1,721,013 research outputs found
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
Automated generation of flat tileable patterns and 3D reduced model simulation
Full text linkThe computational fabrication community is developing an increasing interest in the use of patterned surfaces, which can be designed to show ornamental and unconventional aesthetics or to perform as a proper structural material with a wide range of features. Geometrically designing and controlling the deformation capabilities of these patterns in response to external stimuli is a complex task due to the large number of variables involved. This paper introduces a method for generating sets of tileable and exchangeable flat patterns as well as a model-reduction strategy that enables their mechanical simulation at interactive rates. This method is included in a design pipeline that aims to turn any general flat surface into a pattern tessellation, which is able to deform under a given loading scenario. To validate our approach, we apply it to different contexts, including real-scale 3D printed specimens, for which we compare our results with the ones provided by a ground-truth solver
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
VALUTAZIONE DELLE PRESTAZIONI MECCANICHE, COSTRUTTIVE E DI SOSTENIBILITÀ DEI GRIDSHELL FREEGRID
No full textConcept 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
Automatic Design of Cable-Tensioned Glass Shells
No full textWe propose an optimization algorithm for the design of post-tensioned architectural shell structures, composed of triangular glass panels, in which glass has a load-bearing function. Due to its brittle nature, glass can fail when it is subject to tensile forces. Hence, we enrich the structure with a cable net, which is specifically designed to post-tension the shell, relieving the underlying glass structure from tension. We automatically derive an optimized cable layout, together with the appropriate pre-load of each cable. The method is driven by a physically based static analysis of the shell subject to its service load. We assess our approach by applying non-linear finite element analysis to several real-scale application scenarios. Such a method of cable tensioning produces glass shells that are optimized from the material usage viewpoint since they exploit the high compression strength of glass. As a result, they are lightweight and robust. Both aesthetic and static qualities are improved with respect to grid shell competitors
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mutation analysis of the HDAC 1, 2, 8 and CDKL5 genes in Rett syndrome patients without mutations in MECP2
No full textMutations in the MECP2 gene are found in only 80% of patients with Rett syndrome (RTT). Therefore other genes have to be involved in the pathogenesis of RTT. By using our defined diagnostic criteria we first re-evaluated 50 girls with possible RTT in whom the sequencing of the MECP2 gene had not revealed any mutations. Only 15 of theses patients fulfilled all criteria for RTT and could be considered to have classical RTT. In eight of these, further molecular analyses revealed large deletions of the MECP2 gene. In the remaining seven girls we then analyzed the genes HDAC1, HDAC2, and HDAC8 that encode for the histone deacetylases 1, 2, and 8 which interact with McCP2 and are essential for its function. Although these histone deacetylase genes have been considered as good candidate genes for RTT, our molecular analysis of these genes did not detect any mutations. Because recently mutations in CDKL5 were reported in patients with RTT, we included this gene in our analysis but failed to detect any mutations. We conclude that only a subgroup of girls with possible RTT and no detectable mutation in the sequencing of the MECP2 gene do really have classical RTT. In many of those large MECP2 gene deletions can be detected by further analysis. The genes HDAC1, HDAC2, and HDAC8 do not seem to play a role in the pathogenesis of RTT and at least in our subgroup no mutations in the CDKL5 gene were detected. (c) 2005 Wiley-Liss, Inc
Dynamics of a new seismic isolation device based on tribological smooth rocking (TROCKSISD)
Full text linkA novel isolation device is introduced to seismically protect slender structures or historic assets within the philosophy of Damage Avoidance Design (DAD). This device is conceived to allow smooth, controlled and damped rocking thanks to spherical contact surfaces, elastic springs which ensure re-centering, frictional layers and viscous elastic dampers able to dissipate energy during motion. The conceptual framework of the device is analyzed, and corresponding equations of motions obtained for the equivalent two degrees-of-freedom system. The proposed Performance Based Approach allows identifying geometric and mechanical features of the system. Extensive dynamic analyses with spectra-compatible ground motions are performed and the primary contribution of friction, developed by the relative slip of the two spherical surfaces, is discussed. Finally, the dynamic response under selected earthquakes is evaluated by comparing the isolated and the corresponding not isolated response, to highlight the beneficial effects produced by the proposed isolation technique
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