of such a design approach

Progetto di un padiglione integralmente vitreo costruito mediante telai ibridi TVT di grande luce

La richiesta architettonica di una progressiva, completa smaterializzazione delle strutture portanti può essere soddisfatta solo entro certi limiti mediante l’impiego esclusivo di vetro strutturale. Quando a questa esigenza si aggiunge quella del superamento di grandi luci o grandi altezze è indispensabile ricorrere a sistemi costruttivi di tipo ibrido vetro-acciaio nei quali il vetro, fragile ma resistente a compressione, viene posto in associazione simbiotica con l’acciaio, duttile e resistente a trazione. Nella presente nota viene presentato lo studio di fattibilità di un padiglione integralmente vetrato costituito da una serie di telai trasversali ad alta trasparenza tamponati e controventati da pannelli vitrei ibridi precompressi. Le traverse dei portali, aventi circa 20 metri di luce, ed i piedritti, alti circa 8 metri, sono progettati mediante elementi del tipo TVT- bis (Travi Vitree Tensegrity). La capacità della costruzione di sostenere in sicurezza elevate condizioni di carico statico e dinamico è dimostrata attraverso analisi numeriche multi-scala tarate sulla base dei risultati sperimentali raccolti nelle campagne di test effettuati sui prototipi TVT e TVT e spinti fino a rottura. The architectural demand for a complete de-materialisation of load bearing structures can be satisfied only in limited cases with the exclusive structural use of glass. Otherwise, it is necessary to use hybrid glass-steel structures to achieve challenging applications as long spanned or high rise constructions. Hence, glass, fragile but highly compressive resistant, is associated with steel, ductile and tensile resistant. The present research presents the feasibility study for a fully glazed pavilion, made of six TVT-bis (Travi Vitree Tensegrity) portal frames and hybrid pre-stressed panels as bracing system. The frames are about 20 m spanned and 8 m height. The structural performance to withstand heavy static and dynamic loads is assessed by means of multiscalar FEM numerical analyses, calibrated on the collapse tests performed on TVT e TVT prototypes

ONE-SIDED rocking analysis of corner mechanisms in masonry structures: Influence of geometry, energy dissipation, boundary conditions

The corner mechanism in masonry structures is one of the out-of-plane modes that may frequently occur under dynamic actions such as earthquakes. The three dimensional motion, in principle complex to treat, can be simplified into a two-dimensional problem, where a prismatic equivalent block is associated to the corner mechanism. This paper provides a method to treat the corner mechanism in two dimensional rocking analysis, taking into account the roof actions especially the roof thrust that acts as destabilizing force in the preliminary phases of motion and the boundary conditions such as the transverse walls. A case study is taken as benchmark to perform rocking non-linear analyses and discuss the role of geometry, energy dissipation and boundary conditions. It is shown the relevant influence of the geometry and of the coefficient of restitution on the stability conditions, whenever the oscillation produce horizontal displacement values of some cm. The results of the case study, subjected to the Central Italy earthquake, are compared to the actual response of the corner mechanism, which collapsed during this seismic swarm, showing that the rocking analysis on the equivalent block correctly predicts the collapse occurred.The Authors thank the Italian Department of Civil Protection and the Consortium RELUIS (2018) for funding this research activity. This work was partially financed by FEDER funds through the Competitiveness Factors Operational Program - COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633

Struttura di Trave Composita Perfezionata

La domanda di brevetto riguarda una serie di invenzioni tecniche per il perfezionamento del brevetto depositato nel 2006 riguardante le cosidette Travi TVT. Con i perfezionamenti introdotti il sistema strutturale può raggiungere luci molto elevate, dell'ordine dei 30 metri

Nodo strutturale per il collegamento di elementi di involucro edilizio, e struttura reticolare comprendente detto nodo

La presente invenzione riguarda un nodo strutturale perfezionato per collegare tra di loro elementi di involucro edilizio o di strutture in genere, quali pannelli poligonali opachi o trasparenti, in particolare pannelli poligonali in vetro