Atkinson-Noland & Associates, Inc.
Bridge Diagnostics, Inc.
Atkinson-Noland & Associates, Inc.


Historic masonry arch bridges were not designed to carry modern truck and rail loads. However, due to their inherent strength and durability, many masonry arch bridges remain in daily service the logical question is: “Do these bridges have an adequate factor of safety for modern loads?” Semi-empirical rating methods can be overly conservative and lead to unwarranted load postings. A more refined approach, based on Finite Element Method (FEM) or Discrete Element Analysis (DEA), can provide improved understanding of the actual behavior of arch bridges and possibly predict their complex failure mechanism. However, this requires that the assumptions on material properties, soilproperties, soil-structure interaction and other parameters are realistic. To improve the accuracy of computer models of masonry arch bridges, nondestructive evaluation (NDE) techniques can be employed to provide additional information. Impulse radar can be used to provide additional geometric data such as the depth and configuration of the fill over the arch barrel, the thickness of the arch barrel and the location of utilities or voids in the fill. Further verification of the model can be accomplished by a simple load test on the bridge, which measures the bridge’s response to a known load.

Key words
Masonry arch, load rating, nondestructive evaluation, load testing