Analysis of residual stresses at holes near edges in tempered glass

Point‐fixed glazings of tempered glass are popular in facade and roof constructions. The distances from the hole to the glass edge specified in DIN 18008 are restrictive for many designers and should be reduced from an aesthetic point of view. However, if the specified distances are not reached, only the strength of the basic glass can be applied according to the standard. In the presented paper, residual stresses at holes near the edges of tempered glass are analyzed experimentally. For this purpose, photoelastic measurements and four‐point bending tests are carried out on a series of modified standard specimens with different edge distances and hole diameters. The results of the investigation show that the depth of the residual stress zones, hole and edge, are significantly influenced by the glass thickness and the hole diameter. In addition, it was shown that the characteristic bending strength of these tempered glass panes with near‐edge holes was achieved for almost all test series. The achieved results could lead to a reduction of the edge distances of holes in tempered glass in the future standard.