Steel truss bridges are built by connecting many metal bars into a strong, load-bearing structure. But sometimes, if one part breaks, the damage spreads and causes the whole bridge to collapse. Other times, the bridge stays standing, even with a broken piece. Until now, scientists have not fully understood why.
In a new study, researchers from the Universitat Politècnica de València and the University of Vigo discovered hidden backup systems inside these bridges. These secondary resistance mechanisms help the structure stay strong even after a key part fails.
Their behavior is surprisingly similar to spider webs, which can keep working even after parts are damaged.
José M. Adam, researcher at the ICITECH Institute of the Universitat Politècnica de València, and Coordinator of the Pont3 project that this work forms part of, said, “We have shown that, just as spider webs can adapt and continue to trap prey after suffering damage, damaged steel truss bridges may still be able to withstand loads even greater than those they bear under normal conditions of use and not collapse.”
Engineers have long puzzled over why some steel truss bridges collapse after a small part fails, while others stay standing with barely a hiccup.
Their research reveals that these bridges have secondary resistance mechanisms, like backup systems, that kick in when a primary component fails. Instead of collapsing, the structure adapts and redistributes the load. It’s like a spider web: even when part of it is damaged, the rest keeps working.
These findings open new doors for designing safer, more resilient bridges, improving how we monitor, evaluate, and repair aging infrastructure, and setting new standards for bridge robustness in the face of disasters.
“All this with one fundamental objective: improving the safety of these infrastructures, which are so significant and widespread in transport networks. And the key lies, once again, in Nature; last year, we discovered how to prevent buildings from collapsing in the event of an extreme event by imitating lizards.”
“This time, we have learned from spider webs, whose behavior is similar to steel truss bridges. We have demonstrated this by comparing our work with another study published in Nature in 2012, which focused precisely on spider webs,” concludes José M. Adam.
Journal Reference:
- Juan C. Reyes-Suárez et al, Latent resistance mechanisms of steel truss bridges after critical failures, Nature (2025). DOI: 10.1038/s41586-025-09300-8