1,720,974 research outputs found
Tra stereotomia, statica e cinematica: indagine teorico- sperimentale sull'equilibrio a scorrimento di archi tozzi a conci rigidi
No full textIn the present paper, the problem of the sliding collapse of vaults is examined from a theoretical and experimental point of view. A comparison between the theoretical results and the experimental tests on physical marble models shows that sliding depends both on the friction angle and on the geometry of the vault, whereas it does not depend on the weight of the material. For different structures, the minimum value of the friction angle and the thrust at the crown section corresponding to this limit condition is evaluated
Morphogenesis of a bundled tall building: Biomimetic, structural, and wind-energy design of a multi-core-outrigger system combined with diagrid
No full textSkyscrapers are among the most distinctive building types of the modern age. Since many resources are attributed to these buildings, their design should consider a proper performance-based construction economy and environmental sustainable development. This research introduces a new concept for a bundled tall building founded on the use of a multi-core-outrigger system, which is additionally enriched with diagrid structures. The concept is inspired by the bamboo plant and follows the biomimetic design principles for the structural organization and performance-based criteria for optimizing the lateral stiffness and for shaping the cross section. Particularly, the incident wind speed is maximized to exploit Vertical Axis Wind Turbines (VAWTs), which are located along the whole building height at the center of the bundled towers. The building morphogenesis is accomplished by a multistep methodology that is fully developed in a parametric environment and includes structural and computational fluid dynamic analyses. With the aim of validating the proposed concept, a case study of a 320-m-tall three-core building has been designed for the city of Pisa, Italy. The use of VAWTs results in an annual emissions reduction of about 10 kgCO2/m2
Experimental and numerical investigation on a passive control system for the mitigation of vibrations on SDOF and MDOF Structures: mini Tribological ROCKing Seismic Isolation Device (miniTROCKSISD)
Full text linkThis paper illustrates the results of an experimental campaign performed on a scale prototype of a base dissipator called Mini Tribological ROCKing Seismic Isolation Device. This device allows a smooth, controlled and damped rocking by means of frictional layers and viscous elastic springs, which aim at decoupling the frequencies of the superstructure, at dissipating energy during motion and at re-centering the system once the external action vanishes. Four superstructures are tested–a shear type frame, braced and unbraced, a multi-story frame and a SDOF oscillator–with 96 ambient vibration and impulsive tests. An analytical model is illustrated and validated by the experimental tests. The reduction of relative displacement demand is analyzed for all the cases together with the reduction of the acceleration demand, showing positive effects of the base dissipator on the dynamic behavior of all the superstructures
Discontinuous Deformation of Tensile Steel Bars: Experimental Results
No full textMarked differences have been observed between the global and the local responses of tensile steel bars – the first traditionally defined by considering average strains (displacement of the bar’s ends divided by its undistorted length), and the second obtained by local strain measures through high performance resistance strain gauges. This distinction highlights the peculiarities of various qualities of steel normally employed as reinforcement in concrete. In particular, the phenomenon of serrated deformation at yielding (the Portevin-Le Chatelier effect) and the peculiarities of this metastable state, when unloading sequences are performed, will be discussed. It will be shown how the presence of ribs can influence the local behaviour and how this is reflected in the gross response. In the analysis, the importance of strain hardening in improving the ductility performance of steel bars is observe
A Mechanical Model for the Elastic-Plastic Behavior of Metallic Bars
No full textA simple mechanical model appears suitable for describing the various aspects of the elastic-plastic behavior of steel bars: oscillation in the average stress-strain curve, local and global responses, instability due to the transition from an upper to a lower yield point, the spread of plastic deformations, strain-hardening behavior
A pilot test on the problem of joining steel plates to bamboo rods
No full textRapporto tecnico pubblicato negli atti del Dipartimento di Ingegneria Strutturale dell'Università di Pis
Concept and cable-tensioning optimization of post-tensioned shells made of structural glass
Full text linkShells made of structural glass are charming objects from both the aesthetics and the engineering point of view. However, they pose two signicant challenges: the rst one is to assure adequate safety and redundancy concerning possible global collapse; the second one is to guarantee the economy for replacing collapsed components. To address both requirements, this research explores a novel concept where triangular panels of structural glass are both post-tensioned and reinforced to create 3D free-form systems. Hence, the ligree steel truss, made of edges reinforcements, is sized in performance-based perspective to bear at least the weight of all panels in the occurrence of simultaneous cracks (worst-case scenario). The panels are post-tensioned using a set of edge-aligned cables that add benecial compressive stress on the surface. The cable placement and pre-loads are optimized to minimize the tensile stress acting on the shell and match the manufacturing constraints. These shells optimize material usage by providing not only a transparent and fascinating building separation but also load-bearing capabilities. Visual and structural lightness are improved to grid shell competitors
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