Post-Fire Assessment of Prestressed Concrete Bridges in Indiana

US Transportation Collectionhttps://doi.org/10.5703/12882843172902021PDFTech ReportVarma, Amit H.Olek, JanWilliams, Christopher S.Tseng, Tzu-ChunPurdue University. Joint Transportation Research ProgramIndiana. Dept. of TransportationUnited States. Department of Transportation. Federal Highway AdministrationPurdue University. Joint Transportation Research ProgramIndianaUnited StatesDeteriorationEvaluation and assessmentFiresInspectionPrestressed concrete bridgesState of the practiceStructural analysisPrestressed concreteFireAssessmentsGirdersBridgesPost-fireDamageFHWA/IN/JTRP-2021/05SPR-4221Final ReportThis project focused on evaluating the effects of fire-induced damage on concrete bridge elements, including prestressed concrete bridge girders. A series of controlled heating experiments, pool fire tests, material tests, and structural loading tests were conducted. Experimental results indicate that the portion of concrete subjected to temperatures higher than 400\ub0C loses significant amounts of calcium hydroxide (CH). Decomposition of CH increases porosity and causes significant cracking. The portion of concrete exposed to temperatures higher than 400\ub0C should be repaired or replaced. When subjected to ISO-834 standard fire heating, approximately 0.25 in. and 0.75 in. of concrete from the exposed surface are damaged after 40 minutes and 80 minutes of heating, respectively. Prestressed concrete girders exposed to about 50 minutes of hydrocarbon fire undergo superficial concrete material damage with loss of CH and extensive cracking and spalling extending to the depth of 0.75\u20131.0 in. from the exposed surface. These girders do not undergo significant reduction in flexural strength or shear strength. The reduction in the initial stiffness may be notable due to concrete cracking and spalling. Bridge inspectors can use these findings to infer the extent of material and structural damage to prestressed concrete bridge girders in the event of a fire and develop a post-fire assessment plan.120