Comparative Study of Post-tensioned Glass Beams with Bonded Tendons

This paper explores the system of laminated annealed glass beams post-tensioned through stainless steel tendons bonded to the lower glass edge. The tendons are first pre-tensioned and then adhesively bonded to the glass. The compressive pre-stress applied by the tendon increases the fracture strength of the beam; in case of glass fracture, the steel tendon provides ductility enhancing the post-fracture behaviour of the beam. In order to explore the optimal adhesive properties for such application, three types of structural adhesives were selected and applied in a post-tensioned glass beam system. The selected adhesives cover a range of stiffness from semi-rigid to rigid. Simple laminated glass beams were post-tensioned with a 15 kN force applied through the tendons and subsequently tested in four-point bending. The results show a structural response strongly dependent on the properties of the adhesive. While the application of pre-tension through stiffer adhesives significantly increased the initial fracture strength of the beams, an immediate loss of pre-stress was observed with the most flexible adhesive. Nevertheless, all the beams showed, to a varying extent, ductile postfracture behaviour and reached ultimate failure loads above the initial fracture load.