Date of Award
Doctor of Philosophy (PhD)
Civil and Environmental Engineering
Riyad S. Aboutaha
Precast-prestressed concrete (PC) girders are among the most cost-effective type of girders used on highway bridges. Unfortunately, in corrosive environments, corrosion of strands may result in cracking or spalling of concrete, cross-section loss of strands and degradation of material properties, which in turn reduces the load-carrying capacity of PC bridges.
This research presents an in-depth analysis of residual flexural strength of corroded AASHTO Type II pretensioned PC girders with a cast-in-place (CIP) concrete deck. The investigation involved development of a detailed Finite Element Analysis (FEA) model of the pretensioned girder-deck system subjected to corrosion. The FEA model developed for this research considered bond deterioration between corroded strands and surrounding concrete, deterioration of material properties and cross-section loss of corroded strands. The FEA model was verified against experimental data from relevant research studies and showed good agreement. Over three hundred pretensioned concrete girder-deck systems were investigated with the developed FEA model. Several design parameters were considered: 1) span-depth ratio, 2) prestressing reinforcement ratio, 3) corrosion level, 4) number of corroded strands, and 5) corrosion length. Results from the FEA model were used to develop a detailed analytical model to study the residual flexural strength of the girder-deck system. Then, the analytical model was applied to study the impact of those five parameters listed above on the residual flexural strength of investigated girder-deck systems.
It was concluded that corrosion of prestressing strands significantly influenced the failure mode and load-bearing capacity of pretensioned PC girder-deck systems. When corrosion level was lower or equal to 7.5%, the girder-deck system failed by crushing of the concrete in the compression zone. For a corrosion level higher or equal to 12.5%, the girder-deck system exhibited a rupture failure of prestressing strands. The girder-deck system that was corroded to a mass loss between 7.5% and 12.5% failed either by crushing of the concrete or strand rupture, depending on parameters such as span-depth ratio, prestressing reinforcement ratio, number of corroded strands, and corrosion length.
When a corroded pretensioned girder-deck system failed by crushing of the concrete, the decrease in flexural capacity was affected mainly by the number of corroded strands and corrosion levels. Impacts of corrosion length, span-depth ratio and prestressing reinforcement ratio on the strength reduction were negligible. When a corroded pretensioned girder-deck system failed by strand rupture, the impact of corrosion length on the strength reduction should also be considered.
Finally, a simplified practical model has been developed to estimate the residual flexural strength of corroded pretensioned girder-deck systems. The simplified model was tested against the data of analytical and FEA models, and showed good agreement.
Yan, Bo, "Residual flexural strength of corroded AASHTO TYPE II pretensioned concrete girder-deck system" (2019). Dissertations - ALL. 1042.