| dc.description.abstract | Two of important factors in longevity of prestressed concrete bridge girder are the effect of corrosion to prestressing reinforcement in concrete and process of stress transferring from prestressing strands to concrete. The process of stress transfer controls the overall quality of structural member in term of providing significant contribution to bridge girder shear capacity. During the process of stress transfer, a bond between prestressing reinforcement and concrete is established by Hoyer’s effect. Prestressed bridges are expected to last approximately 50 years. However, because of the corrosion due to the penetration of chemicals at the end region of the bridge girder, where the process of stress transfer initially occurs, concrete starts spalling and breaks bond between it and prestressing strands. Therefore, the bridge girder loses their shear capacity by time. In some scenarios where shear capacity is slightly affected, the bridge girder can be repaired on site, but replacement of bridge girder is the last option when it is damaged severely.
In this research, the investigation and experiments were conducted to evaluate the feasibility of rehabilitating shear capacity by encapsulating corroded end region with new repair materials as Ultra-High Performance Concrete (UHPC), Fiber-Reinforced Self-Consolidating Concrete (FR-SCC), and Magnesium-Alumino-Liquid Phosphate (MALP) concrete. The purpose of this research does not restore the lost prestressing force at the end region but create large cross-sectional dimensions using high quality materials for retrofitting. The repair materials shall construct a low-permeable or impermeable block around the end region to resist further corrosion occurs. For the research’s experiment, nine half-scale AASHTO Type II girders were constructed with a hollow space, whose dimension was 18 in. x 9 in. x 2 in., at one end of the girder to represent the corroded region. The, the repair materials were cast to encapsulated corroded region and tested to bring out the result of repair’s contribution in rehabilitating the shear strength of girder. The new materials bonded to the conventional concrete well, which pointed out that the integral behavior of composite member was conservative. However, UHPC and FR-SCC increased the girder’s ultimate load capacity while MALP was overestimated as it did not increase the ultimate capacity of the girder as well as other materials. Also, the appearance of the new materials changed the failure mechanism of the girder from bond-shear failure (Mujtaba, 2021) to bond-shear/flexure failure. The outcomes of this research shall provide the Oklahoma Department of Transportation a perspective in comparison of performance between three repair materials, and quality control of each repair materials in use. | en_US |
