摘要: |
This report summarizes findings from monitoring data that was collected over a two-year period from Bridge No. 61390613004101 in the John James Audubon Project, which was formerly designated as Bridge No. 2 prior to construction completion. The bridge was instrumented as part of an earlier project (LTRC Project No. 08-1ST). Results from the first monitoring project warranted resuming data collection to monitor the performance of Bridge No. 61390613004101 over a longer period of time. The focus of the monitoring effort for both projects is on the employed continuity detail, which is based on the recommendation of the National Cooperative Highway Research Program (NCHRP) Final Report 519. Continuity details are typically used to eliminate the needs for highmaintenance joints that often lead to the acceleration of element deterioration near the joints. The employed positive moment continuity detail transfers forces between adjacent girders via positive moment reinforcement that extends out of the bottom flanges of the prestressed concrete (PSC) girders into a continuity diaphragm. The 96-channel monitoring system that was installed as part of Project 08-1ST was reactivated in February 2012. Data from the embedded and surface-mounted sensors that measure strains, temperatures, rotations, and gap openings in critical locations in the monitored segment were collected for a period of two years. The collected data from both projects (12-1ST and 08-1ST) was analyzed and interpreted. Furthermore, four field visits were conducted to document the condition of the girder ends in the monitored segment. Recommendations based on the project findings are drawn. Data shows that 5 years after the construction of the bridge, some long-term effects such as creep and shrinkage have diminished. It is also evident that temperature effects are still a major factor that continues to strain the bridge in such a way that should not be ignored in the design of bridges with similar continuity details. The high-localized strains at girder ends due to thermal variation caused cracking in a few girder ends. |