Experimental Verification of the Buckling Strength of Structural Glass Columns

This paper deals with experimental research of axially loaded members made of structural (laminated) glass. The purpose of the research is the evaluation of buckling strength and actual behaviour of the columns due to the absence of standards for design of glass load-bearing structures. The experimental research follows the previous one focusing on measuring of initial geometrical imperfections of glass members. Within the frame of the research 15 specimens were tested. All of them were of the same geometry (length 1500 mm, width 150 mm and thickness 12 mm) but had different composition - monolithic glass or laminated double or triple glass made of annealed or fully tempered glass panes bonded together by PVB or EVASAFE foil. Due to rectangular cross section and considered boundary conditions, flexural buckling perpendicular to the weak axis of the cross section occurred. During the testing, lateral deflection and normal stresses at mid-span were measured. Maximum force achieved during the testing has been adopted as buckling strength. Euler's critical loads and equivalent geometrical imperfections were evaluated using a Southwell's method. The results of experiments were statistically evaluated according to the European standard for design of structures EN 1990, appendix D. There are significant differences between the specimens made of annealed glass or fully tempered glass and between the specimens laminated with using PVB or EVASAFE foil - the differences are in the values of buckling strengths and load - deflection, load - stress plots. The next step was to determine the design strength by calculation procedure based on buckling curves approach intended for design of steel columns.