Laminated Glass
Despite the apparent variety of modern technological solutions in the field of glass processing, the actual range of measures to improve the reliability and safety of
LAMINATED GLASS TO COMPARE PVB AND SGP GLASS
Despite the apparent variety of modern technological solutions in the field of glass processing, the actual range of measures to improve the reliability and safety of double-glazed building structures is very limited.
Until now, the most used method to reduce the risk of glass destruction in the manufacture of glass structures and their subsequent operation is mechanical processing of the edges of the glass product, in other words, grinding the edges of the glass around the perimeter, which allows you to eliminate micro-cracks on the edges of the glass plate that occur when cutting glass. In addition, when grinding along the perimeter, the corners that are most susceptible to microcracks are “removed”, they are rounded. Mechanical processing is carried out before the glass is tempered.
Currently, the most common solution to this problem is triplexes, with an intermediate layer of polyvinylbuteral film (PVB). It should be said that this method has significant disadvantages when used in large structures.
It is known that the PVB film is an elastic thermoplastic that depends on the ambient temperature, as well as on the duration of exposure to various loads.
Thus, a rigid connection between the layers can only be provided when calculating the effect of short-term loads received from the wind or from various shock effects.
For long-term loads, triplexes using PVB must be calculated using a semi-rigid scheme, which, among other things, depends on temperatures exceeding 23 degrees C. That is, in other words, the semi-rigid circuit will work in the temperature range below 23 degrees C.
At higher temperatures, PVB gradually peels off, and at a temperature above 80 degrees C, which is quite possible on a translucent roof, delamination occurs, i.e. complete separation of it from the glass.
Currently, multilayer glass has begun to use special films that are intended for facades and roofs exposed to high temperatures, i.e. solar overheating: these are adhesive films of EVA, CIP, SPG, which have similar properties to PVB.
The intermediate layer of the SPG type film is specially designed for glazing various buildings and structures erected in hurricane-dangerous areas. The hardness of this layer exceeds PVB by 100 times. And temperatures up to 70 degrees do not affect its strength characteristics. Triplex with such an intermediate layer is designed for the effect of long-term loads on the translucent structure.
The residual carrying capacity of PVB-based triplexes can be increased by using a film of greater thickness. It is also important that the use of SPG significantly reduces deformations after failure.
Additional work on triplexes has shown that the residual load-bearing capacity of triplexes can be significantly increased when introduced into the intermediate layer of fabrics and fibers.
Thus, the modern construction industry continues to actively work towards improving the reliability and safety of glass construction structures.
2020-Apr-19