Experimental, numerical and analytical investigations on the segmented post-tensioned hybrid steel-glass beams TVT

In contemporary architecture, there is an increase in the application of glass as a load-bearing material besides the traditional use as an infill material. Glass columns, glass beams and glass walls are applied in several structures such as footbridges, roof structures, canopy structures and facade structures. This dissertation deals with the structural response and functioning of a specific kind of segmented post-tensioned hybrid steel-glass beams, which combine the compressive strength of glass with the tensile strength and the elastic-plastic behaviour of steel. Segmented post-tensioned hybrid steel-glass beams are composed of post-tensioned steel bars and small laminated glass segments joined by contact without any use of bolted connections, glued connections or other mechanical fixings. Steel bars transfer the tensile forces while the compressive forces are in the compression zone of the glass. No internal tensile forces or cracks occur in the glass thanks to segmentation. As part of the PhD research, a 12-meter-long segmented post-tensioned hybrid steel-glass beam prototype has been designed, constructed and tested. Experimental dynamic investigations have been performed to determine the beam natural frequencies and mode shapes under free vibrations. A four-point bending test was carried out to determine the tensile forces in steel bars and to investigate the stiffness, the strength and the load-bearing capacity of the beam. The structural static response of the 12-meter-long beam has been investigated by using 3D numerical modeling. Geometric nonlinearities, friction and material nonlinearities were implemented in the model, and various numerical analyses were performed to investigate the effects of friction, post-tensioning forces and mechanical properties of the interlayer. An analytical model has been developed to calculate the axial forces in steel bars, the compressive forces in the laminated glass elements and the deformation of the beam. The material nonlinearities and the effects of friction were included in the analytical model as well. Both the numerical and the analytical models were validated by comparing the simulated behavior of the beam with the experimental investigations. The research contributes to a better understanding of the structural behavior of this kind of glass beam and of the parameters that affect its breakage and post-breakage response. The experimental investigations demonstrate that the breakage of the beam is ductile owing to to the plastic deformation of tensile steel bars. The numerical and the analytical models can assist the design of segmented post-tensioned hybrid steel-glass beams.