The paper deals with the construction, the numerical modelling and the experimental investigation of an innovative hybrid steel-glass beam, spanning over 12 meterswhose constructional concept, patented by M. Froli for the University of Pisa, has the basic design aim to avoid or reduce tensile stresses in glass in order to drastically delay the initiation and propagation of cracks which afflicts traditional glass beams and to ensure at the same time ductility and high stiffness. After encouraging theoretical predictions and tests performed on a 3.33 meters spanned prototype (TVT Beta), the 12.00 meters spanned prototype TVT Gamma has been designed, built and submitted to a programme of experimental tests. The TVT Gamma prototype has a height of 1079 mm and a width of 600 mm. It is composed by two vertical glazed twin curtains reciprocally distant 600mm, and by a upper horizontal glass curtain. Each vertical curtain is composed by 19 triangular equilateral laminated glass panels while the top horizontal curtain is made by 10 rectangular laminated glass panels. The post-tension system consists of diagonal and longitudinal steel bars of different diameters disposed following a Warren scheme in the vertical curtains. The connection between steel knots and rounded vertexes of the glass panes is exerted just by means of mono-lateral contact pressures activated by post-tensioned diagonals and longitudinal steel bars. All the glass panels are therefore free from holes and gluing. The prototype has been submitted to a test programme comprising a dynamic characterization and a oligo-cyclical static loading increased up to collapse and performed on a four-point bending scheme. Aim of the tests was to assess the dynamic, the low cycles static behaviour as well as the failure and post-failure behaviour of the prototype and to compare them with numerical predictions. The cyclical static tests extended up to collapse evidenced the permanence of the prototype within its elastic domain under service cyclic loading and exhibited at collapse large ductile displacements as consequence of the tensile steel bars yielding that preceded the buckling of a compressed triangular glass pane, thus completely confirming the preliminary numerical predictions.
|Titolo:||A 12 meters long segmented, post-tensioned steel-glass beam (TVT Gamma)|
|Anno del prodotto:||2014|
|Appare nelle tipologie:||4.1 Contributo in Atti di convegno|