In-situ evaluation of compressed brick veneer using the flatjack technique
The flatjack is a relatively nondestructive tool that allows engineers engaged in the repair and retrofit of masonry buildings (both historic and non-historic) to directly determine the in-situ state of compressive stress in masonry walls. The flatjack technique recently was used on a large modern apartment complex to quantify the compression in a brick veneer that was distressed and had questionable wind-load resistance. The compression in the veneer was due to a combination of concrete frame shrinkage and brick growth in a wall system that lacked horizontal control joints under the steel shelf angles. Although the compression caused spalling in the veneer, it also contributed beneficially to the walls' wind resistance. The amount of compression in the veneer was determined in several location throughout the height of one elevation of the building using flatjacks. The authors found that the compression in the veneer was greater than the flexural tension produced by design wind loads (including a reasonable factor of safety), but below the compressive strength of the brick masonry. This finding allowed a repair solution that was modest relative to strengthening the wall for inadequate wind resistance. Prior to employing the flatjack in the field, the authors conducted in-house research to check the accuracy and reliability of method, and develop their technique. The authors found that by altering gauge points from those locations prescribed by current ASTM standards to those recommended in recent research, greater accuracy could be obtained.
- Research Organization:
- Simpson Gumpertz and Heger Inc., Arlington, MA (US)
- OSTI ID:
- 20003788
- Resource Relation:
- Conference: Symposium on Masonry: Materials, Testing, and Applications, Nashville, TN (US), 12/08/1998; Other Information: PBD: 1999; Related Information: In: Masonry: Materials, testing, and applications. ASTM special technical publication 1356, by Brisch, J.H.; Nelson, R.L.; Francis, H.L. [eds.], 169 pages.
- Country of Publication:
- United States
- Language:
- English
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