Prediction of blast pressure-duration capacity of monolithic Thermally Tempered Glass panes

Most standards and documents for blast-resistant design of glazing systems are based on simplified Single Degree Of Freedom (SDOF) models and triangular blast pressure time histories with no negative phase. Previous experimental studies have clearly indicated that pressure-duration or pressure-impulse design curves generated from such SDOF models may be overconservative, especially during impulsive blast scenarios. In this study, pressure-duration capacity curves for various monolithic Thermally Tempered Glass (TTG) panes are derived using Finite Element (FE) models. Moreover, the imposed blast pressure time histories include both positive and negative phases, which are deemed to be more realistic than considering the positive phase alone. Previous blast tests have shown that TTG panes can experience significant in-plane strain before fracture and exceeding the cracking strength does not necessarily mean fracture and disintegration of the pane. Accordingly, in the present study, glass fracture is judged based on the maximum principal strain rather than the stress criterion which has been widely used in earlier studies. The accuracy of the FE modeling technique and the abovementioned fracture criterion is verified using these blast test results on TTG panes. Pressure-duration curves of predicted capacity are obtained for TTG panes with different aspect ratios (1, 1.25, 1.5, 1.75, 2), different thicknesses (8 mm, 10 mm, 12 mm, 16 mm) and different widths (600 mm, 900 mm, 1,200 mm). Similar to current available standards, four edges of the adopted panes are restrained in the out-of-plane direction, but without in-plane or rotational restraints. The obtained pressure-duration capacity curves are compared with those provided by UFC 3-340-02. This shows that UFC's pressure-duration capacity curves are overconservative in both the impulsive and quasi-static regions.