Bridges are the vital arteries of our transportation networks, connecting communities and facilitating commerce. However, the way we design and build these structures is undergoing a critical shift. Traditionally, bridge design focused primarily on preventing collapse, with less emphasis on a structure's ability to withstand stress and bounce back from unforeseen events.

This approach is evolving with the introduction of performance-based design (PBD).  PBD takes a more comprehensive view,  incorporating risk analysis to define specific performance objectives for a bridge. These objectives consider not just life safety in the event of a major disaster, but also the bridge's ability to function after a less severe event.

For example, a PBD approach might allow for a bridge to sustain minor damage during an earthquake, but remain structurally sound and operational.  This ensures minimal disruption and allows for swift repairs.  In a more catastrophic event, the focus shifts to preventing complete collapse and ensuring life safety.

The Challenge of Retrofitting Existing Infrastructure

While PBD offers significant advantages for new bridge construction, a major challenge remains: our vast network of existing bridges built before these principles were adopted.  These structures may not meet the same performance standards as those designed using PBD.

Evaluating these older bridges requires a multi-disciplinary approach,  combining expertise in structural engineering with data science and historical analysis.  Careful, site-specific assessments are crucial to determine the level of risk and potential mitigation strategies.  These strategies could range from strengthening existing piers  to complete bridge replacement, depending on the specific structure and its assessed vulnerabilities.

Building a More Resilient Future

The integration of PBD principles into bridge design represents a significant step forward in creating safer and more resilient infrastructure.  However, ensuring the safety of our existing bridges requires a comprehensive approach that acknowledges the challenges of retrofitting older structures.  Investment in assessments, potential retrofits, and even replacements may be necessary to guarantee that our bridges can withstand the future and continue to serve our communities effectively