Design and Tests of Structural Post-Tensioned Glass T-Beams

Glass manifests superior properties with high strength and transparency although it may not be considered as a commonly used structural material. This study targets to improve the structural performance of glass by post-tensioning; a series of T-shaped glass beams are tested to develop a proper and safe design. Traditionally, glass is widely used in buildings as windows where its brittleness and strength capacity are not significant. Architects prefer to use glass in the structural field because of aesthetics, recyclability, and transparency. Although there is more demand for the usage of glass as a structural material, a common fear of its brittle nature and lack of research about its structural behavior have mostly hindered it. Since glass is a brittle material and has high compressive strength in the order of 400 to 800 MPa and lower tensile strength (40 to 120 MPa), post-tensioning to target distributed loads is investigated to increase its fracture capacity and even obtain a post-cracking ductile behavior. In this study, several material tests are conducted to confirm the theoretical mechanical properties of glass. After obtaining the bending and compressive strength of the glass, Finite Element Models (FEMs) of the T-beams were generated and analytical hand calculations were conducted. The tests of T-shaped annealed (float) and tempered (toughened) glass beams with and without post-tensioning were conducted. The results of the experiments were compared with the analytical hand calculations and FEM results. A favorable outcome of this study is that float glass’ post cracking strength has been drastically increased and a ductile post-cracking performance is obtained. Tempered glass has a brittle response but with much higher strength, with about 4 times the capacity of annealed glass T-beams