Full-Scale Field Failure Tests of Railway Bridge

Full-scale ultimate load tests were conducted in March 1995 on the bearings of the Strawberry Park Bridge, a two-span, 45 m (148 ft) long ballasted railway bridge typical of many such bridges around the country. The bridge, located in Los Angeles, was scheduled for removal in spring 1995, a fact which allowed for the performance of failure push tests on the bridge, with the pushing loads applied at the bridge abutments. The main objective of this experiment was to identify the extent to which the rails, ties, and ballast and the plate containing the ballast (ballast pan or tie plate) help to strengthen the bridge during a seismic event. The rails, ballast, and ballast pan were completely removed at one end, while the other end was left in its as-built condition. The bridge was then pushed laterally to failure at both ends. Comparison between the failure loads at each end indicated that the as-built end was 45% stronger than the free end.