Field Studies of Strengthened Timber Railroad Bridge

Abstract

Comprehensive field testing had been done previously on a typical three-span, open-deck timber deck railroad bridge. The test program was done in cooperation with the Transportation Technology Center, Inc., of the Association of American Railroads. The bridge was subjected to static and moving train loads as well as controlled actuator ramp loading. The bridge was later stiffened by the addition of a stringer to each chord. The bridge was retested after the stiffening using moving train loads. Results of this field study are reported, and comparisons of the response of the bridge before and after the stiffening are made. The efficiency of the stiffening was between 82 and 97 percent.

General Considerations

“…It is recommended to focus on the overall structural behavior and to measure deck deflections or timber strains during a diagnostic load test (Gentry et al 2007), which can be used to determine the performance, and static and dynamic load distribution characteristics of the timber bridge (Wipf et al 2000). Diagnostic load testing of timber bridges can be used to determine the distribution of loads (Wipf et al 2000) or to evaluate the performance of rehabilitation measures (Gutkowski et al 2001). During the preparation stage of a diagnostic load test, the condition assessment is important to determine the state of the timber bridge and the used material prior to the test.…”

State-of-the-art on load testing of concrete bridges

“…Field tests on other bridge types have also been used to evaluate the performance of new concepts [71][72][73], as well as the performance of retrofitting actions [74][75][76][77]. Since arch bridges (masonry arch bridges or plain concrete arches) have a large redistribution capacity, load testing can be recommended, as analytical assessment virtually never shows sufficient capacity [78].…”