Field Test/Fatigue Investigation of the Summit Bridge

摘要

Based on the controlled and ambient load testing, combined with the fatigue monitoring of the Summit Bridge, the following conclusions can be made. 1. There appears to be minimal in-plane bending occurring in the truss members monitored. This suggests that the bridge is behaving much like an idealized pin connected truss. 2. The maximum stress range in any of the members at Site 1 caused by the 73 kip test truck during the controlled load test was 2.93 ksi (measured in member U3-L4). This occurred during the fast pass, with the truck in the southbound, slow lane. 3. The maximum stress range in any of the members at Site 1 during the two hours of ambient traffic monitoring was 3.68 ksi (measured in member U3-L4). 4. The computed effective stress ranges for Site 1 members L4-L5, L3-L4, U3-L4, and U1-L2 were 1.46, 0.96, 2.38, and 1.87 ksi respectively. 5. The field test provided accurate measures of the effective stress range of the truss members. Based on the measured data, all members at Site 1 experienced some stress cycles greater than the CAFT during the monitoring period. However, based on the very small number of cycles above the CAFT the members were classified as having infinite fatigue life. As a result, no remedial action or repairs to the bridge were ordered.