Equivalent Static Analysis Method for Barge Impact-Resistant Bridge Design

In the United States, barge impact-resistant bridge design typically involves static application of code-prescribed impact loads. However, the existing static analysis procedure neglects crucial dynamic effects in the impacted bridge. Recent experimental and analytical studies have uncovered important impact-related dynamic amplification of pier member demands, primarily stemming from superstructure inertial effects. These studies have focused on the use of dynamic structural analysis as a means of accounting for dynamic amplification. Although time-domain dynamic analysis techniques are capable of accurately predicting amplified member design forces, such techniques may not be warranted during preliminary design iterations when detailed structural parameters have not yet been established. In this paper, a static analysis procedure is developed that emulates pier response modes that arise during dynamic barge impact events. The proposed method provides a simplified means of approximating dynamic amplification effects and is shown to produce conservative predictions (in relation to dynamic analysis) of both pier and foundation design forces.