Date of Award
Master of Science (MS)
Fortney, Patrick J.
Schiff , Scott D.
Rangaraju , Prasad R.
When a prestressed concrete structure is subjected to a severe fire, significant damage is created to the extent that a visual analysis is sufficient in rendering the structure unusable. Although moderate fires also create structural damage, the effects can often not be visually assessed. Therefore, a need exists for a method that allows structures to be evaluated after a fire has occurred and visual observations present no conclusive evidence for making decisions regarding the structural impact of the fire on the structure.
It was assumed that temperature histories of a member arising from a moderate fire can be determined using other analytical forensic techniques such as thermogravimetric analysis (TGA).
Experimental cross-sectional temperature profiles of prestressed concrete beams were measured for different temperature durations using a heating regimen that would represent a moderate fire. Based on these profiles, analytical constituent material models were generated using a cross-sectional fiber analysis program. The residual material properties of steel and concrete used were based on previous research. Moment-curvature relationships were generated for each heating duration. Finally, load tests were performed to measure force-deflection relationships of full scale heat affected concrete beams after cooling.
The results from this project indicate that a cross-sectional analysis program can predict the characteristics of a heat affected concrete beam within a reasonable degree of accuracy. The general degradation of strength and stiffness found from the experimental results were noted in the theoretical output. Based on this research, the structural integrity of heat affected prestressed concrete beams can be better estimated.
Collins, Travis, "Estimating In-Situ Flexural Strength of Heat-Affected Prestressed Concrete Beams Using Constituent Material Models" (2008). All Theses. 443.