Dynamic Anomalies in a Modular Bridge Expansion Joint

Environmental noise complaints from homeowners near bridges with modular bridge expansion joints (MBEJs) led to an engineering investigation into the noise production mechanism. The investigation identified modal vibration frequencies in the MBEJ coupling with acoustic resonances in the chamber cast into the bridge abutment below the MBEJ. This initial acoustic investigation was soon overtaken by observations of fatigue induced cracking in structural beams transverse to the direction of traffic. These beams are, in the English-speaking world, universally referred to as center beams. However, in Europe the term lamellae is equally common. A literature search revealed little to describe the structural dynamics behavior of MBEJs but showed that there was an accepted belief dating from around 1973 that the loading was dynamic. In spite of this knowledge many bridge design codes used throughout the world specify a static or quasi-static load case with no mention of the dynamic behavior. This paper identifies t...