LAMINATED GLASS

INTRODUCTION

Laminated safety glass is a multifunctional glazing material that can be used in applications ranging from residential to commercial installations.
When impacted,laminated glass typically breaks safely and remains an integral part of the opening. The plastic in terlayer minimizes splinters and glass fragments, reducing the risk of injury or property damage.
This is particularly important during natural disasters such as hurricanes, tornadoes and earthquakes ,and it is widely specified for these types of applications. Impulse burglaries can also be resisted by laminated glass because it is difficult to gain access or remove property,even if a puncture is made in the in terlayer.

DESCRIPTION

Laminated safety glass is manufactured by permanently bonding two or more lites of clear, tinted, Low-E, patterned, wired or reflective glass with one more or more layers of polyvinyl butyral (PVB) sheets. Assembly takes place in the carefully controlled environment of a clean room, ensuring no contaminants are trapped in the product. Final bonding is achieved in an air autoclave under heat and pressure, which creates a single solid construction.

The glass can be annealed, heat-strengthened or fully tempered, and the lites can be of equal or unequal thickness. Laminated safety glass can be used as the inboard, outboard or both lites in an insulating glass unit. By combining tinted glass, reflective coatings and pigmented interlayers, a wide array of laminated glass configurations can be used to meet specific visual, aesthetic, security, performance and code requirements.

PERFORMANCE

Structural Strength

Laminated glass strength and deflection are discussed in detail in ASTM E1300 Standard Practice for Determining the Load Resistance of Glass in Buildings. The model building codes contain requirements for wind, snow and dead loads on glass. The applicable state laws and local building codes must be checked to determine minimum glass strength requirements governing each project.



SLOPED AND OVERHEAD GLAZING, SKYLIGHTS AND POINT-SUPPORTED CANOPIES



INTRODUCTION

Glass which slopes more than 15° from the vertical is considered sloped glazing by the major model building codes. Laminated glass is the preferred product for sloped and overhead glazing, because the glass is retained in the opening, even when broken, reducing the possibility of injury from falling glass. Costly and unsightly screens are therefore not required. Laminated products are widely used in malls and in atriums in hotels and offices.

DESCRIPTION

Laminated glass for use in sloped and overhead glazing can be used monolithically or fabricated into insulating glass units. Insulating glass units typically consist of an outboard lite of heat-strengthened or tempered glass that resists accidental damage caused by falling objects, and an inboard laminated glass that captures any fragments. This type of laminated glass often incorporates heat-strengthened glass to meet the structural performance requirement, so that heavy snow loads and high wind loads can be accommodated. In addition, when tinted or reflective glass is used to control the solar heat gain, it is usually necessary to use heat-strengthened or tempered glass to avoid the possibility of thermal breakage. When heat-strengthened or tempered glass is used in a laminated glass, the minimum interlayer thickness is generally 0.76 or more.

CAPABILITIES



Blast-Resistant Glass



INTRODUCTION

In recent years, the bomb has become the weapon of choice for many terrorist attacks. The high explosive detonation, with its associated property damage, injury, flames and noise, draws immediate attention and instills fear beyond that of armed attacks.

It has been documented that the blast energy causes collateral damage to many surrounding structures, not just the intended target. Glass fragmentation hazards have been identified as a main cause of injury in the targeted site, as well as the peripheral sites. Because collateral damage often extends several blocks from the site of the bomb, it can affect hundreds, possibly thousands, of people, especially in urban areas.

DESCRIPTION

Laminated glass is an excellent glazing choice in all types of buildings that may be subjected to bomb blasts. The tough plastic interlayer holds the glass together after an impact, and with the proper framing systems, the glazing will be retained in the opening. Thus, the amount of flying glass, as well as the consequential injuries, can be dramatically reduced.

The pressure from a bomb typically consists of a wave that rises almost instantaneously to a very high peak pressure that falls back to zero in a very short duration, as measured in milliseconds. For example, a 27 lb. bomb detonated from a stand-off distance of 48 ft. produces a peak pressure of 10 psi (1,440 psf ) for 3.3 milliseconds.

The area under the pressure time graph is called the impulse and is measured in psi-ms. Blast wave energy decreases very rapidly with distance so that the most effective protection is to increase this “stand-off ” distance. However, this is not always a viable or economic option.

CAPABILITIES

The following constructions of laminated glass are most commonly specified for bomb-blast resistance.

As with all laminated glazing, the glass can be supplied as tinted or reflective for light and solar control purposes. The lites of glass can be either annealed or heat-strengthened. AluNile Glass does not recommend tempered laminated glass in this type of application. When insulating glass units are required for thermal performance, AluNile Glass recommends that both lites of the IG unit be laminated in order to provide maximum protection for those both inside and outside the building.

If only one lite in the IG unit is to be laminated, it must be the interior lite so as to protect the occupants of the building.