Tubular Glass Columns

Abstract

Glass has become ever more popular in the building industry. Glass is already used in facades, staircases, fins, floors, and beams. Nevertheless, free-standing load-bearing glass columns are rarely used. It needs to be robust, which means that it needs to give a warning before failure so that people can evacuate. Glass is a brittle material and has a sudden failure, which means that it is not directly logical to use solid glass as a load-bearing structural column. Rather despite the high compressive strength, due to complications with manufacturing, spontaneous failure, and lack of satisfactory of fireproof performance, more research needs to be done on the manufacturing, the fire safety, and the robustness of glass columns. In the literature study, the layered tubular glass column was found to be most promising for further investigating. The aim of this research is to design and engineer a transparent tubular glass column as a structural element, which is robust and fireproof. In the literature study a few aspects emerged: the tubular shape, the column needs to be sealed to avoid the column from becoming dirty, end connections, the geometric tolerances in the glass tubes and the robustness. The designs were engineered for the case study Bouwdeel D in Delft, but the designs can also be applied to other buildings: the fire resistance, demountability, the dimensions and the calculated compression loads. With these aspects in mind, three designs were engineered, the MLA (Multi Layered with Air) (2x) and the SLW (Single Layered with water) (1x) which fulfil the defined design criteria/main concerns. Six small samples with a length of 300 mm were produced to test the lamination process with regard to bubble formation and possible breakage of the glass by internal stresses. Three laminated DURAN (annealed) samples and three laminated DURATAN (heat-strengthened) samples were tested. The glass tubes were manufactured by extruding and were made by SCHOTT. H.B.Fuller Kӧmmerling carried out the lamination process. Furthermore, the connection components (steel and POM) were produced and arranged by Octatube, the steel hinges were arranged by Techniparts, and the Hilti mortar was arranged by Hilti. Afterwards, these samples were tested on compression strength, to investigate the behaviour of the interlayer material, the post-failure behaviour of the designs, the differences between annealed and heat-strengthened glass samples, the behaviour of the connections under pressure, and the capacity of the glass tubes and the connections. The first cracks appeared earlier than expected. Nevertheless, the samples seemed to be really robust, because the samples had a large load-bearing capacity even after the first cracks occurred. The first crack appeared between 95-160 kN in the DURAN samples, and after that the samples were still able to carry a load of 700-750 kN. So, after the first crack, the specimens were able to have around 4-5 times more load. The heat-strengthened samples first cracked at 120-160 kN. The maximum force of these samples was 390-490 kN. This means that after the first crack, the specimens were able to have around 3 times more load.