Control Tower Glass Design

Reformulation of ASTM Standard Practice E2461

Overview

Abstract

ASTM published the first version of ASTM E2461-05: Standard Practice for Determining the Thickness of Glass in Airport Traffic Control Tower Cabs in 2005. It was reapproved twice for continued publication. This document facilitated the design of annealed monolithic glass, annealed laminated glass, and insulating glass fabricated with annealed glass plies. The Federal Aviation Administration (FAA) had several reasons supporting its need for its own glass design standard. First, and foremost among the reasons, is that FAA sizes Cab glass to have load resistance (LR) values associated with probabilities of breakage much lower than 8/1000. Second, extant model building codes and standards at the time of its development addressed determination of LR but did not specifically address design. Finally, FAA Cab glass is typically trapezoidal rather than rectangular in shape. After nearly 15 years, the FAA chose to revise the original standard to bring it more in line with existing US glass model standards for architectural glass while maintaining its design aspect. In addition, window dimensions in FAA Control Tower cabs have increased beyond size limitations in the original version. To those ends, the authors revised the original standard. Details of the revision are summarized. Most notably, as in the original version, the use of LR charts to quickly and efficiently determine requisite glass thickness to resist specified loads is described.


Authors

Photo of Daniel McCormack, P.E., PMP, M.ASCE

Daniel McCormack, P.E., PMP, M.ASCE

Federal Aviation Administration

Photo of Stephen M. Morse, Ph.D., P.E., M.ASCE

Stephen M. Morse, Ph.D., P.E., M.ASCE

Assistant Professor

Michigan Tech University

Photo of Scott H. Norville, Ph.D., P.E., F.FTI, F.ASTM, F.ASCE

Scott H. Norville, Ph.D., P.E., F.FTI, F.ASTM, F.ASCE

Professor

Texas Tech University

scott.norville@ttu.edu


Keywords

Introduction

Windows that glaze FAA control tower cabs typically are exceptionally large and lean outward. Because they lean outward, they are trapezoidal in shape. They are fabricated almost exclusively from annealed glass. From 2003 through 2004, researchers at Texas Tech developed he first version of ASTM E2461-05: Standard Practice for Determining the Thickness of Glass in Airport Traffic Control Tower Cabs. Recently, the FAA approached Texas Tech to revise the standard. The first author on this paper served as the contract monitor for the FAA. There were several reasons necessitating the revision. Those reasons, along with significant changes from the previous version are outlined below. At the time of writing, the revision is going through the ASTM balloting process.

Background

Both the original version ASTM E2461 (ASTM, 2005; ASTM 2012) and the revision described herein find their basis in the failure predication model (Beason and Morgan, 1984; Beason and Norville

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Scope and Summary of Use of the Standard

The standard practice addresses the determination of thickness of glass used to glaze airport traffic control towers to resist a specified loading with a selected probability of breakage less than

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Discussion

This paper introduces the latest revision to ASTM E2461-22: Standard Practice for Determining the Thickness of Glass in Airport Traffic Control Tower Cabs. The revised standard practice accommodates larger glass

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Rights and Permissions

ASTM. (2005). “Standard Practice for Determining the Thickness of Glass in Airport Traffic Control Tower Cabs.” ASTM E2461-05, ASTM International, West Conshohocken, PA.

ASTM. (2012). “Standard Practice for Determining the Thickness of Glass in Airport Traffic Control Tower Cabs.” ASTM E2461-12, ASTM International, West Conshohocken, PA.

ASTM. (2016). “Standard practice for determining load resistance of glass in buildings.” ASTM E1300-16, ASTM International, West Conshohocken, PA.

Beason, W. L., and Morgan, J. R. (1984). “Glass failure prediction model,” J. Struct. Eng., 110(2), 197-212.

Beason, W.L. and Norville, H.S. (1989). “Development of a new glass thickness selection procedure," Proceedings, Sixth U.S. National Conference on Wind Engineering, University of Houston, Houston, TX, March 8-10, A-8-1 through A-8-16.

Jackson, R.C. (2001). “Load resistance of trapezoidal window glass.” M. S. Thesis in Civil Engineering, Texas Tech University, December.

Norville, H.S., El-Shami, M.M., Jackson, R., and Johnson, G. (2002). “Wind load resistance of large trapezoidal glass lites," The Use of Glass in Buildings, ASTM Stock Number 1434, 69-89.

Soules, J.G., Morse S.M., and Norville, H.S. (2020). "Application of the glass failure prediction model to flat dd shaped glass using finite element modeling,"Journal of Architectural Engineering, ASCE, https://doi.org/10.1061/(ASCE)AE.1943-5568.0000437.