Standard Practice for Determining the Thickness of Glass in Airport Traffic Control Tower Cabs

Importancia y uso:

5.1 This standard procedure facilitates determination of the thickness of a glass construction required to resist a specified design load with a selected probability of breakage.

5.2 For optical purposes, ATCT cab glass typically utilize only annealed glass products. For this reason, some specifying authorities mandate its use and prohibit heat-strengthened and tempered glass in control cabs. This standard procedure therefore addresses the following glass constructions: annealed monolithic, annealed laminated, and insulating glass fabricated with annealed monolithic or annealed laminated glass, or both. In cases where the specifying authority approves the use of heat-strengthened or fully tempered glass in the control cab or in areas where optical characteristics do not apply but are deemed critical to the facility operation, the NFL values obtained from standard may be adjusted using appropriate Glass Type Factors (GTF) and procedures for their use as specified in Practice E1300.

5.3 Use of these procedures assume:

5.3.1 The glass is free of edge damage and is properly glazed,

5.3.2 The glass has not been subjected to abuse,

5.3.3 The surface condition of the glass is typical of glass that has been in service for several years and is significantly weaker than freshly manufactured glass due to minor abrasions on exposed surfaces,

5.3.4 The glass edge support system is sufficiently stiff to limit the lateral deflections of the supported glass edges to less than ¹/₁₇₅ of their lengths. The specified design load shall be used for this calculation, and

5.3.5 The center of glass deflection shall not result in loss of edge support. Typically maintaining center of glass deflection at or below the magnitude of three times the nominal glass thickness assures that no loss of edge support will occur.

5.4 Many other factors affect the selection of glass type and thickness. These factors include but are not limited to: thermal stresses, the effects of windborne debris, excessive deflections, behavior of glass fragments after breakage, seismic effects, heat flow, edge bite, noise abatement, potential post-breakage consequences, and so forth. In addition, considerations set forth in federal, state, and local building codes along with criteria presented in safety glazing standards and site-specific concerns may control the ultimate glass type and thickness selection.

Subcomité:

E06.52

Volúmen:

04.12

Número ICS:

81.040.20 (Glass in building)

Palabras clave:

annealed glass; deflection; flat glass; glass; insulating glass; laminated glass; load resistance; monolithic glass; probability of breakage; strength; wind load;