Semester

Summer

Date of Graduation

2003

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Samir N. Shoukry.

Abstract

In this thesis, the dowel-pulling force and the dowel-concrete coefficient of friction were measured using a novel laboratory setup of vibrating wire strain gauges embedded in both the dowel and concrete. The gages are set to measure the shrinkage strain induced in the concrete that surrounds the dowel as it cures causing the solidified concrete to clamp on the steel dowel. The measurements reveal that radial strain in concrete around the dowel is not uniform along the dowel circumference. As the dowel is pulled out of concrete, both the dowel-pulling force and the elastic strain recovery in concrete are recorded versus the dowel displacement. A theoretical model is developed to enable calculation of the dowel-concrete friction coefficient. Three-dimensional finite element analysis is used to estimate the stress field in the concrete surrounding dowel bars. Experiments are conducted to examine the effect of dowel bar diameter and type of bond-breaking agent on the friction coefficient and the magnitude of dowel-pulling force. The results indicate that the use of silicone as bond-breaker produces lower dowel-concrete coefficient of friction than that obtained using Tectyl (506). The results from finite element analysis indicate that the magnitudes of stresses in concrete surrounding uncoated steel dowels is higher than those obtained if the dowels are coated using bond-breaker. (Abstract shortened by UMI.).

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