BRIDGE TESTING - A SURPRISE EVERY TIME

Experience with field testing of highway bridges in Ontario, Canada, during recent years shows that nearly every bridge has some aspect of behavior that can escape the attention of even experienced bridge designers and analysts. This paper lists some of the various surprises encountered in bridge testing that may have a significant influence on the load-carrying capacities of bridges. In particular, reference is made to the behavior of bridges with steel girders and concrete deck slabs, and of steel truss bridges. Lessons drawn from tests on these bridges are summarized, so they can provide an advantage in the load-carrying capacity evaluation. It is also shown that in some cases the appearance of a bridge can be misleading with regard to its true load-carrying capacity. In such cases, field testing is shown to be the most effective means of evaluating the bridge.