Date of Award
Master of Science
Civil, Construction, and Environmental Engineering
Lowell F. Greimann
James E. Bolluyt
A pilot study was conducted on the premature failures of neoprene strip seals in expansion joints in Iowa bridges. In a relatively large number of bridges, strip seals have pulled out of the steel extrusions or otherwise failed well before the expected life span of the seal. The most serious consequence of a strip seal failure is damage to the bridge substructure due to salt, water, and debris interacting with the substructure.
A literature review was performed. Manufacturers' specifications and recommendations, practices in the states bordering Iowa, and Iowa DOT design and installation guidelines were reviewed. Iowa DOT bridge databases were analyzed. A national survey was conducted on the use and performance of strip seals.
With guidance from the Iowa DOT, twelve in-service bridges with strip seal expansion joints were selected for detailed investigation. Effective bridge temperatures and corresponding expansion joint openings were measured, DOT inspection reports were reviewed, and likely cause(s) of premature failures of strip seals were proposed.
Experimental results show that for a majority of these serious failures (all in concrete girder bridges), the joint opening at 0°F predicted by the Iowa DOT design equations, the joint opening at 0°F extrapolated from the experimental data, or both, are larger than the movement rating of the strip seal specified on the bridge plans. Other likely causes of premature failures of seals in the twelve bridges include debris and ice in the seal cavity, skew of bridge deck, improper installation, and improper setting of the initial gap.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Kau, Vui-Bin, "Performance of strip seals in Iowa bridges: pilot study" (2001). Retrospective Theses and Dissertations. 17261.