FOUR-POINT BENDING TESTS OF DOUBLE LAMINATED GLASS PANELS WITH EVA INTERLAYER IN VARIOUS LOADING RATES

Abstract

: Current architecture tends to use glass as a load-bearing material thus glass beams, panels, columns or even stairs may be found. These members are mostly made of laminated glass with polymeric interlayer. Laminated glass performs good response in accidental situation because glass fragments stay attached to the interlayer and do not cause harmful injuries. Polymeric interlayer is able to ensure the transfer of shear forces between the individual panes in a perpendicularly loaded panel. This transfer depends on the shear stiffness of the interlayer as a time and temperature-dependent parameter which is not usually available. Civil engineers thus neglect this stiffness to stay on a safe side. This paper shows the experimental data gained from four-point bending tests of double-laminated glass panels with EVA based interlayer (Evalam 80/120 ® ) loaded in three various loading rates and illustrates the influence of the loading rate on the stress-state and vertical deflections of a panel. The analogy with shear stiffness of another EVA based interlayer (Evasafe ® ) is further commented. All experiments were performed at CTU in Prague. time domain. To verify small-scale experiments, large-scale four-point bending tests of double-laminated glass panels are appropriate. This paper describes performed experiments at CTU in Prague and introduces the experimental data, particularly normal stresses and vertical deflections at the mid-span cross section obtained from four-point bending tests of double-laminated heat toughened glass panels laminated with EVA (Evalam 80/120 ® ) interlayer. Bending tests were executed at three various loading rates. The analogy of experimental results with published initial shear stiffness of another EVA based interlayer (Evasafe ® ) obtained from quasi-static tests is further commented. Experimentally verified shear stiffness of polymeric interlayers used in laminated glass enables to capture the shear coupling of glass panes more precisely and enables to design more economical and simultaneously safe glass structures in practice.