The Need for a Methodology to Assess Surface-Damaged Glass

Mark K. Schmidt and William J. Nugent

In the past 18 months, the authors have been retained to assess the aesthetic and structural adequacy of surfacedamaged heat treated glass on several high-rise buildings throughout the United States. Some of these projects involved glass on recently constructed buildings, while others involved glass on buildings more than 30 years old.

Existing and historical standards for architectural glass provide visual criteria for determining the acceptability of various surface flaws in new glass. Standards do not exist for assessing surface flaws in glass that has been in service. The criteria given in the standards for new glass are intended to address aesthetics; the structural implications of allowable flaws are not presented. Most of the damaged glass investigated did not meet existing or, where applicable, historical glass standards for allowable surface flaws. Yet many of these flaws were not visually objectionable to building occupants. The documented glass conditions on these high-rise buildings and similar glass surface flaws on other structures demand a methodology to properly assess such conditions.

This paper presents a compelling case for additional research and testing to determine the structural implications of surface flaws. In the absence of such a methodology, the authors propose a project-specific protocol for evaluating the aesthetic and structural adequacy of glass with significant surface flaws. Issues related to removal of surface flaws are also discussed.

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The Authors

	Mr. Mark Schmidt Structures Unit Manager Wiss, Janney, Elstner Associates, Inc. Read more
	William Nugent Wiss, Janney, Elstner Associates, Inc. Mr. Nugent joined WJE in 1976 and has since completed over 400 investigation, testing, and repair design projects. Mr. Nugent’s experience includes seismic damage assessment and retrofit design, inves... Read more