Designing for Structural Stability
Of the many demands placed on construction projects today, two basic needs have remained constant. The building and all its components must be structurally sound and be able to keep weather elements from entering the building. A breach in the building envelope can produce several undesirable and often dangerous effects:
- Internal pressure
- Exposure of occupants to wind and rain
- Damage to building contents
- Additional debris in the wind stream and hazardous debris falling to the street
- Disruption of business
Laminated Architectural Glass (LAG)
Laminated architectural glass made with Saflex protective interlayer can meet structural codes and building standards in a variety of applications and designs:
- Insulating glass units
- Overhead glazing
- Glass floors
Laminated glass is formed by permanently bonding two pieces of glass to a tough, resilient, protective interlayer through a high-temperature and pressure process. This is important because even when the glass is broken due to sufficient impact, the pieces of glass tend to adhere to the interlayer.
Insulated Glass Units (IG)
Insulating glass contains a sealed air space that results in “load sharing” between lites. The lites will share the load equally if the lites in an IG unit are the same type (AN, HS, FT*), are equal in thickness and are relatively thin. If the glass is not symmetrical, then load sharing will not be equal and needs to be calculated to determine the strength of the unit. Insulating units can utilize laminated lites in one or both glass positions. In most applications, when laminated glass is used as only one lite of an insulating system, the laminate should be placed toward the interior of the building. For optimum protection of occupants and from injuries resulting from falling glass, consider use of a double laminated insulating unit.
*AN = Annealed glass, HS = Heat-strengthened glass, FT = Fully Tempered glass.
Overhead Glazing
The three model building codes define "overhead glazing" as glass that is positioned over space that may be occupied by humans. The model codes, in effect, prescribe laminated glass for overhead glazing that is either a single lite or the lower lite in an insulating glass unit. However, other products are allowed provided post breakage controls are in effect (e.g., mesh under tempered lites). Overhead glazing should not be exposed to the weight of a person and should be designed to discourage people from walking on glass surfaces. If necessary, the ability of a lite in an overhead glazing unit to withstand human loads can be checked using the equation for a concentrated load, based on a floor design.
Glass Floors
Laminated glass floors are popular today. Calculations for floor loads can be found in the model building codes. In the design of glass floors (walking surface of floors, landings, stairwells and similar locations) for human and other loads, it is generally recommended that the following criteria be used:
- Laminated glass should have a minimum of three plies and should be capable of supporting the total design load with any one ply broken
- Surface damage caused by people or by objects placed on glass can significantly reduce the strength of glass (subjecting it to breakage under subsequent loads) and should therefore be considered in the design
- Glass floors may be subject to conditions that make them slippery or targets of high-pressure or high-impact loads
- The surface of the glass and the application areas should be given special consideration during design
Laminated Glazing Has Additional Benefits
In addition to structural benefits, Saflex interlayer provides all the other benefits inherent to laminated glass, including:
For more information on Saflex interlayer, contact us.
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